Variable

java.lang.Object
- org.jpl7.Term
- - org.jpl7.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
This library is free software; you can redistribute it and/or modify it under the terms of the GNU Library Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.
This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Library Public License for more details.

Version:

$Revision$

Author:

Fred Dushin

Field Summary

Fields
Modifier and Type Field and Description

protected int index

java.lang.String name
the name of this Variable

protected term_t term_
defined between Query.open() and Query.get2()

Fields
Modifier and Type	Field and Description
`protected int`	`index`
`java.lang.String`	`name` the name of this Variable
`protected term_t`	`term_` defined between Query.open() and Query.get2()

Constructor Summary

Constructors
Constructor and Description
`Variable()` Create a new Variable with new sequential name of the form "_261".
`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.

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`Term[]`	`args()` The (nonexistent) args of this Variable
`int`	`arity()` returns, as an int, the arity of a Term
`boolean`	`equals(java.lang.Object obj)` A Variable is equal to another if their names are the same and they are not anonymous.
`protected void`	`getSubst(java.util.Map<java.lang.String,Term> varnames_to_Terms, java.util.Map<term_t,Variable> vars_to_Vars)` If this Variable instance is not an anonymous or (in dont-tell-me mode) a dont-tell-me variable, and its binding is not already in the varnames_to_Terms Map, put the result of converting the term_t to which this variable has been unified to a Term in the Map, keyed on this Variable's name.
`boolean`	`hasFunctor(double value, int arity)` Tests whether this Term's functor has (double) 'name' and 'arity' Returns false if called inappropriately
`boolean`	`hasFunctor(int value, int arity)` Tests whether this Term's functor has (int) 'name' and 'arity' Returns false if called inappropriately
`boolean`	`hasFunctor(java.lang.String name, int arity)` Tests whether this Term's functor has (String) 'name' and 'arity' Returns false if called inappropriately
`java.lang.String`	`name()` the lexical name of this Variable
`protected void`	`put(java.util.Map<java.lang.String,term_t> varnames_to_vars, term_t term)` To put a Variable, we must check whether a (non-anonymous) variable with the same name has already been put in the Term.
`java.lang.String`	`toString()` Returns a Prolog source text representation of this Variable
`int`	`type()` returns the type of this subclass of Term, i.e.
`java.lang.String`	`typeName()` returns the typeName of this subclass of Term, i.e.

Methods inherited from class org.jpl7.Term
arg, atomType, bigValue, doubleValue, floatValue, getSubsts, getTerm, getTerm, intValue, isAtom, isBigInteger, isCompound, isFloat, isInteger, isJFalse, isJNull, isJObject, isJRef, isJTrue, isJVoid, isListNil, isListPair, isVariable, jrefToObject, listLength, longValue, objectToJRef, put, putParams, putParams, putParams1, putParams2, putTerm, putTerms, terms_equals, toString, toTermArray

Methods inherited from class java.lang.Object
clone, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

- Field Detail
  - index
```
protected transient int index
```
  - name
```
public final java.lang.String name
```
    the name of this Variable
  - term_
```
protected transient term_t term_
```
    defined between Query.open() and Query.get2()
- 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 Term[] args()
```
    The (nonexistent) args of this Variable
    
    Overrides:
    
    args in class Term
    
    Returns:
    
    the (nonexistent) args of this Variable (never)
    
    Throws:
    
    JPLException
  - 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.
  - getSubst
```
protected final void getSubst(java.util.Map<java.lang.String,Term> varnames_to_Terms,
                              java.util.Map<term_t,Variable> vars_to_Vars)
```
    If this Variable instance is not an anonymous or (in dont-tell-me mode) a dont-tell-me variable, and its binding is not already in the varnames_to_Terms Map, put the result of converting the term_t to which this variable has been unified to a Term in the Map, keyed on this Variable's name.
    
    Overrides:
    
    getSubst in class Term
    
    Parameters:
    
    varnames_to_Terms - A Map of bindings from variable names to JPL Terms.
    
    vars_to_Vars - A Map from Prolog variables to JPL Variables.
  - hasFunctor
```
public boolean hasFunctor(java.lang.String name,
                          int arity)
```
    Description copied from class: Term
    
    Tests whether this Term's functor has (String) 'name' and 'arity' Returns false if called inappropriately
    
    Overrides:
    
    hasFunctor in class Term
    
    Returns:
    
    whether this Term's functor has (String) 'name' and 'arity'
  - hasFunctor
```
public boolean hasFunctor(int value,
                          int arity)
```
    Description copied from class: Term
    
    Tests whether this Term's functor has (int) 'name' and 'arity' Returns false if called inappropriately
    
    Overrides:
    
    hasFunctor in class Term
    
    Returns:
    
    whether this Term's functor has (int) 'name' and 'arity'
  - hasFunctor
```
public boolean hasFunctor(double value,
                          int arity)
```
    Description copied from class: Term
    
    Tests whether this Term's functor has (double) 'name' and 'arity' Returns false if called inappropriately
    
    Overrides:
    
    hasFunctor in class Term
    
    Returns:
    
    whether this Term's functor has (double) '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
  - put
```
protected final void put(java.util.Map<java.lang.String,term_t> varnames_to_vars,
                         term_t term)
```
    To put a Variable, we must check whether a (non-anonymous) variable with the same name has already been put in the Term. If one has, then the corresponding Prolog variable has been stashed in the varnames_to_vars Map, keyed by the Variable name, so we can look it up and reuse it (this way, the sharing of variables in the Prolog term reflects the sharing of Variable names in the Term. Otherwise, if this Variable name has not already been seen in the Term, then we put a new Prolog variable and add it into the Map (keyed by this Variable name).
    
    Specified by:
    
    put in class Term
    
    Parameters:
    
    varnames_to_vars - A Map from variable names to Prolog variables.
    
    term - A (previously created) term_t which is to be set to a (new or reused) Prolog 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"

Class Variable

Field Summary

Constructor Summary

Method Summary

Methods inherited from class org.jpl7.Term

Methods inherited from class java.lang.Object

Field Detail

index

name

term_

Constructor Detail

Variable

Variable

Method Detail

args

arity

equals

getSubst

hasFunctor

hasFunctor

hasFunctor

name

put

toString

type

typeName