ModelUndoManager.java :  » IDE-Eclipse » pde » org » eclipse » pde » internal » ui » editor » Java Open Source

/*******************************************************************************
 *  Copyright (c) 2000, 2008 IBM Corporation and others.
 *  All rights reserved. This program and the accompanying materials
 *  are made available under the terms of the Eclipse Public License v1.0
 *  which accompanies this distribution, and is available at
 *  http://www.eclipse.org/legal/epl-v10.html
 * 
 *  Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.pde.internal.ui.editor;

import java.util.List;
import java.util.Vector;
import org.eclipse.jface.action.IAction;
import org.eclipse.osgi.util.NLS;
import org.eclipse.pde.core.*;
import org.eclipse.pde.internal.ui.PDEUIMessages;
import org.eclipse.ui.forms.editor.IFormPage;

public abstract class ModelUndoManager implements IModelUndoManager, IModelChangedListener {
  private boolean ignoreChanges;
  private List operations;
  private int undoLevelLimit = 10;
  private int cursor = -1;
  private IAction undoAction;
  private IAction redoAction;
  private PDEFormEditor editor;

  public ModelUndoManager(PDEFormEditor editor) {
    this.editor = editor;
    operations = new Vector();
  }

  /*
   * @see IModelUndoManager#connect(IModelChangeProvider)
   */
  public void connect(IModelChangeProvider provider) {
    provider.addModelChangedListener(this);
    if (operations == null)
      initialize();
  }

  /*
   * @see IModelUndoManager#disconnect(IModelChangeProvider)
   */
  public void disconnect(IModelChangeProvider provider) {
    provider.removeModelChangedListener(this);
  }

  private void initialize() {
    operations = new Vector();
    cursor = -1;
    updateActions();
  }

  /*
   * @see IModelUndoManager#isUndoable()
   */
  public boolean isUndoable() {
    return cursor >= 0;
  }

  /*
   * @see IModelUndoManager#isRedoable()
   */
  public boolean isRedoable() {
    if (operations == null)
      initialize();
    return (cursor + 1) < operations.size();
  }

  /*
   * @see IModelUndoManager#undo()
   */
  public void undo() {
    IModelChangedEvent op = getCurrentOperation();
    if (op == null)
      return;
    ignoreChanges = true;
    openRelatedPage(op);
    execute(op, true);
    cursor--;
    updateActions();
    ignoreChanges = false;
  }

  /*
   * @see IModelUndoManager#redo()
   */
  public void redo() {
    cursor++;
    IModelChangedEvent op = getCurrentOperation();
    if (op == null)
      return;
    ignoreChanges = true;
    openRelatedPage(op);
    execute(op, false);
    ignoreChanges = false;
    updateActions();
  }

  protected abstract String getPageId(Object object);

  protected abstract void execute(IModelChangedEvent op, boolean undo);

  private void openRelatedPage(IModelChangedEvent op) {
    Object obj = op.getChangedObjects()[0];
    String pageId = getPageId(obj);
    if (pageId != null) {
      IFormPage cpage = editor.getActivePageInstance();
      IFormPage newPage = editor.findPage(pageId);
      if (cpage != newPage)
        editor.setActivePage(newPage.getId());
    }
  }

  /*
   * @see IModelChangedListener#modelChanged(IModelChangedEvent)
   */
  public void modelChanged(IModelChangedEvent event) {
    if (ignoreChanges)
      return;

    if (event.getChangeType() == IModelChangedEvent.WORLD_CHANGED) {
      initialize();
      return;
    }
    addOperation(event);
  }

  private IModelChangedEvent getCurrentOperation() {
    if (cursor == -1 || cursor == operations.size())
      return null;
    return (IModelChangedEvent) operations.get(cursor);
  }

  private IModelChangedEvent getNextOperation() {
    int peekCursor = cursor + 1;
    if (peekCursor >= operations.size())
      return null;
    return (IModelChangedEvent) operations.get(peekCursor);
  }

  private void addOperation(IModelChangedEvent operation) {
    operations.add(operation);
    int size = operations.size();
    if (size > undoLevelLimit) {
      int extra = size - undoLevelLimit;
      // trim
      for (int i = 0; i < extra; i++) {
        operations.remove(i);
      }
    }
    cursor = operations.size() - 1;
    updateActions();
  }

  public void setActions(IAction undoAction, IAction redoAction) {
    this.undoAction = undoAction;
    this.redoAction = redoAction;
    updateActions();
  }

  private void updateActions() {
    if (undoAction != null && redoAction != null) {
      undoAction.setEnabled(isUndoable());
      undoAction.setText(getUndoText());
      redoAction.setEnabled(isRedoable());
      redoAction.setText(getRedoText());
    }
  }

  private String getUndoText() {
    IModelChangedEvent op = getCurrentOperation();
    if (op == null) {
      return PDEUIMessages.UpdateManager_noUndo;
    }
    return NLS.bind(PDEUIMessages.UpdateManager_undo, getOperationText(op));
  }

  private String getRedoText() {
    IModelChangedEvent op = getNextOperation();
    if (op == null) {
      return PDEUIMessages.UpdateManager_noRedo;
    }
    return NLS.bind(PDEUIMessages.UpdateManager_redo, getOperationText(op));
  }

  private String getOperationText(IModelChangedEvent op) {
    String opText = ""; //$NON-NLS-1$
    switch (op.getChangeType()) {
      case IModelChangedEvent.INSERT :
        opText = PDEUIMessages.UpdateManager_op_add;
        break;
      case IModelChangedEvent.REMOVE :
        opText = PDEUIMessages.UpdateManager_op_remove;
        break;
      case IModelChangedEvent.CHANGE :
        opText = PDEUIMessages.UpdateManager_op_change;
        break;
    }
    return opText;
  }

  public void setUndoLevelLimit(int limit) {
    this.undoLevelLimit = limit;
  }

  public void setIgnoreChanges(boolean ignore) {
    this.ignoreChanges = ignore;
  }
}