Class JAXPVariable
- java.lang.Object
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- net.sf.saxon.xpath.JAXPVariable
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- All Implemented Interfaces:
Binding
,VariableDeclaration
public final class JAXPVariable extends java.lang.Object implements VariableDeclaration, Binding
An object representing an XPath variable for use in the JAXP XPath API. The object is created at compile time when the parser tries to bind a variable reference; the value is fetched at run-time from the XPathVariableResolver. With this interface, there is no way of reporting a static error if the variable has not been declared.In Saxon terms, this class is both a VariableDeclaration and a Binding. Unlike a normal VariableDeclaration, it isn't created in advance, but is created on demand when the parser encounters a variable reference. This actually means that if the XPath expression contains two references to the same variable, two VariableDeclarations will be created; however, they will be indistinguishable to the VariableResolver. Acting as a VariableDeclaration, the object goes through the motions of fixing up a binding to a variable reference (in practice, of course, there is exactly one reference to the variable). Acting as a run-time binding, it then evaluates the variable by calling the XPathVariableResolver supplied by the API caller. If no XPathVariableResolver was supplied, an error is reported when a variable is encountered; but if the variable resolver doesn't recognize the variable name, it returns null, which is treated as an empty sequence.
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Constructor Summary
Constructors Modifier Constructor Description protected
JAXPVariable(StructuredQName name, javax.xml.xpath.XPathVariableResolver resolver)
Private constructor: for use only be the protected factory method make()
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description void
addReference(boolean isLoopingReference)
Register a variable reference that refers to the variable bound in this expressionValueRepresentation
evaluateVariable(XPathContext context)
Get the value of the variable.IntegerValue[]
getIntegerBoundsForVariable()
If the variable is bound to an integer, get the minimum and maximum possible values.int
getLocalSlotNumber()
If this is a local variable held on the local stack frame, return the corresponding slot number.SequenceType
getRequiredType()
Get the declared type of the variableStructuredQName
getVariableQName()
Get the name of the variable as a structured QNameboolean
isAssignable()
Test whether it is permitted to assign to the variable using the saxon:assign extension element.boolean
isGlobal()
Indicate whether the binding is local or global.(package private) javax.xml.namespace.QName
makeQName(QNameValue in)
Construct a JAXP QName from a Saxon QNameValuevoid
registerReference(BindingReference ref)
Method called by the XPath expression parser to register a reference to this variable.
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Constructor Detail
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JAXPVariable
protected JAXPVariable(StructuredQName name, javax.xml.xpath.XPathVariableResolver resolver)
Private constructor: for use only be the protected factory method make()- Parameters:
name
- the name of the variableresolver
- the resolver used in conjunction with this variable
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Method Detail
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getRequiredType
public SequenceType getRequiredType()
Description copied from interface:Binding
Get the declared type of the variable- Specified by:
getRequiredType
in interfaceBinding
- Returns:
- the declared type
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isGlobal
public boolean isGlobal()
Indicate whether the binding is local or global. A global binding is one that has a fixed value for the life of a query or transformation; any other binding is local.
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isAssignable
public final boolean isAssignable()
Test whether it is permitted to assign to the variable using the saxon:assign extension element. This will only be for an XSLT global variable where the extra attribute saxon:assignable="yes" is present.- Specified by:
isAssignable
in interfaceBinding
- Returns:
- true if the binding is assignable
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getLocalSlotNumber
public int getLocalSlotNumber()
If this is a local variable held on the local stack frame, return the corresponding slot number. In other cases, return -1.- Specified by:
getLocalSlotNumber
in interfaceBinding
- Returns:
- the slot number on the local stack frame
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getVariableQName
public StructuredQName getVariableQName()
Get the name of the variable as a structured QName- Specified by:
getVariableQName
in interfaceBinding
- Specified by:
getVariableQName
in interfaceVariableDeclaration
- Returns:
- the variable name
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addReference
public void addReference(boolean isLoopingReference)
Description copied from interface:Binding
Register a variable reference that refers to the variable bound in this expression- Specified by:
addReference
in interfaceBinding
- Parameters:
isLoopingReference
- - true if the reference occurs within a loop, such as the predicate of a filter expression
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registerReference
public void registerReference(BindingReference ref)
Method called by the XPath expression parser to register a reference to this variable. This method should not be called by users of the API.- Specified by:
registerReference
in interfaceVariableDeclaration
- Parameters:
ref
- the variable reference
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evaluateVariable
public ValueRepresentation evaluateVariable(XPathContext context) throws XPathException
Get the value of the variable. This method is used by the XPath execution engine to retrieve the value.- Specified by:
evaluateVariable
in interfaceBinding
- Parameters:
context
- The dynamic evaluation context- Returns:
- The value of the variable
- Throws:
XPathException
- if an error occurs while evaluating the variable
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getIntegerBoundsForVariable
public IntegerValue[] getIntegerBoundsForVariable()
If the variable is bound to an integer, get the minimum and maximum possible values. Return null if unknown or not applicable- Specified by:
getIntegerBoundsForVariable
in interfaceBinding
- Returns:
- a pair of integers containing the minimum and maximum values for the integer value; or null if the value is not an integer or the range is unknown
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makeQName
javax.xml.namespace.QName makeQName(QNameValue in)
Construct a JAXP QName from a Saxon QNameValue- Parameters:
in
- the Saxon QNameValue- Returns:
- the JAXP QName
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