Package org.jpl7

Class Variable


  • public class Variable
    extends Term
    This class supports Java representations of Prolog variables.

    A jpl.Variable instance is equivalent to a variable in a fragment of Prolog source text: it is *not* a "live" variable within a Prolog stack or heap. A corresponding Prolog variable is created only upon opening a Query whose goal refers to a Variable (and then only temporarily).


    Copyright (C) 2004 Paul Singleton

    Copyright (C) 1998 Fred Dushin

    Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

    1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
    2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.

    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.


    • Field Detail

      • name

        public final java.lang.String name
        the name of this Variable
    • Constructor Detail

      • Variable

        public Variable()
        Create a new Variable with new sequential name of the form "_261".
      • Variable

        public Variable​(java.lang.String name)
        Create a new Variable with 'name' (which must not be null or ""), and may one day be constrained to comply with traditional Prolog syntax.
        Parameters:
        name - the source name of this Variable
    • Method Detail

      • args

        public final Term[] args()
        Description copied from class: Term
        The arguments of this Term.

        Note that a SWI Prolog 7.x compound term can have zero arguments.

        This method returns an empty Term[] from an Atom, Float, Integer or JRef, approximating the behaviour of SWI Prolog's =../2

        Overrides:
        args in class Term
        Returns:
        the arguments of a Compound
      • arity

        public int arity()
        returns, as an int, the arity of a Term
        Overrides:
        arity in class Term
        Returns:
        the arity of a Term
      • equals

        public final boolean equals​(java.lang.Object obj)
        A Variable is equal to another if their names are the same and they are not anonymous.
        Overrides:
        equals in class java.lang.Object
        Parameters:
        obj - The Object to compare.
        Returns:
        true if the Object is a Variable and the above condition apply.
      • hasFunctor

        public boolean hasFunctor​(java.math.BigInteger value,
                                  int arity)
        Description copied from class: Term
        Tests whether this Term's functor has 'name' and 'arity'

        For Float and Integer, mimics behaviour of SWI Prolog's functor/3

        Overrides:
        hasFunctor in class Term
        Parameters:
        value - a possible name for the functor of a term
        arity - an arity 0+
        Returns:
        whether this Term's functor has 'name' and 'arity'
      • hasFunctor

        public boolean hasFunctor​(java.lang.String name,
                                  int arity)
        Description copied from class: Term
        Whether this Term's functor has 'name' and 'arity' (c.f. behaviour of SWI Prolog's functor/3)
        Overrides:
        hasFunctor in class Term
        Parameters:
        name - a possible name for the functor of a term
        arity - an arity 0+
        Returns:
        whether this Term's functor has 'name' and 'arity'
      • hasFunctor

        public boolean hasFunctor​(long value,
                                  int arity)
        Description copied from class: Term
        Tests whether this Term's functor has 'name' and 'arity'

        For Float and Integer, mimics behaviour of SWI Prolog's functor/3

        Overrides:
        hasFunctor in class Term
        Parameters:
        value - a possible name for the functor of a term
        arity - an arity 0+
        Returns:
        whether this Term's functor has 'name' and 'arity'
      • hasFunctor

        public boolean hasFunctor​(double value,
                                  int arity)
        Description copied from class: Term
        Tests whether this Term's functor has 'name' and 'arity'

        For Float and Integer, mimics behaviour of SWI Prolog's functor/3

        Overrides:
        hasFunctor in class Term
        Parameters:
        value - a possible name for the functor of a term
        arity - an arity 0+
        Returns:
        whether this Term's functor has 'name' and 'arity'
      • name

        public final java.lang.String name()
        the lexical name of this Variable
        Overrides:
        name in class Term
        Returns:
        the lexical name of this Variable
      • toString

        public java.lang.String toString()
        Returns a Prolog source text representation of this Variable
        Overrides:
        toString in class java.lang.Object
        Returns:
        a Prolog source text representation of this Variable
      • type

        public final int type()
        returns the type of this subclass of Term, i.e. Prolog.VARIABLE
        Specified by:
        type in class Term
        Returns:
        the type of this subclass of Term, i.e. Prolog.VARIABLE
      • typeName

        public java.lang.String typeName()
        returns the typeName of this subclass of Term, i.e. "Variable"
        Specified by:
        typeName in class Term
        Returns:
        the typeName of this subclass of Term, i.e. "Variable"