@Override
public IUndoableOperation getUndoOperation(IUndoContext context) {
Assert.isNotNull(context);
synchronized (undoRedoHistoryLock) {
for (int i = undoList.size() - 1; i >= 0; i--) {
IUndoableOperation operation = undoList.get(i);
if (operation.hasContext(context)) {
return operation;
}
}
}
return null;
}
/*
* Filter the specified list to include only the specified undo context.
*/
private IUndoableOperation[] filter(List<IUndoableOperation> list, IUndoContext context) {
/*
* This method is used whenever there is a need to filter the undo or
* redo history on a particular context. Currently there are no caches
* kept to optimize repeated requests for the same filter. If benchmarks
* show this to be a common pattern that causes performances problems,
* we could implement a filtered cache here that is nullified whenever
* the global history changes.
*/
List<IUndoableOperation> filtered = new ArrayList<>();
synchronized (undoRedoHistoryLock) {
Iterator<IUndoableOperation> iterator = list.iterator();
while (iterator.hasNext()) {
IUndoableOperation operation = iterator.next();
if (operation.hasContext(context)) {
filtered.add(operation);
}
}
}
return filtered.toArray(new IUndoableOperation[filtered.size()]);
}
