/*!

* LESS - Leaner CSS v1.6.3 
* http://lesscss.org 
* 
* Copyright (c) 2009-2014, Alexis Sellier <self@cloudhead.net> 
* Licensed under the Apache v2 License. 
* 
*/ 

/** * @license Apache v2
*/

(function (window, undefined) {// // Stub out ‘require` in the browser // function require(arg) {

return window.less[arg.split('/')[1]];

};

if (typeof(window.less) === ‘undefined’ || typeof(window.less.nodeType) !== ‘undefined’) { window.less = {}; } less = window.less; tree = window.less.tree = {}; less.mode = ‘browser’;

var less, tree;

// Node.js does not have a header file added which defines less if (less === undefined) {

less = exports;
tree = require('./tree');
less.mode = 'node';

} // // less.js - parser // // A relatively straight-forward predictive parser. // There is no tokenization/lexing stage, the input is parsed // in one sweep. // // To make the parser fast enough to run in the browser, several // optimization had to be made: // // - Matching and slicing on a huge input is often cause of slowdowns. // The solution is to chunkify the input into smaller strings. // The chunks are stored in the ‘chunks` var, // `j` holds the current chunk index, and `currentPos` holds // the index of the current chunk in relation to `input`. // This gives us an almost 4x speed-up. // // - In many cases, we don’t need to match individual tokens; // for example, if a value doesn’t hold any variables, operations // or dynamic references, the parser can effectively ‘skip’ it, // treating it as a literal. // An example would be ‘1px solid #000’ - which evaluates to itself, // we don’t need to know what the individual components are. // The drawback, of course is that you don’t get the benefits of // syntax-checking on the CSS. This gives us a 50% speed-up in the parser, // and a smaller speed-up in the code-gen. // // // Token matching is done with the ‘$` function, which either takes // a terminal string or regexp, or a non-terminal function to call. // It also takes care of moving all the indices forwards. // // less.Parser = function Parser(env) {

var input,       // LeSS input string
    i,           // current index in `input`
    j,           // current chunk
    temp,        // temporarily holds a chunk's state, for backtracking
    memo,        // temporarily holds `i`, when backtracking
    furthest,    // furthest index the parser has gone to
    chunks,      // chunkified input
    current,     // current chunk
    currentPos,  // index of current chunk, in `input`
    parser,
    parsers,
    rootFilename = env && env.filename;

// Top parser on an import tree must be sure there is one "env"
// which will then be passed around by reference.
if (!(env instanceof tree.parseEnv)) {
    env = new tree.parseEnv(env);
}

var imports = this.imports = {
    paths: env.paths || [],  // Search paths, when importing
    queue: [],               // Files which haven't been imported yet
    files: env.files,        // Holds the imported parse trees
    contents: env.contents,  // Holds the imported file contents
    contentsIgnoredChars: env.contentsIgnoredChars, // lines inserted, not in the original less
    mime:  env.mime,         // MIME type of .less files
    error: null,             // Error in parsing/evaluating an import
    push: function (path, currentFileInfo, importOptions, callback) {
        var parserImports = this;
        this.queue.push(path);

        var fileParsedFunc = function (e, root, fullPath) {
            parserImports.queue.splice(parserImports.queue.indexOf(path), 1); // Remove the path from the queue

            var importedPreviously = fullPath in parserImports.files || fullPath === rootFilename;

            parserImports.files[fullPath] = root;                        // Store the root

            if (e && !parserImports.error) { parserImports.error = e; }

            callback(e, root, importedPreviously, fullPath);
        };

        if (less.Parser.importer) {
            less.Parser.importer(path, currentFileInfo, fileParsedFunc, env);
        } else {
            less.Parser.fileLoader(path, currentFileInfo, function(e, contents, fullPath, newFileInfo) {
                if (e) {fileParsedFunc(e); return;}

                var newEnv = new tree.parseEnv(env);

                newEnv.currentFileInfo = newFileInfo;
                newEnv.processImports = false;
                newEnv.contents[fullPath] = contents;

                if (currentFileInfo.reference || importOptions.reference) {
                    newFileInfo.reference = true;
                }

                if (importOptions.inline) {
                    fileParsedFunc(null, contents, fullPath);
                } else {
                    new(less.Parser)(newEnv).parse(contents, function (e, root) {
                        fileParsedFunc(e, root, fullPath);
                    });
                }
            }, env);
        }
    }
};

function save()    { temp = current; memo = currentPos = i; }
function restore() { current = temp; currentPos = i = memo; }

function sync() {
    if (i > currentPos) {
        current = current.slice(i - currentPos);
        currentPos = i;
    }
}
function isWhitespace(str, pos) {
    var code = str.charCodeAt(pos | 0);
    return (code <= 32) && (code === 32 || code === 10 || code === 9);
}
//
// Parse from a token, regexp or string, and move forward if match
//
function $(tok) {
    var tokType = typeof tok,
        match, length;

    // Either match a single character in the input,
    // or match a regexp in the current chunk (`current`).
    //
    if (tokType === "string") {
        if (input.charAt(i) !== tok) {
            return null;
        }
        skipWhitespace(1);
        return tok;
    }

    // regexp
    sync ();
    if (! (match = tok.exec(current))) {
        return null;
    }

    length = match[0].length;

    // The match is confirmed, add the match length to `i`,
    // and consume any extra white-space characters (' ' || '\n')
    // which come after that. The reason for this is that LeSS's
    // grammar is mostly white-space insensitive.
    //
    skipWhitespace(length);

    if(typeof(match) === 'string') {
        return match;
    } else {
        return match.length === 1 ? match[0] : match;
    }
}

// Specialization of $(tok)
function $re(tok) {
    if (i > currentPos) {
        current = current.slice(i - currentPos);
        currentPos = i;
    }
    var m = tok.exec(current);
    if (!m) {
        return null;
    }

    skipWhitespace(m[0].length);
    if(typeof m === "string") {
        return m;
    }

    return m.length === 1 ? m[0] : m;
}

var _$re = $re;

// Specialization of $(tok)
function $char(tok) {
    if (input.charAt(i) !== tok) {
        return null;
    }
    skipWhitespace(1);
    return tok;
}

function skipWhitespace(length) {
    var oldi = i, oldj = j,
        curr = i - currentPos,
        endIndex = i + current.length - curr,
        mem = (i += length),
        inp = input,
        c;

    for (; i < endIndex; i++) {
        c = inp.charCodeAt(i);
        if (c > 32) {
            break;
        }

        if ((c !== 32) && (c !== 10) && (c !== 9) && (c !== 13)) {
            break;
        }
     }

    current = current.slice(length + i - mem + curr);
    currentPos = i;

    if (!current.length && (j < chunks.length - 1)) {
        current = chunks[++j];
        skipWhitespace(0); // skip space at the beginning of a chunk
        return true; // things changed
    }

    return oldi !== i || oldj !== j;
}

function expect(arg, msg) {
    // some older browsers return typeof 'function' for RegExp
    var result = (Object.prototype.toString.call(arg) === '[object Function]') ? arg.call(parsers) : $(arg);
    if (result) {
        return result;
    }
    error(msg || (typeof(arg) === 'string' ? "expected '" + arg + "' got '" + input.charAt(i) + "'"
                                           : "unexpected token"));
}

// Specialization of expect()
function expectChar(arg, msg) {
    if (input.charAt(i) === arg) {
        skipWhitespace(1);
        return arg;
    }
    error(msg || "expected '" + arg + "' got '" + input.charAt(i) + "'");
}

function error(msg, type) {
    var e = new Error(msg);
    e.index = i;
    e.type = type || 'Syntax';
    throw e;
}

// Same as $(), but don't change the state of the parser,
// just return the match.
function peek(tok) {
    if (typeof(tok) === 'string') {
        return input.charAt(i) === tok;
    } else {
        return tok.test(current);
    }
}

// Specialization of peek()
function peekChar(tok) {
    return input.charAt(i) === tok;
}

function getInput(e, env) {
    if (e.filename && env.currentFileInfo.filename && (e.filename !== env.currentFileInfo.filename)) {
        return parser.imports.contents[e.filename];
    } else {
        return input;
    }
}

function getLocation(index, inputStream) {
    var n = index + 1,
        line = null,
        column = -1;

    while (--n >= 0 && inputStream.charAt(n) !== '\n') {
        column++;
    }

    if (typeof index === 'number') {
        line = (inputStream.slice(0, index).match(/\n/g) || "").length;
    }

    return {
        line: line,
        column: column
    };
}

function getDebugInfo(index, inputStream, env) {
    var filename = env.currentFileInfo.filename;
    if(less.mode !== 'browser' && less.mode !== 'rhino') {
        filename = require('path').resolve(filename);
    }

    return {
        lineNumber: getLocation(index, inputStream).line + 1,
        fileName: filename
    };
}

function LessError(e, env) {
    var input = getInput(e, env),
        loc = getLocation(e.index, input),
        line = loc.line,
        col  = loc.column,
        callLine = e.call && getLocation(e.call, input).line,
        lines = input.split('\n');

    this.type = e.type || 'Syntax';
    this.message = e.message;
    this.filename = e.filename || env.currentFileInfo.filename;
    this.index = e.index;
    this.line = typeof(line) === 'number' ? line + 1 : null;
    this.callLine = callLine + 1;
    this.callExtract = lines[callLine];
    this.stack = e.stack;
    this.column = col;
    this.extract = [
        lines[line - 1],
        lines[line],
        lines[line + 1]
    ];
}

LessError.prototype = new Error();
LessError.prototype.constructor = LessError;

this.env = env = env || {};

// The optimization level dictates the thoroughness of the parser,
// the lower the number, the less nodes it will create in the tree.
// This could matter for debugging, or if you want to access
// the individual nodes in the tree.
this.optimization = ('optimization' in this.env) ? this.env.optimization : 1;

//
// The Parser
//
parser = {

    imports: imports,
    //
    // Parse an input string into an abstract syntax tree,
    // @param str A string containing 'less' markup
    // @param callback call `callback` when done.
    // @param [additionalData] An optional map which can contains vars - a map (key, value) of variables to apply
    //
    parse: function (str, callback, additionalData) {
        var root, line, lines, error = null, globalVars, modifyVars, preText = "";

        i = j = currentPos = furthest = 0;

        globalVars = (additionalData && additionalData.globalVars) ? less.Parser.serializeVars(additionalData.globalVars) + '\n' : '';
        modifyVars = (additionalData && additionalData.modifyVars) ? '\n' + less.Parser.serializeVars(additionalData.modifyVars) : '';

        if (globalVars || (additionalData && additionalData.banner)) {
            preText = ((additionalData && additionalData.banner) ? additionalData.banner : "") + globalVars;
            parser.imports.contentsIgnoredChars[env.currentFileInfo.filename] = preText.length;
        }

        str = str.replace(/\r\n/g, '\n');
        // Remove potential UTF Byte Order Mark
        input = str = preText + str.replace(/^\uFEFF/, '') + modifyVars;
        parser.imports.contents[env.currentFileInfo.filename] = str;

        // Split the input into chunks.
        chunks = (function (input) {
            var len = input.length, level = 0, parenLevel = 0,
                lastOpening, lastOpeningParen, lastMultiComment, lastMultiCommentEndBrace,
                chunks = [], emitFrom = 0,
                parserCurrentIndex, currentChunkStartIndex, cc, cc2, matched;

            function fail(msg, index) {
                error = new(LessError)({
                    index: index || parserCurrentIndex,
                    type: 'Parse',
                    message: msg,
                    filename: env.currentFileInfo.filename
                }, env);
            }

            function emitChunk(force) {
                var len = parserCurrentIndex - emitFrom;
                if (((len < 512) && !force) || !len) {
                    return;
                }
                chunks.push(input.slice(emitFrom, parserCurrentIndex + 1));
                emitFrom = parserCurrentIndex + 1;
            }

            for (parserCurrentIndex = 0; parserCurrentIndex < len; parserCurrentIndex++) {
                cc = input.charCodeAt(parserCurrentIndex);
                if (((cc >= 97) && (cc <= 122)) || (cc < 34)) {
                    // a-z or whitespace
                    continue;
                }

                switch (cc) {
                    case 40:                        // (
                        parenLevel++; 
                        lastOpeningParen = parserCurrentIndex; 
                        continue;
                    case 41:                        // )
                        if (--parenLevel < 0) {
                            return fail("missing opening `(`");
                        }
                        continue;
                    case 59:                        // ;
                        if (!parenLevel) { emitChunk(); }
                        continue;
                    case 123:                       // {
                        level++; 
                        lastOpening = parserCurrentIndex; 
                        continue;
                    case 125:                       // }
                        if (--level < 0) {
                            return fail("missing opening `{`");
                        }
                        if (!level) { emitChunk(); }
                        continue;
                    case 92:                        // \
                        if (parserCurrentIndex < len - 1) { parserCurrentIndex++; continue; }
                        return fail("unescaped `\\`");
                    case 34:
                    case 39:
                    case 96:                        // ", ' and `
                        matched = 0;
                        currentChunkStartIndex = parserCurrentIndex;
                        for (parserCurrentIndex = parserCurrentIndex + 1; parserCurrentIndex < len; parserCurrentIndex++) {
                            cc2 = input.charCodeAt(parserCurrentIndex);
                            if (cc2 > 96) { continue; }
                            if (cc2 == cc) { matched = 1; break; }
                            if (cc2 == 92) {        // \
                                if (parserCurrentIndex == len - 1) {
                                    return fail("unescaped `\\`");
                                }
                                parserCurrentIndex++;
                            }
                        }
                        if (matched) { continue; }
                        return fail("unmatched `" + String.fromCharCode(cc) + "`", currentChunkStartIndex);
                    case 47:                        // /, check for comment
                        if (parenLevel || (parserCurrentIndex == len - 1)) { continue; }
                        cc2 = input.charCodeAt(parserCurrentIndex + 1);
                        if (cc2 == 47) {
                            // //, find lnfeed
                            for (parserCurrentIndex = parserCurrentIndex + 2; parserCurrentIndex < len; parserCurrentIndex++) {
                                cc2 = input.charCodeAt(parserCurrentIndex);
                                if ((cc2 <= 13) && ((cc2 == 10) || (cc2 == 13))) { break; }
                            }
                        } else if (cc2 == 42) {
                            // /*, find */
                            lastMultiComment = currentChunkStartIndex = parserCurrentIndex;
                            for (parserCurrentIndex = parserCurrentIndex + 2; parserCurrentIndex < len - 1; parserCurrentIndex++) {
                                cc2 = input.charCodeAt(parserCurrentIndex);
                                if (cc2 == 125) { lastMultiCommentEndBrace = parserCurrentIndex; }
                                if (cc2 != 42) { continue; }
                                if (input.charCodeAt(parserCurrentIndex + 1) == 47) { break; }
                            }
                            if (parserCurrentIndex == len - 1) {
                                return fail("missing closing `*/`", currentChunkStartIndex);
                            }
                            parserCurrentIndex++;
                        }
                        continue;
                    case 42:                       // *, check for unmatched */
                        if ((parserCurrentIndex < len - 1) && (input.charCodeAt(parserCurrentIndex + 1) == 47)) {
                            return fail("unmatched `/*`");
                        }
                        continue;
                }
            }

            if (level !== 0) {
                if ((lastMultiComment > lastOpening) && (lastMultiCommentEndBrace > lastMultiComment)) {
                    return fail("missing closing `}` or `*/`", lastOpening);
                } else {
                    return fail("missing closing `}`", lastOpening);
                }
            } else if (parenLevel !== 0) {
                return fail("missing closing `)`", lastOpeningParen);
            }

            emitChunk(true);
            return chunks;
        })(str);

        if (error) {
            return callback(new(LessError)(error, env));
        }

        current = chunks[0];

        // Start with the primary rule.
        // The whole syntax tree is held under a Ruleset node,
        // with the `root` property set to true, so no `{}` are
        // output. The callback is called when the input is parsed.
        try {
            root = new(tree.Ruleset)(null, this.parsers.primary());
            root.root = true;
            root.firstRoot = true;
        } catch (e) {
            return callback(new(LessError)(e, env));
        }

        root.toCSS = (function (evaluate) {
            return function (options, variables) {
                options = options || {};
                var evaldRoot,
                    css,
                    evalEnv = new tree.evalEnv(options);

                //
                // Allows setting variables with a hash, so:
                //
                //   `{ color: new(tree.Color)('#f01') }` will become:
                //
                //   new(tree.Rule)('@color',
                //     new(tree.Value)([
                //       new(tree.Expression)([
                //         new(tree.Color)('#f01')
                //       ])
                //     ])
                //   )
                //
                if (typeof(variables) === 'object' && !Array.isArray(variables)) {
                    variables = Object.keys(variables).map(function (k) {
                        var value = variables[k];

                        if (! (value instanceof tree.Value)) {
                            if (! (value instanceof tree.Expression)) {
                                value = new(tree.Expression)([value]);
                            }
                            value = new(tree.Value)([value]);
                        }
                        return new(tree.Rule)('@' + k, value, false, null, 0);
                    });
                    evalEnv.frames = [new(tree.Ruleset)(null, variables)];
                }

                try {
                    var preEvalVisitors = [],
                        visitors = [
                            new(tree.joinSelectorVisitor)(),
                            new(tree.processExtendsVisitor)(),
                            new(tree.toCSSVisitor)({compress: Boolean(options.compress)})
                        ], i, root = this;

                    if (options.plugins) {
                        for(i =0; i < options.plugins.length; i++) {
                            if (options.plugins[i].isPreEvalVisitor) {
                                preEvalVisitors.push(options.plugins[i]);
                            } else {
                                if (options.plugins[i].isPreVisitor) {
                                    visitors.splice(0, 0, options.plugins[i]);
                                } else {
                                    visitors.push(options.plugins[i]);
                                }
                            }
                        }
                    }

                    for(i = 0; i < preEvalVisitors.length; i++) {
                        preEvalVisitors[i].run(root);
                    }

                    evaldRoot = evaluate.call(root, evalEnv);

                    for(i = 0; i < visitors.length; i++) {
                        visitors[i].run(evaldRoot);
                    }

                    if (options.sourceMap) {
                        evaldRoot = new tree.sourceMapOutput(
                            {
                                contentsIgnoredCharsMap: parser.imports.contentsIgnoredChars,
                                writeSourceMap: options.writeSourceMap,
                                rootNode: evaldRoot,
                                contentsMap: parser.imports.contents,
                                sourceMapFilename: options.sourceMapFilename,
                                sourceMapURL: options.sourceMapURL,
                                outputFilename: options.sourceMapOutputFilename,
                                sourceMapBasepath: options.sourceMapBasepath,
                                sourceMapRootpath: options.sourceMapRootpath,
                                outputSourceFiles: options.outputSourceFiles,
                                sourceMapGenerator: options.sourceMapGenerator
                            });
                    }

                    css = evaldRoot.toCSS({
                            compress: Boolean(options.compress),
                            dumpLineNumbers: env.dumpLineNumbers,
                            strictUnits: Boolean(options.strictUnits),
                            numPrecision: 8});
                } catch (e) {
                    throw new(LessError)(e, env);
                }

                if (options.cleancss && less.mode === 'node') {
                    var CleanCSS = require('clean-css'),
                        cleancssOptions = options.cleancssOptions || {};

                    if (cleancssOptions.keepSpecialComments === undefined) {
                        cleancssOptions.keepSpecialComments = "*";
                    }
                    cleancssOptions.processImport = false;
                    cleancssOptions.noRebase = true;
                    if (cleancssOptions.noAdvanced === undefined) {
                        cleancssOptions.noAdvanced = true;
                    }

                    return new CleanCSS(cleancssOptions).minify(css);
                } else if (options.compress) {
                    return css.replace(/(^(\s)+)|((\s)+$)/g, "");
                } else {
                    return css;
                }
            };
        })(root.eval);

        // If `i` is smaller than the `input.length - 1`,
        // it means the parser wasn't able to parse the whole
        // string, so we've got a parsing error.
        //
        // We try to extract a \n delimited string,
        // showing the line where the parse error occured.
        // We split it up into two parts (the part which parsed,
        // and the part which didn't), so we can color them differently.
        if (i < input.length - 1) {
            i = furthest;
            var loc = getLocation(i, input);
            lines = input.split('\n');
            line = loc.line + 1;

            error = {
                type: "Parse",
                message: "Unrecognised input",
                index: i,
                filename: env.currentFileInfo.filename,
                line: line,
                column: loc.column,
                extract: [
                    lines[line - 2],
                    lines[line - 1],
                    lines[line]
                ]
            };
        }

        var finish = function (e) {
            e = error || e || parser.imports.error;

            if (e) {
                if (!(e instanceof LessError)) {
                    e = new(LessError)(e, env);
                }

                return callback(e);
            }
            else {
                return callback(null, root);
            }
        };

        if (env.processImports !== false) {
            new tree.importVisitor(this.imports, finish)
                .run(root);
        } else {
            return finish();
        }
    },

    //
    // Here in, the parsing rules/functions
    //
    // The basic structure of the syntax tree generated is as follows:
    //
    //   Ruleset ->  Rule -> Value -> Expression -> Entity
    //
    // Here's some LESS code:
    //
    //    .class {
    //      color: #fff;
    //      border: 1px solid #000;
    //      width: @w + 4px;
    //      > .child {...}
    //    }
    //
    // And here's what the parse tree might look like:
    //
    //     Ruleset (Selector '.class', [
    //         Rule ("color",  Value ([Expression [Color #fff]]))
    //         Rule ("border", Value ([Expression [Dimension 1px][Keyword "solid"][Color #000]]))
    //         Rule ("width",  Value ([Expression [Operation "+" [Variable "@w"][Dimension 4px]]]))
    //         Ruleset (Selector [Element '>', '.child'], [...])
    //     ])
    //
    //  In general, most rules will try to parse a token with the `$()` function, and if the return
    //  value is truly, will return a new node, of the relevant type. Sometimes, we need to check
    //  first, before parsing, that's when we use `peek()`.
    //
    parsers: parsers = {
        //
        // The `primary` rule is the *entry* and *exit* point of the parser.
        // The rules here can appear at any level of the parse tree.
        //
        // The recursive nature of the grammar is an interplay between the `block`
        // rule, which represents `{ ... }`, the `ruleset` rule, and this `primary` rule,
        // as represented by this simplified grammar:
        //
        //     primary  →  (ruleset | rule)+
        //     ruleset  →  selector+ block
        //     block    →  '{' primary '}'
        //
        // Only at one point is the primary rule not called from the
        // block rule: at the root level.
        //
        primary: function () {
            var mixin = this.mixin, $re = _$re, root = [], node;

            while (current)
            {
                node = this.extendRule() || mixin.definition() || this.rule() || this.ruleset() ||
                    mixin.call() || this.comment() || this.directive();
                if (node) {
                    root.push(node);
                } else {
                    if (!($re(/^[\s\n]+/) || $re(/^;+/))) {
                        break;
                    }
                }
            }

            return root;
        },

        // We create a Comment node for CSS comments `/* */`,
        // but keep the LeSS comments `//` silent, by just skipping
        // over them.
        comment: function () {
            var comment;

            if (input.charAt(i) !== '/') { return; }

            if (input.charAt(i + 1) === '/') {
                return new(tree.Comment)($re(/^\/\/.*/), true, i, env.currentFileInfo);
            }
            comment = $re(/^\/\*(?:[^*]|\*+[^\/*])*\*+\/\n?/);
            if (comment) {
                return new(tree.Comment)(comment, false, i, env.currentFileInfo);
            }
        },

        comments: function () {
            var comment, comments = [];

            while(true) {
                comment = this.comment();
                if (!comment) {
                    break;
                }
                comments.push(comment);
            }

            return comments;
        },

        //
        // Entities are tokens which can be found inside an Expression
        //
        entities: {
            //
            // A string, which supports escaping " and '
            //
            //     "milky way" 'he\'s the one!'
            //
            quoted: function () {
                var str, j = i, e, index = i;

                if (input.charAt(j) === '~') { j++; e = true; } // Escaped strings
                if (input.charAt(j) !== '"' && input.charAt(j) !== "'") { return; }

                if (e) { $char('~'); }

                str = $re(/^"((?:[^"\\\r\n]|\\.)*)"|'((?:[^'\\\r\n]|\\.)*)'/);
                if (str) {
                    return new(tree.Quoted)(str[0], str[1] || str[2], e, index, env.currentFileInfo);
                }
            },

            //
            // A catch-all word, such as:
            //
            //     black border-collapse
            //
            keyword: function () {
                var k;

                k = $re(/^[_A-Za-z-][_A-Za-z0-9-]*/);
                if (k) {
                    var color = tree.Color.fromKeyword(k);
                    if (color) {
                        return color;
                    }
                    return new(tree.Keyword)(k);
                }
            },

            //
            // A function call
            //
            //     rgb(255, 0, 255)
            //
            // We also try to catch IE's `alpha()`, but let the `alpha` parser
            // deal with the details.
            //
            // The arguments are parsed with the `entities.arguments` parser.
            //
            call: function () {
                var name, nameLC, args, alpha_ret, index = i;

                name = /^([\w-]+|%|progid:[\w\.]+)\(/.exec(current);
                if (!name) { return; }

                name = name[1];
                nameLC = name.toLowerCase();
                if (nameLC === 'url') {
                    return null;
                }

                i += name.length;

                if (nameLC === 'alpha') {
                    alpha_ret = parsers.alpha();
                    if(typeof alpha_ret !== 'undefined') {
                        return alpha_ret;
                    }
                }

                $char('('); // Parse the '(' and consume whitespace.

                args = this.arguments();

                if (! $char(')')) {
                    return;
                }

                if (name) { return new(tree.Call)(name, args, index, env.currentFileInfo); }
            },
            arguments: function () {
                var args = [], arg;

                while (true) {
                    arg = this.assignment() || parsers.expression();
                    if (!arg) {
                        break;
                    }
                    args.push(arg);
                    if (! $char(',')) {
                        break;
                    }
                }
                return args;
            },
            literal: function () {
                return this.dimension() ||
                       this.color() ||
                       this.quoted() ||
                       this.unicodeDescriptor();
            },

            // Assignments are argument entities for calls.
            // They are present in ie filter properties as shown below.
            //
            //     filter: progid:DXImageTransform.Microsoft.Alpha( *opacity=50* )
            //

            assignment: function () {
                var key, value;
                key = $re(/^\w+(?=\s?=)/i);
                if (!key) {
                    return;
                }
                if (!$char('=')) {
                    return;
                }
                value = parsers.entity();
                if (value) {
                    return new(tree.Assignment)(key, value);
                }
            },

            //
            // Parse url() tokens
            //
            // We use a specific rule for urls, because they don't really behave like
            // standard function calls. The difference is that the argument doesn't have
            // to be enclosed within a string, so it can't be parsed as an Expression.
            //
            url: function () {
                var value;

                if (input.charAt(i) !== 'u' || !$re(/^url\(/)) {
                    return;
                }

                value = this.quoted() || this.variable() ||
                        $re(/^(?:(?:\\[\(\)'"])|[^\(\)'"])+/) || "";

                expectChar(')');

                return new(tree.URL)((value.value != null || value instanceof tree.Variable)
                                    ? value : new(tree.Anonymous)(value), env.currentFileInfo);
            },

            //
            // A Variable entity, such as `@fink`, in
            //
            //     width: @fink + 2px
            //
            // We use a different parser for variable definitions,
            // see `parsers.variable`.
            //
            variable: function () {
                var name, index = i;

                if (input.charAt(i) === '@' && (name = $re(/^@@?[\w-]+/))) {
                    return new(tree.Variable)(name, index, env.currentFileInfo);
                }
            },

            // A variable entity useing the protective {} e.g. @{var}
            variableCurly: function () {
                var curly, index = i;

                if (input.charAt(i) === '@' && (curly = $re(/^@\{([\w-]+)\}/))) {
                    return new(tree.Variable)("@" + curly[1], index, env.currentFileInfo);
                }
            },

            //
            // A Hexadecimal color
            //
            //     #4F3C2F
            //
            // `rgb` and `hsl` colors are parsed through the `entities.call` parser.
            //
            color: function () {
                var rgb;

                if (input.charAt(i) === '#' && (rgb = $re(/^#([A-Fa-f0-9]{6}|[A-Fa-f0-9]{3})/))) {
                    return new(tree.Color)(rgb[1]);
                }
            },

            //
            // A Dimension, that is, a number and a unit
            //
            //     0.5em 95%
            //
            dimension: function () {
                var value, c = input.charCodeAt(i);
                //Is the first char of the dimension 0-9, '.', '+' or '-'
                if ((c > 57 || c < 43) || c === 47 || c == 44) {
                    return;
                }

                value = $re(/^([+-]?\d*\.?\d+)(%|[a-z]+)?/);
                if (value) {
                    return new(tree.Dimension)(value[1], value[2]);
                }
            },

            //
            // A unicode descriptor, as is used in unicode-range
            //
            // U+0??  or U+00A1-00A9
            //
            unicodeDescriptor: function () {
                var ud;

                ud = $re(/^U\+[0-9a-fA-F?]+(\-[0-9a-fA-F?]+)?/);
                if (ud) {
                    return new(tree.UnicodeDescriptor)(ud[0]);
                }
            },

            //
            // JavaScript code to be evaluated
            //
            //     `window.location.href`
            //
            javascript: function () {
                var str, j = i, e;

                if (input.charAt(j) === '~') { j++; e = true; } // Escaped strings
                if (input.charAt(j) !== '`') { return; }
                if (env.javascriptEnabled !== undefined && !env.javascriptEnabled) {
                    error("You are using JavaScript, which has been disabled.");
                }

                if (e) { $char('~'); }

                str = $re(/^`([^`]*)`/);
                if (str) {
                    return new(tree.JavaScript)(str[1], i, e);
                }
            }
        },

        //
        // The variable part of a variable definition. Used in the `rule` parser
        //
        //     @fink:
        //
        variable: function () {
            var name;

            if (input.charAt(i) === '@' && (name = $re(/^(@[\w-]+)\s*:/))) { return name[1]; }
        },

        //
        // extend syntax - used to extend selectors
        //
        extend: function(isRule) {
            var elements, e, index = i, option, extendList, extend;

            if (!(isRule ? $re(/^&:extend\(/) : $re(/^:extend\(/))) { return; }

            do {
                option = null;
                elements = null;
                while (! (option = $re(/^(all)(?=\s*(\)|,))/))) {
                    e = this.element();
                    if (!e) { break; }
                    if (elements) { elements.push(e); } else { elements = [ e ]; }
                }

                option = option && option[1];

                extend = new(tree.Extend)(new(tree.Selector)(elements), option, index);
                if (extendList) { extendList.push(extend); } else { extendList = [ extend ]; }

            } while($char(","));

            expect(/^\)/);

            if (isRule) {
                expect(/^;/);
            }

            return extendList;
        },

        //
        // extendRule - used in a rule to extend all the parent selectors
        //
        extendRule: function() {
            return this.extend(true);
        },

        //
        // Mixins
        //
        mixin: {
            //
            // A Mixin call, with an optional argument list
            //
            //     #mixins > .square(#fff);
            //     .rounded(4px, black);
            //     .button;
            //
            // The `while` loop is there because mixins can be
            // namespaced, but we only support the child and descendant
            // selector for now.
            //
            call: function () {
                var s = input.charAt(i), important = false, index = i, elemIndex,
                    elements, elem, e, c, args;

                if (s !== '.' && s !== '#') { return; }

                save(); // stop us absorbing part of an invalid selector

                while (true) {
                    elemIndex = i;
                    e = $re(/^[#.](?:[\w-]|\\(?:[A-Fa-f0-9]{1,6} ?|[^A-Fa-f0-9]))+/);
                    if (!e) {
                        break;
                    }
                    elem = new(tree.Element)(c, e, elemIndex, env.currentFileInfo);
                    if (elements) { elements.push(elem); } else { elements = [ elem ]; }
                    c = $char('>');
                }

                if (elements) {
                    if ($char('(')) {
                        args = this.args(true).args;
                        expectChar(')');
                    }

                    if (parsers.important()) {
                        important = true;
                    }

                    if (parsers.end()) {
                        return new(tree.mixin.Call)(elements, args, index, env.currentFileInfo, important);
                    }
                }

                restore();
            },
            args: function (isCall) {
                var parsers = parser.parsers, entities = parsers.entities,
                    returner = { args:null, variadic: false },
                    expressions = [], argsSemiColon = [], argsComma = [],
                    isSemiColonSeperated, expressionContainsNamed, name, nameLoop, value, arg;

                while (true) {
                    if (isCall) {
                        arg = parsers.expression();
                    } else {
                        parsers.comments();
                        if (input.charAt(i) === '.' && $re(/^\.{3}/)) {
                            returner.variadic = true;
                            if ($char(";") && !isSemiColonSeperated) {
                                isSemiColonSeperated = true;
                            }
                            (isSemiColonSeperated ? argsSemiColon : argsComma)
                                .push({ variadic: true });
                            break;
                        }
                        arg = entities.variable() || entities.literal() || entities.keyword();
                    }

                    if (!arg) {
                        break;
                    }

                    nameLoop = null;
                    if (arg.throwAwayComments) {
                        arg.throwAwayComments();
                    }
                    value = arg;
                    var val = null;

                    if (isCall) {
                        // Variable
                        if (arg.value.length == 1) {
                            val = arg.value[0];
                        }
                    } else {
                        val = arg;
                    }

                    if (val && val instanceof tree.Variable) {
                        if ($char(':')) {
                            if (expressions.length > 0) {
                                if (isSemiColonSeperated) {
                                    error("Cannot mix ; and , as delimiter types");
                                }
                                expressionContainsNamed = true;
                            }
                            value = expect(parsers.expression);
                            nameLoop = (name = val.name);
                        } else if (!isCall && $re(/^\.{3}/)) {
                            returner.variadic = true;
                            if ($char(";") && !isSemiColonSeperated) {
                                isSemiColonSeperated = true;
                            }
                            (isSemiColonSeperated ? argsSemiColon : argsComma)
                                .push({ name: arg.name, variadic: true });
                            break;
                        } else if (!isCall) {
                            name = nameLoop = val.name;
                            value = null;
                        }
                    }

                    if (value) {
                        expressions.push(value);
                    }

                    argsComma.push({ name:nameLoop, value:value });

                    if ($char(',')) {
                        continue;
                    }

                    if ($char(';') || isSemiColonSeperated) {

                        if (expressionContainsNamed) {
                            error("Cannot mix ; and , as delimiter types");
                        }

                        isSemiColonSeperated = true;

                        if (expressions.length > 1) {
                            value = new(tree.Value)(expressions);
                        }
                        argsSemiColon.push({ name:name, value:value });

                        name = null;
                        expressions = [];
                        expressionContainsNamed = false;
                    }
                }

                returner.args = isSemiColonSeperated ? argsSemiColon : argsComma;
                return returner;
            },
            //
            // A Mixin definition, with a list of parameters
            //
            //     .rounded (@radius: 2px, @color) {
            //        ...
            //     }
            //
            // Until we have a finer grained state-machine, we have to
            // do a look-ahead, to make sure we don't have a mixin call.
            // See the `rule` function for more information.
            //
            // We start by matching `.rounded (`, and then proceed on to
            // the argument list, which has optional default values.
            // We store the parameters in `params`, with a `value` key,
            // if there is a value, such as in the case of `@radius`.
            //
            // Once we've got our params list, and a closing `)`, we parse
            // the `{...}` block.
            //
            definition: function () {
                var name, params = [], match, ruleset, cond, variadic = false;
                if ((input.charAt(i) !== '.' && input.charAt(i) !== '#') ||
                    peek(/^[^{]*\}/)) {
                    return;
                }

                save();

                match = $re(/^([#.](?:[\w-]|\\(?:[A-Fa-f0-9]{1,6} ?|[^A-Fa-f0-9]))+)\s*\(/);
                if (match) {
                    name = match[1];

                    var argInfo = this.args(false);
                    params = argInfo.args;
                    variadic = argInfo.variadic;

                    // .mixincall("@{a}");
                    // looks a bit like a mixin definition.. so we have to be nice and restore
                    if (!$char(')')) {
                        furthest = i;
                        restore();
                    }

                    parsers.comments();

                    if ($re(/^when/)) { // Guard
                        cond = expect(parsers.conditions, 'expected condition');
                    }

                    ruleset = parsers.block();

                    if (ruleset) {
                        return new(tree.mixin.Definition)(name, params, ruleset, cond, variadic);
                    } else {
                        restore();
                    }
                }
            }
        },

        //
        // Entities are the smallest recognized token,
        // and can be found inside a rule's value.
        //
        entity: function () {
            var entities = this.entities;

            return entities.literal() || entities.variable() || entities.url() ||
                   entities.call()    || entities.keyword()  || entities.javascript() ||
                   this.comment();
        },

        //
        // A Rule terminator. Note that we use `peek()` to check for '}',
        // because the `block` rule will be expecting it, but we still need to make sure
        // it's there, if ';' was ommitted.
        //
        end: function () {
            return $char(';') || peekChar('}');
        },

        //
        // IE's alpha function
        //
        //     alpha(opacity=88)
        //
        alpha: function () {
            var value;

            if (! $re(/^\(opacity=/i)) { return; }
            value = $re(/^\d+/) || this.entities.variable();
            if (value) {
                expectChar(')');
                return new(tree.Alpha)(value);
            }
        },

        //
        // A Selector Element
        //
        //     div
        //     + h1
        //     #socks
        //     input[type="text"]
        //
        // Elements are the building blocks for Selectors,
        // they are made out of a `Combinator` (see combinator rule),
        // and an element name, such as a tag a class, or `*`.
        //
        element: function () {
            var e, c, v, index = i;

            c = this.combinator();

            e = $re(/^(?:\d+\.\d+|\d+)%/) || $re(/^(?:[.#]?|:*)(?:[\w-]|[^\x00-\x9f]|\\(?:[A-Fa-f0-9]{1,6} ?|[^A-Fa-f0-9]))+/) ||
                $char('*') || $char('&') || this.attribute() || $re(/^\([^()@]+\)/) || $re(/^[\.#](?=@)/) ||
                this.entities.variableCurly();

            if (! e) {
                if ($char('(')) {
                    if ((v = this.selector()) && $char(')')) {
                        e = new(tree.Paren)(v);
                    }
                }
            }

            if (e) { return new(tree.Element)(c, e, index, env.currentFileInfo); }
        },

        //
        // Combinators combine elements together, in a Selector.
        //
        // Because our parser isn't white-space sensitive, special care
        // has to be taken, when parsing the descendant combinator, ` `,
        // as it's an empty space. We have to check the previous character
        // in the input, to see if it's a ` ` character. More info on how
        // we deal with this in *combinator.js*.
        //
        combinator: function () {
            var c = input.charAt(i);

            if (c === '>' || c === '+' || c === '~' || c === '|' || c === '^') {
                i++;
                if (input.charAt(i) === '^') {
                    c = '^^';
                    i++;
                }
                while (isWhitespace(input, i)) { i++; }
                return new(tree.Combinator)(c);
            } else if (isWhitespace(input, i - 1)) {
                return new(tree.Combinator)(" ");
            } else {
                return new(tree.Combinator)(null);
            }
        },
        //
        // A CSS selector (see selector below)
        // with less extensions e.g. the ability to extend and guard
        //
        lessSelector: function () {
            return this.selector(true);
        },
        //
        // A CSS Selector
        //
        //     .class > div + h1
        //     li a:hover
        //
        // Selectors are made out of one or more Elements, see above.
        //
        selector: function (isLess) {
            var index = i, $re = _$re, elements, extendList, c, e, extend, when, condition;

            while ((isLess && (extend = this.extend())) || (isLess && (when = $re(/^when/))) || (e = this.element())) {
                if (when) {
                    condition = expect(this.conditions, 'expected condition');
                } else if (condition) {
                    error("CSS guard can only be used at the end of selector");
                } else if (extend) {
                    if (extendList) { extendList.push(extend); } else { extendList = [ extend ]; }
                } else {
                    if (extendList) { error("Extend can only be used at the end of selector"); }
                    c = input.charAt(i);
                    if (elements) { elements.push(e); } else { elements = [ e ]; }
                    e = null;
                }
                if (c === '{' || c === '}' || c === ';' || c === ',' || c === ')') {
                    break;
                }
            }

            if (elements) { return new(tree.Selector)(elements, extendList, condition, index, env.currentFileInfo); }
            if (extendList) { error("Extend must be used to extend a selector, it cannot be used on its own"); }
        },
        attribute: function () {
            if (! $char('[')) { return; }

            var entities = this.entities,
                key, val, op;

            if (!(key = entities.variableCurly())) {
                key = expect(/^(?:[_A-Za-z0-9-\*]*\|)?(?:[_A-Za-z0-9-]|\\.)+/);
            }

            op = $re(/^[|~*$^]?=/);
            if (op) {
                val = entities.quoted() || $re(/^[0-9]+%/) || $re(/^[\w-]+/) || entities.variableCurly();
            }

            expectChar(']');

            return new(tree.Attribute)(key, op, val);
        },

        //
        // The `block` rule is used by `ruleset` and `mixin.definition`.
        // It's a wrapper around the `primary` rule, with added `{}`.
        //
        block: function () {
            var content;
            if ($char('{') && (content = this.primary()) && $char('}')) {
                return content;
            }
        },

        //
        // div, .class, body > p {...}
        //
        ruleset: function () {
            var selectors, s, rules, debugInfo;

            save();

            if (env.dumpLineNumbers) {
                debugInfo = getDebugInfo(i, input, env);
            }

            while (true) {
                s = this.lessSelector();
                if (!s) {
                    break;
                }
                if (selectors) { selectors.push(s); } else { selectors = [ s ]; }
                this.comments();
                if (s.condition && selectors.length > 1) {
                    error("Guards are only currently allowed on a single selector.");
                }
                if (! $char(',')) { break; }
                if (s.condition) {
                    error("Guards are only currently allowed on a single selector.");
                }
                this.comments();
            }

            if (selectors && (rules = this.block())) {
                var ruleset = new(tree.Ruleset)(selectors, rules, env.strictImports);
                if (env.dumpLineNumbers) {
                    ruleset.debugInfo = debugInfo;
                }
                return ruleset;
            } else {
                // Backtrack
                furthest = i;
                restore();
            }
        },
        rule: function (tryAnonymous) {
            var name, value, c = input.charAt(i), important, merge = false;
            save();

            if (c === '.' || c === '#' || c === '&') { return; }

            name = this.variable() || this.ruleProperty();
            if (name) {
                // prefer to try to parse first if its a variable or we are compressing
                // but always fallback on the other one
                value = !tryAnonymous && (env.compress || (name.charAt && (name.charAt(0) === '@'))) ?
                    (this.value() || this.anonymousValue()) :
                    (this.anonymousValue() || this.value());

                important = this.important();

                // a name returned by this.ruleProperty() is always an array of the form:
                // [string-1, ..., string-n, ""] or [string-1, ..., string-n, "+"]
                // where each item is a tree.Keyword or tree.Variable
                merge = name.pop && (name.pop().value === "+");

                if (value && this.end()) {
                    return new (tree.Rule)(name, value, important, merge, memo, env.currentFileInfo);
                } else {
                    furthest = i;
                    restore();
                    if (value && !tryAnonymous) {
                        return this.rule(true);
                    }
                }
            }
        },
        anonymousValue: function () {
            var match;
            match = /^([^@+\/'"*`(;{}-]*);/.exec(current);
            if (match) {
                i += match[0].length - 1;
                return new(tree.Anonymous)(match[1]);
            }
        },

        //
        // An @import directive
        //
        //     @import "lib";
        //
        // Depending on our environemnt, importing is done differently:
        // In the browser, it's an XHR request, in Node, it would be a
        // file-system operation. The function used for importing is
        // stored in `import`, which we pass to the Import constructor.
        //
        "import": function () {
            var path, features, index = i;

            save();

            var dir = $re(/^@import?\s+/);

            var options = (dir ? this.importOptions() : null) || {};

            if (dir && (path = this.entities.quoted() || this.entities.url())) {
                features = this.mediaFeatures();
                if ($char(';')) {
                    features = features && new(tree.Value)(features);
                    return new(tree.Import)(path, features, options, index, env.currentFileInfo);
                }
            }

            restore();
        },

        importOptions: function() {
            var o, options = {}, optionName, value;

            // list of options, surrounded by parens
            if (! $char('(')) { return null; }
            do {
                o = this.importOption();
                if (o) {
                    optionName = o;
                    value = true;
                    switch(optionName) {
                        case "css":
                            optionName = "less";
                            value = false;
                        break;
                        case "once":
                            optionName = "multiple";
                            value = false;
                        break;
                    }
                    options[optionName] = value;
                    if (! $char(',')) { break; }
                }
            } while (o);
            expectChar(')');
            return options;
        },

        importOption: function() {
            var opt = $re(/^(less|css|multiple|once|inline|reference)/);
            if (opt) {
                return opt[1];
            }
        },

        mediaFeature: function () {
            var entities = this.entities, nodes = [], e, p;
            do {
                e = entities.keyword() || entities.variable();
                if (e) {
                    nodes.push(e);
                } else if ($char('(')) {
                    p = this.property();
                    e = this.value();
                    if ($char(')')) {
                        if (p && e) {
                            nodes.push(new(tree.Paren)(new(tree.Rule)(p, e, null, null, i, env.currentFileInfo, true)));
                        } else if (e) {
                            nodes.push(new(tree.Paren)(e));
                        } else {
                            return null;
                        }
                    } else { return null; }
                }
            } while (e);

            if (nodes.length > 0) {
                return new(tree.Expression)(nodes);
            }
        },

        mediaFeatures: function () {
            var entities = this.entities, features = [], e;
            do {
                e = this.mediaFeature();
                if (e) {
                    features.push(e);
                    if (! $char(',')) { break; }
                } else {
                    e = entities.variable();
                    if (e) {
                        features.push(e);
                        if (! $char(',')) { break; }
                    }
                }
            } while (e);

            return features.length > 0 ? features : null;
        },

        media: function () {
            var features, rules, media, debugInfo;

            if (env.dumpLineNumbers) {
                debugInfo = getDebugInfo(i, input, env);
            }

            if ($re(/^@media/)) {
                features = this.mediaFeatures();

                rules = this.block();
                if (rules) {
                    media = new(tree.Media)(rules, features, i, env.currentFileInfo);
                    if (env.dumpLineNumbers) {
                        media.debugInfo = debugInfo;
                    }
                    return media;
                }
            }
        },

        //
        // A CSS Directive
        //
        //     @charset "utf-8";
        //
        directive: function () {
            var index = i, name, value, rules, nonVendorSpecificName,
                hasBlock, hasIdentifier, hasExpression, identifier;

            if (input.charAt(i) !== '@') { return; }

            value = this['import']() || this.media();
            if (value) {
                return value;
            }

            save();

            name = $re(/^@[a-z-]+/);

            if (!name) { return; }

            nonVendorSpecificName = name;
            if (name.charAt(1) == '-' && name.indexOf('-', 2) > 0) {
                nonVendorSpecificName = "@" + name.slice(name.indexOf('-', 2) + 1);
            }

            switch(nonVendorSpecificName) {
                case "@font-face":
                    hasBlock = true;
                    break;
                case "@viewport":
                case "@top-left":
                case "@top-left-corner":
                case "@top-center":
                case "@top-right":
                case "@top-right-corner":
                case "@bottom-left":
                case "@bottom-left-corner":
                case "@bottom-center":
                case "@bottom-right":
                case "@bottom-right-corner":
                case "@left-top":
                case "@left-middle":
                case "@left-bottom":
                case "@right-top":
                case "@right-middle":
                case "@right-bottom":
                    hasBlock = true;
                    break;
                case "@host":
                case "@page":
                case "@document":
                case "@supports":
                case "@keyframes":
                    hasBlock = true;
                    hasIdentifier = true;
                    break;
                case "@namespace":
                    hasExpression = true;
                    break;
            }

            if (hasIdentifier) {
                identifier = ($re(/^[^{]+/) || '').trim();
                if (identifier) {
                    name += " " + identifier;
                }
            }

            if (hasBlock) {
                rules = this.block();
                if (rules) {
                    return new(tree.Directive)(name, rules, index, env.currentFileInfo);
                }
            } else {
                value = hasExpression ? this.expression() : this.entity();
                if (value && $char(';')) {
                    var directive = new(tree.Directive)(name, value, index, env.currentFileInfo);
                    if (env.dumpLineNumbers) {
                        directive.debugInfo = getDebugInfo(i, input, env);
                    }
                    return directive;
                }
            }

            restore();
        },

        //
        // A Value is a comma-delimited list of Expressions
        //
        //     font-family: Baskerville, Georgia, serif;
        //
        // In a Rule, a Value represents everything after the `:`,
        // and before the `;`.
        //
        value: function () {
            var e, expressions = [];

            do {
                e = this.expression();
                if (e) {
                    expressions.push(e);
                    if (! $char(',')) { break; }
                }
            } while(e);

            if (expressions.length > 0) {
                return new(tree.Value)(expressions);
            }
        },
        important: function () {
            if (input.charAt(i) === '!') {
                return $re(/^! *important/);
            }
        },
        sub: function () {
            var a, e;

            if ($char('(')) {
                a = this.addition();
                if (a) {
                    e = new(tree.Expression)([a]);
                    expectChar(')');
                    e.parens = true;
                    return e;
                }
            }
        },
        multiplication: function () {
            var m, a, op, operation, isSpaced;
            m = this.operand();
            if (m) {
                isSpaced = isWhitespace(input, i - 1);
                while (true) {
                    if (peek(/^\/[*\/]/)) {
                        break;
                    }
                    op = $char('/') || $char('*');

                    if (!op) { break; }

                    a = this.operand();

                    if (!a) { break; }

                    m.parensInOp = true;
                    a.parensInOp = true;
                    operation = new(tree.Operation)(op, [operation || m, a], isSpaced);
                    isSpaced = isWhitespace(input, i - 1);
                }
                return operation || m;
            }
        },
        addition: function () {
            var m, a, op, operation, isSpaced;
            m = this.multiplication();
            if (m) {
                isSpaced = isWhitespace(input, i - 1);
                while (true) {
                    op = $re(/^[-+]\s+/) || (!isSpaced && ($char('+') || $char('-')));
                    if (!op) {
                        break;
                    }
                    a = this.multiplication();
                    if (!a) {
                        break;
                    }

                    m.parensInOp = true;
                    a.parensInOp = true;
                    operation = new(tree.Operation)(op, [operation || m, a], isSpaced);
                    isSpaced = isWhitespace(input, i - 1);
                }
                return operation || m;
            }
        },
        conditions: function () {
            var a, b, index = i, condition;

            a = this.condition();
            if (a) {
                while (true) {
                    if (!peek(/^,\s*(not\s*)?\(/) || !$char(',')) {
                        break;
                    }
                    b = this.condition();
                    if (!b) {
                        break;
                    }
                    condition = new(tree.Condition)('or', condition || a, b, index);
                }
                return condition || a;
            }
        },
        condition: function () {
            var entities = this.entities, index = i, negate = false,
                a, b, c, op;

            if ($re(/^not/)) { negate = true; }
            expectChar('(');
            a = this.addition() || entities.keyword() || entities.quoted();
            if (a) {
                op = $re(/^(?:>=|<=|=<|[<=>])/);
                if (op) {
                    b = this.addition() || entities.keyword() || entities.quoted();
                    if (b) {
                        c = new(tree.Condition)(op, a, b, index, negate);
                    } else {
                        error('expected expression');
                    }
                } else {
                    c = new(tree.Condition)('=', a, new(tree.Keyword)('true'), index, negate);
                }
                expectChar(')');
                return $re(/^and/) ? new(tree.Condition)('and', c, this.condition()) : c;
            }
        },

        //
        // An operand is anything that can be part of an operation,
        // such as a Color, or a Variable
        //
        operand: function () {
            var entities = this.entities,
                p = input.charAt(i + 1), negate;

            if (input.charAt(i) === '-' && (p === '@' || p === '(')) { negate = $char('-'); }
            var o = this.sub() || entities.dimension() ||
                    entities.color() || entities.variable() ||
                    entities.call();

            if (negate) {
                o.parensInOp = true;
                o = new(tree.Negative)(o);
            }

            return o;
        },

        //
        // Expressions either represent mathematical operations,
        // or white-space delimited Entities.
        //
        //     1px solid black
        //     @var * 2
        //
        expression: function () {
            var entities = [], e, delim;

            do {
                e = this.addition() || this.entity();
                if (e) {
                    entities.push(e);
                    // operations do not allow keyword "/" dimension (e.g. small/20px) so we support that here
                    if (!peek(/^\/[\/*]/)) {
                        delim = $char('/');
                        if (delim) {
                            entities.push(new(tree.Anonymous)(delim));
                        }
                    }
                }
            } while (e);
            if (entities.length > 0) {
                return new(tree.Expression)(entities);
            }
        },
        property: function () {
            var name = $re(/^(\*?-?[_a-zA-Z0-9-]+)\s*:/);
            if (name) {
                return name[1];
            }
        },
        ruleProperty: function () {
            var c = current, name = [], index = [], length = 0, s, k;

            function match(re) {
                var a = re.exec(c);
                if (a) {
                    index.push(i + length);
                    length += a[0].length;
                    c = c.slice(a[1].length);
                    return name.push(a[1]);
                }
            }

            match(/^(\*?)/);
            while (match(/^((?:[\w-]+)|(?:@\{[\w-]+\}))/)); // !
            if ((name.length > 1) && match(/^\s*(\+?)\s*:/)) {
                // at last, we have the complete match now. move forward, 
                // convert name particles to tree objects and return:
                skipWhitespace(length);
                if (name[0] === '') {
                    name.shift();
                    index.shift();
                }
                for (k = 0; k < name.length; k++) {
                    s = name[k];
                    name[k] = (s.charAt(0) !== '@')
                        ? new(tree.Keyword)(s)
                        : new(tree.Variable)('@' + s.slice(2, -1), 
                            index[k], env.currentFileInfo);
                }
                return name;
            }
        }
    }
};
return parser;

}; less.Parser.serializeVars = function(vars) {

var s = '';

for (var name in vars) {
    if (Object.hasOwnProperty.call(vars, name)) {
        var value = vars[name];
        s += ((name[0] === '@') ? '' : '@') + name +': '+ value +
                ((('' + value).slice(-1) === ';') ? '' : ';');
    }
}

return s;

};

(function (tree) {

tree.functions = {

rgb: function (r, g, b) {
    return this.rgba(r, g, b, 1.0);
},
rgba: function (r, g, b, a) {
    var rgb = [r, g, b].map(function (c) { return scaled(c, 255); });
    a = number(a);
    return new(tree.Color)(rgb, a);
},
hsl: function (h, s, l) {
    return this.hsla(h, s, l, 1.0);
},
hsla: function (h, s, l, a) {
    function hue(h) {
        h = h < 0 ? h + 1 : (h > 1 ? h - 1 : h);
        if      (h * 6 < 1) { return m1 + (m2 - m1) * h * 6; }
        else if (h * 2 < 1) { return m2; }
        else if (h * 3 < 2) { return m1 + (m2 - m1) * (2/3 - h) * 6; }
        else                { return m1; }
    }

    h = (number(h) % 360) / 360;
    s = clamp(number(s)); l = clamp(number(l)); a = clamp(number(a));

    var m2 = l <= 0.5 ? l * (s + 1) : l + s - l * s;
    var m1 = l * 2 - m2;

    return this.rgba(hue(h + 1/3) * 255,
                     hue(h)       * 255,
                     hue(h - 1/3) * 255,
                     a);
},

hsv: function(h, s, v) {
    return this.hsva(h, s, v, 1.0);
},

hsva: function(h, s, v, a) {
    h = ((number(h) % 360) / 360) * 360;
    s = number(s); v = number(v); a = number(a);

    var i, f;
    i = Math.floor((h / 60) % 6);
    f = (h / 60) - i;

    var vs = [v,
              v * (1 - s),
              v * (1 - f * s),
              v * (1 - (1 - f) * s)];
    var perm = [[0, 3, 1],
                [2, 0, 1],
                [1, 0, 3],
                [1, 2, 0],
                [3, 1, 0],
                [0, 1, 2]];

    return this.rgba(vs[perm[i][0]] * 255,
                     vs[perm[i][1]] * 255,
                     vs[perm[i][2]] * 255,
                     a);
},

hue: function (color) {
    return new(tree.Dimension)(Math.round(color.toHSL().h));
},
saturation: function (color) {
    return new(tree.Dimension)(Math.round(color.toHSL().s * 100), '%');
},
lightness: function (color) {
    return new(tree.Dimension)(Math.round(color.toHSL().l * 100), '%');
},
hsvhue: function(color) {
    return new(tree.Dimension)(Math.round(color.toHSV().h));
},
hsvsaturation: function (color) {
    return new(tree.Dimension)(Math.round(color.toHSV().s * 100), '%');
},
hsvvalue: function (color) {
    return new(tree.Dimension)(Math.round(color.toHSV().v * 100), '%');
},
red: function (color) {
    return new(tree.Dimension)(color.rgb[0]);
},
green: function (color) {
    return new(tree.Dimension)(color.rgb[1]);
},
blue: function (color) {
    return new(tree.Dimension)(color.rgb[2]);
},
alpha: function (color) {
    return new(tree.Dimension)(color.toHSL().a);
},
luma: function (color) {
    return new(tree.Dimension)(Math.round(color.luma() * color.alpha * 100), '%');
},
saturate: function (color, amount) {
    // filter: saturate(3.2);
    // should be kept as is, so check for color
    if (!color.rgb) {
        return null;
    }
    var hsl = color.toHSL();

    hsl.s += amount.value / 100;
    hsl.s = clamp(hsl.s);
    return hsla(hsl);
},
desaturate: function (color, amount) {
    var hsl = color.toHSL();

    hsl.s -= amount.value / 100;
    hsl.s = clamp(hsl.s);
    return hsla(hsl);
},
lighten: function (color, amount) {
    var hsl = color.toHSL();

    hsl.l += amount.value / 100;
    hsl.l = clamp(hsl.l);
    return hsla(hsl);
},
darken: function (color, amount) {
    var hsl = color.toHSL();

    hsl.l -= amount.value / 100;
    hsl.l = clamp(hsl.l);
    return hsla(hsl);
},
fadein: function (color, amount) {
    var hsl = color.toHSL();

    hsl.a += amount.value / 100;
    hsl.a = clamp(hsl.a);
    return hsla(hsl);
},
fadeout: function (color, amount) {
    var hsl = color.toHSL();

    hsl.a -= amount.value / 100;
    hsl.a = clamp(hsl.a);
    return hsla(hsl);
},
fade: function (color, amount) {
    var hsl = color.toHSL();

    hsl.a = amount.value / 100;
    hsl.a = clamp(hsl.a);
    return hsla(hsl);
},
spin: function (color, amount) {
    var hsl = color.toHSL();
    var hue = (hsl.h + amount.value) % 360;

    hsl.h = hue < 0 ? 360 + hue : hue;

    return hsla(hsl);
},
//
// Copyright (c) 2006-2009 Hampton Catlin, Nathan Weizenbaum, and Chris Eppstein
// http://sass-lang.com
//
mix: function (color1, color2, weight) {
    if (!weight) {
        weight = new(tree.Dimension)(50);
    }
    var p = weight.value / 100.0;
    var w = p * 2 - 1;
    var a = color1.toHSL().a - color2.toHSL().a;

    var w1 = (((w * a == -1) ? w : (w + a) / (1 + w * a)) + 1) / 2.0;
    var w2 = 1 - w1;

    var rgb = [color1.rgb[0] * w1 + color2.rgb[0] * w2,
               color1.rgb[1] * w1 + color2.rgb[1] * w2,
               color1.rgb[2] * w1 + color2.rgb[2] * w2];

    var alpha = color1.alpha * p + color2.alpha * (1 - p);

    return new(tree.Color)(rgb, alpha);
},
greyscale: function (color) {
    return this.desaturate(color, new(tree.Dimension)(100));
},
contrast: function (color, dark, light, threshold) {
    // filter: contrast(3.2);
    // should be kept as is, so check for color
    if (!color.rgb) {
        return null;
    }
    if (typeof light === 'undefined') {
        light = this.rgba(255, 255, 255, 1.0);
    }
    if (typeof dark === 'undefined') {
        dark = this.rgba(0, 0, 0, 1.0);
    }
    //Figure out which is actually light and dark!
    if (dark.luma() > light.luma()) {
        var t = light;
        light = dark;
        dark = t;
    }
    if (typeof threshold === 'undefined') {
        threshold = 0.43;
    } else {
        threshold = number(threshold);
    }
    if (color.luma() < threshold) {
        return light;
    } else {
        return dark;
    }
},
e: function (str) {
    return new(tree.Anonymous)(str instanceof tree.JavaScript ? str.evaluated : str);
},
escape: function (str) {
    return new(tree.Anonymous)(encodeURI(str.value).replace(/=/g, "%3D").replace(/:/g, "%3A").replace(/#/g, "%23").replace(/;/g, "%3B").replace(/\(/g, "%28").replace(/\)/g, "%29"));
},
'%': function (quoted /* arg, arg, ...*/) {
    var args = Array.prototype.slice.call(arguments, 1),
        str = quoted.value;

    for (var i = 0; i < args.length; i++) {
        /*jshint loopfunc:true */
        str = str.replace(/%[sda]/i, function(token) {
            var value = token.match(/s/i) ? args[i].value : args[i].toCSS();
            return token.match(/[A-Z]$/) ? encodeURIComponent(value) : value;
        });
    }
    str = str.replace(/%%/g, '%');
    return new(tree.Quoted)('"' + str + '"', str);
},
unit: function (val, unit) {
    if(!(val instanceof tree.Dimension)) {
        throw { type: "Argument", message: "the first argument to unit must be a number" + (val instanceof tree.Operation ? ". Have you forgotten parenthesis?" : "") };
    }
    return new(tree.Dimension)(val.value, unit ? unit.toCSS() : "");
},
convert: function (val, unit) {
    return val.convertTo(unit.value);
},
round: function (n, f) {
    var fraction = typeof(f) === "undefined" ? 0 : f.value;
    return _math(function(num) { return num.toFixed(fraction); }, null, n);
},
pi: function () {
    return new(tree.Dimension)(Math.PI);
},
mod: function(a, b) {
    return new(tree.Dimension)(a.value % b.value, a.unit);
},
pow: function(x, y) {
    if (typeof x === "number" && typeof y === "number") {
        x = new(tree.Dimension)(x);
        y = new(tree.Dimension)(y);
    } else if (!(x instanceof tree.Dimension) || !(y instanceof tree.Dimension)) {
        throw { type: "Argument", message: "arguments must be numbers" };
    }

    return new(tree.Dimension)(Math.pow(x.value, y.value), x.unit);
},
_minmax: function (isMin, args) {
    args = Array.prototype.slice.call(args);
    switch(args.length) {
    case 0: throw { type: "Argument", message: "one or more arguments required" };
    case 1: return args[0];
    }
    var i, j, current, currentUnified, referenceUnified, unit,
        order  = [], // elems only contains original argument values.
        values = {}; // key is the unit.toString() for unified tree.Dimension values,
                     // value is the index into the order array.
    for (i = 0; i < args.length; i++) {
        current = args[i];
        if (!(current instanceof tree.Dimension)) {
            order.push(current);
            continue;
        }
        currentUnified = current.unify();
        unit = currentUnified.unit.toString();
        j = values[unit];
        if (j === undefined) {
            values[unit] = order.length;
            order.push(current);
            continue;
        }
        referenceUnified = order[j].unify();
        if ( isMin && currentUnified.value < referenceUnified.value ||
            !isMin && currentUnified.value > referenceUnified.value) {
            order[j] = current;
        }
    }
    if (order.length == 1) {
        return order[0];
    }
    args = order.map(function (a) { return a.toCSS(this.env); })
                .join(this.env.compress ? "," : ", ");
    return new(tree.Anonymous)((isMin ? "min" : "max") + "(" + args + ")");
},
min: function () {
    return this._minmax(true, arguments);
},
max: function () {
    return this._minmax(false, arguments);
},
argb: function (color) {
    return new(tree.Anonymous)(color.toARGB());
},
percentage: function (n) {
    return new(tree.Dimension)(n.value * 100, '%');
},
color: function (n) {
    if (n instanceof tree.Quoted) {
        var colorCandidate = n.value,
            returnColor;
        returnColor = tree.Color.fromKeyword(colorCandidate);
        if (returnColor) {
            return returnColor;
        }
        if (/^#([A-Fa-f0-9]{6}|[A-Fa-f0-9]{3})/.test(colorCandidate)) {
            return new(tree.Color)(colorCandidate.slice(1));
        }
        throw { type: "Argument", message: "argument must be a color keyword or 3/6 digit hex e.g. #FFF" };
    } else {
        throw { type: "Argument", message: "argument must be a string" };
    }
},
iscolor: function (n) {
    return this._isa(n, tree.Color);
},
isnumber: function (n) {
    return this._isa(n, tree.Dimension);
},
isstring: function (n) {
    return this._isa(n, tree.Quoted);
},
iskeyword: function (n) {
    return this._isa(n, tree.Keyword);
},
isurl: function (n) {
    return this._isa(n, tree.URL);
},
ispixel: function (n) {
    return this.isunit(n, 'px');
},
ispercentage: function (n) {
    return this.isunit(n, '%');
},
isem: function (n) {
    return this.isunit(n, 'em');
},
isunit: function (n, unit) {
    return (n instanceof tree.Dimension) && n.unit.is(unit.value || unit) ? tree.True : tree.False;
},
_isa: function (n, Type) {
    return (n instanceof Type) ? tree.True : tree.False;
},
tint: function(color, amount) {
    return this.mix(this.rgb(255,255,255), color, amount);
},
shade: function(color, amount) {
    return this.mix(this.rgb(0, 0, 0), color, amount);
},   
extract: function(values, index) {
    index = index.value - 1; // (1-based index)       
    // handle non-array values as an array of length 1
    // return 'undefined' if index is invalid
    return Array.isArray(values.value) 
        ? values.value[index] : Array(values)[index];
},
length: function(values) {
    var n = Array.isArray(values.value) ? values.value.length : 1;
    return new tree.Dimension(n);
},

"data-uri": function(mimetypeNode, filePathNode) {

    if (typeof window !== 'undefined') {
        return new tree.URL(filePathNode || mimetypeNode, this.currentFileInfo).eval(this.env);
    }

    var mimetype = mimetypeNode.value;
    var filePath = (filePathNode && filePathNode.value);

    var fs = require('fs'),
        path = require('path'),
        useBase64 = false;

    if (arguments.length < 2) {
        filePath = mimetype;
    }

    if (this.env.isPathRelative(filePath)) {
        if (this.currentFileInfo.relativeUrls) {
            filePath = path.join(this.currentFileInfo.currentDirectory, filePath);
        } else {
            filePath = path.join(this.currentFileInfo.entryPath, filePath);
        }
    }

    // detect the mimetype if not given
    if (arguments.length < 2) {
        var mime;
        try {
            mime = require('mime');
        } catch (ex) {
            mime = tree._mime;
        }

        mimetype = mime.lookup(filePath);

        // use base 64 unless it's an ASCII or UTF-8 format
        var charset = mime.charsets.lookup(mimetype);
        useBase64 = ['US-ASCII', 'UTF-8'].indexOf(charset) < 0;
        if (useBase64) { mimetype += ';base64'; }
    }
    else {
        useBase64 = /;base64$/.test(mimetype);
    }

    var buf = fs.readFileSync(filePath);

    // IE8 cannot handle a data-uri larger than 32KB. If this is exceeded
    // and the --ieCompat flag is enabled, return a normal url() instead.
    var DATA_URI_MAX_KB = 32,
        fileSizeInKB = parseInt((buf.length / 1024), 10);
    if (fileSizeInKB >= DATA_URI_MAX_KB) {

        if (this.env.ieCompat !== false) {
            if (!this.env.silent) {
                console.warn("Skipped data-uri embedding of %s because its size (%dKB) exceeds IE8-safe %dKB!", filePath, fileSizeInKB, DATA_URI_MAX_KB);
            }

            return new tree.URL(filePathNode || mimetypeNode, this.currentFileInfo).eval(this.env);
        }
    }

    buf = useBase64 ? buf.toString('base64')
                    : encodeURIComponent(buf);

    var uri = "\"data:" + mimetype + ',' + buf + "\"";
    return new(tree.URL)(new(tree.Anonymous)(uri));
},

"svg-gradient": function(direction) {

    function throwArgumentDescriptor() {
        throw { type: "Argument", message: "svg-gradient expects direction, start_color [start_position], [color position,]..., end_color [end_position]" };
    }

    if (arguments.length < 3) {
        throwArgumentDescriptor();
    }
    var stops = Array.prototype.slice.call(arguments, 1),
        gradientDirectionSvg,
        gradientType = "linear",
        rectangleDimension = 'x="0" y="0" width="1" height="1"',
        useBase64 = true,
        renderEnv = {compress: false},
        returner,
        directionValue = direction.toCSS(renderEnv),
        i, color, position, positionValue, alpha;

    switch (directionValue) {
        case "to bottom":
            gradientDirectionSvg = 'x1="0%" y1="0%" x2="0%" y2="100%"';
            break;
        case "to right":
            gradientDirectionSvg = 'x1="0%" y1="0%" x2="100%" y2="0%"';
            break;
        case "to bottom right":
            gradientDirectionSvg = 'x1="0%" y1="0%" x2="100%" y2="100%"';
            break;
        case "to top right":
            gradientDirectionSvg = 'x1="0%" y1="100%" x2="100%" y2="0%"';
            break;
        case "ellipse":
        case "ellipse at center":
            gradientType = "radial";
            gradientDirectionSvg = 'cx="50%" cy="50%" r="75%"';
            rectangleDimension = 'x="-50" y="-50" width="101" height="101"';
            break;
        default:
            throw { type: "Argument", message: "svg-gradient direction must be 'to bottom', 'to right', 'to bottom right', 'to top right' or 'ellipse at center'" };
    }
    returner = '<?xml version="1.0" ?>' +
        '<svg xmlns="http://www.w3.org/2000/svg" version="1.1" width="100%" height="100%" viewBox="0 0 1 1" preserveAspectRatio="none">' +
        '<' + gradientType + 'Gradient id="gradient" gradientUnits="userSpaceOnUse" ' + gradientDirectionSvg + '>';

    for (i = 0; i < stops.length; i+= 1) {
        if (stops[i].value) {
            color = stops[i].value[0];
            position = stops[i].value[1];
        } else {
            color = stops[i];
            position = undefined;
        }

        if (!(color instanceof tree.Color) || (!((i === 0 || i+1 === stops.length) && position === undefined) && !(position instanceof tree.Dimension))) {
            throwArgumentDescriptor();
        }
        positionValue = position ? position.toCSS(renderEnv) : i === 0 ? "0%" : "100%";
        alpha = color.alpha;
        returner += '<stop offset="' + positionValue + '" stop-color="' + color.toRGB() + '"' + (alpha < 1 ? ' stop-opacity="' + alpha + '"' : '') + '/>';
    }
    returner += '</' + gradientType + 'Gradient>' +
                '<rect ' + rectangleDimension + ' fill="url(#gradient)" /></svg>';

    if (useBase64) {
        try {
            returner = require('./encoder').encodeBase64(returner); // TODO browser implementation
        } catch(e) {
            useBase64 = false;
        }
    }

    returner = "'data:image/svg+xml" + (useBase64 ? ";base64" : "") + "," + returner + "'";
    return new(tree.URL)(new(tree.Anonymous)(returner));
}

};

// these static methods are used as a fallback when the optional ‘mime’ dependency is missing tree._mime = {

// this map is intentionally incomplete
// if you want more, install 'mime' dep
_types: {
    '.htm' : 'text/html',
    '.html': 'text/html',
    '.gif' : 'image/gif',
    '.jpg' : 'image/jpeg',
    '.jpeg': 'image/jpeg',
    '.png' : 'image/png'
},
lookup: function (filepath) {
    var ext = require('path').extname(filepath),
        type = tree._mime._types[ext];
    if (type === undefined) {
        throw new Error('Optional dependency "mime" is required for ' + ext);
    }
    return type;
},
charsets: {
    lookup: function (type) {
        // assumes all text types are UTF-8
        return type && (/^text\//).test(type) ? 'UTF-8' : '';
    }
}

};

// Math

var mathFunctions = {

// name,  unit
   ceil:  null, 
   floor: null, 
   sqrt:  null, 
   abs:   null,
   tan:   "", 
   sin:   "", 
   cos:   "",
   atan:  "rad", 
   asin:  "rad", 
   acos:  "rad"

};

function _math(fn, unit, n) {

if (!(n instanceof tree.Dimension)) {
    throw { type: "Argument", message: "argument must be a number" };
}
if (unit == null) {
    unit = n.unit;
} else {
    n = n.unify();
}
return new(tree.Dimension)(fn(parseFloat(n.value)), unit);

}

// ~ End of Math

// Color Blending // ref: www.w3.org/TR/compositing-1

function colorBlend(mode, color1, color2) {

var ab = color1.alpha, cb, // backdrop
    as = color2.alpha, cs, // source
    ar, cr, r = [];        // result

ar = as + ab * (1 - as);
for (var i = 0; i < 3; i++) {
    cb = color1.rgb[i] / 255;
    cs = color2.rgb[i] / 255;
    cr = mode(cb, cs);
    if (ar) {
        cr = (as * cs + ab * (cb 
            - as * (cb + cs - cr))) / ar;
    }
    r[i] = cr * 255;
}

return new(tree.Color)(r, ar);

}

var colorBlendMode = {

multiply: function(cb, cs) {
    return cb * cs;
},
screen: function(cb, cs) {
    return cb + cs - cb * cs;
},   
overlay: function(cb, cs) {
    cb *= 2;
    return (cb <= 1)
        ? colorBlendMode.multiply(cb, cs)
        : colorBlendMode.screen(cb - 1, cs);
},
softlight: function(cb, cs) {
    var d = 1, e = cb;
    if (cs > 0.5) {
        e = 1;
        d = (cb > 0.25) ? Math.sqrt(cb)
            : ((16 * cb - 12) * cb + 4) * cb;
    }            
    return cb - (1 - 2 * cs) * e * (d - cb);
},
hardlight: function(cb, cs) {
    return colorBlendMode.overlay(cs, cb);
},
difference: function(cb, cs) {
    return Math.abs(cb - cs);
},
exclusion: function(cb, cs) {
    return cb + cs - 2 * cb * cs;
},

// non-w3c functions:
average: function(cb, cs) {
    return (cb + cs) / 2;
},
negation: function(cb, cs) {
    return 1 - Math.abs(cb + cs - 1);
}

};

// ~ End of Color Blending

tree.defaultFunc = {

eval: function () {
    var v = this.value_, e = this.error_;
    if (e) {
        throw e;
    }
    if (v != null) {
        return v ? tree.True : tree.False;
    }
},
value: function (v) {
    this.value_ = v;
},
error: function (e) {
    this.error_ = e;
},
reset: function () {
    this.value_ = this.error_ = null;
}

};

function initFunctions() {

var f, tf = tree.functions;

// math
for (f in mathFunctions) {
    if (mathFunctions.hasOwnProperty(f)) {
        tf[f] = _math.bind(null, Math[f], mathFunctions[f]);
    }
}

// color blending
for (f in colorBlendMode) {
    if (colorBlendMode.hasOwnProperty(f)) {
        tf[f] = colorBlend.bind(null, colorBlendMode[f]);
    }
}

// default
f = tree.defaultFunc;
tf["default"] = f.eval.bind(f);

} initFunctions();

function hsla(color) {

return tree.functions.hsla(color.h, color.s, color.l, color.a);

}

function scaled(n, size) {

if (n instanceof tree.Dimension && n.unit.is('%')) {
    return parseFloat(n.value * size / 100);
} else {
    return number(n);
}

}

function number(n) {

if (n instanceof tree.Dimension) {
    return parseFloat(n.unit.is('%') ? n.value / 100 : n.value);
} else if (typeof(n) === 'number') {
    return n;
} else {
    throw {
        error: "RuntimeError",
        message: "color functions take numbers as parameters"
    };
}

}

function clamp(val) {

return Math.min(1, Math.max(0, val));

}

tree.fround = function(env, value) {

var p;
if (env && (env.numPrecision != null)) {
    p = Math.pow(10, env.numPrecision);
    return Math.round(value * p) / p;
} else {
    return value;
}

};

tree.functionCall = function(env, currentFileInfo) {

this.env = env;
this.currentFileInfo = currentFileInfo;

};

tree.functionCall.prototype = tree.functions;

})(require(‘./tree’));

(function (tree) {

tree.colors = {
    'aliceblue':'#f0f8ff',
    'antiquewhite':'#faebd7',
    'aqua':'#00ffff',
    'aquamarine':'#7fffd4',
    'azure':'#f0ffff',
    'beige':'#f5f5dc',
    'bisque':'#ffe4c4',
    'black':'#000000',
    'blanchedalmond':'#ffebcd',
    'blue':'#0000ff',
    'blueviolet':'#8a2be2',
    'brown':'#a52a2a',
    'burlywood':'#deb887',
    'cadetblue':'#5f9ea0',
    'chartreuse':'#7fff00',
    'chocolate':'#d2691e',
    'coral':'#ff7f50',
    'cornflowerblue':'#6495ed',
    'cornsilk':'#fff8dc',
    'crimson':'#dc143c',
    'cyan':'#00ffff',
    'darkblue':'#00008b',
    'darkcyan':'#008b8b',
    'darkgoldenrod':'#b8860b',
    'darkgray':'#a9a9a9',
    'darkgrey':'#a9a9a9',
    'darkgreen':'#006400',
    'darkkhaki':'#bdb76b',
    'darkmagenta':'#8b008b',
    'darkolivegreen':'#556b2f',
    'darkorange':'#ff8c00',
    'darkorchid':'#9932cc',
    'darkred':'#8b0000',
    'darksalmon':'#e9967a',
    'darkseagreen':'#8fbc8f',
    'darkslateblue':'#483d8b',
    'darkslategray':'#2f4f4f',
    'darkslategrey':'#2f4f4f',
    'darkturquoise':'#00ced1',
    'darkviolet':'#9400d3',
    'deeppink':'#ff1493',
    'deepskyblue':'#00bfff',
    'dimgray':'#696969',
    'dimgrey':'#696969',
    'dodgerblue':'#1e90ff',
    'firebrick':'#b22222',
    'floralwhite':'#fffaf0',
    'forestgreen':'#228b22',
    'fuchsia':'#ff00ff',
    'gainsboro':'#dcdcdc',
    'ghostwhite':'#f8f8ff',
    'gold':'#ffd700',
    'goldenrod':'#daa520',
    'gray':'#808080',
    'grey':'#808080',
    'green':'#008000',
    'greenyellow':'#adff2f',
    'honeydew':'#f0fff0',
    'hotpink':'#ff69b4',
    'indianred':'#cd5c5c',
    'indigo':'#4b0082',
    'ivory':'#fffff0',
    'khaki':'#f0e68c',
    'lavender':'#e6e6fa',
    'lavenderblush':'#fff0f5',
    'lawngreen':'#7cfc00',
    'lemonchiffon':'#fffacd',
    'lightblue':'#add8e6',
    'lightcoral':'#f08080',
    'lightcyan':'#e0ffff',
    'lightgoldenrodyellow':'#fafad2',
    'lightgray':'#d3d3d3',
    'lightgrey':'#d3d3d3',
    'lightgreen':'#90ee90',
    'lightpink':'#ffb6c1',
    'lightsalmon':'#ffa07a',
    'lightseagreen':'#20b2aa',
    'lightskyblue':'#87cefa',
    'lightslategray':'#778899',
    'lightslategrey':'#778899',
    'lightsteelblue':'#b0c4de',
    'lightyellow':'#ffffe0',
    'lime':'#00ff00',
    'limegreen':'#32cd32',
    'linen':'#faf0e6',
    'magenta':'#ff00ff',
    'maroon':'#800000',
    'mediumaquamarine':'#66cdaa',
    'mediumblue':'#0000cd',
    'mediumorchid':'#ba55d3',
    'mediumpurple':'#9370d8',
    'mediumseagreen':'#3cb371',
    'mediumslateblue':'#7b68ee',
    'mediumspringgreen':'#00fa9a',
    'mediumturquoise':'#48d1cc',
    'mediumvioletred':'#c71585',
    'midnightblue':'#191970',
    'mintcream':'#f5fffa',
    'mistyrose':'#ffe4e1',
    'moccasin':'#ffe4b5',
    'navajowhite':'#ffdead',
    'navy':'#000080',
    'oldlace':'#fdf5e6',
    'olive':'#808000',
    'olivedrab':'#6b8e23',
    'orange':'#ffa500',
    'orangered':'#ff4500',
    'orchid':'#da70d6',
    'palegoldenrod':'#eee8aa',
    'palegreen':'#98fb98',
    'paleturquoise':'#afeeee',
    'palevioletred':'#d87093',
    'papayawhip':'#ffefd5',
    'peachpuff':'#ffdab9',
    'peru':'#cd853f',
    'pink':'#ffc0cb',
    'plum':'#dda0dd',
    'powderblue':'#b0e0e6',
    'purple':'#800080',
    'red':'#ff0000',
    'rosybrown':'#bc8f8f',
    'royalblue':'#4169e1',
    'saddlebrown':'#8b4513',
    'salmon':'#fa8072',
    'sandybrown':'#f4a460',
    'seagreen':'#2e8b57',
    'seashell':'#fff5ee',
    'sienna':'#a0522d',
    'silver':'#c0c0c0',
    'skyblue':'#87ceeb',
    'slateblue':'#6a5acd',
    'slategray':'#708090',
    'slategrey':'#708090',
    'snow':'#fffafa',
    'springgreen':'#00ff7f',
    'steelblue':'#4682b4',
    'tan':'#d2b48c',
    'teal':'#008080',
    'thistle':'#d8bfd8',
    'tomato':'#ff6347',
    'turquoise':'#40e0d0',
    'violet':'#ee82ee',
    'wheat':'#f5deb3',
    'white':'#ffffff',
    'whitesmoke':'#f5f5f5',
    'yellow':'#ffff00',
    'yellowgreen':'#9acd32'
};

})(require(‘./tree’));

(function (tree) {

tree.debugInfo = function(env, ctx, lineSeperator) {

var result="";
if (env.dumpLineNumbers && !env.compress) {
    switch(env.dumpLineNumbers) {
        case 'comments':
            result = tree.debugInfo.asComment(ctx);
            break;
        case 'mediaquery':
            result = tree.debugInfo.asMediaQuery(ctx);
            break;
        case 'all':
            result = tree.debugInfo.asComment(ctx) + (lineSeperator || "") + tree.debugInfo.asMediaQuery(ctx);
            break;
    }
}
return result;

};

tree.debugInfo.asComment = function(ctx) {

return '/* line ' + ctx.debugInfo.lineNumber + ', ' + ctx.debugInfo.fileName + ' */\n';

};

tree.debugInfo.asMediaQuery = function(ctx) {

return '@media -sass-debug-info{filename{font-family:' +
    ('file://' + ctx.debugInfo.fileName).replace(/([.:\/\\])/g, function (a) {
        if (a == '\\') {
            a = '\/';
        }
        return '\\' + a;
    }) +
    '}line{font-family:\\00003' + ctx.debugInfo.lineNumber + '}}\n';

};

tree.find = function (obj, fun) {

for (var i = 0, r; i < obj.length; i++) {
    r = fun.call(obj, obj[i]);
    if (r) { return r; }
}
return null;

};

tree.jsify = function (obj) {

if (Array.isArray(obj.value) && (obj.value.length > 1)) {
    return '[' + obj.value.map(function (v) { return v.toCSS(false); }).join(', ') + ']';
} else {
    return obj.toCSS(false);
}

};

tree.toCSS = function (env) {

var strs = [];
this.genCSS(env, {
    add: function(chunk, fileInfo, index) {
        strs.push(chunk);
    },
    isEmpty: function () {
        return strs.length === 0;
    }
});
return strs.join('');

};

tree.outputRuleset = function (env, output, rules) {

var ruleCnt = rules.length, i;
env.tabLevel = (env.tabLevel | 0) + 1;

// Compressed
if (env.compress) {
    output.add('{');
    for (i = 0; i < ruleCnt; i++) {
        rules[i].genCSS(env, output);
    }
    output.add('}');
    env.tabLevel--;
    return;
}

// Non-compressed
var tabSetStr = '\n' + Array(env.tabLevel).join("  "), tabRuleStr = tabSetStr + "  ";
if (!ruleCnt) {
    output.add(" {" + tabSetStr + '}');
} else {
    output.add(" {" + tabRuleStr);
    rules[0].genCSS(env, output);
    for (i = 1; i < ruleCnt; i++) {
        output.add(tabRuleStr);
        rules[i].genCSS(env, output);
    }
    output.add(tabSetStr + '}');
}

env.tabLevel--;

};

})(require(‘./tree’));

(function (tree) {

tree.Alpha = function (val) {

this.value = val;

}; tree.Alpha.prototype = {

type: "Alpha",
accept: function (visitor) {
    this.value = visitor.visit(this.value);
},
eval: function (env) {
    if (this.value.eval) { return new tree.Alpha(this.value.eval(env)); }
    return this;
},
genCSS: function (env, output) {
    output.add("alpha(opacity=");

    if (this.value.genCSS) {
        this.value.genCSS(env, output);
    } else {
        output.add(this.value);
    }

    output.add(")");
},
toCSS: tree.toCSS

};

})(require(‘../tree’));

(function (tree) {

tree.Anonymous = function (string, index, currentFileInfo, mapLines) {

this.value = string.value || string;
this.index = index;
this.mapLines = mapLines;
this.currentFileInfo = currentFileInfo;

}; tree.Anonymous.prototype = {

type: "Anonymous",
eval: function () { 
    return new tree.Anonymous(this.value, this.index, this.currentFileInfo, this.mapLines);
},
compare: function (x) {
    if (!x.toCSS) {
        return -1;
    }

    var left = this.toCSS(),
        right = x.toCSS();

    if (left === right) {
        return 0;
    }

    return left < right ? -1 : 1;
},
genCSS: function (env, output) {
    output.add(this.value, this.currentFileInfo, this.index, this.mapLines);
},
toCSS: tree.toCSS

};

})(require(‘../tree’));

(function (tree) {

tree.Assignment = function (key, val) {

this.key = key;
this.value = val;

}; tree.Assignment.prototype = {

type: "Assignment",
accept: function (visitor) {
    this.value = visitor.visit(this.value);
},
eval: function (env) {
    if (this.value.eval) {
        return new(tree.Assignment)(this.key, this.value.eval(env));
    }
    return this;
},
genCSS: function (env, output) {
    output.add(this.key + '=');
    if (this.value.genCSS) {
        this.value.genCSS(env, output);
    } else {
        output.add(this.value);
    }
},
toCSS: tree.toCSS

};

})(require(‘../tree’));

(function (tree) {

// // A function call node. // tree.Call = function (name, args, index, currentFileInfo) {

this.name = name;
this.args = args;
this.index = index;
this.currentFileInfo = currentFileInfo;

}; tree.Call.prototype = {

type: "Call",
accept: function (visitor) {
    if (this.args) {
        this.args = visitor.visitArray(this.args);
    }
},
//
// When evaluating a function call,
// we either find the function in `tree.functions` [1],
// in which case we call it, passing the  evaluated arguments,
// if this returns null or we cannot find the function, we 
// simply print it out as it appeared originally [2].
//
// The *functions.js* file contains the built-in functions.
//
// The reason why we evaluate the arguments, is in the case where
// we try to pass a variable to a function, like: `saturate(@color)`.
// The function should receive the value, not the variable.
//
eval: function (env) {
    var args = this.args.map(function (a) { return a.eval(env); }),
        nameLC = this.name.toLowerCase(),
        result, func;

    if (nameLC in tree.functions) { // 1.
        try {
            func = new tree.functionCall(env, this.currentFileInfo);
            result = func[nameLC].apply(func, args);
            if (result != null) {
                return result;
            }
        } catch (e) {
            throw { type: e.type || "Runtime",
                    message: "error evaluating function `" + this.name + "`" +
                             (e.message ? ': ' + e.message : ''),
                    index: this.index, filename: this.currentFileInfo.filename };
        }
    }

    return new tree.Call(this.name, args, this.index, this.currentFileInfo);
},

genCSS: function (env, output) {
    output.add(this.name + "(", this.currentFileInfo, this.index);

    for(var i = 0; i < this.args.length; i++) {
        this.args[i].genCSS(env, output);
        if (i + 1 < this.args.length) {
            output.add(", ");
        }
    }

    output.add(")");
},

toCSS: tree.toCSS

};

})(require(‘../tree’));

(function (tree) { // // RGB Colors - ff0014, eee // tree.Color = function (rgb, a) {

//
// The end goal here, is to parse the arguments
// into an integer triplet, such as `128, 255, 0`
//
// This facilitates operations and conversions.
//
if (Array.isArray(rgb)) {
    this.rgb = rgb;
} else if (rgb.length == 6) {
    this.rgb = rgb.match(/.{2}/g).map(function (c) {
        return parseInt(c, 16);
    });
} else {
    this.rgb = rgb.split('').map(function (c) {
        return parseInt(c + c, 16);
    });
}
this.alpha = typeof(a) === 'number' ? a : 1;

};

var transparentKeyword = “transparent”;

tree.Color.prototype = {

type: "Color",
eval: function () { return this; },
luma: function () { return (0.2126 * this.rgb[0] / 255) + (0.7152 * this.rgb[1] / 255) + (0.0722 * this.rgb[2] / 255); },

genCSS: function (env, output) {
    output.add(this.toCSS(env));
},
toCSS: function (env, doNotCompress) {
    var compress = env && env.compress && !doNotCompress,
        alpha = tree.fround(env, this.alpha);

    // If we have some transparency, the only way to represent it
    // is via `rgba`. Otherwise, we use the hex representation,
    // which has better compatibility with older browsers.
    // Values are capped between `0` and `255`, rounded and zero-padded.
    if (alpha < 1) {
        if (alpha === 0 && this.isTransparentKeyword) {
            return transparentKeyword;
        }
        return "rgba(" + this.rgb.map(function (c) {
            return clamp(Math.round(c), 255);
        }).concat(clamp(alpha, 1))
            .join(',' + (compress ? '' : ' ')) + ")";
    } else {
        var color = this.toRGB();

        if (compress) {
            var splitcolor = color.split('');

            // Convert color to short format
            if (splitcolor[1] === splitcolor[2] && splitcolor[3] === splitcolor[4] && splitcolor[5] === splitcolor[6]) {
                color = '#' + splitcolor[1] + splitcolor[3] + splitcolor[5];
            }
        }

        return color;
    }
},

//
// Operations have to be done per-channel, if not,
// channels will spill onto each other. Once we have
// our result, in the form of an integer triplet,
// we create a new Color node to hold the result.
//
operate: function (env, op, other) {
    var rgb = [];
    var alpha = this.alpha * (1 - other.alpha) + other.alpha;
    for (var c = 0; c < 3; c++) {
        rgb[c] = tree.operate(env, op, this.rgb[c], other.rgb[c]);
    }
    return new(tree.Color)(rgb, alpha);
},

toRGB: function () {
    return toHex(this.rgb);
},

toHSL: function () {
    var r = this.rgb[0] / 255,
        g = this.rgb[1] / 255,
        b = this.rgb[2] / 255,
        a = this.alpha;

    var max = Math.max(r, g, b), min = Math.min(r, g, b);
    var h, s, l = (max + min) / 2, d = max - min;

    if (max === min) {
        h = s = 0;
    } else {
        s = l > 0.5 ? d / (2 - max - min) : d / (max + min);

        switch (max) {
            case r: h = (g - b) / d + (g < b ? 6 : 0); break;
            case g: h = (b - r) / d + 2;               break;
            case b: h = (r - g) / d + 4;               break;
        }
        h /= 6;
    }
    return { h: h * 360, s: s, l: l, a: a };
},
//Adapted from http://mjijackson.com/2008/02/rgb-to-hsl-and-rgb-to-hsv-color-model-conversion-algorithms-in-javascript
toHSV: function () {
    var r = this.rgb[0] / 255,
        g = this.rgb[1] / 255,
        b = this.rgb[2] / 255,
        a = this.alpha;

    var max = Math.max(r, g, b), min = Math.min(r, g, b);
    var h, s, v = max;

    var d = max - min;
    if (max === 0) {
        s = 0;
    } else {
        s = d / max;
    }

    if (max === min) {
        h = 0;
    } else {
        switch(max){
            case r: h = (g - b) / d + (g < b ? 6 : 0); break;
            case g: h = (b - r) / d + 2; break;
            case b: h = (r - g) / d + 4; break;
        }
        h /= 6;
    }
    return { h: h * 360, s: s, v: v, a: a };
},
toARGB: function () {
    return toHex([this.alpha * 255].concat(this.rgb));
},
compare: function (x) {
    if (!x.rgb) {
        return -1;
    }

    return (x.rgb[0] === this.rgb[0] &&
        x.rgb[1] === this.rgb[1] &&
        x.rgb[2] === this.rgb[2] &&
        x.alpha === this.alpha) ? 0 : -1;
}

};

tree.Color.fromKeyword = function(keyword) {

keyword = keyword.toLowerCase();

if (tree.colors.hasOwnProperty(keyword)) {
    // detect named color
    return new(tree.Color)(tree.colors[keyword].slice(1));
}
if (keyword === transparentKeyword) {
    var transparent = new(tree.Color)([0, 0, 0], 0);
    transparent.isTransparentKeyword = true;
    return transparent;
}

};

function toHex(v) {

return '#' + v.map(function (c) {
    c = clamp(Math.round(c), 255);
    return (c < 16 ? '0' : '') + c.toString(16);
}).join('');

}

function clamp(v, max) {

return Math.min(Math.max(v, 0), max);

}

})(require(‘../tree’));

(function (tree) {

tree.Comment = function (value, silent, index, currentFileInfo) {

this.value = value;
this.silent = !!silent;
this.currentFileInfo = currentFileInfo;

}; tree.Comment.prototype = {

type: "Comment",
genCSS: function (env, output) {
    if (this.debugInfo) {
        output.add(tree.debugInfo(env, this), this.currentFileInfo, this.index);
    }
    output.add(this.value.trim()); //TODO shouldn't need to trim, we shouldn't grab the \n
},
toCSS: tree.toCSS,
isSilent: function(env) {
    var isReference = (this.currentFileInfo && this.currentFileInfo.reference && !this.isReferenced),
        isCompressed = env.compress && !this.value.match(/^\/\*!/);
    return this.silent || isReference || isCompressed;
},
eval: function () { return this; },
markReferenced: function () {
    this.isReferenced = true;
}

};

})(require(‘../tree’));

(function (tree) {

tree.Condition = function (op, l, r, i, negate) {

this.op = op.trim();
this.lvalue = l;
this.rvalue = r;
this.index = i;
this.negate = negate;

}; tree.Condition.prototype = {

type: "Condition",
accept: function (visitor) {
    this.lvalue = visitor.visit(this.lvalue);
    this.rvalue = visitor.visit(this.rvalue);
},
eval: function (env) {
    var a = this.lvalue.eval(env),
        b = this.rvalue.eval(env);

    var i = this.index, result;

    result = (function (op) {
        switch (op) {
            case 'and':
                return a && b;
            case 'or':
                return a || b;
            default:
                if (a.compare) {
                    result = a.compare(b);
                } else if (b.compare) {
                    result = b.compare(a);
                } else {
                    throw { type: "Type",
                            message: "Unable to perform comparison",
                            index: i };
                }
                switch (result) {
                    case -1: return op === '<' || op === '=<' || op === '<=';
                    case  0: return op === '=' || op === '>=' || op === '=<' || op === '<=';
                    case  1: return op === '>' || op === '>=';
                }
        }
    })(this.op);
    return this.negate ? !result : result;
}

};

})(require(‘../tree’));

(function (tree) {

// // A number with a unit // tree.Dimension = function (value, unit) {

this.value = parseFloat(value);
this.unit = (unit && unit instanceof tree.Unit) ? unit :
  new(tree.Unit)(unit ? [unit] : undefined);

};

tree.Dimension.prototype = {

type: "Dimension",
accept: function (visitor) {
    this.unit = visitor.visit(this.unit);
},
eval: function (env) {
    return this;
},
toColor: function () {
    return new(tree.Color)([this.value, this.value, this.value]);
},
genCSS: function (env, output) {
    if ((env && env.strictUnits) && !this.unit.isSingular()) {
        throw new Error("Multiple units in dimension. Correct the units or use the unit function. Bad unit: "+this.unit.toString());
    }

    var value = tree.fround(env, this.value),
        strValue = String(value);

    if (value !== 0 && value < 0.000001 && value > -0.000001) {
        // would be output 1e-6 etc.
        strValue = value.toFixed(20).replace(/0+$/, "");
    }

    if (env && env.compress) {
        // Zero values doesn't need a unit
        if (value === 0 && this.unit.isLength()) {
            output.add(strValue);
            return;
        }

        // Float values doesn't need a leading zero
        if (value > 0 && value < 1) {
            strValue = (strValue).substr(1);
        }
    }

    output.add(strValue);
    this.unit.genCSS(env, output);
},
toCSS: tree.toCSS,

// In an operation between two Dimensions,
// we default to the first Dimension's unit,
// so `1px + 2` will yield `3px`.
operate: function (env, op, other) {
    /*jshint noempty:false */
    var value = tree.operate(env, op, this.value, other.value),
        unit = this.unit.clone();

    if (op === '+' || op === '-') {
        if (unit.numerator.length === 0 && unit.denominator.length === 0) {
            unit.numerator = other.unit.numerator.slice(0);
            unit.denominator = other.unit.denominator.slice(0);
        } else if (other.unit.numerator.length === 0 && unit.denominator.length === 0) {
            // do nothing
        } else {
            other = other.convertTo(this.unit.usedUnits());

            if(env.strictUnits && other.unit.toString() !== unit.toString()) {
              throw new Error("Incompatible units. Change the units or use the unit function. Bad units: '" + unit.toString() +
                "' and '" + other.unit.toString() + "'.");
            }

            value = tree.operate(env, op, this.value, other.value);
        }
    } else if (op === '*') {
        unit.numerator = unit.numerator.concat(other.unit.numerator).sort();
        unit.denominator = unit.denominator.concat(other.unit.denominator).sort();
        unit.cancel();
    } else if (op === '/') {
        unit.numerator = unit.numerator.concat(other.unit.denominator).sort();
        unit.denominator = unit.denominator.concat(other.unit.numerator).sort();
        unit.cancel();
    }
    return new(tree.Dimension)(value, unit);
},

compare: function (other) {
    if (other instanceof tree.Dimension) {
        var a = this.unify(), b = other.unify(),
            aValue = a.value, bValue = b.value;

        if (bValue > aValue) {
            return -1;
        } else if (bValue < aValue) {
            return 1;
        } else {
            if (!b.unit.isEmpty() && a.unit.compare(b.unit) !== 0) {
                return -1;
            }
            return 0;
        }
    } else {
        return -1;
    }
},

unify: function () {
    return this.convertTo({ length: 'm', duration: 's', angle: 'rad' });
},

convertTo: function (conversions) {
    var value = this.value, unit = this.unit.clone(),
        i, groupName, group, targetUnit, derivedConversions = {}, applyUnit;

    if (typeof conversions === 'string') {
        for(i in tree.UnitConversions) {
            if (tree.UnitConversions[i].hasOwnProperty(conversions)) {
                derivedConversions = {};
                derivedConversions[i] = conversions;
            }
        }
        conversions = derivedConversions;
    }
    applyUnit = function (atomicUnit, denominator) {
      /*jshint loopfunc:true */
        if (group.hasOwnProperty(atomicUnit)) {
            if (denominator) {
                value = value / (group[atomicUnit] / group[targetUnit]);
            } else {
                value = value * (group[atomicUnit] / group[targetUnit]);
            }

            return targetUnit;
        }

        return atomicUnit;
    };

    for (groupName in conversions) {
        if (conversions.hasOwnProperty(groupName)) {
            targetUnit = conversions[groupName];
            group = tree.UnitConversions[groupName];

            unit.map(applyUnit);
        }
    }

    unit.cancel();

    return new(tree.Dimension)(value, unit);
}

};

// www.w3.org/TR/css3-values/#absolute-lengths tree.UnitConversions = {

length: {
     'm': 1,
    'cm': 0.01,
    'mm': 0.001,
    'in': 0.0254,
    'pt': 0.0254 / 72,
    'pc': 0.0254 / 72 * 12
},
duration: {
    's': 1,
    'ms': 0.001
},
angle: {
    'rad': 1/(2*Math.PI),
    'deg': 1/360,
    'grad': 1/400,
    'turn': 1
}

};

tree.Unit = function (numerator, denominator, backupUnit) {

this.numerator = numerator ? numerator.slice(0).sort() : [];
this.denominator = denominator ? denominator.slice(0).sort() : [];
this.backupUnit = backupUnit;

};

tree.Unit.prototype = {

type: "Unit",
clone: function () {
    return new tree.Unit(this.numerator.slice(0), this.denominator.slice(0), this.backupUnit);
},
genCSS: function (env, output) {
    if (this.numerator.length >= 1) {
        output.add(this.numerator[0]);
    } else
    if (this.denominator.length >= 1) {
        output.add(this.denominator[0]);
    } else
    if ((!env || !env.strictUnits) && this.backupUnit) {
        output.add(this.backupUnit);
    }
},
toCSS: tree.toCSS,

toString: function () {
  var i, returnStr = this.numerator.join("*");
  for (i = 0; i < this.denominator.length; i++) {
      returnStr += "/" + this.denominator[i];
  }
  return returnStr;
},

compare: function (other) {
    return this.is(other.toString()) ? 0 : -1;
},

is: function (unitString) {
    return this.toString() === unitString;
},

isLength: function () {
    return Boolean(this.toCSS().match(/px|em|%|in|cm|mm|pc|pt|ex/));
},

isEmpty: function () {
    return this.numerator.length === 0 && this.denominator.length === 0;
},

isSingular: function() {
    return this.numerator.length <= 1 && this.denominator.length === 0;
},

map: function(callback) {
    var i;

    for (i = 0; i < this.numerator.length; i++) {
        this.numerator[i] = callback(this.numerator[i], false);
    }

    for (i = 0; i < this.denominator.length; i++) {
        this.denominator[i] = callback(this.denominator[i], true);
    }
},

usedUnits: function() {
    var group, result = {}, mapUnit;

    mapUnit = function (atomicUnit) {
    /*jshint loopfunc:true */
        if (group.hasOwnProperty(atomicUnit) && !result[groupName]) {
            result[groupName] = atomicUnit;
        }

        return atomicUnit;
    };

    for (var groupName in tree.UnitConversions) {
        if (tree.UnitConversions.hasOwnProperty(groupName)) {
            group = tree.UnitConversions[groupName];

            this.map(mapUnit);
        }
    }

    return result;
},

cancel: function () {
    var counter = {}, atomicUnit, i, backup;

    for (i = 0; i < this.numerator.length; i++) {
        atomicUnit = this.numerator[i];
        if (!backup) {
            backup = atomicUnit;
        }
        counter[atomicUnit] = (counter[atomicUnit] || 0) + 1;
    }

    for (i = 0; i < this.denominator.length; i++) {
        atomicUnit = this.denominator[i];
        if (!backup) {
            backup = atomicUnit;
        }
        counter[atomicUnit] = (counter[atomicUnit] || 0) - 1;
    }

    this.numerator = [];
    this.denominator = [];

    for (atomicUnit in counter) {
        if (counter.hasOwnProperty(atomicUnit)) {
            var count = counter[atomicUnit];

            if (count > 0) {
                for (i = 0; i < count; i++) {
                    this.numerator.push(atomicUnit);
                }
            } else if (count < 0) {
                for (i = 0; i < -count; i++) {
                    this.denominator.push(atomicUnit);
                }
            }
        }
    }

    if (this.numerator.length === 0 && this.denominator.length === 0 && backup) {
        this.backupUnit = backup;
    }

    this.numerator.sort();
    this.denominator.sort();
}

};

})(require(‘../tree’));

(function (tree) {

tree.Directive = function (name, value, index, currentFileInfo) {

this.name = name;

if (Array.isArray(value)) {
    this.rules = [new(tree.Ruleset)(null, value)];
    this.rules[0].allowImports = true;
} else {
    this.value = value;
}
this.index = index;
this.currentFileInfo = currentFileInfo;

}; tree.Directive.prototype = {

type: "Directive",
accept: function (visitor) {
    if (this.rules) {
        this.rules = visitor.visitArray(this.rules);
    }
    if (this.value) {
        this.value = visitor.visit(this.value);
    }
},
genCSS: function (env, output) {
    output.add(this.name, this.currentFileInfo, this.index);
    if (this.rules) {
        tree.outputRuleset(env, output, this.rules);
    } else {
        output.add(' ');
        this.value.genCSS(env, output);
        output.add(';');
    }
},
toCSS: tree.toCSS,
eval: function (env) {
    var evaldDirective = this;
    if (this.rules) {
        env.frames.unshift(this);
        evaldDirective = new(tree.Directive)(this.name, null, this.index, this.currentFileInfo);
        evaldDirective.rules = [this.rules[0].eval(env)];
        evaldDirective.rules[0].root = true;
        env.frames.shift();
    }
    return evaldDirective;
},
variable: function (name) { return tree.Ruleset.prototype.variable.call(this.rules[0], name); },
find: function () { return tree.Ruleset.prototype.find.apply(this.rules[0], arguments); },
rulesets: function () { return tree.Ruleset.prototype.rulesets.apply(this.rules[0]); },
markReferenced: function () {
    var i, rules;
    this.isReferenced = true;
    if (this.rules) {
        rules = this.rules[0].rules;
        for (i = 0; i < rules.length; i++) {
            if (rules[i].markReferenced) {
                rules[i].markReferenced();
            }
        }
    }
}

};

})(require(‘../tree’));

(function (tree) {

tree.Element = function (combinator, value, index, currentFileInfo) {

this.combinator = combinator instanceof tree.Combinator ?
                  combinator : new(tree.Combinator)(combinator);

if (typeof(value) === 'string') {
    this.value = value.trim();
} else if (value) {
    this.value = value;
} else {
    this.value = "";
}
this.index = index;
this.currentFileInfo = currentFileInfo;

}; tree.Element.prototype = {

type: "Element",
accept: function (visitor) {
    var value = this.value;
    this.combinator = visitor.visit(this.combinator);
    if (typeof value === "object") {
        this.value = visitor.visit(value);
    }
},
eval: function (env) {
    return new(tree.Element)(this.combinator,
                             this.value.eval ? this.value.eval(env) : this.value,
                             this.index,
                             this.currentFileInfo);
},
genCSS: function (env, output) {
    output.add(this.toCSS(env), this.currentFileInfo, this.index);
},
toCSS: function (env) {
    var value = (this.value.toCSS ? this.value.toCSS(env) : this.value);
    if (value === '' && this.combinator.value.charAt(0) === '&') {
        return '';
    } else {
        return this.combinator.toCSS(env || {}) + value;
    }
}

};

tree.Attribute = function (key, op, value) {

this.key = key;
this.op = op;
this.value = value;

}; tree.Attribute.prototype = {

type: "Attribute",
eval: function (env) {
    return new(tree.Attribute)(this.key.eval ? this.key.eval(env) : this.key,
        this.op, (this.value && this.value.eval) ? this.value.eval(env) : this.value);
},
genCSS: function (env, output) {
    output.add(this.toCSS(env));
},
toCSS: function (env) {
    var value = this.key.toCSS ? this.key.toCSS(env) : this.key;

    if (this.op) {
        value += this.op;
        value += (this.value.toCSS ? this.value.toCSS(env) : this.value);
    }

    return '[' + value + ']';
}

};

tree.Combinator = function (value) {

if (value === ' ') {
    this.value = ' ';
} else {
    this.value = value ? value.trim() : "";
}

}; tree.Combinator.prototype = {

type: "Combinator",
_outputMap: {
    ''  : '',
    ' ' : ' ',
    ':' : ' :',
    '+' : ' + ',
    '~' : ' ~ ',
    '>' : ' > ',
    '|' : '|',
    '^' : ' ^ ',
    '^^' : ' ^^ '
},
_outputMapCompressed: {
    ''  : '',
    ' ' : ' ',
    ':' : ' :',
    '+' : '+',
    '~' : '~',
    '>' : '>',
    '|' : '|',
    '^' : '^',
    '^^' : '^^'
},
genCSS: function (env, output) {
    output.add((env.compress ? this._outputMapCompressed : this._outputMap)[this.value]);
},
toCSS: tree.toCSS

};

})(require(‘../tree’));

(function (tree) {

tree.Expression = function (value) { this.value = value; }; tree.Expression.prototype = {

type: "Expression",
accept: function (visitor) {
    if (this.value) {
        this.value = visitor.visitArray(this.value);
    }
},
eval: function (env) {
    var returnValue,
        inParenthesis = this.parens && !this.parensInOp,
        doubleParen = false;
    if (inParenthesis) {
        env.inParenthesis();
    }
    if (this.value.length > 1) {
        returnValue = new(tree.Expression)(this.value.map(function (e) {
            return e.eval(env);
        }));
    } else if (this.value.length === 1) {
        if (this.value[0].parens && !this.value[0].parensInOp) {
            doubleParen = true;
        }
        returnValue = this.value[0].eval(env);
    } else {
        returnValue = this;
    }
    if (inParenthesis) {
        env.outOfParenthesis();
    }
    if (this.parens && this.parensInOp && !(env.isMathOn()) && !doubleParen) {
        returnValue = new(tree.Paren)(returnValue);
    }
    return returnValue;
},
genCSS: function (env, output) {
    for(var i = 0; i < this.value.length; i++) {
        this.value[i].genCSS(env, output);
        if (i + 1 < this.value.length) {
            output.add(" ");
        }
    }
},
toCSS: tree.toCSS,
throwAwayComments: function () {
    this.value = this.value.filter(function(v) {
        return !(v instanceof tree.Comment);
    });
}

};

})(require(‘../tree’));

(function (tree) {

tree.Extend = function Extend(selector, option, index) {

this.selector = selector;
this.option = option;
this.index = index;
this.object_id = tree.Extend.next_id++;
this.parent_ids = [this.object_id];

switch(option) {
    case "all":
        this.allowBefore = true;
        this.allowAfter = true;
    break;
    default:
        this.allowBefore = false;
        this.allowAfter = false;
    break;
}

}; tree.Extend.next_id = 0;

tree.Extend.prototype = {

type: "Extend",
accept: function (visitor) {
    this.selector = visitor.visit(this.selector);
},
eval: function (env) {
    return new(tree.Extend)(this.selector.eval(env), this.option, this.index);
},
clone: function (env) {
    return new(tree.Extend)(this.selector, this.option, this.index);
},
findSelfSelectors: function (selectors) {
    var selfElements = [],
        i,
        selectorElements;

    for(i = 0; i < selectors.length; i++) {
        selectorElements = selectors[i].elements;
        // duplicate the logic in genCSS function inside the selector node.
        // future TODO - move both logics into the selector joiner visitor
        if (i > 0 && selectorElements.length && selectorElements[0].combinator.value === "") {
            selectorElements[0].combinator.value = ' ';
        }
        selfElements = selfElements.concat(selectors[i].elements);
    }

    this.selfSelectors = [{ elements: selfElements }];
}

};

})(require(‘../tree’));

(function (tree) { // // CSS @import node // // The general strategy here is that we don’t want to wait // for the parsing to be completed, before we start importing // the file. That’s because in the context of a browser, // most of the time will be spent waiting for the server to respond. // // On creation, we push the import path to our import queue, though // ‘import,push`, we also pass it a callback, which it’ll call once // the file has been fetched, and parsed. // tree.Import = function (path, features, options, index, currentFileInfo) {

this.options = options;
this.index = index;
this.path = path;
this.features = features;
this.currentFileInfo = currentFileInfo;

if (this.options.less !== undefined || this.options.inline) {
    this.css = !this.options.less || this.options.inline;
} else {
    var pathValue = this.getPath();
    if (pathValue && /css([\?;].*)?$/.test(pathValue)) {
        this.css = true;
    }
}

};

// // The actual import node doesn’t return anything, when converted to CSS. // The reason is that it’s used at the evaluation stage, so that the rules // it imports can be treated like any other rules. // // In ‘eval`, we make sure all Import nodes get evaluated, recursively, so // we end up with a flat structure, which can easily be imported in the parent // ruleset. // tree.Import.prototype = {

type: "Import",
accept: function (visitor) {
    if (this.features) {
        this.features = visitor.visit(this.features);
    }
    this.path = visitor.visit(this.path);
    if (!this.options.inline && this.root) {
        this.root = visitor.visit(this.root);
    }
},
genCSS: function (env, output) {
    if (this.css) {
        output.add("@import ", this.currentFileInfo, this.index);
        this.path.genCSS(env, output);
        if (this.features) {
            output.add(" ");
            this.features.genCSS(env, output);
        }
        output.add(';');
    }
},
toCSS: tree.toCSS,
getPath: function () {
    if (this.path instanceof tree.Quoted) {
        var path = this.path.value;
        return (this.css !== undefined || /(\.[a-z]*$)|([\?;].*)$/.test(path)) ? path : path + '.less';
    } else if (this.path instanceof tree.URL) {
        return this.path.value.value;
    }
    return null;
},
evalForImport: function (env) {
    return new(tree.Import)(this.path.eval(env), this.features, this.options, this.index, this.currentFileInfo);
},
evalPath: function (env) {
    var path = this.path.eval(env);
    var rootpath = this.currentFileInfo && this.currentFileInfo.rootpath;

    if (!(path instanceof tree.URL)) {
        if (rootpath) {
            var pathValue = path.value;
            // Add the base path if the import is relative
            if (pathValue && env.isPathRelative(pathValue)) {
                path.value = rootpath +pathValue;
            }
        }
        path.value = env.normalizePath(path.value);
    }

    return path;
},
eval: function (env) {
    var ruleset, features = this.features && this.features.eval(env);

    if (this.skip) { return []; }

    if (this.options.inline) {
        //todo needs to reference css file not import
        var contents = new(tree.Anonymous)(this.root, 0, {filename: this.importedFilename}, true);
        return this.features ? new(tree.Media)([contents], this.features.value) : [contents];
    } else if (this.css) {
        var newImport = new(tree.Import)(this.evalPath(env), features, this.options, this.index);
        if (!newImport.css && this.error) {
            throw this.error;
        }
        return newImport;
    } else {
        ruleset = new(tree.Ruleset)(null, this.root.rules.slice(0));

        ruleset.evalImports(env);

        return this.features ? new(tree.Media)(ruleset.rules, this.features.value) : ruleset.rules;
    }
}

};

})(require(‘../tree’));

(function (tree) {

tree.JavaScript = function (string, index, escaped) {

this.escaped = escaped;
this.expression = string;
this.index = index;

}; tree.JavaScript.prototype = {

type: "JavaScript",
eval: function (env) {
    var result,
        that = this,
        context = {};

    var expression = this.expression.replace(/@\{([\w-]+)\}/g, function (_, name) {
        return tree.jsify(new(tree.Variable)('@' + name, that.index).eval(env));
    });

    try {
        expression = new(Function)('return (' + expression + ')');
    } catch (e) {
        throw { message: "JavaScript evaluation error: " + e.message + " from `" + expression + "`" ,
                index: this.index };
    }

    var variables = env.frames[0].variables();
    for (var k in variables) {
        if (variables.hasOwnProperty(k)) {
            /*jshint loopfunc:true */
            context[k.slice(1)] = {
                value: variables[k].value,
                toJS: function () {
                    return this.value.eval(env).toCSS();
                }
            };
        }
    }

    try {
        result = expression.call(context);
    } catch (e) {
        throw { message: "JavaScript evaluation error: '" + e.name + ': ' + e.message.replace(/["]/g, "'") + "'" ,
                index: this.index };
    }
    if (typeof(result) === 'number') {
        return new(tree.Dimension)(result);
    } else if (typeof(result) === 'string') {
        return new(tree.Quoted)('"' + result + '"', result, this.escaped, this.index);
    } else if (Array.isArray(result)) {
        return new(tree.Anonymous)(result.join(', '));
    } else {
        return new(tree.Anonymous)(result);
    }
}

};

})(require(‘../tree’));

(function (tree) {

tree.Keyword = function (value) { this.value = value; }; tree.Keyword.prototype = {

type: "Keyword",
eval: function () { return this; },
genCSS: function (env, output) {
    output.add(this.value);
},
toCSS: tree.toCSS,
compare: function (other) {
    if (other instanceof tree.Keyword) {
        return other.value === this.value ? 0 : 1;
    } else {
        return -1;
    }
}

};

tree.True = new(tree.Keyword)(‘true’); tree.False = new(tree.Keyword)(‘false’);

})(require(‘../tree’));

(function (tree) {

tree.Media = function (value, features, index, currentFileInfo) {

this.index = index;
this.currentFileInfo = currentFileInfo;

var selectors = this.emptySelectors();

this.features = new(tree.Value)(features);
this.rules = [new(tree.Ruleset)(selectors, value)];
this.rules[0].allowImports = true;

}; tree.Media.prototype = {

type: "Media",
accept: function (visitor) {
    if (this.features) {
        this.features = visitor.visit(this.features);
    }
    if (this.rules) {
        this.rules = visitor.visitArray(this.rules);
    }
},
genCSS: function (env, output) {
    output.add('@media ', this.currentFileInfo, this.index);
    this.features.genCSS(env, output);
    tree.outputRuleset(env, output, this.rules);
},
toCSS: tree.toCSS,
eval: function (env) {
    if (!env.mediaBlocks) {
        env.mediaBlocks = [];
        env.mediaPath = [];
    }

    var media = new(tree.Media)(null, [], this.index, this.currentFileInfo);
    if(this.debugInfo) {
        this.rules[0].debugInfo = this.debugInfo;
        media.debugInfo = this.debugInfo;
    }
    var strictMathBypass = false;
    if (!env.strictMath) {
        strictMathBypass = true;
        env.strictMath = true;
    }
    try {
        media.features = this.features.eval(env);
    }
    finally {
        if (strictMathBypass) {
            env.strictMath = false;
        }
    }

    env.mediaPath.push(media);
    env.mediaBlocks.push(media);

    env.frames.unshift(this.rules[0]);
    media.rules = [this.rules[0].eval(env)];
    env.frames.shift();

    env.mediaPath.pop();

    return env.mediaPath.length === 0 ? media.evalTop(env) :
                media.evalNested(env);
},
variable: function (name) { return tree.Ruleset.prototype.variable.call(this.rules[0], name); },
find: function () { return tree.Ruleset.prototype.find.apply(this.rules[0], arguments); },
rulesets: function () { return tree.Ruleset.prototype.rulesets.apply(this.rules[0]); },
emptySelectors: function() { 
    var el = new(tree.Element)('', '&', this.index, this.currentFileInfo),
        sels = [new(tree.Selector)([el], null, null, this.index, this.currentFileInfo)];
    sels[0].mediaEmpty = true;
    return sels;
},
markReferenced: function () {
    var i, rules = this.rules[0].rules;
    this.isReferenced = true;
    for (i = 0; i < rules.length; i++) {
        if (rules[i].markReferenced) {
            rules[i].markReferenced();
        }
    }
},

evalTop: function (env) {
    var result = this;

    // Render all dependent Media blocks.
    if (env.mediaBlocks.length > 1) {
        var selectors = this.emptySelectors();
        result = new(tree.Ruleset)(selectors, env.mediaBlocks);
        result.multiMedia = true;
    }

    delete env.mediaBlocks;
    delete env.mediaPath;

    return result;
},
evalNested: function (env) {
    var i, value,
        path = env.mediaPath.concat([this]);

    // Extract the media-query conditions separated with `,` (OR).
    for (i = 0; i < path.length; i++) {
        value = path[i].features instanceof tree.Value ?
                    path[i].features.value : path[i].features;
        path[i] = Array.isArray(value) ? value : [value];
    }

    // Trace all permutations to generate the resulting media-query.
    //
    // (a, b and c) with nested (d, e) ->
    //    a and d
    //    a and e
    //    b and c and d
    //    b and c and e
    this.features = new(tree.Value)(this.permute(path).map(function (path) {
        path = path.map(function (fragment) {
            return fragment.toCSS ? fragment : new(tree.Anonymous)(fragment);
        });

        for(i = path.length - 1; i > 0; i--) {
            path.splice(i, 0, new(tree.Anonymous)("and"));
        }

        return new(tree.Expression)(path);
    }));

    // Fake a tree-node that doesn't output anything.
    return new(tree.Ruleset)([], []);
},
permute: function (arr) {
  if (arr.length === 0) {
      return [];
  } else if (arr.length === 1) {
      return arr[0];
  } else {
      var result = [];
      var rest = this.permute(arr.slice(1));
      for (var i = 0; i < rest.length; i++) {
          for (var j = 0; j < arr[0].length; j++) {
              result.push([arr[0][j]].concat(rest[i]));
          }
      }
      return result;
  }
},
bubbleSelectors: function (selectors) {
  this.rules = [new(tree.Ruleset)(selectors.slice(0), [this.rules[0]])];
}

};

})(require(‘../tree’));

(function (tree) {

tree.mixin = {}; tree.mixin.Call = function (elements, args, index, currentFileInfo, important) {

this.selector = new(tree.Selector)(elements);
this.arguments = (args && args.length) ? args : null;
this.index = index;
this.currentFileInfo = currentFileInfo;
this.important = important;

}; tree.mixin.Call.prototype = {

type: "MixinCall",
accept: function (visitor) {
    if (this.selector) {
        this.selector = visitor.visit(this.selector);
    }
    if (this.arguments) {
        this.arguments = visitor.visitArray(this.arguments);
    }
},
eval: function (env) {
    var mixins, mixin, args, rules = [], match = false, i, m, f, isRecursive, isOneFound, rule,
        candidates = [], candidate, conditionResult = [], defaultFunc = tree.defaultFunc,
        defaultResult, defNone = 0, defTrue = 1, defFalse = 2, count; 

    args = this.arguments && this.arguments.map(function (a) {
        return { name: a.name, value: a.value.eval(env) };
    });

    for (i = 0; i < env.frames.length; i++) {
        if ((mixins = env.frames[i].find(this.selector)).length > 0) {
            isOneFound = true;

            // To make `default()` function independent of definition order we have two "subpasses" here.
            // At first we evaluate each guard *twice* (with `default() == true` and `default() == false`),
            // and build candidate list with corresponding flags. Then, when we know all possible matches,
            // we make a final decision.

            for (m = 0; m < mixins.length; m++) {
                mixin = mixins[m];
                isRecursive = false;
                for(f = 0; f < env.frames.length; f++) {
                    if ((!(mixin instanceof tree.mixin.Definition)) && mixin === (env.frames[f].originalRuleset || env.frames[f])) {
                        isRecursive = true;
                        break;
                    }
                }
                if (isRecursive) {
                    continue;
                }

                if (mixin.matchArgs(args, env)) {  
                    candidate = {mixin: mixin, group: defNone};

                    if (mixin.matchCondition) { 
                        for (f = 0; f < 2; f++) {
                            defaultFunc.value(f);
                            conditionResult[f] = mixin.matchCondition(args, env);
                        }
                        if (conditionResult[0] || conditionResult[1]) {
                            if (conditionResult[0] != conditionResult[1]) {
                                candidate.group = conditionResult[1] ?
                                    defTrue : defFalse;
                            }

                            candidates.push(candidate);
                        }   
                    }
                    else {
                        candidates.push(candidate);
                    }

                    match = true;
                }
            }

            defaultFunc.reset();

            count = [0, 0, 0];
            for (m = 0; m < candidates.length; m++) {
                count[candidates[m].group]++;
            }

            if (count[defNone] > 0) {
                defaultResult = defFalse;
            } else {
                defaultResult = defTrue;
                if ((count[defTrue] + count[defFalse]) > 1) {
                    throw { type: 'Runtime',
                        message: 'Ambiguous use of `default()` found when matching for `'
                            + this.format(args) + '`',
                        index: this.index, filename: this.currentFileInfo.filename };
                }
            }

            for (m = 0; m < candidates.length; m++) {
                candidate = candidates[m].group;
                if ((candidate === defNone) || (candidate === defaultResult)) {
                    try {
                        mixin = candidates[m].mixin;
                        if (!(mixin instanceof tree.mixin.Definition)) {
                            mixin = new tree.mixin.Definition("", [], mixin.rules, null, false);
                            mixin.originalRuleset = mixins[m].originalRuleset || mixins[m];
                        }
                        Array.prototype.push.apply(
                              rules, mixin.eval(env, args, this.important).rules);
                    } catch (e) {
                        throw { message: e.message, index: this.index, filename: this.currentFileInfo.filename, stack: e.stack };
                    }
                }
            }

            if (match) {
                if (!this.currentFileInfo || !this.currentFileInfo.reference) {
                    for (i = 0; i < rules.length; i++) {
                        rule = rules[i];
                        if (rule.markReferenced) {
                            rule.markReferenced();
                        }
                    }
                }
                return rules;
            }
        }
    }
    if (isOneFound) {
        throw { type:    'Runtime',
                message: 'No matching definition was found for `' + this.format(args) + '`',
                index:   this.index, filename: this.currentFileInfo.filename };
    } else {
        throw { type:    'Name',
                message: this.selector.toCSS().trim() + " is undefined",
                index:   this.index, filename: this.currentFileInfo.filename };
    }
},
format: function (args) {
    return this.selector.toCSS().trim() + '(' +
        (args ? args.map(function (a) {
            var argValue = "";
            if (a.name) {
                argValue += a.name + ":";
            }
            if (a.value.toCSS) {
                argValue += a.value.toCSS();
            } else {
                argValue += "???";
            }
            return argValue;
        }).join(', ') : "") + ")";
}

};

tree.mixin.Definition = function (name, params, rules, condition, variadic) {

this.name = name;
this.selectors = [new(tree.Selector)([new(tree.Element)(null, name, this.index, this.currentFileInfo)])];
this.params = params;
this.condition = condition;
this.variadic = variadic;
this.arity = params.length;
this.rules = rules;
this._lookups = {};
this.required = params.reduce(function (count, p) {
    if (!p.name || (p.name && !p.value)) { return count + 1; }
    else                                 { return count; }
}, 0);
this.parent = tree.Ruleset.prototype;
this.frames = [];

}; tree.mixin.Definition.prototype = {

type: "MixinDefinition",
accept: function (visitor) {
    if (this.params && this.params.length) {
        this.params = visitor.visitArray(this.params);
    }
    this.rules = visitor.visitArray(this.rules);
    if (this.condition) {
        this.condition = visitor.visit(this.condition);
    }
},
variable:  function (name) { return this.parent.variable.call(this, name); },
variables: function ()     { return this.parent.variables.call(this); },
find:      function ()     { return this.parent.find.apply(this, arguments); },
rulesets:  function ()     { return this.parent.rulesets.apply(this); },

evalParams: function (env, mixinEnv, args, evaldArguments) {
    /*jshint boss:true */
    var frame = new(tree.Ruleset)(null, null),
        varargs, arg,
        params = this.params.slice(0),
        i, j, val, name, isNamedFound, argIndex;

    mixinEnv = new tree.evalEnv(mixinEnv, [frame].concat(mixinEnv.frames));

    if (args) {
        args = args.slice(0);

        for(i = 0; i < args.length; i++) {
            arg = args[i];
            if (name = (arg && arg.name)) {
                isNamedFound = false;
                for(j = 0; j < params.length; j++) {
                    if (!evaldArguments[j] && name === params[j].name) {
                        evaldArguments[j] = arg.value.eval(env);
                        frame.prependRule(new(tree.Rule)(name, arg.value.eval(env)));
                        isNamedFound = true;
                        break;
                    }
                }
                if (isNamedFound) {
                    args.splice(i, 1);
                    i--;
                    continue;
                } else {
                    throw { type: 'Runtime', message: "Named argument for " + this.name +
                        ' ' + args[i].name + ' not found' };
                }
            }
        }
    }
    argIndex = 0;
    for (i = 0; i < params.length; i++) {
        if (evaldArguments[i]) { continue; }

        arg = args && args[argIndex];

        if (name = params[i].name) {
            if (params[i].variadic && args) {
                varargs = [];
                for (j = argIndex; j < args.length; j++) {
                    varargs.push(args[j].value.eval(env));
                }
                frame.prependRule(new(tree.Rule)(name, new(tree.Expression)(varargs).eval(env)));
            } else {
                val = arg && arg.value;
                if (val) {
                    val = val.eval(env);
                } else if (params[i].value) {
                    val = params[i].value.eval(mixinEnv);
                    frame.resetCache();
                } else {
                    throw { type: 'Runtime', message: "wrong number of arguments for " + this.name +
                        ' (' + args.length + ' for ' + this.arity + ')' };
                }

                frame.prependRule(new(tree.Rule)(name, val));
                evaldArguments[i] = val;
            }
        }

        if (params[i].variadic && args) {
            for (j = argIndex; j < args.length; j++) {
                evaldArguments[j] = args[j].value.eval(env);
            }
        }
        argIndex++;
    }

    return frame;
},
eval: function (env, args, important) {
    var _arguments = [],
        mixinFrames = this.frames.concat(env.frames),
        frame = this.evalParams(env, new(tree.evalEnv)(env, mixinFrames), args, _arguments),
        rules, ruleset;

    frame.prependRule(new(tree.Rule)('@arguments', new(tree.Expression)(_arguments).eval(env)));

    rules = this.rules.slice(0);

    ruleset = new(tree.Ruleset)(null, rules);
    ruleset.originalRuleset = this;
    ruleset = ruleset.eval(new(tree.evalEnv)(env, [this, frame].concat(mixinFrames)));
    if (important) {
        ruleset = this.parent.makeImportant.apply(ruleset);
    }
    return ruleset;
},
matchCondition: function (args, env) {
    if (this.condition && !this.condition.eval(
        new(tree.evalEnv)(env,
            [this.evalParams(env, new(tree.evalEnv)(env, this.frames.concat(env.frames)), args, [])] // the parameter variables
                .concat(this.frames) // the parent namespace/mixin frames
                .concat(env.frames)))) { // the current environment frames
        return false;
    }
    return true;
},
matchArgs: function (args, env) {
    var argsLength = (args && args.length) || 0, len;

    if (! this.variadic) {
        if (argsLength < this.required)                               { return false; }
        if (argsLength > this.params.length)                          { return false; }
    } else {
        if (argsLength < (this.required - 1))                         { return false; }
    }

    len = Math.min(argsLength, this.arity);

    for (var i = 0; i < len; i++) {
        if (!this.params[i].name && !this.params[i].variadic) {
            if (args[i].value.eval(env).toCSS() != this.params[i].value.eval(env).toCSS()) {
                return false;
            }
        }
    }
    return true;
}

};

})(require(‘../tree’));

(function (tree) {

tree.Negative = function (node) {

this.value = node;

}; tree.Negative.prototype = {

type: "Negative",
accept: function (visitor) {
    this.value = visitor.visit(this.value);
},
genCSS: function (env, output) {
    output.add('-');
    this.value.genCSS(env, output);
},
toCSS: tree.toCSS,
eval: function (env) {
    if (env.isMathOn()) {
        return (new(tree.Operation)('*', [new(tree.Dimension)(-1), this.value])).eval(env);
    }
    return new(tree.Negative)(this.value.eval(env));
}

};

})(require(‘../tree’));

(function (tree) {

tree.Operation = function (op, operands, isSpaced) {

this.op = op.trim();
this.operands = operands;
this.isSpaced = isSpaced;

}; tree.Operation.prototype = {

type: "Operation",
accept: function (visitor) {
    this.operands = visitor.visit(this.operands);
},
eval: function (env) {
    var a = this.operands[0].eval(env),
        b = this.operands[1].eval(env);

    if (env.isMathOn()) {
        if (a instanceof tree.Dimension && b instanceof tree.Color) {
            a = a.toColor();
        }
        if (b instanceof tree.Dimension && a instanceof tree.Color) {
            b = b.toColor();
        }
        if (!a.operate) {
            throw { type: "Operation",
                    message: "Operation on an invalid type" };
        }

        return a.operate(env, this.op, b);
    } else {
        return new(tree.Operation)(this.op, [a, b], this.isSpaced);
    }
},
genCSS: function (env, output) {
    this.operands[0].genCSS(env, output);
    if (this.isSpaced) {
        output.add(" ");
    }
    output.add(this.op);
    if (this.isSpaced) {
        output.add(" ");
    }
    this.operands[1].genCSS(env, output);
},
toCSS: tree.toCSS

};

tree.operate = function (env, op, a, b) {

switch (op) {
    case '+': return a + b;
    case '-': return a - b;
    case '*': return a * b;
    case '/': return a / b;
}

};

})(require(‘../tree’));

(function (tree) {

tree.Paren = function (node) {

this.value = node;

}; tree.Paren.prototype = {

type: "Paren",
accept: function (visitor) {
    this.value = visitor.visit(this.value);
},
genCSS: function (env, output) {
    output.add('(');
    this.value.genCSS(env, output);
    output.add(')');
},
toCSS: tree.toCSS,
eval: function (env) {
    return new(tree.Paren)(this.value.eval(env));
}

};

})(require(‘../tree’));

(function (tree) {

tree.Quoted = function (str, content, escaped, index, currentFileInfo) {

this.escaped = escaped;
this.value = content || '';
this.quote = str.charAt(0);
this.index = index;
this.currentFileInfo = currentFileInfo;

}; tree.Quoted.prototype = {

type: "Quoted",
genCSS: function (env, output) {
    if (!this.escaped) {
        output.add(this.quote, this.currentFileInfo, this.index);
    }
    output.add(this.value);
    if (!this.escaped) {
        output.add(this.quote);
    }
},
toCSS: tree.toCSS,
eval: function (env) {
    var that = this;
    var value = this.value.replace(/`([^`]+)`/g, function (_, exp) {
        return new(tree.JavaScript)(exp, that.index, true).eval(env).value;
    }).replace(/@\{([\w-]+)\}/g, function (_, name) {
        var v = new(tree.Variable)('@' + name, that.index, that.currentFileInfo).eval(env, true);
        return (v instanceof tree.Quoted) ? v.value : v.toCSS();
    });
    return new(tree.Quoted)(this.quote + value + this.quote, value, this.escaped, this.index, this.currentFileInfo);
},
compare: function (x) {
    if (!x.toCSS) {
        return -1;
    }

    var left = this.toCSS(),
        right = x.toCSS();

    if (left === right) {
        return 0;
    }

    return left < right ? -1 : 1;
}

};

})(require(‘../tree’));

(function (tree) {

tree.Rule = function (name, value, important, merge, index, currentFileInfo, inline) {

this.name = name;
this.value = (value instanceof tree.Value) ? value : new(tree.Value)([value]);
this.important = important ? ' ' + important.trim() : '';
this.merge = merge;
this.index = index;
this.currentFileInfo = currentFileInfo;
this.inline = inline || false;
this.variable = name.charAt && (name.charAt(0) === '@');

};

tree.Rule.prototype = {

type: "Rule",
accept: function (visitor) {
    this.value = visitor.visit(this.value);
},
genCSS: function (env, output) {
    output.add(this.name + (env.compress ? ':' : ': '), this.currentFileInfo, this.index);
    try {
        this.value.genCSS(env, output);
    }
    catch(e) {
        e.index = this.index;
        e.filename = this.currentFileInfo.filename;
        throw e;
    }
    output.add(this.important + ((this.inline || (env.lastRule && env.compress)) ? "" : ";"), this.currentFileInfo, this.index);
},
toCSS: tree.toCSS,
eval: function (env) {
    var strictMathBypass = false, name = this.name;    
    if (typeof name !== "string") {
        // expand 'primitive' name directly to get
        // things faster (~10% for benchmark.less):
        name = (name.length === 1) 
            && (name[0] instanceof tree.Keyword)
                ? name[0].value : evalName(env, name);
    }
    if (name === "font" && !env.strictMath) {
        strictMathBypass = true;
        env.strictMath = true;
    }
    try {
        return new(tree.Rule)(name,
                          this.value.eval(env),
                          this.important,
                          this.merge,
                          this.index, this.currentFileInfo, this.inline);
    }
    catch(e) {
        e.index = e.index || this.index;
        throw e;
    }
    finally {
        if (strictMathBypass) {
            env.strictMath = false;
        }
    }
},
makeImportant: function () {
    return new(tree.Rule)(this.name,
                          this.value,
                          "!important",
                          this.merge,
                          this.index, this.currentFileInfo, this.inline);
}

};

function evalName(env, name) {

var value = "", i, n = name.length,
    output = {add: function (s) {value += s;}};
for (i = 0; i < n; i++) {
    name[i].eval(env).genCSS(env, output);
}
return value;

}

})(require(‘../tree’));

(function (tree) {

tree.Ruleset = function (selectors, rules, strictImports) {

this.selectors = selectors;
this.rules = rules;
this._lookups = {};
this.strictImports = strictImports;

}; tree.Ruleset.prototype = {

type: "Ruleset",
accept: function (visitor) {
    if (this.paths) {
        visitor.visitArray(this.paths, true);
    } else if (this.selectors) {
        this.selectors = visitor.visitArray(this.selectors);
    }
    if (this.rules && this.rules.length) {
        this.rules = visitor.visitArray(this.rules);
    }
},
eval: function (env) {
    var thisSelectors = this.selectors, selectors, 
        selCnt, i, defaultFunc = tree.defaultFunc;
    if (thisSelectors && (selCnt = thisSelectors.length)) {
        selectors = [];
        defaultFunc.error({
            type: "Syntax", 
            message: "it is currently only allowed in parametric mixin guards," 
        });
        for (i = 0; i < selCnt; i++) {
            selectors.push(thisSelectors[i].eval(env));
        }
        defaultFunc.reset();  
    }

    var rules = this.rules ? this.rules.slice(0) : null,
        ruleset = new(tree.Ruleset)(selectors, rules, this.strictImports),
        rule, subRule;

    ruleset.originalRuleset = this;
    ruleset.root = this.root;
    ruleset.firstRoot = this.firstRoot;
    ruleset.allowImports = this.allowImports;

    if(this.debugInfo) {
        ruleset.debugInfo = this.debugInfo;
    }

    // push the current ruleset to the frames stack
    var envFrames = env.frames;
    envFrames.unshift(ruleset);

    // currrent selectors
    var envSelectors = env.selectors;
    if (!envSelectors) {
        env.selectors = envSelectors = [];
    }
    envSelectors.unshift(this.selectors);

    // Evaluate imports
    if (ruleset.root || ruleset.allowImports || !ruleset.strictImports) {
        ruleset.evalImports(env);
    }

    // Store the frames around mixin definitions,
    // so they can be evaluated like closures when the time comes.
    var rsRules = ruleset.rules, rsRuleCnt = rsRules ? rsRules.length : 0;
    for (i = 0; i < rsRuleCnt; i++) {
        if (rsRules[i] instanceof tree.mixin.Definition) {
            rsRules[i].frames = envFrames.slice(0);
        }
    }

    var mediaBlockCount = (env.mediaBlocks && env.mediaBlocks.length) || 0;

    // Evaluate mixin calls.
    for (i = 0; i < rsRuleCnt; i++) {
        if (rsRules[i] instanceof tree.mixin.Call) {
            /*jshint loopfunc:true */
            rules = rsRules[i].eval(env).filter(function(r) {
                if ((r instanceof tree.Rule) && r.variable) {
                    // do not pollute the scope if the variable is
                    // already there. consider returning false here
                    // but we need a way to "return" variable from mixins
                    return !(ruleset.variable(r.name));
                }
                return true;
            });
            rsRules.splice.apply(rsRules, [i, 1].concat(rules));
            rsRuleCnt += rules.length - 1;
            i += rules.length-1;
            ruleset.resetCache();
        }
    }

    // Evaluate everything else
    for (i = 0; i < rsRules.length; i++) {
        rule = rsRules[i];
        if (! (rule instanceof tree.mixin.Definition)) {
            rsRules[i] = rule = rule.eval ? rule.eval(env) : rule;
            // for rulesets, check if it is a css guard and can be removed
            if (rule instanceof tree.Ruleset && rule.selectors && rule.selectors.length === 1) {
                // check if it can be folded in (e.g. & where)
                if (rule.selectors[0].isJustParentSelector()) {
                    rsRules.splice(i--, 1);
                    // cannot call if there is no selector, so we can just continue
                    if (!rule.selectors[0].evaldCondition) {
                        continue;
                    }
                    for(var j = 0; j < rule.rules.length; j++) {
                        subRule = rule.rules[j];
                        if (!(subRule instanceof tree.Rule) || !subRule.variable) {
                            rsRules.splice(++i, 0, subRule);
                        }
                    }
                }
            }
        }
    }

    // Pop the stack
    envFrames.shift();
    envSelectors.shift();

    if (env.mediaBlocks) {
        for (i = mediaBlockCount; i < env.mediaBlocks.length; i++) {
            env.mediaBlocks[i].bubbleSelectors(selectors);
        }
    }

    return ruleset;
},
evalImports: function(env) {
    var rules = this.rules, i, importRules;
    if (!rules) { return; }

    for (i = 0; i < rules.length; i++) {
        if (rules[i] instanceof tree.Import) {
            importRules = rules[i].eval(env);
            if (importRules && importRules.length) {
                rules.splice.apply(rules, [i, 1].concat(importRules));
                i+= importRules.length-1;
            } else {
                rules.splice(i, 1, importRules);
            }
            this.resetCache();
        }
    }
},
makeImportant: function() {
    return new tree.Ruleset(this.selectors, this.rules.map(function (r) {
                if (r.makeImportant) {
                    return r.makeImportant();
                } else {
                    return r;
                }
            }), this.strictImports);
},
matchArgs: function (args) {
    return !args || args.length === 0;
},
// lets you call a css selector with a guard
matchCondition: function (args, env) {
    var lastSelector = this.selectors[this.selectors.length-1];
    if (!lastSelector.evaldCondition) {
        return false;
    }
    if (lastSelector.condition &&
        !lastSelector.condition.eval(
            new(tree.evalEnv)(env,
                env.frames))) {
        return false;
    }
    return true;
},
resetCache: function () {
    this._rulesets = null;
    this._variables = null;
    this._lookups = {};
},
variables: function () {
    if (!this._variables) {
        this._variables = !this.rules ? {} : this.rules.reduce(function (hash, r) {
            if (r instanceof tree.Rule && r.variable === true) {
                hash[r.name] = r;
            }
            return hash;
        }, {});
    }
    return this._variables;
},
variable: function (name) {
    return this.variables()[name];
},
rulesets: function () {
    if (!this.rules) { return null; }

    var _Ruleset = tree.Ruleset, _MixinDefinition = tree.mixin.Definition,
        filtRules = [], rules = this.rules, cnt = rules.length,
        i, rule;

    for (i = 0; i < cnt; i++) {
        rule = rules[i];
        if ((rule instanceof _Ruleset) || (rule instanceof _MixinDefinition)) {
            filtRules.push(rule);
        }
    }

    return filtRules;
},
prependRule: function (rule) {
    var rules = this.rules;
    if (rules) { rules.unshift(rule); } else { this.rules = [ rule ]; }
},
find: function (selector, self) {
    self = self || this;
    var rules = [], match,
        key = selector.toCSS();

    if (key in this._lookups) { return this._lookups[key]; }

    this.rulesets().forEach(function (rule) {
        if (rule !== self) {
            for (var j = 0; j < rule.selectors.length; j++) {
                match = selector.match(rule.selectors[j]);
                if (match) {
                    if (selector.elements.length > match) {
                        Array.prototype.push.apply(rules, rule.find(
                            new(tree.Selector)(selector.elements.slice(match)), self));
                    } else {
                        rules.push(rule);
                    }
                    break;
                }
            }
        }
    });
    this._lookups[key] = rules;
    return rules;
},
genCSS: function (env, output) {
    var i, j,
        ruleNodes = [],
        rulesetNodes = [],
        rulesetNodeCnt,
        debugInfo,     // Line number debugging
        rule,
        path;

    env.tabLevel = (env.tabLevel || 0);

    if (!this.root) {
        env.tabLevel++;
    }

    var tabRuleStr = env.compress ? '' : Array(env.tabLevel + 1).join("  "),
        tabSetStr = env.compress ? '' : Array(env.tabLevel).join("  "),
        sep;

    for (i = 0; i < this.rules.length; i++) {
        rule = this.rules[i];
        if (rule.rules || (rule instanceof tree.Media) || rule instanceof tree.Directive || (this.root && rule instanceof tree.Comment)) {
            rulesetNodes.push(rule);
        } else {
            ruleNodes.push(rule);
        }
    }

    // If this is the root node, we don't render
    // a selector, or {}.
    if (!this.root) {
        debugInfo = tree.debugInfo(env, this, tabSetStr);

        if (debugInfo) {
            output.add(debugInfo);
            output.add(tabSetStr);
        }

        var paths = this.paths, pathCnt = paths.length,
            pathSubCnt;

        sep = env.compress ? ',' : (',\n' + tabSetStr);

        for (i = 0; i < pathCnt; i++) {
            path = paths[i];
            if (!(pathSubCnt = path.length)) { continue; }
            if (i > 0) { output.add(sep); }

            env.firstSelector = true;
            path[0].genCSS(env, output);

            env.firstSelector = false;
            for (j = 1; j < pathSubCnt; j++) {
                path[j].genCSS(env, output);
            }
        }

        output.add((env.compress ? '{' : ' {\n') + tabRuleStr);
    }

    // Compile rules and rulesets
    for (i = 0; i < ruleNodes.length; i++) {
        rule = ruleNodes[i];

        // @page{ directive ends up with root elements inside it, a mix of rules and rulesets
        // In this instance we do not know whether it is the last property
        if (i + 1 === ruleNodes.length && (!this.root || rulesetNodes.length === 0 || this.firstRoot)) {
            env.lastRule = true;
        }

        if (rule.genCSS) {
            rule.genCSS(env, output);
        } else if (rule.value) {
            output.add(rule.value.toString());
        }

        if (!env.lastRule) {
            output.add(env.compress ? '' : ('\n' + tabRuleStr));
        } else {
            env.lastRule = false;
        }
    }

    if (!this.root) {
        output.add((env.compress ? '}' : '\n' + tabSetStr + '}'));
        env.tabLevel--;
    }

    sep = (env.compress ? "" : "\n") + (this.root ? tabRuleStr : tabSetStr);
    rulesetNodeCnt = rulesetNodes.length;
    if (rulesetNodeCnt) {
        if (ruleNodes.length && sep) { output.add(sep); }
        rulesetNodes[0].genCSS(env, output);
        for (i = 1; i < rulesetNodeCnt; i++) {
            if (sep) { output.add(sep); }
            rulesetNodes[i].genCSS(env, output);
        }
    }

    if (!output.isEmpty() && !env.compress && this.firstRoot) {
        output.add('\n');
    }
},

toCSS: tree.toCSS,

markReferenced: function () {
    for (var s = 0; s < this.selectors.length; s++) {
        this.selectors[s].markReferenced();
    }
},

joinSelectors: function (paths, context, selectors) {
    for (var s = 0; s < selectors.length; s++) {
        this.joinSelector(paths, context, selectors[s]);
    }
},

joinSelector: function (paths, context, selector) {

    var i, j, k, 
        hasParentSelector, newSelectors, el, sel, parentSel, 
        newSelectorPath, afterParentJoin, newJoinedSelector, 
        newJoinedSelectorEmpty, lastSelector, currentElements,
        selectorsMultiplied;

    for (i = 0; i < selector.elements.length; i++) {
        el = selector.elements[i];
        if (el.value === '&') {
            hasParentSelector = true;
        }
    }

    if (!hasParentSelector) {
        if (context.length > 0) {
            for (i = 0; i < context.length; i++) {
                paths.push(context[i].concat(selector));
            }
        }
        else {
            paths.push([selector]);
        }
        return;
    }

    // The paths are [[Selector]]
    // The first list is a list of comma seperated selectors
    // The inner list is a list of inheritance seperated selectors
    // e.g.
    // .a, .b {
    //   .c {
    //   }
    // }
    // == [[.a] [.c]] [[.b] [.c]]
    //

    // the elements from the current selector so far
    currentElements = [];
    // the current list of new selectors to add to the path.
    // We will build it up. We initiate it with one empty selector as we "multiply" the new selectors
    // by the parents
    newSelectors = [[]];

    for (i = 0; i < selector.elements.length; i++) {
        el = selector.elements[i];
        // non parent reference elements just get added
        if (el.value !== "&") {
            currentElements.push(el);
        } else {
            // the new list of selectors to add
            selectorsMultiplied = [];

            // merge the current list of non parent selector elements
            // on to the current list of selectors to add
            if (currentElements.length > 0) {
                this.mergeElementsOnToSelectors(currentElements, newSelectors);
            }

            // loop through our current selectors
            for (j = 0; j < newSelectors.length; j++) {
                sel = newSelectors[j];
                // if we don't have any parent paths, the & might be in a mixin so that it can be used
                // whether there are parents or not
                if (context.length === 0) {
                    // the combinator used on el should now be applied to the next element instead so that
                    // it is not lost
                    if (sel.length > 0) {
                        sel[0].elements = sel[0].elements.slice(0);
                        sel[0].elements.push(new(tree.Element)(el.combinator, '', el.index, el.currentFileInfo));
                    }
                    selectorsMultiplied.push(sel);
                }
                else {
                    // and the parent selectors
                    for (k = 0; k < context.length; k++) {
                        parentSel = context[k];
                        // We need to put the current selectors
                        // then join the last selector's elements on to the parents selectors

                        // our new selector path
                        newSelectorPath = [];
                        // selectors from the parent after the join
                        afterParentJoin = [];
                        newJoinedSelectorEmpty = true;

                        //construct the joined selector - if & is the first thing this will be empty,
                        // if not newJoinedSelector will be the last set of elements in the selector
                        if (sel.length > 0) {
                            newSelectorPath = sel.slice(0);
                            lastSelector = newSelectorPath.pop();
                            newJoinedSelector = selector.createDerived(lastSelector.elements.slice(0));
                            newJoinedSelectorEmpty = false;
                        }
                        else {
                            newJoinedSelector = selector.createDerived([]);
                        }

                        //put together the parent selectors after the join
                        if (parentSel.length > 1) {
                            afterParentJoin = afterParentJoin.concat(parentSel.slice(1));
                        }

                        if (parentSel.length > 0) {
                            newJoinedSelectorEmpty = false;

                            // join the elements so far with the first part of the parent
                            newJoinedSelector.elements.push(new(tree.Element)(el.combinator, parentSel[0].elements[0].value, el.index, el.currentFileInfo));
                            newJoinedSelector.elements = newJoinedSelector.elements.concat(parentSel[0].elements.slice(1));
                        }

                        if (!newJoinedSelectorEmpty) {
                            // now add the joined selector
                            newSelectorPath.push(newJoinedSelector);
                        }

                        // and the rest of the parent
                        newSelectorPath = newSelectorPath.concat(afterParentJoin);

                        // add that to our new set of selectors
                        selectorsMultiplied.push(newSelectorPath);
                    }
                }
            }

            // our new selectors has been multiplied, so reset the state
            newSelectors = selectorsMultiplied;
            currentElements = [];
        }
    }

    // if we have any elements left over (e.g. .a& .b == .b)
    // add them on to all the current selectors
    if (currentElements.length > 0) {
        this.mergeElementsOnToSelectors(currentElements, newSelectors);
    }

    for (i = 0; i < newSelectors.length; i++) {
        if (newSelectors[i].length > 0) {
            paths.push(newSelectors[i]);
        }
    }
},

mergeElementsOnToSelectors: function(elements, selectors) {
    var i, sel;

    if (selectors.length === 0) {
        selectors.push([ new(tree.Selector)(elements) ]);
        return;
    }

    for (i = 0; i < selectors.length; i++) {
        sel = selectors[i];

        // if the previous thing in sel is a parent this needs to join on to it
        if (sel.length > 0) {
            sel[sel.length - 1] = sel[sel.length - 1].createDerived(sel[sel.length - 1].elements.concat(elements));
        }
        else {
            sel.push(new(tree.Selector)(elements));
        }
    }
}

}; })(require(‘../tree’));

(function (tree) {

tree.Selector = function (elements, extendList, condition, index, currentFileInfo, isReferenced) {

this.elements = elements;
this.extendList = extendList;
this.condition = condition;
this.currentFileInfo = currentFileInfo || {};
this.isReferenced = isReferenced;
if (!condition) {
    this.evaldCondition = true;
}

}; tree.Selector.prototype = {

type: "Selector",
accept: function (visitor) {
    if (this.elements) {
        this.elements = visitor.visitArray(this.elements);
    }
    if (this.extendList) {
        this.extendList = visitor.visitArray(this.extendList);
    }
    if (this.condition) {
        this.condition = visitor.visit(this.condition);
    }
},
createDerived: function(elements, extendList, evaldCondition) {
    evaldCondition = (evaldCondition != null) ? evaldCondition : this.evaldCondition;
    var newSelector = new(tree.Selector)(elements, extendList || this.extendList, null, this.index, this.currentFileInfo, this.isReferenced);
    newSelector.evaldCondition = evaldCondition;
    newSelector.mediaEmpty = this.mediaEmpty;
    return newSelector;
},
match: function (other) {
    var elements = this.elements,
        len = elements.length,
        olen, i;

    other.CacheElements();

    olen = other._elements.length;
    if (olen === 0 || len < olen) {
        return 0;
    } else {
        for (i = 0; i < olen; i++) {
            if (elements[i].value !== other._elements[i]) {
                return 0;
            }
        }
    }

    return olen; // return number of matched elements
},
CacheElements: function(){
    var css = '', len, v, i;

    if( !this._elements ){

        len = this.elements.length;
        for(i = 0; i < len; i++){

            v = this.elements[i];
            css += v.combinator.value;

            if( !v.value.value ){
                css += v.value;
                continue;
            }

            if( typeof v.value.value !== "string" ){
                css = '';
                break;
            }
            css += v.value.value;
        }

        this._elements = css.match(/[,&#\.\w-]([\w-]|(\\.))*/g);

        if (this._elements) {
            if (this._elements[0] === "&") {
                this._elements.shift();
            }

        } else {
            this._elements = [];
        }

    }
},
isJustParentSelector: function() {
    return !this.mediaEmpty && 
        this.elements.length === 1 && 
        this.elements[0].value === '&' && 
        (this.elements[0].combinator.value === ' ' || this.elements[0].combinator.value === '');
},
eval: function (env) {
    var evaldCondition = this.condition && this.condition.eval(env),
        elements = this.elements, extendList = this.extendList;

    elements = elements && elements.map(function (e) { return e.eval(env); });
    extendList = extendList && extendList.map(function(extend) { return extend.eval(env); });

    return this.createDerived(elements, extendList, evaldCondition);
},
genCSS: function (env, output) {
    var i, element;
    if ((!env || !env.firstSelector) && this.elements[0].combinator.value === "") {
        output.add(' ', this.currentFileInfo, this.index);
    }
    if (!this._css) {
        //TODO caching? speed comparison?
        for(i = 0; i < this.elements.length; i++) {
            element = this.elements[i];
            element.genCSS(env, output);
        }
    }
},
toCSS: tree.toCSS,
markReferenced: function () {
    this.isReferenced = true;
},
getIsReferenced: function() {
    return !this.currentFileInfo.reference || this.isReferenced;
},
getIsOutput: function() {
    return this.evaldCondition;
}

};

})(require(‘../tree’));

(function (tree) {

tree.UnicodeDescriptor = function (value) {

this.value = value;

}; tree.UnicodeDescriptor.prototype = {

type: "UnicodeDescriptor",
genCSS: function (env, output) {
    output.add(this.value);
},
toCSS: tree.toCSS,
eval: function () { return this; }

};

})(require(‘../tree’));

(function (tree) {

tree.URL = function (val, currentFileInfo, isEvald) {

this.value = val;
this.currentFileInfo = currentFileInfo;
this.isEvald = isEvald;

}; tree.URL.prototype = {

type: "Url",
accept: function (visitor) {
    this.value = visitor.visit(this.value);
},
genCSS: function (env, output) {
    output.add("url(");
    this.value.genCSS(env, output);
    output.add(")");
},
toCSS: tree.toCSS,
eval: function (ctx) {
    var val = this.value.eval(ctx),
        rootpath;

    if (!this.isEvald) {
        // Add the base path if the URL is relative
        rootpath = this.currentFileInfo && this.currentFileInfo.rootpath;
        if (rootpath && typeof val.value === "string" && ctx.isPathRelative(val.value)) {
            if (!val.quote) {
                rootpath = rootpath.replace(/[\(\)'"\s]/g, function(match) { return "\\"+match; });
            }
            val.value = rootpath + val.value;
        }

        val.value = ctx.normalizePath(val.value);

        // Add url args if enabled
        if (ctx.urlArgs) {
            if (!val.value.match(/^\s*data:/)) {
                var delimiter = val.value.indexOf('?') === -1 ? '?' : '&';
                var urlArgs = delimiter + ctx.urlArgs;
                if (val.value.indexOf('#') !== -1) {
                    val.value = val.value.replace('#', urlArgs + '#');
                } else {
                    val.value += urlArgs;
                }
            }
        }
    }

    return new(tree.URL)(val, this.currentFileInfo, true);
}

};

})(require(‘../tree’));

(function (tree) {

tree.Value = function (value) {

this.value = value;

}; tree.Value.prototype = {

type: "Value",
accept: function (visitor) {
    if (this.value) {
        this.value = visitor.visitArray(this.value);
    }
},
eval: function (env) {
    if (this.value.length === 1) {
        return this.value[0].eval(env);
    } else {
        return new(tree.Value)(this.value.map(function (v) {
            return v.eval(env);
        }));
    }
},
genCSS: function (env, output) {
    var i;
    for(i = 0; i < this.value.length; i++) {
        this.value[i].genCSS(env, output);
        if (i+1 < this.value.length) {
            output.add((env && env.compress) ? ',' : ', ');
        }
    }
},
toCSS: tree.toCSS

};

})(require(‘../tree’));

(function (tree) {

tree.Variable = function (name, index, currentFileInfo) {

this.name = name;
this.index = index;
this.currentFileInfo = currentFileInfo || {};

}; tree.Variable.prototype = {

type: "Variable",
eval: function (env) {
    var variable, name = this.name;

    if (name.indexOf('@@') === 0) {
        name = '@' + new(tree.Variable)(name.slice(1)).eval(env).value;
    }

    if (this.evaluating) {
        throw { type: 'Name',
                message: "Recursive variable definition for " + name,
                filename: this.currentFileInfo.file,
                index: this.index };
    }

    this.evaluating = true;

    variable = tree.find(env.frames, function (frame) {
        var v = frame.variable(name);
        if (v) {
            return v.value.eval(env);
        }
    });
    if (variable) { 
        this.evaluating = false;
        return variable;
    } else {
        throw { type: 'Name',
                message: "variable " + name + " is undefined",
                filename: this.currentFileInfo.filename,
                index: this.index };
    }
}

};

})(require(‘../tree’));

(function (tree) {

var parseCopyProperties = [
    'paths',            // option - unmodified - paths to search for imports on
    'optimization',     // option - optimization level (for the chunker)
    'files',            // list of files that have been imported, used for import-once
    'contents',         // map - filename to contents of all the files
    'contentsIgnoredChars', // map - filename to lines at the begining of each file to ignore
    'relativeUrls',     // option - whether to adjust URL's to be relative
    'rootpath',         // option - rootpath to append to URL's
    'strictImports',    // option -
    'insecure',         // option - whether to allow imports from insecure ssl hosts
    'dumpLineNumbers',  // option - whether to dump line numbers
    'compress',         // option - whether to compress
    'processImports',   // option - whether to process imports. if false then imports will not be imported
    'syncImport',       // option - whether to import synchronously
    'javascriptEnabled',// option - whether JavaScript is enabled. if undefined, defaults to true
    'mime',             // browser only - mime type for sheet import
    'useFileCache',     // browser only - whether to use the per file session cache
    'currentFileInfo'   // information about the current file - for error reporting and importing and making urls relative etc.
];

//currentFileInfo = {
//  'relativeUrls' - option - whether to adjust URL's to be relative
//  'filename' - full resolved filename of current file
//  'rootpath' - path to append to normal URLs for this node
//  'currentDirectory' - path to the current file, absolute
//  'rootFilename' - filename of the base file
//  'entryPath' - absolute path to the entry file
//  'reference' - whether the file should not be output and only output parts that are referenced

tree.parseEnv = function(options) {
    copyFromOriginal(options, this, parseCopyProperties);

    if (!this.contents) { this.contents = {}; }
    if (!this.contentsIgnoredChars) { this.contentsIgnoredChars = {}; }
    if (!this.files) { this.files = {}; }

    if (!this.currentFileInfo) {
        var filename = (options && options.filename) || "input";
        var entryPath = filename.replace(/[^\/\\]*$/, "");
        if (options) {
            options.filename = null;
        }
        this.currentFileInfo = {
            filename: filename,
            relativeUrls: this.relativeUrls,
            rootpath: (options && options.rootpath) || "",
            currentDirectory: entryPath,
            entryPath: entryPath,
            rootFilename: filename
        };
    }
};

var evalCopyProperties = [
    'silent',         // whether to swallow errors and warnings
    'verbose',        // whether to log more activity
    'compress',       // whether to compress
    'yuicompress',    // whether to compress with the outside tool yui compressor
    'ieCompat',       // whether to enforce IE compatibility (IE8 data-uri)
    'strictMath',     // whether math has to be within parenthesis
    'strictUnits',    // whether units need to evaluate correctly
    'cleancss',       // whether to compress with clean-css
    'sourceMap',      // whether to output a source map
    'importMultiple', // whether we are currently importing multiple copies
    'urlArgs'         // whether to add args into url tokens
    ];

tree.evalEnv = function(options, frames) {
    copyFromOriginal(options, this, evalCopyProperties);

    this.frames = frames || [];
};

tree.evalEnv.prototype.inParenthesis = function () {
    if (!this.parensStack) {
        this.parensStack = [];
    }
    this.parensStack.push(true);
};

tree.evalEnv.prototype.outOfParenthesis = function () {
    this.parensStack.pop();
};

tree.evalEnv.prototype.isMathOn = function () {
    return this.strictMath ? (this.parensStack && this.parensStack.length) : true;
};

tree.evalEnv.prototype.isPathRelative = function (path) {
    return !/^(?:[a-z-]+:|\/)/.test(path);
};

tree.evalEnv.prototype.normalizePath = function( path ) {
    var
      segments = path.split("/").reverse(),
      segment;

    path = [];
    while (segments.length !== 0 ) {
        segment = segments.pop();
        switch( segment ) {
            case ".":
                break;
            case "..":
                if ((path.length === 0) || (path[path.length - 1] === "..")) {
                    path.push( segment );
                } else {
                    path.pop();
                }
                break;
            default:
                path.push( segment );
                break;
        }
    }

    return path.join("/");
};

//todo - do the same for the toCSS env
//tree.toCSSEnv = function (options) {
//};

var copyFromOriginal = function(original, destination, propertiesToCopy) {
    if (!original) { return; }

    for(var i = 0; i < propertiesToCopy.length; i++) {
        if (original.hasOwnProperty(propertiesToCopy[i])) {
            destination[propertiesToCopy[i]] = original[propertiesToCopy[i]];
        }
    }
};

})(require(‘./tree’));

(function (tree) {

var _visitArgs = { visitDeeper: true },
    _hasIndexed = false;

function _noop(node) {
    return node;
}

function indexNodeTypes(parent, ticker) {
    // add .typeIndex to tree node types for lookup table
    var key, child;
    for (key in parent) {
        if (parent.hasOwnProperty(key)) {
            child = parent[key];
            switch (typeof child) {
                case "function":
                    // ignore bound functions directly on tree which do not have a prototype
                    // or aren't nodes
                    if (child.prototype && child.prototype.type) {
                        child.prototype.typeIndex = ticker++;
                    }
                    break;
                case "object":
                    ticker = indexNodeTypes(child, ticker);
                    break;
            }
        }
    }
    return ticker;
}

tree.visitor = function(implementation) {
    this._implementation = implementation;
    this._visitFnCache = [];

    if (!_hasIndexed) {
        indexNodeTypes(tree, 1);
        _hasIndexed = true;
    }
};

tree.visitor.prototype = {
    visit: function(node) {
        if (!node) {
            return node;
        }

        var nodeTypeIndex = node.typeIndex;
        if (!nodeTypeIndex) {
            return node;
        }

        var visitFnCache = this._visitFnCache,
            impl = this._implementation,
            aryIndx = nodeTypeIndex << 1,
            outAryIndex = aryIndx | 1,
            func = visitFnCache[aryIndx],
            funcOut = visitFnCache[outAryIndex],
            visitArgs = _visitArgs,
            fnName;

        visitArgs.visitDeeper = true;

        if (!func) {
            fnName = "visit" + node.type;
            func = impl[fnName] || _noop;
            funcOut = impl[fnName + "Out"] || _noop;
            visitFnCache[aryIndx] = func;
            visitFnCache[outAryIndex] = funcOut;
        }

        if (func !== _noop) {
            var newNode = func.call(impl, node, visitArgs);
            if (impl.isReplacing) {
                node = newNode;
            }
        }

        if (visitArgs.visitDeeper && node && node.accept) {
            node.accept(this);
        }

        if (funcOut != _noop) {
            funcOut.call(impl, node);
        }

        return node;
    },
    visitArray: function(nodes, nonReplacing) {
        if (!nodes) {
            return nodes;
        }

        var cnt = nodes.length, i;

        // Non-replacing
        if (nonReplacing || !this._implementation.isReplacing) {
            for (i = 0; i < cnt; i++) {
                this.visit(nodes[i]);
            }
            return nodes;
        }

        // Replacing
        var out = [];
        for (i = 0; i < cnt; i++) {
            var evald = this.visit(nodes[i]);
            if (!evald.splice) {
                out.push(evald);
            } else if (evald.length) {
                this.flatten(evald, out);
            }
        }
        return out;
    },
    flatten: function(arr, out) {
        if (!out) {
            out = [];
        }

        var cnt, i, item,
            nestedCnt, j, nestedItem;

        for (i = 0, cnt = arr.length; i < cnt; i++) {
            item = arr[i];
            if (!item.splice) {
                out.push(item);
                continue;
            }

            for (j = 0, nestedCnt = item.length; j < nestedCnt; j++) {
                nestedItem = item[j];
                if (!nestedItem.splice) {
                    out.push(nestedItem);
                } else if (nestedItem.length) {
                    this.flatten(nestedItem, out);
                }
            }
        }

        return out;
    }
};

})(require(‘./tree’)); (function (tree) {

tree.importVisitor = function(importer, finish, evalEnv) {
    this._visitor = new tree.visitor(this);
    this._importer = importer;
    this._finish = finish;
    this.env = evalEnv || new tree.evalEnv();
    this.importCount = 0;
};

tree.importVisitor.prototype = {
    isReplacing: true,
    run: function (root) {
        var error;
        try {
            // process the contents
            this._visitor.visit(root);
        }
        catch(e) {
            error = e;
        }

        this.isFinished = true;

        if (this.importCount === 0) {
            this._finish(error);
        }
    },
    visitImport: function (importNode, visitArgs) {
        var importVisitor = this,
            evaldImportNode,
            inlineCSS = importNode.options.inline;

        if (!importNode.css || inlineCSS) {

            try {
                evaldImportNode = importNode.evalForImport(this.env);
            } catch(e){
                if (!e.filename) { e.index = importNode.index; e.filename = importNode.currentFileInfo.filename; }
                // attempt to eval properly and treat as css
                importNode.css = true;
                // if that fails, this error will be thrown
                importNode.error = e;
            }

            if (evaldImportNode && (!evaldImportNode.css || inlineCSS)) {
                importNode = evaldImportNode;
                this.importCount++;
                var env = new tree.evalEnv(this.env, this.env.frames.slice(0));

                if (importNode.options.multiple) {
                    env.importMultiple = true;
                }

                this._importer.push(importNode.getPath(), importNode.currentFileInfo, importNode.options, function (e, root, imported, fullPath) {
                    if (e && !e.filename) { e.index = importNode.index; e.filename = importNode.currentFileInfo.filename; }

                    if (imported && !env.importMultiple) { importNode.skip = imported; }

                    var subFinish = function(e) {
                        importVisitor.importCount--;

                        if (importVisitor.importCount === 0 && importVisitor.isFinished) {
                            importVisitor._finish(e);
                        }
                    };

                    if (root) {
                        importNode.root = root;
                        importNode.importedFilename = fullPath;
                        if (!inlineCSS && !importNode.skip) {
                            new(tree.importVisitor)(importVisitor._importer, subFinish, env)
                                .run(root);
                            return;
                        }
                    }

                    subFinish();
                });
            }
        }
        visitArgs.visitDeeper = false;
        return importNode;
    },
    visitRule: function (ruleNode, visitArgs) {
        visitArgs.visitDeeper = false;
        return ruleNode;
    },
    visitDirective: function (directiveNode, visitArgs) {
        this.env.frames.unshift(directiveNode);
        return directiveNode;
    },
    visitDirectiveOut: function (directiveNode) {
        this.env.frames.shift();
    },
    visitMixinDefinition: function (mixinDefinitionNode, visitArgs) {
        this.env.frames.unshift(mixinDefinitionNode);
        return mixinDefinitionNode;
    },
    visitMixinDefinitionOut: function (mixinDefinitionNode) {
        this.env.frames.shift();
    },
    visitRuleset: function (rulesetNode, visitArgs) {
        this.env.frames.unshift(rulesetNode);
        return rulesetNode;
    },
    visitRulesetOut: function (rulesetNode) {
        this.env.frames.shift();
    },
    visitMedia: function (mediaNode, visitArgs) {
        this.env.frames.unshift(mediaNode.ruleset);
        return mediaNode;
    },
    visitMediaOut: function (mediaNode) {
        this.env.frames.shift();
    }
};

})(require(‘./tree’)); (function (tree) {

tree.joinSelectorVisitor = function() {
    this.contexts = [[]];
    this._visitor = new tree.visitor(this);
};

tree.joinSelectorVisitor.prototype = {
    run: function (root) {
        return this._visitor.visit(root);
    },
    visitRule: function (ruleNode, visitArgs) {
        visitArgs.visitDeeper = false;
    },
    visitMixinDefinition: function (mixinDefinitionNode, visitArgs) {
        visitArgs.visitDeeper = false;
    },

    visitRuleset: function (rulesetNode, visitArgs) {
        var context = this.contexts[this.contexts.length - 1],
            paths = [], selectors;

        this.contexts.push(paths);

        if (! rulesetNode.root) {
            selectors = rulesetNode.selectors;
            if (selectors) {
                selectors = selectors.filter(function(selector) { return selector.getIsOutput(); });
                rulesetNode.selectors = selectors.length ? selectors : (selectors = null);
                if (selectors) { rulesetNode.joinSelectors(paths, context, selectors); }
            }
            if (!selectors) { rulesetNode.rules = null; }
            rulesetNode.paths = paths;
        }
    },
    visitRulesetOut: function (rulesetNode) {
        this.contexts.length = this.contexts.length - 1;
    },
    visitMedia: function (mediaNode, visitArgs) {
        var context = this.contexts[this.contexts.length - 1];
        mediaNode.rules[0].root = (context.length === 0 || context[0].multiMedia);
    }
};

})(require(‘./tree’)); (function (tree) {

tree.toCSSVisitor = function(env) {
    this._visitor = new tree.visitor(this);
    this._env = env;
};

tree.toCSSVisitor.prototype = {
    isReplacing: true,
    run: function (root) {
        return this._visitor.visit(root);
    },

    visitRule: function (ruleNode, visitArgs) {
        if (ruleNode.variable) {
            return [];
        }
        return ruleNode;
    },

    visitMixinDefinition: function (mixinNode, visitArgs) {
        // mixin definitions do not get eval'd - this means they keep state
        // so we have to clear that state here so it isn't used if toCSS is called twice
        mixinNode.frames = [];
        return [];
    },

    visitExtend: function (extendNode, visitArgs) {
        return [];
    },

    visitComment: function (commentNode, visitArgs) {
        if (commentNode.isSilent(this._env)) {
            return [];
        }
        return commentNode;
    },

    visitMedia: function(mediaNode, visitArgs) {
        mediaNode.accept(this._visitor);
        visitArgs.visitDeeper = false;

        if (!mediaNode.rules.length) {
            return [];
        }
        return mediaNode;
    },

    visitDirective: function(directiveNode, visitArgs) {
        if (directiveNode.currentFileInfo.reference && !directiveNode.isReferenced) {
            return [];
        }
        if (directiveNode.name === "@charset") {
            // Only output the debug info together with subsequent @charset definitions
            // a comment (or @media statement) before the actual @charset directive would
            // be considered illegal css as it has to be on the first line
            if (this.charset) {
                if (directiveNode.debugInfo) {
                    var comment = new tree.Comment("/* " + directiveNode.toCSS(this._env).replace(/\n/g, "")+" */\n");
                    comment.debugInfo = directiveNode.debugInfo;
                    return this._visitor.visit(comment);
                }
                return [];
            }
            this.charset = true;
        }
        return directiveNode;
    },

    checkPropertiesInRoot: function(rules) {
        var ruleNode;
        for(var i = 0; i < rules.length; i++) {
            ruleNode = rules[i];
            if (ruleNode instanceof tree.Rule && !ruleNode.variable) {
                throw { message: "properties must be inside selector blocks, they cannot be in the root.",
                    index: ruleNode.index, filename: ruleNode.currentFileInfo ? ruleNode.currentFileInfo.filename : null};
            }
        }
    },

    visitRuleset: function (rulesetNode, visitArgs) {
        var rule, rulesets = [];
        if (rulesetNode.firstRoot) {
            this.checkPropertiesInRoot(rulesetNode.rules);
        }
        if (! rulesetNode.root) {
            if (rulesetNode.paths) {
                rulesetNode.paths = rulesetNode.paths
                    .filter(function(p) {
                        var i;
                        if (p[0].elements[0].combinator.value === ' ') {
                            p[0].elements[0].combinator = new(tree.Combinator)('');
                        }
                        for(i = 0; i < p.length; i++) {
                            if (p[i].getIsReferenced() && p[i].getIsOutput()) {
                                return true;
                            }
                        }
                        return false;
                    });
            }

            // Compile rules and rulesets
            var nodeRules = rulesetNode.rules, nodeRuleCnt = nodeRules ? nodeRules.length : 0;
            for (var i = 0; i < nodeRuleCnt; ) {
                rule = nodeRules[i];
                if (rule && rule.rules) {
                    // visit because we are moving them out from being a child
                    rulesets.push(this._visitor.visit(rule));
                    nodeRules.splice(i, 1);
                    nodeRuleCnt--;
                    continue;
                }
                i++;
            }
            // accept the visitor to remove rules and refactor itself
            // then we can decide now whether we want it or not
            if (nodeRuleCnt > 0) {
                rulesetNode.accept(this._visitor);
            } else {
                rulesetNode.rules = null;
            }
            visitArgs.visitDeeper = false;

            nodeRules = rulesetNode.rules;
            if (nodeRules) {
                this._mergeRules(nodeRules);
                nodeRules = rulesetNode.rules;
            }
            if (nodeRules) {
                this._removeDuplicateRules(nodeRules);
                nodeRules = rulesetNode.rules;
            }

            // now decide whether we keep the ruleset
            if (nodeRules && nodeRules.length > 0 && rulesetNode.paths.length > 0) {
                rulesets.splice(0, 0, rulesetNode);
            }
        } else {
            rulesetNode.accept(this._visitor);
            visitArgs.visitDeeper = false;
            if (rulesetNode.firstRoot || (rulesetNode.rules && rulesetNode.rules.length > 0)) {
                rulesets.splice(0, 0, rulesetNode);
            }
        }
        if (rulesets.length === 1) {
            return rulesets[0];
        }
        return rulesets;
    },

    _removeDuplicateRules: function(rules) {
        if (!rules) { return; }

        // remove duplicates
        var ruleCache = {},
            ruleList, rule, i;

        for(i = rules.length - 1; i >= 0 ; i--) {
            rule = rules[i];
            if (rule instanceof tree.Rule) {
                if (!ruleCache[rule.name]) {
                    ruleCache[rule.name] = rule;
                } else {
                    ruleList = ruleCache[rule.name];
                    if (ruleList instanceof tree.Rule) {
                        ruleList = ruleCache[rule.name] = [ruleCache[rule.name].toCSS(this._env)];
                    }
                    var ruleCSS = rule.toCSS(this._env);
                    if (ruleList.indexOf(ruleCSS) !== -1) {
                        rules.splice(i, 1);
                    } else {
                        ruleList.push(ruleCSS);
                    }
                }
            }
        }
    },

    _mergeRules: function (rules) {
        if (!rules) { return; }

        var groups = {},
            parts,
            rule,
            key;

        for (var i = 0; i < rules.length; i++) {
            rule = rules[i];

            if ((rule instanceof tree.Rule) && rule.merge) {
                key = [rule.name,
                    rule.important ? "!" : ""].join(",");

                if (!groups[key]) {
                    groups[key] = [];
                } else {
                    rules.splice(i--, 1);
                }

                groups[key].push(rule);
            }
        }

        Object.keys(groups).map(function (k) {
            parts = groups[k];

            if (parts.length > 1) {
                rule = parts[0];

                rule.value = new (tree.Value)(parts.map(function (p) {
                    return p.value;
                }));
            }
        });
    }
};

})(require(‘./tree’)); (function (tree) {

/*jshint loopfunc:true */

tree.extendFinderVisitor = function() {
    this._visitor = new tree.visitor(this);
    this.contexts = [];
    this.allExtendsStack = [[]];
};

tree.extendFinderVisitor.prototype = {
    run: function (root) {
        root = this._visitor.visit(root);
        root.allExtends = this.allExtendsStack[0];
        return root;
    },
    visitRule: function (ruleNode, visitArgs) {
        visitArgs.visitDeeper = false;
    },
    visitMixinDefinition: function (mixinDefinitionNode, visitArgs) {
        visitArgs.visitDeeper = false;
    },
    visitRuleset: function (rulesetNode, visitArgs) {
        if (rulesetNode.root) {
            return;
        }

        var i, j, extend, allSelectorsExtendList = [], extendList;

        // get &:extend(.a); rules which apply to all selectors in this ruleset
        var rules = rulesetNode.rules, ruleCnt = rules ? rules.length : 0;
        for(i = 0; i < ruleCnt; i++) {
            if (rulesetNode.rules[i] instanceof tree.Extend) {
                allSelectorsExtendList.push(rules[i]);
                rulesetNode.extendOnEveryPath = true;
            }
        }

        // now find every selector and apply the extends that apply to all extends
        // and the ones which apply to an individual extend
        var paths = rulesetNode.paths;
        for(i = 0; i < paths.length; i++) {
            var selectorPath = paths[i],
                selector = selectorPath[selectorPath.length - 1],
                selExtendList = selector.extendList;

            extendList = selExtendList ? selExtendList.slice(0).concat(allSelectorsExtendList)
                                       : allSelectorsExtendList;

            if (extendList) {
                extendList = extendList.map(function(allSelectorsExtend) {
                    return allSelectorsExtend.clone();
                });
            }

            for(j = 0; j < extendList.length; j++) {
                this.foundExtends = true;
                extend = extendList[j];
                extend.findSelfSelectors(selectorPath);
                extend.ruleset = rulesetNode;
                if (j === 0) { extend.firstExtendOnThisSelectorPath = true; }
                this.allExtendsStack[this.allExtendsStack.length-1].push(extend);
            }
        }

        this.contexts.push(rulesetNode.selectors);
    },
    visitRulesetOut: function (rulesetNode) {
        if (!rulesetNode.root) {
            this.contexts.length = this.contexts.length - 1;
        }
    },
    visitMedia: function (mediaNode, visitArgs) {
        mediaNode.allExtends = [];
        this.allExtendsStack.push(mediaNode.allExtends);
    },
    visitMediaOut: function (mediaNode) {
        this.allExtendsStack.length = this.allExtendsStack.length - 1;
    },
    visitDirective: function (directiveNode, visitArgs) {
        directiveNode.allExtends = [];
        this.allExtendsStack.push(directiveNode.allExtends);
    },
    visitDirectiveOut: function (directiveNode) {
        this.allExtendsStack.length = this.allExtendsStack.length - 1;
    }
};

tree.processExtendsVisitor = function() {
    this._visitor = new tree.visitor(this);
};

tree.processExtendsVisitor.prototype = {
    run: function(root) {
        var extendFinder = new tree.extendFinderVisitor();
        extendFinder.run(root);
        if (!extendFinder.foundExtends) { return root; }
        root.allExtends = root.allExtends.concat(this.doExtendChaining(root.allExtends, root.allExtends));
        this.allExtendsStack = [root.allExtends];
        return this._visitor.visit(root);
    },
    doExtendChaining: function (extendsList, extendsListTarget, iterationCount) {
        //
        // chaining is different from normal extension.. if we extend an extend then we are not just copying, altering and pasting
        // the selector we would do normally, but we are also adding an extend with the same target selector
        // this means this new extend can then go and alter other extends
        //
        // this method deals with all the chaining work - without it, extend is flat and doesn't work on other extend selectors
        // this is also the most expensive.. and a match on one selector can cause an extension of a selector we had already processed if
        // we look at each selector at a time, as is done in visitRuleset

        var extendIndex, targetExtendIndex, matches, extendsToAdd = [], newSelector, extendVisitor = this, selectorPath, extend, targetExtend, newExtend;

        iterationCount = iterationCount || 0;

        //loop through comparing every extend with every target extend.
        // a target extend is the one on the ruleset we are looking at copy/edit/pasting in place
        // e.g.  .a:extend(.b) {}  and .b:extend(.c) {} then the first extend extends the second one
        // and the second is the target.
        // the seperation into two lists allows us to process a subset of chains with a bigger set, as is the
        // case when processing media queries
        for(extendIndex = 0; extendIndex < extendsList.length; extendIndex++){
            for(targetExtendIndex = 0; targetExtendIndex < extendsListTarget.length; targetExtendIndex++){

                extend = extendsList[extendIndex];
                targetExtend = extendsListTarget[targetExtendIndex];

                // look for circular references
                if( extend.parent_ids.indexOf( targetExtend.object_id ) >= 0 ){ continue; }

                // find a match in the target extends self selector (the bit before :extend)
                selectorPath = [targetExtend.selfSelectors[0]];
                matches = extendVisitor.findMatch(extend, selectorPath);

                if (matches.length) {

                    // we found a match, so for each self selector..
                    extend.selfSelectors.forEach(function(selfSelector) {

                        // process the extend as usual
                        newSelector = extendVisitor.extendSelector(matches, selectorPath, selfSelector);

                        // but now we create a new extend from it
                        newExtend = new(tree.Extend)(targetExtend.selector, targetExtend.option, 0);
                        newExtend.selfSelectors = newSelector;

                        // add the extend onto the list of extends for that selector
                        newSelector[newSelector.length-1].extendList = [newExtend];

                        // record that we need to add it.
                        extendsToAdd.push(newExtend);
                        newExtend.ruleset = targetExtend.ruleset;

                        //remember its parents for circular references
                        newExtend.parent_ids = newExtend.parent_ids.concat(targetExtend.parent_ids, extend.parent_ids);

                        // only process the selector once.. if we have :extend(.a,.b) then multiple
                        // extends will look at the same selector path, so when extending
                        // we know that any others will be duplicates in terms of what is added to the css
                        if (targetExtend.firstExtendOnThisSelectorPath) {
                            newExtend.firstExtendOnThisSelectorPath = true;
                            targetExtend.ruleset.paths.push(newSelector);
                        }
                    });
                }
            }
        }

        if (extendsToAdd.length) {
            // try to detect circular references to stop a stack overflow.
            // may no longer be needed.
            this.extendChainCount++;
            if (iterationCount > 100) {
                var selectorOne = "{unable to calculate}";
                var selectorTwo = "{unable to calculate}";
                try
                {
                    selectorOne = extendsToAdd[0].selfSelectors[0].toCSS();
                    selectorTwo = extendsToAdd[0].selector.toCSS();
                }
                catch(e) {}
                throw {message: "extend circular reference detected. One of the circular extends is currently:"+selectorOne+":extend(" + selectorTwo+")"};
            }

            // now process the new extends on the existing rules so that we can handle a extending b extending c ectending d extending e...
            return extendsToAdd.concat(extendVisitor.doExtendChaining(extendsToAdd, extendsListTarget, iterationCount+1));
        } else {
            return extendsToAdd;
        }
    },
    visitRule: function (ruleNode, visitArgs) {
        visitArgs.visitDeeper = false;
    },
    visitMixinDefinition: function (mixinDefinitionNode, visitArgs) {
        visitArgs.visitDeeper = false;
    },
    visitSelector: function (selectorNode, visitArgs) {
        visitArgs.visitDeeper = false;
    },
    visitRuleset: function (rulesetNode, visitArgs) {
        if (rulesetNode.root) {
            return;
        }
        var matches, pathIndex, extendIndex, allExtends = this.allExtendsStack[this.allExtendsStack.length-1], selectorsToAdd = [], extendVisitor = this, selectorPath;

        // look at each selector path in the ruleset, find any extend matches and then copy, find and replace

        for(extendIndex = 0; extendIndex < allExtends.length; extendIndex++) {
            for(pathIndex = 0; pathIndex < rulesetNode.paths.length; pathIndex++) {
                selectorPath = rulesetNode.paths[pathIndex];

                // extending extends happens initially, before the main pass
                if (rulesetNode.extendOnEveryPath) { continue; }
                var extendList = selectorPath[selectorPath.length-1].extendList;
                if (extendList && extendList.length) { continue; }

                matches = this.findMatch(allExtends[extendIndex], selectorPath);

                if (matches.length) {

                    allExtends[extendIndex].selfSelectors.forEach(function(selfSelector) {
                        selectorsToAdd.push(extendVisitor.extendSelector(matches, selectorPath, selfSelector));
                    });
                }
            }
        }
        rulesetNode.paths = rulesetNode.paths.concat(selectorsToAdd);
    },
    findMatch: function (extend, haystackSelectorPath) {
        //
        // look through the haystack selector path to try and find the needle - extend.selector
        // returns an array of selector matches that can then be replaced
        //
        var haystackSelectorIndex, hackstackSelector, hackstackElementIndex, haystackElement,
            targetCombinator, i,
            extendVisitor = this,
            needleElements = extend.selector.elements,
            potentialMatches = [], potentialMatch, matches = [];

        // loop through the haystack elements
        for(haystackSelectorIndex = 0; haystackSelectorIndex < haystackSelectorPath.length; haystackSelectorIndex++) {
            hackstackSelector = haystackSelectorPath[haystackSelectorIndex];

            for(hackstackElementIndex = 0; hackstackElementIndex < hackstackSelector.elements.length; hackstackElementIndex++) {

                haystackElement = hackstackSelector.elements[hackstackElementIndex];

                // if we allow elements before our match we can add a potential match every time. otherwise only at the first element.
                if (extend.allowBefore || (haystackSelectorIndex === 0 && hackstackElementIndex === 0)) {
                    potentialMatches.push({pathIndex: haystackSelectorIndex, index: hackstackElementIndex, matched: 0, initialCombinator: haystackElement.combinator});
                }

                for(i = 0; i < potentialMatches.length; i++) {
                    potentialMatch = potentialMatches[i];

                    // selectors add " " onto the first element. When we use & it joins the selectors together, but if we don't
                    // then each selector in haystackSelectorPath has a space before it added in the toCSS phase. so we need to work out
                    // what the resulting combinator will be
                    targetCombinator = haystackElement.combinator.value;
                    if (targetCombinator === '' && hackstackElementIndex === 0) {
                        targetCombinator = ' ';
                    }

                    // if we don't match, null our match to indicate failure
                    if (!extendVisitor.isElementValuesEqual(needleElements[potentialMatch.matched].value, haystackElement.value) ||
                        (potentialMatch.matched > 0 && needleElements[potentialMatch.matched].combinator.value !== targetCombinator)) {
                        potentialMatch = null;
                    } else {
                        potentialMatch.matched++;
                    }

                    // if we are still valid and have finished, test whether we have elements after and whether these are allowed
                    if (potentialMatch) {
                        potentialMatch.finished = potentialMatch.matched === needleElements.length;
                        if (potentialMatch.finished &&
                            (!extend.allowAfter && (hackstackElementIndex+1 < hackstackSelector.elements.length || haystackSelectorIndex+1 < haystackSelectorPath.length))) {
                            potentialMatch = null;
                        }
                    }
                    // if null we remove, if not, we are still valid, so either push as a valid match or continue
                    if (potentialMatch) {
                        if (potentialMatch.finished) {
                            potentialMatch.length = needleElements.length;
                            potentialMatch.endPathIndex = haystackSelectorIndex;
                            potentialMatch.endPathElementIndex = hackstackElementIndex + 1; // index after end of match
                            potentialMatches.length = 0; // we don't allow matches to overlap, so start matching again
                            matches.push(potentialMatch);
                        }
                    } else {
                        potentialMatches.splice(i, 1);
                        i--;
                    }
                }
            }
        }
        return matches;
    },
    isElementValuesEqual: function(elementValue1, elementValue2) {
        if (typeof elementValue1 === "string" || typeof elementValue2 === "string") {
            return elementValue1 === elementValue2;
        }
        if (elementValue1 instanceof tree.Attribute) {
            if (elementValue1.op !== elementValue2.op || elementValue1.key !== elementValue2.key) {
                return false;
            }
            if (!elementValue1.value || !elementValue2.value) {
                if (elementValue1.value || elementValue2.value) {
                    return false;
                }
                return true;
            }
            elementValue1 = elementValue1.value.value || elementValue1.value;
            elementValue2 = elementValue2.value.value || elementValue2.value;
            return elementValue1 === elementValue2;
        }
        elementValue1 = elementValue1.value;
        elementValue2 = elementValue2.value;
        if (elementValue1 instanceof tree.Selector) {
            if (!(elementValue2 instanceof tree.Selector) || elementValue1.elements.length !== elementValue2.elements.length) {
                return false;
            }
            for(var i = 0; i <elementValue1.elements.length; i++) {
                if (elementValue1.elements[i].combinator.value !== elementValue2.elements[i].combinator.value) {
                    if (i !== 0 || (elementValue1.elements[i].combinator.value || ' ') !== (elementValue2.elements[i].combinator.value || ' ')) {
                        return false;
                    }
                }
                if (!this.isElementValuesEqual(elementValue1.elements[i].value, elementValue2.elements[i].value)) {
                    return false;
                }
            }
            return true;
        }
        return false;
    },
    extendSelector:function (matches, selectorPath, replacementSelector) {

        //for a set of matches, replace each match with the replacement selector

        var currentSelectorPathIndex = 0,
            currentSelectorPathElementIndex = 0,
            path = [],
            matchIndex,
            selector,
            firstElement,
            match,
            newElements;

        for (matchIndex = 0; matchIndex < matches.length; matchIndex++) {
            match = matches[matchIndex];
            selector = selectorPath[match.pathIndex];
            firstElement = new tree.Element(
                match.initialCombinator,
                replacementSelector.elements[0].value,
                replacementSelector.elements[0].index,
                replacementSelector.elements[0].currentFileInfo
            );

            if (match.pathIndex > currentSelectorPathIndex && currentSelectorPathElementIndex > 0) {
                path[path.length - 1].elements = path[path.length - 1].elements.concat(selectorPath[currentSelectorPathIndex].elements.slice(currentSelectorPathElementIndex));
                currentSelectorPathElementIndex = 0;
                currentSelectorPathIndex++;
            }

            newElements = selector.elements
                .slice(currentSelectorPathElementIndex, match.index)
                .concat([firstElement])
                .concat(replacementSelector.elements.slice(1));

            if (currentSelectorPathIndex === match.pathIndex && matchIndex > 0) {
                path[path.length - 1].elements =
                    path[path.length - 1].elements.concat(newElements);
            } else {
                path = path.concat(selectorPath.slice(currentSelectorPathIndex, match.pathIndex));

                path.push(new tree.Selector(
                    newElements
                ));
            }
            currentSelectorPathIndex = match.endPathIndex;
            currentSelectorPathElementIndex = match.endPathElementIndex;
            if (currentSelectorPathElementIndex >= selectorPath[currentSelectorPathIndex].elements.length) {
                currentSelectorPathElementIndex = 0;
                currentSelectorPathIndex++;
            }
        }

        if (currentSelectorPathIndex < selectorPath.length && currentSelectorPathElementIndex > 0) {
            path[path.length - 1].elements = path[path.length - 1].elements.concat(selectorPath[currentSelectorPathIndex].elements.slice(currentSelectorPathElementIndex));
            currentSelectorPathIndex++;
        }

        path = path.concat(selectorPath.slice(currentSelectorPathIndex, selectorPath.length));

        return path;
    },
    visitRulesetOut: function (rulesetNode) {
    },
    visitMedia: function (mediaNode, visitArgs) {
        var newAllExtends = mediaNode.allExtends.concat(this.allExtendsStack[this.allExtendsStack.length-1]);
        newAllExtends = newAllExtends.concat(this.doExtendChaining(newAllExtends, mediaNode.allExtends));
        this.allExtendsStack.push(newAllExtends);
    },
    visitMediaOut: function (mediaNode) {
        this.allExtendsStack.length = this.allExtendsStack.length - 1;
    },
    visitDirective: function (directiveNode, visitArgs) {
        var newAllExtends = directiveNode.allExtends.concat(this.allExtendsStack[this.allExtendsStack.length-1]);
        newAllExtends = newAllExtends.concat(this.doExtendChaining(newAllExtends, directiveNode.allExtends));
        this.allExtendsStack.push(newAllExtends);
    },
    visitDirectiveOut: function (directiveNode) {
        this.allExtendsStack.length = this.allExtendsStack.length - 1;
    }
};

})(require(‘./tree’));

(function (tree) {

tree.sourceMapOutput = function (options) {
    this._css = [];
    this._rootNode = options.rootNode;
    this._writeSourceMap = options.writeSourceMap;
    this._contentsMap = options.contentsMap;
    this._contentsIgnoredCharsMap = options.contentsIgnoredCharsMap;
    this._sourceMapFilename = options.sourceMapFilename;
    this._outputFilename = options.outputFilename;
    this._sourceMapURL = options.sourceMapURL;
    if (options.sourceMapBasepath) {
        this._sourceMapBasepath = options.sourceMapBasepath.replace(/\\/g, '/');
    }
    this._sourceMapRootpath = options.sourceMapRootpath;
    this._outputSourceFiles = options.outputSourceFiles;
    this._sourceMapGeneratorConstructor = options.sourceMapGenerator || require("source-map").SourceMapGenerator;

    if (this._sourceMapRootpath && this._sourceMapRootpath.charAt(this._sourceMapRootpath.length-1) !== '/') {
        this._sourceMapRootpath += '/';
    }

    this._lineNumber = 0;
    this._column = 0;
};

tree.sourceMapOutput.prototype.normalizeFilename = function(filename) {
    filename = filename.replace(/\\/g, '/');

    if (this._sourceMapBasepath && filename.indexOf(this._sourceMapBasepath) === 0) {
        filename = filename.substring(this._sourceMapBasepath.length);
        if (filename.charAt(0) === '\\' || filename.charAt(0) === '/') {
           filename = filename.substring(1);
        }
    }
    return (this._sourceMapRootpath || "") + filename;
};

tree.sourceMapOutput.prototype.add = function(chunk, fileInfo, index, mapLines) {

    //ignore adding empty strings
    if (!chunk) {
        return;
    }

    var lines,
        sourceLines,
        columns,
        sourceColumns,
        i;

    if (fileInfo) {
        var inputSource = this._contentsMap[fileInfo.filename];

        // remove vars/banner added to the top of the file
        if (this._contentsIgnoredCharsMap[fileInfo.filename]) {
            // adjust the index
            index -= this._contentsIgnoredCharsMap[fileInfo.filename];
            if (index < 0) { index = 0; }
            // adjust the source
            inputSource = inputSource.slice(this._contentsIgnoredCharsMap[fileInfo.filename]);
        }
        inputSource = inputSource.substring(0, index);
        sourceLines = inputSource.split("\n");
        sourceColumns = sourceLines[sourceLines.length-1];
    }

    lines = chunk.split("\n");
    columns = lines[lines.length-1];

    if (fileInfo) {
        if (!mapLines) {
            this._sourceMapGenerator.addMapping({ generated: { line: this._lineNumber + 1, column: this._column},
                original: { line: sourceLines.length, column: sourceColumns.length},
                source: this.normalizeFilename(fileInfo.filename)});
        } else {
            for(i = 0; i < lines.length; i++) {
                this._sourceMapGenerator.addMapping({ generated: { line: this._lineNumber + i + 1, column: i === 0 ? this._column : 0},
                    original: { line: sourceLines.length + i, column: i === 0 ? sourceColumns.length : 0},
                    source: this.normalizeFilename(fileInfo.filename)});
            }
        }
    }

    if (lines.length === 1) {
        this._column += columns.length;
    } else {
        this._lineNumber += lines.length - 1;
        this._column = columns.length;
    }

    this._css.push(chunk);
};

tree.sourceMapOutput.prototype.isEmpty = function() {
    return this._css.length === 0;
};

tree.sourceMapOutput.prototype.toCSS = function(env) {
    this._sourceMapGenerator = new this._sourceMapGeneratorConstructor({ file: this._outputFilename, sourceRoot: null });

    if (this._outputSourceFiles) {
        for(var filename in this._contentsMap) {
            if (this._contentsMap.hasOwnProperty(filename))
            {
                var source = this._contentsMap[filename];
                if (this._contentsIgnoredCharsMap[filename]) {
                    source = source.slice(this._contentsIgnoredCharsMap[filename]);
                }
                this._sourceMapGenerator.setSourceContent(this.normalizeFilename(filename), source);
            }
        }
    }

    this._rootNode.genCSS(env, this);

    if (this._css.length > 0) {
        var sourceMapURL,
            sourceMapContent = JSON.stringify(this._sourceMapGenerator.toJSON());

        if (this._sourceMapURL) {
            sourceMapURL = this._sourceMapURL;
        } else if (this._sourceMapFilename) {
            sourceMapURL = this.normalizeFilename(this._sourceMapFilename);
        }

        if (this._writeSourceMap) {
            this._writeSourceMap(sourceMapContent);
        } else {
            sourceMapURL = "data:application/json," + encodeURIComponent(sourceMapContent);
        }

        if (sourceMapURL) {
            this._css.push("/*# sourceMappingURL=" + sourceMapURL + " */");
        }
    }

    return this._css.join('');
};

})(require(‘./tree’));

// // browser.js - client-side engine // /*global less, window, document, XMLHttpRequest, location */

var isFileProtocol = /^(file|chrome(-extension)?|resource|qrc|app):/.test(location.protocol);

less.env = less.env || (location.hostname == ‘127.0.0.1’ ||

location.hostname == '0.0.0.0'   ||
location.hostname == 'localhost' ||
(location.port &&
  location.port.length > 0)      ||
isFileProtocol                   ? 'development'
                                 : 'production');

var logLevel = {

info: 2,
errors: 1,
none: 0

};

// The amount of logging in the javascript console. // 2 - Information and errors // 1 - Errors // 0 - None // Defaults to 2 less.logLevel = typeof(less.logLevel) != ‘undefined’ ? less.logLevel : logLevel.info;

// Load styles asynchronously (default: false) // // This is set to ‘false` by default, so that the body // doesn’t start loading before the stylesheets are parsed. // Setting this to ‘true` can result in flickering. // less.async = less.async || false; less.fileAsync = less.fileAsync || false;

// Interval between watch polls less.poll = less.poll || (isFileProtocol ? 1000 : 1500);

//Setup user functions if (less.functions) {

 for(var func in less.functions) {
     if (less.functions.hasOwnProperty(func)) {
         less.tree.functions[func] = less.functions[func];
     }
}

}

var dumpLineNumbers = /!dumpLineNumbers:(comments|mediaquery|all)/.exec(location.hash); if (dumpLineNumbers) {

less.dumpLineNumbers = dumpLineNumbers[1];

}

var typePattern = /^text/(x-)?less$/; var cache = null; var fileCache = {};

function log(str, level) {

if (less.env == 'development' && typeof(console) !== 'undefined' && less.logLevel >= level) {
    console.log('less: ' + str);
}

}

function extractId(href) {

return href.replace(/^[a-z-]+:\/+?[^\/]+/, '' )  // Remove protocol & domain
    .replace(/^\//,                 '' )  // Remove root /
    .replace(/\.[a-zA-Z]+$/,        '' )  // Remove simple extension
    .replace(/[^\.\w-]+/g,          '-')  // Replace illegal characters
    .replace(/\./g,                 ':'); // Replace dots with colons(for valid id)

}

function errorConsole(e, rootHref) {

var template = '{line} {content}';
var filename = e.filename || rootHref;
var errors = [];
var content = (e.type || "Syntax") + "Error: " + (e.message || 'There is an error in your .less file') +
    " in " + filename + " ";

var errorline = function (e, i, classname) {
    if (e.extract[i] !== undefined) {
        errors.push(template.replace(/\{line\}/, (parseInt(e.line, 10) || 0) + (i - 1))
            .replace(/\{class\}/, classname)
            .replace(/\{content\}/, e.extract[i]));
    }
};

if (e.extract) {
    errorline(e, 0, '');
    errorline(e, 1, 'line');
    errorline(e, 2, '');
    content += 'on line ' + e.line + ', column ' + (e.column + 1) + ':\n' +
        errors.join('\n');
} else if (e.stack) {
    content += e.stack;
}
log(content, logLevel.errors);

}

function createCSS(styles, sheet, lastModified) {

// Strip the query-string
var href = sheet.href || '';

// If there is no title set, use the filename, minus the extension
var id = 'less:' + (sheet.title || extractId(href));

// If this has already been inserted into the DOM, we may need to replace it
var oldCss = document.getElementById(id);
var keepOldCss = false;

// Create a new stylesheet node for insertion or (if necessary) replacement
var css = document.createElement('style');
css.setAttribute('type', 'text/css');
if (sheet.media) {
    css.setAttribute('media', sheet.media);
}
css.id = id;

if (css.styleSheet) { // IE
    try {
        css.styleSheet.cssText = styles;
    } catch (e) {
        throw new(Error)("Couldn't reassign styleSheet.cssText.");
    }
} else {
    css.appendChild(document.createTextNode(styles));

    // If new contents match contents of oldCss, don't replace oldCss
    keepOldCss = (oldCss !== null && oldCss.childNodes.length > 0 && css.childNodes.length > 0 &&
        oldCss.firstChild.nodeValue === css.firstChild.nodeValue);
}

var head = document.getElementsByTagName('head')[0];

// If there is no oldCss, just append; otherwise, only append if we need
// to replace oldCss with an updated stylesheet
if (oldCss === null || keepOldCss === false) {
    var nextEl = sheet && sheet.nextSibling || null;
    if (nextEl) {
        nextEl.parentNode.insertBefore(css, nextEl);
    } else {
        head.appendChild(css);
    }
}
if (oldCss && keepOldCss === false) {
    oldCss.parentNode.removeChild(oldCss);
}

// Don't update the local store if the file wasn't modified
if (lastModified && cache) {
    log('saving ' + href + ' to cache.', logLevel.info);
    try {
        cache.setItem(href, styles);
        cache.setItem(href + ':timestamp', lastModified);
    } catch(e) {
        //TODO - could do with adding more robust error handling
        log('failed to save', logLevel.errors);
    }
}

}

function errorHTML(e, rootHref) {

var id = 'less-error-message:' + extractId(rootHref || "");
var template = '<li><label>{line}</label><pre class="{class}">{content}</pre></li>';
var elem = document.createElement('div'), timer, content, errors = [];
var filename = e.filename || rootHref;
var filenameNoPath = filename.match(/([^\/]+(\?.*)?)$/)[1];

elem.id        = id;
elem.className = "less-error-message";

content = '<h3>'  + (e.type || "Syntax") + "Error: " + (e.message || 'There is an error in your .less file') +
    '</h3>' + '<p>in <a href="' + filename   + '">' + filenameNoPath + "</a> ";

var errorline = function (e, i, classname) {
    if (e.extract[i] !== undefined) {
        errors.push(template.replace(/\{line\}/, (parseInt(e.line, 10) || 0) + (i - 1))
            .replace(/\{class\}/, classname)
            .replace(/\{content\}/, e.extract[i]));
    }
};

if (e.extract) {
    errorline(e, 0, '');
    errorline(e, 1, 'line');
    errorline(e, 2, '');
    content += 'on line ' + e.line + ', column ' + (e.column + 1) + ':</p>' +
        '<ul>' + errors.join('') + '</ul>';
} else if (e.stack) {
    content += '<br/>' + e.stack.split('\n').slice(1).join('<br/>');
}
elem.innerHTML = content;

// CSS for error messages
createCSS([
    '.less-error-message ul, .less-error-message li {',
    'list-style-type: none;',
    'margin-right: 15px;',
    'padding: 4px 0;',
    'margin: 0;',
    '}',
    '.less-error-message label {',
    'font-size: 12px;',
    'margin-right: 15px;',
    'padding: 4px 0;',
    'color: #cc7777;',
    '}',
    '.less-error-message pre {',
    'color: #dd6666;',
    'padding: 4px 0;',
    'margin: 0;',
    'display: inline-block;',
    '}',
    '.less-error-message pre.line {',
    'color: #ff0000;',
    '}',
    '.less-error-message h3 {',
    'font-size: 20px;',
    'font-weight: bold;',
    'padding: 15px 0 5px 0;',
    'margin: 0;',
    '}',
    '.less-error-message a {',
    'color: #10a',
    '}',
    '.less-error-message .error {',
    'color: red;',
    'font-weight: bold;',
    'padding-bottom: 2px;',
    'border-bottom: 1px dashed red;',
    '}'
].join('\n'), { title: 'error-message' });

elem.style.cssText = [
    "font-family: Arial, sans-serif",
    "border: 1px solid #e00",
    "background-color: #eee",
    "border-radius: 5px",
    "-webkit-border-radius: 5px",
    "-moz-border-radius: 5px",
    "color: #e00",
    "padding: 15px",
    "margin-bottom: 15px"
].join(';');

if (less.env == 'development') {
    timer = setInterval(function () {
        if (document.body) {
            if (document.getElementById(id)) {
                document.body.replaceChild(elem, document.getElementById(id));
            } else {
                document.body.insertBefore(elem, document.body.firstChild);
            }
            clearInterval(timer);
        }
    }, 10);
}

}

function error(e, rootHref) {

if (!less.errorReporting || less.errorReporting === "html") {
    errorHTML(e, rootHref);
} else if (less.errorReporting === "console") {
    errorConsole(e, rootHref);
} else if (typeof less.errorReporting === 'function') {
    less.errorReporting("add", e, rootHref);
}

}

function removeErrorHTML(path) {

var node = document.getElementById('less-error-message:' + extractId(path));
if (node) {
    node.parentNode.removeChild(node);
}

}

function removeErrorConsole(path) {

//no action

}

function removeError(path) {

if (!less.errorReporting || less.errorReporting === "html") {
    removeErrorHTML(path);
} else if (less.errorReporting === "console") {
    removeErrorConsole(path);
} else if (typeof less.errorReporting === 'function') {
    less.errorReporting("remove", path);
}

}

function loadStyles(modifyVars) {

var styles = document.getElementsByTagName('style'),
    style;
for (var i = 0; i < styles.length; i++) {
    style = styles[i];
    if (style.type.match(typePattern)) {
        var env = new less.tree.parseEnv(less),
            lessText = style.innerHTML || '';
        env.filename = document.location.href.replace(/#.*$/, '');

        if (modifyVars || less.globalVars) {
            env.useFileCache = true;
        }

        /*jshint loopfunc:true */
        // use closure to store current value of i
        var callback = (function(style) {
            return function (e, cssAST) {
                if (e) {
                    return error(e, "inline");
                }
                var css = cssAST.toCSS(less);
                style.type = 'text/css';
                if (style.styleSheet) {
                    style.styleSheet.cssText = css;
                } else {
                    style.innerHTML = css;
                }
            };
        })(style);
        new(less.Parser)(env).parse(lessText, callback, {globalVars: less.globalVars, modifyVars: modifyVars});
    }
}

}

function extractUrlParts(url, baseUrl) {

// urlParts[1] = protocol&hostname || /
// urlParts[2] = / if path relative to host base
// urlParts[3] = directories
// urlParts[4] = filename
// urlParts[5] = parameters

var urlPartsRegex = /^((?:[a-z-]+:)?\/+?(?:[^\/\?#]*\/)|([\/\\]))?((?:[^\/\\\?#]*[\/\\])*)([^\/\\\?#]*)([#\?].*)?$/i,
    urlParts = url.match(urlPartsRegex),
    returner = {}, directories = [], i, baseUrlParts;

if (!urlParts) {
    throw new Error("Could not parse sheet href - '"+url+"'");
}

// Stylesheets in IE don't always return the full path
if (!urlParts[1] || urlParts[2]) {
    baseUrlParts = baseUrl.match(urlPartsRegex);
    if (!baseUrlParts) {
        throw new Error("Could not parse page url - '"+baseUrl+"'");
    }
    urlParts[1] = urlParts[1] || baseUrlParts[1] || "";
    if (!urlParts[2]) {
        urlParts[3] = baseUrlParts[3] + urlParts[3];
    }
}

if (urlParts[3]) {
    directories = urlParts[3].replace(/\\/g, "/").split("/");

    // extract out . before .. so .. doesn't absorb a non-directory
    for(i = 0; i < directories.length; i++) {
        if (directories[i] === ".") {
            directories.splice(i, 1);
            i -= 1;
        }
    }

    for(i = 0; i < directories.length; i++) {
        if (directories[i] === ".." && i > 0) {
            directories.splice(i-1, 2);
            i -= 2;
        }
    }
}

returner.hostPart = urlParts[1];
returner.directories = directories;
returner.path = urlParts[1] + directories.join("/");
returner.fileUrl = returner.path + (urlParts[4] || "");
returner.url = returner.fileUrl + (urlParts[5] || "");
return returner;

}

function pathDiff(url, baseUrl) {

// diff between two paths to create a relative path

var urlParts = extractUrlParts(url),
    baseUrlParts = extractUrlParts(baseUrl),
    i, max, urlDirectories, baseUrlDirectories, diff = "";
if (urlParts.hostPart !== baseUrlParts.hostPart) {
    return "";
}
max = Math.max(baseUrlParts.directories.length, urlParts.directories.length);
for(i = 0; i < max; i++) {
    if (baseUrlParts.directories[i] !== urlParts.directories[i]) { break; }
}
baseUrlDirectories = baseUrlParts.directories.slice(i);
urlDirectories = urlParts.directories.slice(i);
for(i = 0; i < baseUrlDirectories.length-1; i++) {
    diff += "../";
}
for(i = 0; i < urlDirectories.length-1; i++) {
    diff += urlDirectories[i] + "/";
}
return diff;

}

function getXMLHttpRequest() {

if (window.XMLHttpRequest) {
    return new XMLHttpRequest();
} else {
    try {
        /*global ActiveXObject */
        return new ActiveXObject("MSXML2.XMLHTTP.3.0");
    } catch (e) {
        log("browser doesn't support AJAX.", logLevel.errors);
        return null;
    }
}

}

function doXHR(url, type, callback, errback) {

var xhr = getXMLHttpRequest();
var async = isFileProtocol ? less.fileAsync : less.async;

if (typeof(xhr.overrideMimeType) === 'function') {
    xhr.overrideMimeType('text/css');
}
log("XHR: Getting '" + url + "'", logLevel.info);
xhr.open('GET', url, async);
xhr.setRequestHeader('Accept', type || 'text/x-less, text/css; q=0.9, */*; q=0.5');
xhr.send(null);

function handleResponse(xhr, callback, errback) {
    if (xhr.status >= 200 && xhr.status < 300) {
        callback(xhr.responseText,
            xhr.getResponseHeader("Last-Modified"));
    } else if (typeof(errback) === 'function') {
        errback(xhr.status, url);
    }
}

if (isFileProtocol && !less.fileAsync) {
    if (xhr.status === 0 || (xhr.status >= 200 && xhr.status < 300)) {
        callback(xhr.responseText);
    } else {
        errback(xhr.status, url);
    }
} else if (async) {
    xhr.onreadystatechange = function () {
        if (xhr.readyState == 4) {
            handleResponse(xhr, callback, errback);
        }
    };
} else {
    handleResponse(xhr, callback, errback);
}

}

function loadFile(originalHref, currentFileInfo, callback, env, modifyVars) {

if (currentFileInfo && currentFileInfo.currentDirectory && !/^([a-z-]+:)?\//.test(originalHref)) {
    originalHref = currentFileInfo.currentDirectory + originalHref;
}

// sheet may be set to the stylesheet for the initial load or a collection of properties including
// some env variables for imports
var hrefParts = extractUrlParts(originalHref, window.location.href);
var href      = hrefParts.url;
var newFileInfo = {
    currentDirectory: hrefParts.path,
    filename: href
};

if (currentFileInfo) {
    newFileInfo.entryPath = currentFileInfo.entryPath;
    newFileInfo.rootpath = currentFileInfo.rootpath;
    newFileInfo.rootFilename = currentFileInfo.rootFilename;
    newFileInfo.relativeUrls = currentFileInfo.relativeUrls;
} else {
    newFileInfo.entryPath = hrefParts.path;
    newFileInfo.rootpath = less.rootpath || hrefParts.path;
    newFileInfo.rootFilename = href;
    newFileInfo.relativeUrls = env.relativeUrls;
}

if (newFileInfo.relativeUrls) {
    if (env.rootpath) {
        newFileInfo.rootpath = extractUrlParts(env.rootpath + pathDiff(hrefParts.path, newFileInfo.entryPath)).path;
    } else {
        newFileInfo.rootpath = hrefParts.path;
    }
}

if (env.useFileCache && fileCache[href]) {
    try {
        var lessText = fileCache[href];
        callback(null, lessText, href, newFileInfo, { lastModified: new Date() });
    } catch (e) {
        callback(e, null, href);
    }
    return;
}

doXHR(href, env.mime, function (data, lastModified) {
    // per file cache
    fileCache[href] = data;

    // Use remote copy (re-parse)
    try {
        callback(null, data, href, newFileInfo, { lastModified: lastModified });
    } catch (e) {
        callback(e, null, href);
    }
}, function (status, url) {
    callback({ type: 'File', message: "'" + url + "' wasn't found (" + status + ")" }, null, href);
});

}

function loadStyleSheet(sheet, callback, reload, remaining, modifyVars) {

var env = new less.tree.parseEnv(less);
env.mime = sheet.type;

if (modifyVars || less.globalVars) {
    env.useFileCache = true;
}

loadFile(sheet.href, null, function(e, data, path, newFileInfo, webInfo) {

    if (webInfo) {
        webInfo.remaining = remaining;

        var css       = cache && cache.getItem(path),
            timestamp = cache && cache.getItem(path + ':timestamp');

        if (!reload && timestamp && webInfo.lastModified &&
            (new(Date)(webInfo.lastModified).valueOf() ===
                new(Date)(timestamp).valueOf())) {
            // Use local copy
            createCSS(css, sheet);
            webInfo.local = true;
            callback(null, null, data, sheet, webInfo, path);
            return;
        }
    }

    //TODO add tests around how this behaves when reloading
    removeError(path);

    if (data) {
        env.currentFileInfo = newFileInfo;
        new(less.Parser)(env).parse(data, function (e, root) {
            if (e) { return callback(e, null, null, sheet); }
            try {
                callback(e, root, data, sheet, webInfo, path);
            } catch (e) {
                callback(e, null, null, sheet);
            }
        }, {modifyVars: modifyVars, globalVars: less.globalVars});
    } else {
        callback(e, null, null, sheet, webInfo, path);
    }
}, env, modifyVars);

}

function loadStyleSheets(callback, reload, modifyVars) {

for (var i = 0; i < less.sheets.length; i++) {
    loadStyleSheet(less.sheets[i], callback, reload, less.sheets.length - (i + 1), modifyVars);
}

}

function initRunningMode(){

if (less.env === 'development') {
    less.optimization = 0;
    less.watchTimer = setInterval(function () {
        if (less.watchMode) {
            loadStyleSheets(function (e, root, _, sheet, env) {
                if (e) {
                    error(e, sheet.href);
                } else if (root) {
                    createCSS(root.toCSS(less), sheet, env.lastModified);
                }
            });
        }
    }, less.poll);
} else {
    less.optimization = 3;
}

}

// // Watch mode // less.watch = function () {

if (!less.watchMode ){
    less.env = 'development';
     initRunningMode();
}
this.watchMode = true;
return true;

};

less.unwatch = function () {clearInterval(less.watchTimer); this.watchMode = false; return false; };

if (/!watch/.test(location.hash)) {

less.watch();

}

if (less.env != ‘development’) {

try {
    cache = (typeof(window.localStorage) === 'undefined') ? null : window.localStorage;
} catch (_) {}

}

// // Get all <link> tags with the ‘rel’ attribute set to “stylesheet/less” // var links = document.getElementsByTagName(‘link’);

less.sheets = [];

for (var i = 0; i < links.length; i++) {

if (links[i].rel === 'stylesheet/less' || (links[i].rel.match(/stylesheet/) &&
   (links[i].type.match(typePattern)))) {
    less.sheets.push(links[i]);
}

}

// // With this function, it’s possible to alter variables and re-render // CSS without reloading less-files // less.modifyVars = function(record) {

less.refresh(false, record);

};

less.refresh = function (reload, modifyVars) {

var startTime, endTime;
startTime = endTime = new Date();

loadStyleSheets(function (e, root, _, sheet, env) {
    if (e) {
        return error(e, sheet.href);
    }
    if (env.local) {
        log("loading " + sheet.href + " from cache.", logLevel.info);
    } else {
        log("parsed " + sheet.href + " successfully.", logLevel.info);
        createCSS(root.toCSS(less), sheet, env.lastModified);
    }
    log("css for " + sheet.href + " generated in " + (new Date() - endTime) + 'ms', logLevel.info);
    if (env.remaining === 0) {
        log("css generated in " + (new Date() - startTime) + 'ms', logLevel.info);
    }
    endTime = new Date();
}, reload, modifyVars);

loadStyles(modifyVars);

};

less.refreshStyles = loadStyles;

less.Parser.fileLoader = loadFile;

less.refresh(less.env === ‘development’);

// amd.js // // Define Less as an AMD module. if (typeof define === “function” && define.amd) {

define(function () { return less; } );

}

})(window);