bundles/org.eclipse.ui.workbench/Eclipse UI/org/eclipse/ui/internal/commands/CommandStateProxy.java - platform/eclipse.platform.ui - Git at Google

 /*******************************************************************************
  * Copyright (c) 2000, 2007 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.ui.internal.commands;

 import org.eclipse.core.commands.IStateListener;
 import org.eclipse.core.commands.State;
 import org.eclipse.core.runtime.CoreException;
 import org.eclipse.core.runtime.IConfigurationElement;
 import org.eclipse.core.runtime.IStatus;
 import org.eclipse.core.runtime.Status;
 import org.eclipse.jface.commands.PersistentState;
 import org.eclipse.jface.preference.IPreferenceStore;
 import org.eclipse.ui.internal.WorkbenchPlugin;

 /**
  * <p>
  * A proxy for handler state that has been defined in XML. This delays the class
  * loading until the state is really asked for information. Asking a proxy for
  * anything (except disposing, and adding and removing listeners) will cause the
  * proxy to instantiate the proxied handler.
  * </p>
  * <p>
  * Loading the proxied state will automatically cause it to load its value from
  * the preference store. Disposing of the state will cause it to persist its
  * value.
  * </p>
  * <p>
  * This class is not intended for use outside of the
  * <code>org.eclipse.ui.workbench</code> plug-in.
  * </p>
  *
  * @since 3.2
  */
 public final class CommandStateProxy extends PersistentState {

 	/**
 	 * The configuration element from which the state can be created. This value
 	 * will exist until the element is converted into a real class -- at which
 	 * point this value will be set to <code>null</code>.
 	 */
 	private IConfigurationElement configurationElement;

 	/**
 	 * The key in the preference store to locate the persisted state.
 	 */
 	private String preferenceKey;

 	/**
 	 * The preference store containing the persisted state, if any.
 	 */
 	private IPreferenceStore preferenceStore;

 	/**
 	 * The real state. This value is <code>null</code> until the proxy is
 	 * forced to load the real state. At this point, the configuration element
 	 * is converted, nulled out, and this state gains a reference.
 	 */
 	private State state = null;

 	/**
 	 * The name of the configuration element attribute which contains the
 	 * information necessary to instantiate the real state.
 	 */
 	private final String stateAttributeName;

 	/**
 	 * Constructs a new instance of <code>HandlerState</code> with all the
 	 * information it needs to create the real state later.
 	 *
 	 * @param configurationElement
 	 *            The configuration element from which the real class can be
 	 *            loaded at run-time; must not be <code>null</code>.
 	 * @param stateAttributeName
 	 *            The name of the attribute or element containing the state
 	 *            executable extension; must not be <code>null</code>.
 	 * @param preferenceStore
 	 *            The preference store to which any persistent data should be
 	 *            written, and from which it should be loaded; may be
 	 *            <code>null</code>.
 	 * @param preferenceKey
 	 *            The key at which the persistent data is located within the
 	 *            preference store.
 	 */
 	public CommandStateProxy(final IConfigurationElement configurationElement,
 			final String stateAttributeName,
 			final IPreferenceStore preferenceStore, final String preferenceKey) {

 		if (configurationElement == null) {
 			throw new NullPointerException(
 					"The configuration element backing a state proxy cannot be null"); //$NON-NLS-1$
 		}

 		if (stateAttributeName == null) {
 			throw new NullPointerException(
 					"The attribute containing the state class must be known"); //$NON-NLS-1$
 		}

 		this.configurationElement = configurationElement;
 		this.stateAttributeName = stateAttributeName;
 		this.preferenceKey = preferenceKey;
 		this.preferenceStore = preferenceStore;
 	}

 	public final void addListener(final IStateListener listener) {
 		if (state == null) {
 			addListenerObject(listener);
 		} else {
 			state.addListener(listener);
 		}
 	}

 	public final void dispose() {
 		if (state != null) {
 			state.dispose();
 			if (state instanceof PersistentState) {
 				final PersistentState persistableState = (PersistentState) state;
 				if (persistableState.shouldPersist() && preferenceStore != null
 						&& preferenceKey != null) {
 					persistableState.save(preferenceStore, preferenceKey);
 				}
 			}
 		}
 	}

 	public final Object getValue() {
 		if (loadState()) {
 			return state.getValue();
 		}

 		return null;
 	}

 	public final void load(final IPreferenceStore store,
 			final String preferenceKey) {
 		if (loadState() && state instanceof PersistentState) {
 			final PersistentState persistableState = (PersistentState) state;
 			if (persistableState.shouldPersist() && preferenceStore != null
 					&& preferenceKey != null) {
 				persistableState.load(preferenceStore, preferenceKey);
 			}
 		}
 	}

 	/**
 	 * Loads the state, if possible. If the state is loaded, then the member
 	 * variables are updated accordingly and the state is told to load its value
 	 * from the preference store.
 	 *
 	 * @return <code>true</code> if the state is now non-null;
 	 *         <code>false</code> otherwise.
 	 */
 	private final boolean loadState() {
 		return loadState(false);
 	}

 	/**
 	 * Loads the state, if possible. If the state is loaded, then the member
 	 * variables are updated accordingly and the state is told to load its value
 	 * from the preference store.
 	 *
 	 * @param readPersistence
 	 *            Whether the persistent state for this object should be read.
 	 * @return <code>true</code> if the state is now non-null;
 	 *         <code>false</code> otherwise.
 	 */
 	private final boolean loadState(final boolean readPersistence) {
 		if (state == null) {
 			try {
 				state = (State) configurationElement
 						.createExecutableExtension(stateAttributeName);
 				state.setId(getId());
 				configurationElement = null;

 				// Try to load the persistent state, if possible.
 				if (readPersistence && state instanceof PersistentState) {
 					final PersistentState persistentState = (PersistentState) state;
 					persistentState.setShouldPersist(true);
 				}
 				load(preferenceStore, preferenceKey);

 				// Transfer the local listeners to the real state.
 				final Object[] listenerArray = getListeners();
 				for (int i = 0; i < listenerArray.length; i++) {
 					state.addListener((IStateListener) listenerArray[i]);
 				}
 				clearListeners();

 				return true;

 			} catch (final ClassCastException e) {
 				final String message = "The proxied state was the wrong class"; //$NON-NLS-1$
 				final IStatus status = new Status(IStatus.ERROR,
 						WorkbenchPlugin.PI_WORKBENCH, 0, message, e);
 				WorkbenchPlugin.log(message, status);
 				return false;

 			} catch (final CoreException e) {
 				final String message = "The proxied state for '" + configurationElement.getAttribute(stateAttributeName) //$NON-NLS-1$
 						+ "' could not be loaded"; //$NON-NLS-1$
 				IStatus status = new Status(IStatus.ERROR,
 						WorkbenchPlugin.PI_WORKBENCH, 0, message, e);
 				WorkbenchPlugin.log(message, status);
 				return false;
 			}
 		}

 		return true;
 	}

 	public final void removeListener(final IStateListener listener) {
 		if (state == null) {
 			removeListenerObject(listener);
 		} else {
 			state.removeListener(listener);
 		}
 	}

 	public final void save(final IPreferenceStore store,
 			final String preferenceKey) {
 		if (loadState() && state instanceof PersistentState) {
 			((PersistentState) state).save(store, preferenceKey);
 		}
 	}

 	public final void setId(final String id) {
 		super.setId(id);
 		if (state != null) {
 			state.setId(id);
 		}
 	}

 	public final void setShouldPersist(final boolean persisted) {
 		if (loadState(persisted) && state instanceof PersistentState) {
 			((PersistentState) state).setShouldPersist(persisted);
 		}
 	}

 	public final void setValue(final Object value) {
 		if (loadState()) {
 			state.setValue(value);
 		}
 	}

 	public final boolean shouldPersist() {
 		if (loadState() && state instanceof PersistentState) {
 			return ((PersistentState) state).shouldPersist();
 		}

 		return false;
 	}

 	public final String toString() {
 		if (state == null) {
 			return configurationElement.getAttribute(stateAttributeName);
 		}

 		return state.toString();
 	}
 }
	/*******************************************************************************
	* Copyright (c) 2000, 2007 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.ui.internal.commands;

	import org.eclipse.core.commands.IStateListener;
	import org.eclipse.core.commands.State;
	import org.eclipse.core.runtime.CoreException;
	import org.eclipse.core.runtime.IConfigurationElement;
	import org.eclipse.core.runtime.IStatus;
	import org.eclipse.core.runtime.Status;
	import org.eclipse.jface.commands.PersistentState;
	import org.eclipse.jface.preference.IPreferenceStore;
	import org.eclipse.ui.internal.WorkbenchPlugin;

	/**
	* <p>
	* A proxy for handler state that has been defined in XML. This delays the class
	* loading until the state is really asked for information. Asking a proxy for
	* anything (except disposing, and adding and removing listeners) will cause the
	* proxy to instantiate the proxied handler.
	* </p>
	* <p>
	* Loading the proxied state will automatically cause it to load its value from
	* the preference store. Disposing of the state will cause it to persist its
	* value.
	* </p>
	* <p>
	* This class is not intended for use outside of the
	* <code>org.eclipse.ui.workbench</code> plug-in.
	* </p>
	*
	* @since 3.2
	*/
	public final class CommandStateProxy extends PersistentState {

	/**
	* The configuration element from which the state can be created. This value
	* will exist until the element is converted into a real class -- at which
	* point this value will be set to <code>null</code>.
	*/
	private IConfigurationElement configurationElement;

	/**
	* The key in the preference store to locate the persisted state.
	*/
	private String preferenceKey;

	/**
	* The preference store containing the persisted state, if any.
	*/
	private IPreferenceStore preferenceStore;

	/**
	* The real state. This value is <code>null</code> until the proxy is
	* forced to load the real state. At this point, the configuration element
	* is converted, nulled out, and this state gains a reference.
	*/
	private State state = null;

	/**
	* The name of the configuration element attribute which contains the
	* information necessary to instantiate the real state.
	*/
	private final String stateAttributeName;

	/**
	* Constructs a new instance of <code>HandlerState</code> with all the
	* information it needs to create the real state later.
	*
	* @param configurationElement
	* The configuration element from which the real class can be
	* loaded at run-time; must not be <code>null</code>.
	* @param stateAttributeName
	* The name of the attribute or element containing the state
	* executable extension; must not be <code>null</code>.
	* @param preferenceStore
	* The preference store to which any persistent data should be
	* written, and from which it should be loaded; may be
	* <code>null</code>.
	* @param preferenceKey
	* The key at which the persistent data is located within the
	* preference store.
	*/
	public CommandStateProxy(final IConfigurationElement configurationElement,
	final String stateAttributeName,
	final IPreferenceStore preferenceStore, final String preferenceKey) {

	if (configurationElement == null) {
	throw new NullPointerException(
	"The configuration element backing a state proxy cannot be null"); //$NON-NLS-1$
	}

	if (stateAttributeName == null) {
	throw new NullPointerException(
	"The attribute containing the state class must be known"); //$NON-NLS-1$
	}

	this.configurationElement = configurationElement;
	this.stateAttributeName = stateAttributeName;
	this.preferenceKey = preferenceKey;
	this.preferenceStore = preferenceStore;
	}

	public final void addListener(final IStateListener listener) {
	if (state == null) {
	addListenerObject(listener);
	} else {
	state.addListener(listener);
	}
	}

	public final void dispose() {
	if (state != null) {
	state.dispose();
	if (state instanceof PersistentState) {
	final PersistentState persistableState = (PersistentState) state;
	if (persistableState.shouldPersist() && preferenceStore != null
	&& preferenceKey != null) {
	persistableState.save(preferenceStore, preferenceKey);
	}
	}
	}
	}

	public final Object getValue() {
	if (loadState()) {
	return state.getValue();
	}

	return null;
	}

	public final void load(final IPreferenceStore store,
	final String preferenceKey) {
	if (loadState() && state instanceof PersistentState) {
	final PersistentState persistableState = (PersistentState) state;
	if (persistableState.shouldPersist() && preferenceStore != null
	&& preferenceKey != null) {
	persistableState.load(preferenceStore, preferenceKey);
	}
	}
	}

	/**
	* Loads the state, if possible. If the state is loaded, then the member
	* variables are updated accordingly and the state is told to load its value
	* from the preference store.
	*
	* @return <code>true</code> if the state is now non-null;
	* <code>false</code> otherwise.
	*/
	private final boolean loadState() {
	return loadState(false);
	}

	/**
	* Loads the state, if possible. If the state is loaded, then the member
	* variables are updated accordingly and the state is told to load its value
	* from the preference store.
	*
	* @param readPersistence
	* Whether the persistent state for this object should be read.
	* @return <code>true</code> if the state is now non-null;
	* <code>false</code> otherwise.
	*/
	private final boolean loadState(final boolean readPersistence) {
	if (state == null) {
	try {
	state = (State) configurationElement
	.createExecutableExtension(stateAttributeName);
	state.setId(getId());
	configurationElement = null;

	// Try to load the persistent state, if possible.
	if (readPersistence && state instanceof PersistentState) {
	final PersistentState persistentState = (PersistentState) state;
	persistentState.setShouldPersist(true);
	}
	load(preferenceStore, preferenceKey);

	// Transfer the local listeners to the real state.
	final Object[] listenerArray = getListeners();
	for (int i = 0; i < listenerArray.length; i++) {
	state.addListener((IStateListener) listenerArray[i]);
	}
	clearListeners();

	return true;

	} catch (final ClassCastException e) {
	final String message = "The proxied state was the wrong class"; //$NON-NLS-1$
	final IStatus status = new Status(IStatus.ERROR,
	WorkbenchPlugin.PI_WORKBENCH, 0, message, e);
	WorkbenchPlugin.log(message, status);
	return false;

	} catch (final CoreException e) {
	final String message = "The proxied state for '" + configurationElement.getAttribute(stateAttributeName) //$NON-NLS-1$
	+ "' could not be loaded"; //$NON-NLS-1$
	IStatus status = new Status(IStatus.ERROR,
	WorkbenchPlugin.PI_WORKBENCH, 0, message, e);
	WorkbenchPlugin.log(message, status);
	return false;
	}
	}

	return true;
	}

	public final void removeListener(final IStateListener listener) {
	if (state == null) {
	removeListenerObject(listener);
	} else {
	state.removeListener(listener);
	}
	}

	public final void save(final IPreferenceStore store,
	final String preferenceKey) {
	if (loadState() && state instanceof PersistentState) {
	((PersistentState) state).save(store, preferenceKey);
	}
	}

	public final void setId(final String id) {
	super.setId(id);
	if (state != null) {
	state.setId(id);
	}
	}

	public final void setShouldPersist(final boolean persisted) {
	if (loadState(persisted) && state instanceof PersistentState) {
	((PersistentState) state).setShouldPersist(persisted);
	}
	}

	public final void setValue(final Object value) {
	if (loadState()) {
	state.setValue(value);
	}
	}

	public final boolean shouldPersist() {
	if (loadState() && state instanceof PersistentState) {
	return ((PersistentState) state).shouldPersist();
	}

	return false;
	}

	public final String toString() {
	if (state == null) {
	return configurationElement.getAttribute(stateAttributeName);
	}

	return state.toString();
	}
	}