| /******************************************************************************* |
| * Copyright (c) 2007, 2008 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.equinox.internal.provisional.p2.query; |
| |
| import java.util.Iterator; |
| |
| /** |
| * The superclass of all queries that can be performed on an {@link IQueryable}. |
| * <p> |
| * This class may be subclassed by clients. Subclasses should specify the type |
| * of object they support querying on. Subclasses are also encouraged to clearly |
| * specify their match algorithm, and expose the parameters involved in the match |
| * computation, to allow {@link IQueryable} implementations to optimize their |
| * execution of the query. |
| */ |
| public abstract class Query { |
| /** |
| * Creates a new query. |
| */ |
| public Query() { |
| super(); |
| } |
| |
| /** |
| * Returns whether the given object satisfies the parameters of this query. |
| * |
| * @param candidate The object to perform the query against |
| * @return <code>true</code> if the unit satisfies the parameters |
| * of this query, and <code>false</code> otherwise |
| */ |
| public abstract boolean isMatch(Object candidate); |
| |
| /** |
| * Performs this query on the given iterator, passing all objects in the iterator |
| * that match the criteria of this query to the given result. |
| */ |
| public Collector perform(Iterator iterator, Collector result) { |
| while (iterator.hasNext()) { |
| Object candidate = iterator.next(); |
| if (isMatch(candidate)) |
| result.accept(candidate); |
| } |
| return result; |
| } |
| } |