| /******************************************************************************* |
| * Copyright (c) 2003 International Business Machines Corp. and others. |
| * All rights reserved. This program and the accompanying materials |
| * are made available under the terms of the Common Public License v0.5 |
| * which accompanies this distribution, and is available at |
| * http://www.eclipse.org/legal/cpl-v05.html |
| * |
| * Contributors: |
| * IBM Corporation - initial API and implementation |
| ******************************************************************************/ |
| package org.eclipse.core.expressions; |
| |
| import org.eclipse.core.runtime.CoreException; |
| import org.eclipse.core.runtime.IConfigurationElement; |
| |
| import org.eclipse.core.internal.expressions.CompositeExpression; |
| import org.eclipse.core.internal.expressions.StandardElementHandler; |
| |
| |
| /** |
| * An element handler converts an {@link IConfigurationElement} into a |
| * corresponding expression object. |
| * <p> |
| * The class should be subclassed by clients wishing to provide an element |
| * handler for special expressions. |
| * </p> |
| * @since 3.0 |
| */ |
| public abstract class ElementHandler { |
| |
| private static final ElementHandler INSTANCE= new StandardElementHandler(); |
| |
| /** |
| * The default element handler which can cope with all XML expression elements |
| * defined by the common expression language. |
| * |
| * @return the default element handler |
| */ |
| public static ElementHandler getDefault() { |
| return INSTANCE; |
| } |
| |
| /** |
| * Creates the corresponding expression for the given configuration element. |
| * |
| * @param converter the expression converter used to initiate the |
| * conversion process |
| * |
| * @param config the configuration element to convert |
| * |
| * @return the corresponding expression |
| * |
| * @throws CoreException if the conversion failed |
| */ |
| public abstract Expression create(ExpressionConverter converter, IConfigurationElement config) throws CoreException; |
| |
| /** |
| * Converts the children of the given configuration element and adds them |
| * to the given composite expression. |
| * <p> |
| * Note this is an internal method and should not be called by clients. |
| * </p> |
| * @param converter the converter used to do the actual conversion |
| * @param element the configuration element for which the children |
| * are to be processed |
| * @param expression the composite expression representing the result |
| * of the conversion |
| * |
| * @throws CoreException if the conversion failed |
| */ |
| protected void processChildren(ExpressionConverter converter, IConfigurationElement element, CompositeExpression expression) throws CoreException { |
| converter.processChildren(element, expression); |
| } |
| } |