ubc.cs.JLog.Builtins.Goals
Class jIsGoal

java.lang.Object
  ubc.cs.JLog.Foundation.jGoal
      ubc.cs.JLog.Builtins.Goals.jIsGoal

All Implemented Interfaces:

iName, iNameArity

public class jIsGoal
extends jGoal

Field Summary

protected jIs	is
jTerm	lhs
jTerm	rhs
jUnifiedVector	unified

Fields inherited from class ubc.cs.JLog.Foundation.jGoal

next

Constructor Summary

jIsGoal(jIs i, jTerm l, jTerm r)

Method Summary

int	getArity() Returns the arity of this instance.
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.
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

is

protected jIs is

lhs

public jTerm lhs

rhs

public jTerm rhs

unified

public jUnifiedVector unified

Constructor Detail

jIsGoal

public jIsGoal(jIs i,
               jTerm l,
               jTerm r)

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 final 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 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 String toString()

Overrides:

toString in class Object