| /******************************************************************************* |
| * Copyright (c) 2005, 2006 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.core.commands; |
| |
| import java.util.HashMap; |
| import java.util.Map; |
| import java.util.Set; |
| |
| /** |
| * <p> |
| * An abstract implementation of {@link IObjectWithState}. This provides basic |
| * handling for adding and remove state. When state is added, the handler |
| * attaches itself as a listener and fire a handleStateChange event to notify |
| * this handler. When state is removed, the handler removes itself as a |
| * listener. |
| * </p> |
| * <p> |
| * Clients may extend this class. |
| * </p> |
| * |
| * @since 3.2 |
| */ |
| public abstract class AbstractHandlerWithState extends AbstractHandler |
| implements IObjectWithState, IStateListener { |
| |
| /** |
| * The map of states currently held by this handler. If this handler has no |
| * state (generally, when inactive), then this will be <code>null</code>. |
| */ |
| private Map states = null; |
| |
| /** |
| * <p> |
| * Adds a state to this handler. This will add this handler as a listener to |
| * the state, and then fire a handleStateChange so that the handler can |
| * respond to the incoming state. |
| * </p> |
| * <p> |
| * Clients may extend this method, but they should call this super method |
| * first before doing anything else. |
| * </p> |
| * |
| * @param stateId |
| * The identifier indicating the type of state being added; must |
| * not be <code>null</code>. |
| * @param state |
| * The state to add; must not be <code>null</code>. |
| */ |
| public void addState(final String stateId, final State state) { |
| if (state == null) { |
| throw new NullPointerException("Cannot add a null state"); //$NON-NLS-1$ |
| } |
| |
| if (states == null) { |
| states = new HashMap(3); |
| } |
| states.put(stateId, state); |
| state.addListener(this); |
| handleStateChange(state, null); |
| } |
| |
| public final State getState(final String stateId) { |
| if ((states == null) || (states.isEmpty())) { |
| return null; |
| } |
| |
| return (State) states.get(stateId); |
| } |
| |
| public final String[] getStateIds() { |
| if ((states == null) || (states.isEmpty())) { |
| return null; |
| } |
| |
| final Set stateIds = states.keySet(); |
| return (String[]) stateIds.toArray(new String[stateIds.size()]); |
| } |
| |
| /** |
| * <p> |
| * Removes a state from this handler. This will remove this handler as a |
| * listener to the state. No event is fired to notify the handler of this |
| * change. |
| * </p> |
| * <p> |
| * Clients may extend this method, but they should call this super method |
| * first before doing anything else. |
| * </p> |
| * |
| * @param stateId |
| * The identifier of the state to remove; must not be |
| * <code>null</code>. |
| */ |
| public void removeState(final String stateId) { |
| if (stateId == null) { |
| throw new NullPointerException("Cannot remove a null state"); //$NON-NLS-1$ |
| } |
| |
| final State state = (State) states.get(stateId); |
| if (state != null) { |
| state.removeListener(this); |
| if (states != null) { |
| states.remove(state); |
| if (states.isEmpty()) { |
| states = null; |
| } |
| } |
| } |
| } |
| } |