CommandTracker.java

/*
 * Copyright 2010 The Rabbit Eclipse Plug-in Project
 * 
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not
 * use this file except in compliance with the License. You may obtain a copy of
 * the License at
 * 
 * http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations under
 * the License.
 */
package rabbit.tracking.internal.trackers;

import rabbit.data.handler.DataHandler;
import rabbit.data.store.IStorer;
import rabbit.data.store.model.CommandEvent;

import org.eclipse.core.commands.ExecutionEvent;
import org.eclipse.core.commands.ExecutionException;
import org.eclipse.core.commands.IExecutionListener;
import org.eclipse.core.commands.NotHandledException;
import org.eclipse.ui.PlatformUI;
import org.eclipse.ui.commands.ICommandService;
import org.joda.time.DateTime;

/**
 * Tracks command executions.
 */
public class CommandTracker extends AbstractTracker<CommandEvent> implements
    IExecutionListener {

  /*
   * We only record commands that have been successfully executed, therefore we
   * only use postExecuteSuccess(String, Object) to record the event.
   * 
   * Note that preExecute(String, ExecutionEvent) will always be called when a
   * command is called to be execute, even if the command is non-executable at
   * that moment. For example, when there is nothing to undo in an editor, the
   * "Undo" menu is disabled, but if the user uses Ctrl+Z, the undo command will
   * still be called. Therefore we don't use preExecute(String, ExecutionEvent).
   */

  /**
   * The last recorded ExecutionEvent, to be updated every time
   * {@link #preExecute(String, ExecutionEvent)} is called. We need this because
   * {@link #postExecuteSuccess(String, Object)} does not have an
   * {@link ExecutionEvent} parameter. This variable is null from the beginning.
   */
  private ExecutionEvent lastEvent;
  
  /** Constructor. */
  public CommandTracker() {
    super();
    lastEvent = null;
  }

  @Override
  public void notHandled(String commandId, NotHandledException exception) {
  }

  @Override
  public void postExecuteFailure(String commandId, ExecutionException e) {
  }

  @Override
  public void postExecuteSuccess(String commandId, Object returnValue) {
    if (lastEvent != null && lastEvent.getCommand().getId().equals(commandId)) {
      addData(new CommandEvent(new DateTime(), lastEvent));
    }
  }

  @Override
  public void preExecute(String commandId, ExecutionEvent event) {
    lastEvent = event;
  }

  @Override
  protected IStorer<CommandEvent> createDataStorer() {
    return DataHandler.getStorer(CommandEvent.class);
  }

  @Override
  protected void doDisable() {
    getCommandService().removeExecutionListener(this);
  }

  @Override
  protected void doEnable() {
    getCommandService().addExecutionListener(this);
  }

  private ICommandService getCommandService() {
    return (ICommandService) PlatformUI.getWorkbench().getService(
        ICommandService.class);
  }

}