public NodeToken backtrack() {
backtrackLeafArcTokens();
NodeToken resultToken = null;
while (!queue.isEmpty()) {
NodeToken token = queue.first();
queue.remove(token);
if (token.getExecutionType().isBacktracked()) {
continue;
}
token.getNode().backtrack(engine, token);
boolean isDestination = token.equals(destinationToken);
if (isDestination) {
resultToken = backtrackCompletedToken(token, ExecutionType.Forward);
} else {
NodeToken backtrackToken = backtrackToken(token);
if (backtrackToken != token) {
backtrackToken.markBacktracked();
NodeTokenEvent.fireBacktrackedEvent(engine, backtrackToken);
backtrackToken.markComplete();
NodeTokenEvent.fireCompletedEvent(engine, backtrackToken, null);
}
}
}
reactivateTokenSets();
return resultToken;
}
private NodeToken backtrackToken(final NodeToken token) {
NodeToken backtrackToken = token;
if (!token.isComplete()) {
token.markComplete();
NodeTokenEvent.fireCompletedEvent(engine, backtrackToken, null);
token.markBacktracked();
NodeTokenEvent.fireBacktrackedEvent(engine, token);
token.getProcess().removeActiveNodeToken(token);
} else if (!token.getExecutionType().isBacktracked()) {
if (token.getChildTokens().isEmpty()) {
token.markBacktracked();
NodeTokenEvent.fireBacktrackedEvent(engine, token);
} else {
backtrackToken = backtrackCompletedToken(token, ExecutionType.Backtracked);
backtrackToken.setGuardAction(GuardAction.SkipNode);
NodeTokenEvent.fireSkippedEvent(engine, backtrackToken, null);
}
}
for (ArcToken parent : getParents(token)) {
boolean backtrackParent = visited.contains(parent.getParentToken());
token.getProcess().removeActiveArcToken(parent);
parent.markBacktracked();
ArcTokenEvent.fireBacktrackedEvent(engine, parent);
ArcToken backtrackArcToken =
engine
.getFactory()
.newArcToken(
token.getProcess(),
parent.getArc(),
backtrackParent ? ExecutionType.Backtracked : ExecutionType.UTurn,
backtrackToken);
ArcTokenEvent.fireCreatedEvent(engine, backtrackArcToken);
backtrackToken.getChildTokens().add(backtrackArcToken);
shareTokenSets(backtrackArcToken, parent);
if (backtrackParent && parent.getExecutionType() != ExecutionType.Forward) {
ArcToken mirror = backtrackMirror.getMirror(parent);
arcTokenMap.put(mirror, backtrackArcToken);
finishArcTokenBacktrack(backtrackArcToken, mirror);
} else {
finishArcTokenBacktrack(backtrackArcToken, parent);
}
}
return backtrackToken;
}