bundles/org.eclipse.ui.navigator/src/org/eclipse/ui/internal/navigator/CustomAndExpression.java

/*******************************************************************************
 * 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.navigator;

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

import org.eclipse.core.expressions.ElementHandler;
import org.eclipse.core.expressions.EvaluationResult;
import org.eclipse.core.expressions.Expression;
import org.eclipse.core.expressions.ExpressionConverter;
import org.eclipse.core.expressions.IEvaluationContext;
import org.eclipse.core.runtime.Assert;
import org.eclipse.core.runtime.CoreException;
import org.eclipse.core.runtime.IConfigurationElement;
import org.eclipse.core.runtime.IStatus;

/**
 * Create an AND-type core expression from an IConfigurationElement of arbitrary
 * name.
 * 
 */
public class CustomAndExpression extends Expression {

	protected List fExpressions;

	/**
	 * Create an AND-type core expression from an IConfigurationElement of
	 * arbitrary name. The children elements are combined using boolean AND
	 * semantics to evaluate the expression.
	 * 
	 * @param element
	 *            An IConfigurationElement of arbitrary name.
	 */
	public CustomAndExpression(IConfigurationElement element) {
		Assert.isNotNull(element);

		IConfigurationElement[] children = element.getChildren();

		if (children.length > 0) {
			fExpressions = new ArrayList();
		}
		for (int i = 0; i < children.length; i++) {
			try {
				fExpressions.add(ElementHandler.getDefault().create(
						ExpressionConverter.getDefault(), children[i]));
			} catch (CoreException ce) {
				NavigatorPlugin.log(IStatus.ERROR, 0, ce.getMessage(), ce);
			}
		}
	}

	public EvaluationResult evaluate(IEvaluationContext scope)
			throws CoreException {
		if (fExpressions == null) {
			return EvaluationResult.TRUE;
		}
		EvaluationResult result = EvaluationResult.TRUE;
		for (Iterator iter = fExpressions.iterator(); iter.hasNext();) {
			Expression expression = (Expression) iter.next();
			result = result.and(expression.evaluate(scope));
			// keep iterating even if we have a not loaded found. It can be
			// that we find a false which will result in a better result.
			if (result == EvaluationResult.FALSE) {
				return result;
			}
		}
		return result;
	}

}