| /******************************************************************************* |
| * Copyright (c) 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.core.internal.expressions; |
| |
| import org.w3c.dom.Element; |
| |
| import org.eclipse.core.expressions.EvaluationResult; |
| import org.eclipse.core.expressions.Expression; |
| import org.eclipse.core.expressions.ExpressionInfo; |
| import org.eclipse.core.expressions.IEvaluationContext; |
| |
| import org.eclipse.core.runtime.Assert; |
| import org.eclipse.core.runtime.CoreException; |
| import org.eclipse.core.runtime.IConfigurationElement; |
| |
| /** |
| * This class makes use of the <b>org.eclipse.core.expressions.definitions</b> |
| * extension point to evaluate the current context against pre-defined |
| * expressions. It provides core expression re-use. |
| * |
| * @since 3.3 |
| */ |
| public class ReferenceExpression extends Expression { |
| |
| // consider making this a more general extension manager |
| // for now it's just part of the reference expression |
| private static DefinitionRegistry fgDefinitionRegistry= null; |
| |
| private static DefinitionRegistry getDefinitionRegistry() { |
| if (fgDefinitionRegistry == null) { |
| fgDefinitionRegistry= new DefinitionRegistry(); |
| } |
| return fgDefinitionRegistry; |
| } |
| |
| private static final String ATT_DEFINITION_ID= "definitionId"; //$NON-NLS-1$ |
| |
| /** |
| * The seed for the hash code for all equals expressions. |
| */ |
| private static final int HASH_INITIAL= ReferenceExpression.class.getName().hashCode(); |
| |
| private String fDefinitionId; |
| |
| public ReferenceExpression(String definitionId) { |
| Assert.isNotNull(definitionId); |
| fDefinitionId= definitionId; |
| } |
| |
| public ReferenceExpression(IConfigurationElement element) throws CoreException { |
| fDefinitionId= element.getAttribute(ATT_DEFINITION_ID); |
| Expressions.checkAttribute(ATT_DEFINITION_ID, fDefinitionId); |
| } |
| |
| public ReferenceExpression(Element element) throws CoreException { |
| fDefinitionId= element.getAttribute(ATT_DEFINITION_ID); |
| Expressions.checkAttribute(ATT_DEFINITION_ID, fDefinitionId.length() > 0 ? fDefinitionId : null); |
| } |
| |
| public EvaluationResult evaluate(IEvaluationContext context) throws CoreException { |
| Expression expr= getDefinitionRegistry().getExpression(fDefinitionId); |
| return expr.evaluate(context); |
| } |
| |
| public void collectExpressionInfo(ExpressionInfo info) { |
| Expression expr; |
| try { |
| expr= getDefinitionRegistry().getExpression(fDefinitionId); |
| } catch (CoreException e) { |
| // We didn't find the expression definition. So no |
| // expression info can be collected. |
| return; |
| } |
| expr.collectExpressionInfo(info); |
| } |
| |
| public boolean equals(final Object object) { |
| if (!(object instanceof ReferenceExpression)) |
| return false; |
| |
| final ReferenceExpression that= (ReferenceExpression)object; |
| return this.fDefinitionId.equals(that.fDefinitionId); |
| } |
| |
| protected int computeHashCode() { |
| return HASH_INITIAL * HASH_FACTOR + fDefinitionId.hashCode(); |
| } |
| } |