GNU Prolog for Java

Class BacktrackInfo

  extended by gnu.prolog.vm.BacktrackInfo
Direct Known Subclasses:
CallBacktrackInfo, EnterBacktrackInfo, LeaveBacktrackInfo, LeaveByteCodeBacktrackInfo, Predicate_append.AppendBacktrackInfo, Predicate_call.CallTermBacktrackInfo, Predicate_member.MemberBacktrackInfo, PrologCollectionIterator, RetryBacktrackInfo

public class BacktrackInfo
extends Object

back track information base class

Field Summary
 int codePosition
          A pointer to code position.
 int undoPosition
          A position in undo stack.
Constructor Summary
BacktrackInfo(int undoPosition, int codePosition)
          a constructor
Method Summary
 void undo(Interpreter i)
          undo changes up to creation of this backtrack info
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail


public int codePosition
A pointer to code position. This pointer is interpreted by function that created backtrack information. TODO: what is the meaning of -1 here?


public int undoPosition
A position in undo stack. all actions will be undone up to this position. TODO: what is the meaning of -1 here?

Constructor Detail


public BacktrackInfo(int undoPosition,
                     int codePosition)
a constructor

undoPosition - undoPosition
codePosition - codePosition
Method Detail


public void undo(Interpreter i)
undo changes up to creation of this backtrack info

GNU Prolog for Java