| /******************************************************************************* |
| * Copyright (c) 2005, 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.services; |
| |
| import org.eclipse.core.expressions.Expression; |
| import org.eclipse.core.expressions.IEvaluationContext; |
| import org.eclipse.ui.ISources; |
| |
| /** |
| * <p> |
| * A cache of the result of an expression. This also provides the source |
| * priority for the expression. |
| * </p> |
| * <p> |
| * This interface is not intended to be implemented or extended by clients. |
| * </p> |
| * |
| * @since 3.2 |
| * @see org.eclipse.ui.ISources |
| * @see org.eclipse.ui.ISourceProvider |
| */ |
| public interface IEvaluationResultCache { |
| |
| /** |
| * Clears the cached computation of the <code>evaluate</code> method, if |
| * any. This method is only intended for internal use. It provides a |
| * mechanism by which <code>ISourceProvider</code> events can invalidate |
| * state on a <code>IEvaluationResultCache</code> instance. |
| */ |
| public void clearResult(); |
| |
| /** |
| * Returns the expression controlling the activation or visibility of this |
| * item. |
| * |
| * @return The expression associated with this item; may be |
| * <code>null</code>. |
| */ |
| public Expression getExpression(); |
| |
| /** |
| * Returns the priority that has been given to this expression. |
| * |
| * @return The priority. |
| * @see ISources |
| */ |
| public int getSourcePriority(); |
| |
| /** |
| * Evaluates the expression -- given the current state of the workbench. |
| * This method should cache its computation. The cache will be cleared by a |
| * call to <code>clearResult</code>. |
| * |
| * @param context |
| * The context in which this state should be evaluated; must not |
| * be <code>null</code>. |
| * @return <code>true</code> if the expression currently evaluates to |
| * <code>true</code>; <code>false</code> otherwise. |
| */ |
| public boolean evaluate(IEvaluationContext context); |
| |
| /** |
| * Forces the cached result to be a particular value. This will <b>not</b> |
| * notify any users of the cache that it has changed. |
| * |
| * @param result |
| * The cached result to use. |
| * @since 3.3 |
| */ |
| public void setResult(boolean result); |
| } |