ubc.cs.JLog.Builtins.Goals
Class jReadGoal

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

public class jReadGoal
extends jGoal

Goal for inputing text from the console.

Author:
Glendon Holst

Field Summary
protected  jRead read
           
 jTerm term
           
 jUnifiedVector unified
           
 
Fields inherited from class ubc.cs.JLog.Foundation.jGoal
next
 
Constructor Summary
jReadGoal(jRead r, jTerm t)
           
 
Method Summary
 int getArity()
          Returns the arity of this instance.
protected  jTerm getInput()
           
 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

read

protected jRead read

term

public jTerm term

unified

public jUnifiedVector unified
Constructor Detail

jReadGoal

public jReadGoal(jRead r,
                 jTerm t)
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.

getInput

protected jTerm getInput()

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