gnu.prolog.vm
Class BacktrackInfo

java.lang.Object
  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

codePosition

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?

undoPosition

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

BacktrackInfo

public BacktrackInfo(int undoPosition,
                     int codePosition)

a constructor

Parameters:

undoPosition - undoPosition

codePosition - codePosition

Method Detail

undo

public void undo(Interpreter i)

undo changes up to creation of this backtrack info