ubc.cs.JLog.Terms.Goals
Class jTrinaryBuiltinPredicateGoal

java.lang.Object
  extended by ubc.cs.JLog.Foundation.jGoal
      extended by ubc.cs.JLog.Terms.Goals.jTrinaryBuiltinPredicateGoal
All Implemented Interfaces:
iName, iNameArity

public class jTrinaryBuiltinPredicateGoal
extends jGoal

A very basic goal for trinary builtin predicates. It only attempts to prove once (i.e., the retry fails). It calls the prove(jTrinaryBuiltinPredicateGoal) method of the associated predicate to perform the prove.

Author:
Glendon Holst

Field Summary
protected  jTrinaryBuiltinPredicate predicate
           
 jTerm term1
           
 jTerm term2
           
 jTerm term3
           
 jUnifiedVector unified
           
 
Fields inherited from class ubc.cs.JLog.Foundation.jGoal
next
 
Constructor Summary
jTrinaryBuiltinPredicateGoal(jTrinaryBuiltinPredicate p, jTerm t1, jTerm t2, jTerm t3)
           
 
Method Summary
 int getArity()
          Returns the arity of this instance.
 java.lang.String getName()
          Returns the name of this instance.
 void internal_restore(iGoalStack goals)
          Combines internal_remove with a full restart and resoration of any previous variable state.
 boolean prove(iGoalStack goals, iGoalStack proved)
          Attempt to prove the goal represented by this jGoal.
 boolean retry(iGoalStack goals, iGoalStack proved)
          Attempt to prove the goal represented by this jGoal.
 java.lang.String toString()
           
 
Methods inherited from class ubc.cs.JLog.Foundation.jGoal
internal_remove
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
 

Field Detail

predicate

protected jTrinaryBuiltinPredicate predicate

term1

public jTerm term1

term2

public jTerm term2

term3

public jTerm term3

unified

public jUnifiedVector unified
Constructor Detail

jTrinaryBuiltinPredicateGoal

public jTrinaryBuiltinPredicateGoal(jTrinaryBuiltinPredicate p,
                                    jTerm t1,
                                    jTerm t2,
                                    jTerm t3)
Method Detail

prove

public boolean prove(iGoalStack goals,
                     iGoalStack proved)
Description copied from class: jGoal
Attempt to prove the goal represented by this jGoal. Goal must not be on either stack to prove (pop off goals stack before prove call). Goal must place itself on the appropriate stack before returning. proved stack if 'proved', goals stack otherwise. Since proved doesn't pop the stack we don't need a try/catch block. Must be called at least once before calling retry.

Specified by:
prove in class jGoal
Parameters:
goals - iGoalStack containing goals yet to be proved.
proved - iGoalStack containing evaluated goals (goals that may already be proved, or awaiting their child goals to be proved).
Returns:
boolean is true if this goal ended up on proved, false otherwise.

retry

public boolean retry(iGoalStack goals,
                     iGoalStack proved)
Description copied from class: jGoal
Attempt to prove the goal represented by this jGoal. Goal must not be on either stack to retry (pop off proved stack before retry call). Goal must place itself on the goal stack, and normally need not pop either stack. Since retry doesn't pop the stack we don't need a try/catch block.

Specified by:
retry in class jGoal
Parameters:
goals - iGoalStack containing goals yet to be proved.
proved - iGoalStack containing evaluated goals (goals that may already be proved, or awaiting their child goals to be proved).
Returns:
boolean is true if the prover should attempt a prove on this goal, false otherwise.

internal_restore

public void internal_restore(iGoalStack goals)
Description copied from class: jGoal
Combines internal_remove with a full restart and resoration of any previous variable state. May be called by other goals, such as a jCutGoal. this is still located on proved stack.

Overrides:
internal_restore in class jGoal
Parameters:
goals - iGoalStack containing goals yet to be proved.

getName

public java.lang.String getName()
Description copied from interface: iName
Returns the name of this instance.

Returns:
String containing name of this instance.

getArity

public int getArity()
Description copied from interface: iNameArity
Returns the arity of this instance.

Returns:
int whose value is the arity of this instance.

toString

public java.lang.String toString()
Overrides:
toString in class java.lang.Object