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

 /*******************************************************************************
  * 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.ui.internal.services;

 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.Iterator;
 import java.util.Map;

 import org.eclipse.core.expressions.EvaluationContext;
 import org.eclipse.core.expressions.Expression;
 import org.eclipse.core.expressions.IEvaluationContext;
 import org.eclipse.jface.viewers.ISelection;
 import org.eclipse.jface.viewers.IStructuredSelection;
 import org.eclipse.ui.ISourceProvider;
 import org.eclipse.ui.ISourceProviderListener;
 import org.eclipse.ui.ISources;

 /**
  * <p>
  * Provides common functionality for evaluating expressions and listening to
  * {@link ISourceProvider} (i.e., the common event framework for commands).
  * </p>
  * <p>
  * This class is not intended for use outside of the
  * <code>org.eclipse.ui.workbench</code> plug-in.
  * </p>
  *
  * @since 3.2
  * @see ISourceProvider
  * @see ISources
  * @see Expression
  * @see IEvaluationContext
  */
 public abstract class ExpressionAuthority implements ISourceProviderListener {

 	/**
 	 * The evaluation context instance to use when evaluating expression. This
 	 * context is shared, and so all calls into <code>sourceChanged</code>
 	 * must happen on the event thread.
 	 */
 	private final IEvaluationContext context;

 	/**
 	 * The current state of this authority. This is a child of the
 	 * {@link #context} that has been given the selection as the default
 	 * variable. This value is cleared to <code>null</code> whenever the
 	 * selection changes.
 	 */
 	private IEvaluationContext currentState = null;

 	/**
 	 * The collection of source providers used by this authority. This
 	 * collection is consulted whenever a contribution is made. This collection
 	 * only contains instances of <code>ISourceProvider</code>.
 	 */
 	private final Collection providers = new ArrayList();

 	/**
 	 * Constructs a new instance of <code>ExpressionAuthority</code>.
 	 */
 	protected ExpressionAuthority() {
 		context = new EvaluationContext(null, this);
 	}

 	/**
 	 * Adds a source provider to a list of providers to check when updating.
 	 * This also attaches this authority as a listener to the provider.
 	 *
 	 * @param provider
 	 *            The provider to add; must not be <code>null</code>.
 	 */
 	public final void addSourceProvider(final ISourceProvider provider) {
 		provider.addSourceProviderListener(this);
 		providers.add(provider);

 		// Update the current state.
 		final Map currentState = provider.getCurrentState();
 		final Iterator variableItr = currentState.entrySet().iterator();
 		while (variableItr.hasNext()) {
 			final Map.Entry entry = (Map.Entry) variableItr.next();
 			final String variableName = (String) entry.getKey();
 			final Object variableValue = entry.getValue();

 			/*
 			 * Bug 84056. If we update the active workbench window, then we risk
 			 * falling back to that shell when the active shell has registered
 			 * as "none".
 			 */
 			if ((variableName != null)
 					&& (!ISources.ACTIVE_WORKBENCH_WINDOW_SHELL_NAME
 							.equals(variableName))) {
 				changeVariable(variableName, variableValue);
 			}
 		}
 	}

 	/**
 	 * Removes all of the source provider listeners. Subclasses may extend, but
 	 * must not override.
 	 */
 	public void dispose() {
 		final Iterator providerItr = providers.iterator();
 		while (providerItr.hasNext()) {
 			final ISourceProvider provider = (ISourceProvider) providerItr
 					.next();
 			provider.removeSourceProviderListener(this);
 		}

 		providers.clear();
 	}

 	/**
 	 * Returns whether at least one of the <code>IEvaluationResultCache</code>
 	 * instances in <code>collection</code> evaluates to <code>true</code>.
 	 *
 	 * @param collection
 	 *            The evaluation result caches to check; must not be
 	 *            <code>null</code>, but may be empty.
 	 * @return <code>true</code> if there is at least one expression that
 	 *         evaluates to <code>true</code>; <code>false</code>
 	 *         otherwise.
 	 */
 	protected final boolean evaluate(final Collection collection) {
 		final Iterator iterator = collection.iterator();
 		while (iterator.hasNext()) {
 			final IEvaluationResultCache cache = (IEvaluationResultCache) iterator
 					.next();
 			if (evaluate(cache)) {
 				return true;
 			}
 		}

 		return false;
 	}

 	/**
 	 * Returns whether the <code>IEvaluationResultCache</code> evaluates to
 	 * <code>true</code>.
 	 *
 	 * @param expression
 	 *            The evaluation result cache to check; must not be
 	 *            <code>null</code>.
 	 * @return <code>true</code> if the expression evaluates to
 	 *         <code>true</code>; <code>false</code> otherwise.
 	 */
 	protected final boolean evaluate(final IEvaluationResultCache expression) {
 		final IEvaluationContext contextWithDefaultVariable = getCurrentState();
 		return expression.evaluate(contextWithDefaultVariable);
 	}

 	/**
 	 * Creates a new evaluation context based on the current evaluation context
 	 * (i.e., the current state), and places the current selection as the
 	 * default variable.
 	 *
 	 * @return An evaluation context that can be used for evaluating
 	 *         expressions; never <code>null</code>.
 	 */
 	public final IEvaluationContext getCurrentState() {
 		if (currentState == null) {
 			final Object defaultVariable = context
 					.getVariable(ISources.ACTIVE_CURRENT_SELECTION_NAME);
 			final IEvaluationContext contextWithDefaultVariable;
 			if (defaultVariable instanceof IStructuredSelection) {
 				final IStructuredSelection selection = (IStructuredSelection) defaultVariable;
 				contextWithDefaultVariable = new EvaluationContext(context,
 						selection.toList());
 			} else if ((defaultVariable instanceof ISelection)
 					&& (!((ISelection) defaultVariable).isEmpty())) {
 				contextWithDefaultVariable = new EvaluationContext(context,
 						Collections.singleton(defaultVariable));
 			} else {
 				contextWithDefaultVariable = new EvaluationContext(context,
 						Collections.EMPTY_LIST);
 			}
 			currentState = contextWithDefaultVariable;
 		}

 		return currentState;
 	}

 	/**
 	 * Returns the variable of the given name.
 	 *
 	 * @param name
 	 *            The name of the variable to get; must not be <code>null</code>.
 	 * @return The variable of the given name; <code>null</code> if none.
 	 */
 	protected final Object getVariable(final String name) {
 		return context.getVariable(name);
 	}

 	/**
 	 * Removes this source provider from the list, and detaches this authority
 	 * as a listener.
 	 *
 	 * @param provider
 	 *            The provider to remove; must not be <code>null</code>.
 	 */
 	public final void removeSourceProvider(final ISourceProvider provider) {
 		provider.removeSourceProviderListener(this);
 		providers.remove(provider);

 		final Map currentState = provider.getCurrentState();
 		final Iterator variableItr = currentState.entrySet().iterator();
 		while (variableItr.hasNext()) {
 			final Map.Entry entry = (Map.Entry) variableItr.next();
 			final String variableName = (String) entry.getKey();
 			changeVariable(variableName, null);
 		}
 	}

 	/**
 	 * Changes the variable of the given name. If the <code>value</code> is
 	 * <code>null</code>, then the variable is removed.
 	 *
 	 * @param name
 	 *            The name of the variable to change; must not be
 	 *            <code>null</code>.
 	 * @param value
 	 *            The new value; the variable should be removed if this is
 	 *            <code>null</code>.
 	 */
 	protected final void changeVariable(final String name, final Object value) {
 		if (value == null) {
 			context.removeVariable(name);
 		} else {
 			context.addVariable(name, value);
 		}
 	}

 	/**
 	 * Carries out the actual source change notification. It assumed that by the
 	 * time this method is called, <code>getEvaluationContext()</code> is
 	 * up-to-date with the current state of the application.
 	 *
 	 * @param sourcePriority
 	 *            A bit mask of all the source priorities that have changed.
 	 */
 	protected abstract void sourceChanged(final int sourcePriority);

 	public final void sourceChanged(final int sourcePriority,
 			final Map sourceValuesByName) {
 		// If the selection has changed, invalidate the current state.
 		if (sourceValuesByName
 				.containsKey(ISources.ACTIVE_CURRENT_SELECTION_NAME)) {
 			currentState = null;
 		}

 		final Iterator entryItr = sourceValuesByName.entrySet().iterator();
 		while (entryItr.hasNext()) {
 			final Map.Entry entry = (Map.Entry) entryItr.next();
 			final String sourceName = (String) entry.getKey();
 			final Object sourceValue = entry.getValue();
 			updateEvaluationContext(sourceName, sourceValue);
 		}
 		sourceChanged(sourcePriority);
 	}

 	public final void sourceChanged(final int sourcePriority,
 			final String sourceName, final Object sourceValue) {
 		// If the selection has changed, invalidate the current state.
 		if (ISources.ACTIVE_CURRENT_SELECTION_NAME.equals(sourceName)) {
 			currentState = null;
 		}

 		updateEvaluationContext(sourceName, sourceValue);
 		sourceChanged(sourcePriority);
 	}

 	/**
 	 * Updates the evaluation context with the current state from all of the
 	 * source providers.
 	 */
 	protected final void updateCurrentState() {
 		final Iterator providerItr = providers.iterator();
 		while (providerItr.hasNext()) {
 			final ISourceProvider provider = (ISourceProvider) providerItr
 					.next();
 			final Map currentState = provider.getCurrentState();
 			final Iterator variableItr = currentState.entrySet().iterator();
 			while (variableItr.hasNext()) {
 				final Map.Entry entry = (Map.Entry) variableItr.next();
 				final String variableName = (String) entry.getKey();
 				final Object variableValue = entry.getValue();
 				/*
 				 * Bug 84056. If we update the active workbench window, then we
 				 * risk falling back to that shell when the active shell has
 				 * registered as "none".
 				 */
 				if ((variableName != null)
 						&& (!ISources.ACTIVE_WORKBENCH_WINDOW_SHELL_NAME
 								.equals(variableName))) {
 					changeVariable(variableName, variableValue);
 				}
 			}
 		}
 	}

 	/**
 	 * Updates this authority's evaluation context.
 	 *
 	 * @param name
 	 *            The name of the variable to update; must not be
 	 *            <code>null</code>.
 	 * @param value
 	 *            The new value of the variable. If this value is
 	 *            <code>null</code>, then the variable is removed.
 	 */
 	protected void updateEvaluationContext(final String name, final Object value) {
 		if (name != null) {
 			changeVariable(name, value);
 		}
 	}
 }
	/*******************************************************************************
	* 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.ui.internal.services;

	import java.util.ArrayList;
	import java.util.Collection;
	import java.util.Collections;
	import java.util.Iterator;
	import java.util.Map;

	import org.eclipse.core.expressions.EvaluationContext;
	import org.eclipse.core.expressions.Expression;
	import org.eclipse.core.expressions.IEvaluationContext;
	import org.eclipse.jface.viewers.ISelection;
	import org.eclipse.jface.viewers.IStructuredSelection;
	import org.eclipse.ui.ISourceProvider;
	import org.eclipse.ui.ISourceProviderListener;
	import org.eclipse.ui.ISources;

	/**
	* <p>
	* Provides common functionality for evaluating expressions and listening to
	* {@link ISourceProvider} (i.e., the common event framework for commands).
	* </p>
	* <p>
	* This class is not intended for use outside of the
	* <code>org.eclipse.ui.workbench</code> plug-in.
	* </p>
	*
	* @since 3.2
	* @see ISourceProvider
	* @see ISources
	* @see Expression
	* @see IEvaluationContext
	*/
	public abstract class ExpressionAuthority implements ISourceProviderListener {

	/**
	* The evaluation context instance to use when evaluating expression. This
	* context is shared, and so all calls into <code>sourceChanged</code>
	* must happen on the event thread.
	*/
	private final IEvaluationContext context;

	/**
	* The current state of this authority. This is a child of the
	* {@link #context} that has been given the selection as the default
	* variable. This value is cleared to <code>null</code> whenever the
	* selection changes.
	*/
	private IEvaluationContext currentState = null;

	/**
	* The collection of source providers used by this authority. This
	* collection is consulted whenever a contribution is made. This collection
	* only contains instances of <code>ISourceProvider</code>.
	*/
	private final Collection providers = new ArrayList();

	/**
	* Constructs a new instance of <code>ExpressionAuthority</code>.
	*/
	protected ExpressionAuthority() {
	context = new EvaluationContext(null, this);
	}

	/**
	* Adds a source provider to a list of providers to check when updating.
	* This also attaches this authority as a listener to the provider.
	*
	* @param provider
	* The provider to add; must not be <code>null</code>.
	*/
	public final void addSourceProvider(final ISourceProvider provider) {
	provider.addSourceProviderListener(this);
	providers.add(provider);

	// Update the current state.
	final Map currentState = provider.getCurrentState();
	final Iterator variableItr = currentState.entrySet().iterator();
	while (variableItr.hasNext()) {
	final Map.Entry entry = (Map.Entry) variableItr.next();
	final String variableName = (String) entry.getKey();
	final Object variableValue = entry.getValue();

	/*
	* Bug 84056. If we update the active workbench window, then we risk
	* falling back to that shell when the active shell has registered
	* as "none".
	*/
	if ((variableName != null)
	&& (!ISources.ACTIVE_WORKBENCH_WINDOW_SHELL_NAME
	.equals(variableName))) {
	changeVariable(variableName, variableValue);
	}
	}
	}

	/**
	* Removes all of the source provider listeners. Subclasses may extend, but
	* must not override.
	*/
	public void dispose() {
	final Iterator providerItr = providers.iterator();
	while (providerItr.hasNext()) {
	final ISourceProvider provider = (ISourceProvider) providerItr
	.next();
	provider.removeSourceProviderListener(this);
	}

	providers.clear();
	}

	/**
	* Returns whether at least one of the <code>IEvaluationResultCache</code>
	* instances in <code>collection</code> evaluates to <code>true</code>.
	*
	* @param collection
	* The evaluation result caches to check; must not be
	* <code>null</code>, but may be empty.
	* @return <code>true</code> if there is at least one expression that
	* evaluates to <code>true</code>; <code>false</code>
	* otherwise.
	*/
	protected final boolean evaluate(final Collection collection) {
	final Iterator iterator = collection.iterator();
	while (iterator.hasNext()) {
	final IEvaluationResultCache cache = (IEvaluationResultCache) iterator
	.next();
	if (evaluate(cache)) {
	return true;
	}
	}

	return false;
	}

	/**
	* Returns whether the <code>IEvaluationResultCache</code> evaluates to
	* <code>true</code>.
	*
	* @param expression
	* The evaluation result cache to check; must not be
	* <code>null</code>.
	* @return <code>true</code> if the expression evaluates to
	* <code>true</code>; <code>false</code> otherwise.
	*/
	protected final boolean evaluate(final IEvaluationResultCache expression) {
	final IEvaluationContext contextWithDefaultVariable = getCurrentState();
	return expression.evaluate(contextWithDefaultVariable);
	}

	/**
	* Creates a new evaluation context based on the current evaluation context
	* (i.e., the current state), and places the current selection as the
	* default variable.
	*
	* @return An evaluation context that can be used for evaluating
	* expressions; never <code>null</code>.
	*/
	public final IEvaluationContext getCurrentState() {
	if (currentState == null) {
	final Object defaultVariable = context
	.getVariable(ISources.ACTIVE_CURRENT_SELECTION_NAME);
	final IEvaluationContext contextWithDefaultVariable;
	if (defaultVariable instanceof IStructuredSelection) {
	final IStructuredSelection selection = (IStructuredSelection) defaultVariable;
	contextWithDefaultVariable = new EvaluationContext(context,
	selection.toList());
	} else if ((defaultVariable instanceof ISelection)
	&& (!((ISelection) defaultVariable).isEmpty())) {
	contextWithDefaultVariable = new EvaluationContext(context,
	Collections.singleton(defaultVariable));
	} else {
	contextWithDefaultVariable = new EvaluationContext(context,
	Collections.EMPTY_LIST);
	}
	currentState = contextWithDefaultVariable;
	}

	return currentState;
	}

	/**
	* Returns the variable of the given name.
	*
	* @param name
	* The name of the variable to get; must not be <code>null</code>.
	* @return The variable of the given name; <code>null</code> if none.
	*/
	protected final Object getVariable(final String name) {
	return context.getVariable(name);
	}

	/**
	* Removes this source provider from the list, and detaches this authority
	* as a listener.
	*
	* @param provider
	* The provider to remove; must not be <code>null</code>.
	*/
	public final void removeSourceProvider(final ISourceProvider provider) {
	provider.removeSourceProviderListener(this);
	providers.remove(provider);

	final Map currentState = provider.getCurrentState();
	final Iterator variableItr = currentState.entrySet().iterator();
	while (variableItr.hasNext()) {
	final Map.Entry entry = (Map.Entry) variableItr.next();
	final String variableName = (String) entry.getKey();
	changeVariable(variableName, null);
	}
	}

	/**
	* Changes the variable of the given name. If the <code>value</code> is
	* <code>null</code>, then the variable is removed.
	*
	* @param name
	* The name of the variable to change; must not be
	* <code>null</code>.
	* @param value
	* The new value; the variable should be removed if this is
	* <code>null</code>.
	*/
	protected final void changeVariable(final String name, final Object value) {
	if (value == null) {
	context.removeVariable(name);
	} else {
	context.addVariable(name, value);
	}
	}

	/**
	* Carries out the actual source change notification. It assumed that by the
	* time this method is called, <code>getEvaluationContext()</code> is
	* up-to-date with the current state of the application.
	*
	* @param sourcePriority
	* A bit mask of all the source priorities that have changed.
	*/
	protected abstract void sourceChanged(final int sourcePriority);

	public final void sourceChanged(final int sourcePriority,
	final Map sourceValuesByName) {
	// If the selection has changed, invalidate the current state.
	if (sourceValuesByName
	.containsKey(ISources.ACTIVE_CURRENT_SELECTION_NAME)) {
	currentState = null;
	}

	final Iterator entryItr = sourceValuesByName.entrySet().iterator();
	while (entryItr.hasNext()) {
	final Map.Entry entry = (Map.Entry) entryItr.next();
	final String sourceName = (String) entry.getKey();
	final Object sourceValue = entry.getValue();
	updateEvaluationContext(sourceName, sourceValue);
	}
	sourceChanged(sourcePriority);
	}

	public final void sourceChanged(final int sourcePriority,
	final String sourceName, final Object sourceValue) {
	// If the selection has changed, invalidate the current state.
	if (ISources.ACTIVE_CURRENT_SELECTION_NAME.equals(sourceName)) {
	currentState = null;
	}

	updateEvaluationContext(sourceName, sourceValue);
	sourceChanged(sourcePriority);
	}

	/**
	* Updates the evaluation context with the current state from all of the
	* source providers.
	*/
	protected final void updateCurrentState() {
	final Iterator providerItr = providers.iterator();
	while (providerItr.hasNext()) {
	final ISourceProvider provider = (ISourceProvider) providerItr
	.next();
	final Map currentState = provider.getCurrentState();
	final Iterator variableItr = currentState.entrySet().iterator();
	while (variableItr.hasNext()) {
	final Map.Entry entry = (Map.Entry) variableItr.next();
	final String variableName = (String) entry.getKey();
	final Object variableValue = entry.getValue();
	/*
	* Bug 84056. If we update the active workbench window, then we
	* risk falling back to that shell when the active shell has
	* registered as "none".
	*/
	if ((variableName != null)
	&& (!ISources.ACTIVE_WORKBENCH_WINDOW_SHELL_NAME
	.equals(variableName))) {
	changeVariable(variableName, variableValue);
	}
	}
	}
	}

	/**
	* Updates this authority's evaluation context.
	*
	* @param name
	* The name of the variable to update; must not be
	* <code>null</code>.
	* @param value
	* The new value of the variable. If this value is
	* <code>null</code>, then the variable is removed.
	*/
	protected void updateEvaluationContext(final String name, final Object value) {
	if (name != null) {
	changeVariable(name, value);
	}
	}
	}