source: josm/trunk/src/org/openstreetmap/josm/data/UndoRedoHandler.java@ 444

//License: GPL. Copyright 2007 by Immanuel Scholz and others
package org.openstreetmap.josm.data;

import java.util.Iterator;
import java.util.LinkedList;
import java.util.Stack;

import org.openstreetmap.josm.Main;
import org.openstreetmap.josm.command.Command;
import org.openstreetmap.josm.gui.layer.Layer;
import org.openstreetmap.josm.gui.layer.OsmDataLayer;
import org.openstreetmap.josm.gui.layer.Layer.LayerChangeListener;
import org.openstreetmap.josm.gui.layer.OsmDataLayer.CommandQueueListener;

public class UndoRedoHandler implements LayerChangeListener {

        /**
         * All commands that were made on the dataset. Don't write from outside!
         */
        public final LinkedList<Command> commands = new LinkedList<Command>();
        /**
         * The stack for redoing commands
         */
        private final Stack<Command> redoCommands = new Stack<Command>();

        public final LinkedList<CommandQueueListener> listenerCommands = new LinkedList<CommandQueueListener>();


        public UndoRedoHandler() {
                Layer.listeners.add(this);
        }


        /**
         * Execute the command and add it to the intern command queue.
         */
        public void add(final Command c) {
                c.executeCommand();
                commands.add(c);
                redoCommands.clear();
                if (Main.map != null && Main.map.mapView.getActiveLayer() instanceof OsmDataLayer) {
                        OsmDataLayer data = (OsmDataLayer)Main.map.mapView.getActiveLayer();
                        data.setModified(true);
                        data.fireDataChange();
                }
                fireCommandsChanged();
        }

        /**
         * Undoes the last added command.
         */
        public void undo() {
                if (commands.isEmpty())
                        return;
                final Command c = commands.removeLast();
                c.undoCommand();
                redoCommands.push(c);
                if (Main.map != null && Main.map.mapView.getActiveLayer() instanceof OsmDataLayer) {
                        OsmDataLayer data = (OsmDataLayer)Main.map.mapView.getActiveLayer();
                        data.setModified(data.uploadedModified || !commands.isEmpty());
                        data.fireDataChange();
                        fireCommandsChanged();
                }               
                Main.ds.setSelected();
        }

        /**
         * Redoes the last undoed command.
         * TODO: This has to be moved to a central place in order to support multiple layers.
         */
        public void redo() {
                if (redoCommands.isEmpty())
                        return;
                final Command c = redoCommands.pop();
                c.executeCommand();
                commands.add(c);
                if (Main.map != null && Main.map.mapView.getActiveLayer() instanceof OsmDataLayer) {
                        OsmDataLayer data = (OsmDataLayer)Main.map.mapView.getActiveLayer();
                        data.setModified(true);
                        data.fireDataChange();
                        fireCommandsChanged();
                }
        }

        public void fireCommandsChanged() {
                for (final CommandQueueListener l : listenerCommands)
                        l.commandChanged(commands.size(), redoCommands.size());
        }

        public void clean() {
                redoCommands.clear();
                commands.clear();
                fireCommandsChanged();
        }

        public void layerRemoved(Layer oldLayer) {
                boolean changed = false;
                for (Iterator<Command> it = commands.iterator(); it.hasNext();) {
                        if (it.next().invalidBecauselayerRemoved(oldLayer)) {
                                it.remove();
                                changed = true;
                        }
                }
                for (Iterator<Command> it = redoCommands.iterator(); it.hasNext();) {
                        if (it.next().invalidBecauselayerRemoved(oldLayer)) {
                                it.remove();
                                changed = true;
                        }
                }
                if (changed)
                        fireCommandsChanged();
        }

        public void layerAdded(Layer newLayer) {}
        public void activeLayerChange(Layer oldLayer, Layer newLayer) {}
}