/**
* Attempts to execute a command and adds it to the undo stack if the command executes
* successfully.
*
* @param command The command to execute.
*/
void executeCommand(Command command) {
boolean success = command.execDo();
// Only mess with the command stacks if the command was executed
// successfully.
if (success) {
// If the command invalidates the command stacks then
// clear the command stacks.
if (command.invalidates()) {
undoStack.clear();
redoStack.clear();
}
// If the command is undoable, it must be added to the undo
// stack and the redo stack must be cleared.
if (command.isUndoable()) {
undoStack.addLast(command);
if (undoStack.size() > mThreshold) {
undoStack.removeFirst();
}
redoStack.clear();
}
// Necessary so that the undo/redo menu gets an update
// AFTER the command has successfully executed.
publisher.publishEvent(new Event());
}
}
/**
* Attempts to redo the first command in the redo stack, and adds it to the undo stack if
* successful.
*/
void redoCommand() {
if (!redoStack.isEmpty()) {
Command command = redoStack.removeLast();
boolean success = command.execDo();
if (success) {
undoStack.addLast(command);
}
// Necessary so that the undo/redo menu gets an update
// AFTER the command has successfully executed.
publisher.publishEvent(new Event());
}
}