| /******************************************************************************* |
| * 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.contexts; |
| |
| import org.eclipse.core.expressions.Expression; |
| import org.eclipse.core.expressions.IEvaluationContext; |
| import org.eclipse.ui.ISources; |
| import org.eclipse.ui.contexts.IContextActivation; |
| import org.eclipse.ui.contexts.IContextService; |
| import org.eclipse.ui.internal.services.EvaluationResultCache; |
| |
| /** |
| * <p> |
| * A token representing the activation of a context. This token can later be |
| * used to cancel that activation. Without this token, then the context will |
| * only become inactive if the component in which the context was activated is |
| * destroyed. |
| * </p> |
| * <p> |
| * This caches the context id, so that they can later be identified. |
| * </p> |
| * <p> |
| * Note: this class has a natural ordering that is inconsistent with equals. |
| * </p> |
| * |
| * @since 3.1 |
| */ |
| final class ContextActivation extends EvaluationResultCache implements |
| IContextActivation { |
| |
| /** |
| * The identifier for the context which should be active. This value is |
| * never <code>null</code>. |
| */ |
| private final String contextId; |
| |
| /** |
| * The context service from which this context activation was requested. |
| * This value is never <code>null</code>. |
| */ |
| private final IContextService contextService; |
| |
| /** |
| * Constructs a new instance of <code>ContextActivation</code>. |
| * |
| * @param contextId |
| * The identifier for the context which should be activated. This |
| * value must not be <code>null</code>. |
| * @param expression |
| * The expression that must evaluate to <code>true</code> |
| * before this handler is active. This value may be |
| * <code>null</code> if it is always active. |
| * @param contextService |
| * The context service from which the handler activation was |
| * requested; must not be <code>null</code>. |
| * @see ISources |
| */ |
| public ContextActivation(final String contextId, |
| final Expression expression, final IContextService contextService) { |
| super(expression); |
| |
| if (contextId == null) { |
| throw new NullPointerException( |
| "The context identifier for a context activation cannot be null"); //$NON-NLS-1$ |
| } |
| |
| if (contextService == null) { |
| throw new NullPointerException( |
| "The context service for an activation cannot be null"); //$NON-NLS-1$ |
| } |
| |
| this.contextId = contextId; |
| this.contextService = contextService; |
| } |
| |
| public final void clearActive() { |
| clearResult(); |
| } |
| |
| public final String getContextId() { |
| return contextId; |
| } |
| |
| public final IContextService getContextService() { |
| return contextService; |
| } |
| |
| public final boolean isActive(final IEvaluationContext context) { |
| return evaluate(context); |
| } |
| |
| public final String toString() { |
| final StringBuffer buffer = new StringBuffer(); |
| |
| buffer.append("ContextActivation(contextId="); //$NON-NLS-1$ |
| buffer.append(contextId); |
| buffer.append(",sourcePriority="); //$NON-NLS-1$ |
| buffer.append(getSourcePriority()); |
| buffer.append(')'); |
| |
| return buffer.toString(); |
| } |
| |
| } |