com.svincent.moksa
Class CompoundTerm

java.lang.Object
  |
  +--com.svincent.moksa.WamObject
        |
        +--com.svincent.moksa.PrologTerm
              |
              +--com.svincent.moksa.CompoundTerm

All Implemented Interfaces:

Trailable

public class CompoundTerm

extends PrologTerm

A compoundTerm is a Prolog tree constant (normally of the form f(x1, x2, ..., xn), where f is known as the compoundTerm's functor, and x1 through xn are known as the term's subterms.

The value n is known as the compoundTerm's arity.

Inner Class Summary

static class	CompoundTerm.ListWrapper A wrapper for a CompoundTerm as a list.
static class	CompoundTerm.PrologIterator

Field Summary

static CompoundTerm[]

EmptyArray

Fields inherited from class com.svincent.moksa.PrologTerm

EmptyArray

Constructor Summary

CompoundTerm(PrologEngine _engine, java.lang.String _name, PrologTerm[] _subterms, int _priority)
Builds a new CompoundTerm with the given name.

Method Summary

java.lang.Object	accept(PrologTermVisitor v, java.lang.Object parm) Allow PrologTermVisitor to access this PrologTerm.
CompoundTerm.ListWrapper	asList()
PrologTerm	clonePrologTerm(java.util.Map objs)
PrologTerm	evaluateExpression() Evaluates this term as an expression.
int	getArity() Retrives this CompoundTerm's arity.
WamInteger	getArityConstant() Retrives this CompoundTerm's arity, as a constant.
java.lang.String	getName() Retrieves this CompoundTerm's name.
PrologTerm	getNameConstant()
int	getPriority()
PrologTerm	getSubterm(int idx) Retrieves this CompoundTerm's value.
PrologTerm	getSubtermDeref(int idx)
boolean	isAtom() Returns true iff this is an Atom.
boolean	isCompoundTerm() Returns true iff this is a CompoundTerm.
boolean	isConstant() Returns true iff this is a constant: i.e.
boolean	isEmptyList()
boolean	isInfix()
boolean	isList() Returns true iff this is a List.
boolean	isNonEmptyList()
boolean	isPostfix()
boolean	isPrefix()
boolean	isStructure() Return true iff this is a CompoundTerm or an Atom
protected void	tag(java.io.PrintWriter out) Writes a short human-readable representation of this object to the given Writer.
boolean	unify(PrologTerm _that, boolean doBindings) Unification algorithm.

Methods inherited from class com.svincent.moksa.PrologTerm

clonePrologTerm, deref, floatValue, intValue, isFloat, isInteger, isJavaObject, isStreamId, isVariable, printVariables, setPriority, unify, unifyWithoutBindings, untrail

Methods inherited from class com.svincent.moksa.WamObject

tag

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

EmptyArray

public static final CompoundTerm[] EmptyArray

Constructor Detail

CompoundTerm

public CompoundTerm(PrologEngine _engine,
                    java.lang.String _name,
                    PrologTerm[] _subterms,
                    int _priority)

Builds a new CompoundTerm with the given name. Note that CompoundTerms are intended to be used as constants, so no building API is provided.

Method Detail

getPriority

public int getPriority()

Overrides:

getPriority in class PrologTerm

getName

public java.lang.String getName()

Retrieves this CompoundTerm's name.

Overrides:

getName in class PrologTerm

getNameConstant

public PrologTerm getNameConstant()

Overrides:

getNameConstant in class PrologTerm

getArity

public int getArity()

Retrives this CompoundTerm's arity.

Overrides:

getArity in class PrologTerm

getArityConstant

public WamInteger getArityConstant()

Retrives this CompoundTerm's arity, as a constant.

isStructure

public boolean isStructure()

Return true iff this is a CompoundTerm or an Atom

Overrides:

isStructure in class PrologTerm

isCompoundTerm

public boolean isCompoundTerm()

Returns true iff this is a CompoundTerm.

Overrides:

isCompoundTerm in class PrologTerm

isAtom

public boolean isAtom()

Returns true iff this is an Atom.

Overrides:

isAtom in class PrologTerm

isConstant

public boolean isConstant()

Returns true iff this is a constant: i.e. an Atom, an integer constant, or a floating-point constant.

Overrides:

isConstant in class PrologTerm

getSubterm

public PrologTerm getSubterm(int idx)

Retrieves this CompoundTerm's value.

Parameters:

idx - - the index of the subterm to retrieve: must be in the range 0 through getArity () - 1, inclusively.

getSubtermDeref

public PrologTerm getSubtermDeref(int idx)

accept

public java.lang.Object accept(PrologTermVisitor v,
                               java.lang.Object parm)

Allow PrologTermVisitor to access this PrologTerm.

Overrides:

accept in class PrologTerm

unify

public boolean unify(PrologTerm _that,
                     boolean doBindings)

Unification algorithm. Can cause variables to become bound. (We will eventually have a rollback mechanism to undo these bindings.)

Overrides:

unify in class PrologTerm

Returns:

true iff the two PrologTerms successfully unify.

clonePrologTerm

public PrologTerm clonePrologTerm(java.util.Map objs)

Overrides:

clonePrologTerm in class PrologTerm

evaluateExpression

public PrologTerm evaluateExpression()
                              throws PrologException

Evaluates this term as an expression.

Overrides:

evaluateExpression in class PrologTerm

isInfix

public boolean isInfix()

isPrefix

public boolean isPrefix()

isPostfix

public boolean isPostfix()

isList

public boolean isList()

Description copied from class: PrologTerm

Returns true iff this is a List.

Overrides:

isList in class PrologTerm

isEmptyList

public boolean isEmptyList()

Overrides:

isEmptyList in class PrologTerm

isNonEmptyList

public boolean isNonEmptyList()

Overrides:

isNonEmptyList in class PrologTerm

tag

protected void tag(java.io.PrintWriter out)

Writes a short human-readable representation of this object to the given Writer.

Overrides:

tag in class WamObject

asList

public CompoundTerm.ListWrapper asList()