Commons JXPath example source code file (UnionContext.java)

This example Commons JXPath source code file (UnionContext.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Commons JXPath tags/keywords

arraylist, arraylist, basicnodeset, basicnodeset, evalcontext, evalcontext, iterator, nodepointer, nodesetcontext, unioncontext, unioncontext, util

The Commons JXPath UnionContext.java source code

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.commons.jxpath.ri.axes;

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

import org.apache.commons.jxpath.BasicNodeSet;
import org.apache.commons.jxpath.Pointer;
import org.apache.commons.jxpath.ri.EvalContext;
import org.apache.commons.jxpath.ri.model.NodePointer;

/**
 * EvalContext that represents a union between other contexts - result
 * of a union operation like (a | b)
 *
 * @author Dmitri Plotnikov
 * @version $Revision: 652845 $ $Date: 2008-05-02 12:46:46 -0500 (Fri, 02 May 2008) $
 */
public class UnionContext extends NodeSetContext {
    private EvalContext[] contexts;
    private boolean prepared;

    /**
     * Create a new UnionContext.
     * @param parentContext parent context
     * @param contexts child contexts
     */
    public UnionContext(EvalContext parentContext, EvalContext[] contexts) {
        super(parentContext, new BasicNodeSet());
        this.contexts = contexts;
    }

    public int getDocumentOrder() {
        return contexts.length > 1 ? 1 : super.getDocumentOrder();
    }

    public boolean setPosition(int position) {
        if (!prepared) {
            prepared = true;
            BasicNodeSet nodeSet = (BasicNodeSet) getNodeSet();
            ArrayList pointers = new ArrayList();
            for (int i = 0; i < contexts.length; i++) {
                EvalContext ctx = (EvalContext) contexts[i];
                while (ctx.nextSet()) {
                    while (ctx.nextNode()) {
                        NodePointer ptr = ctx.getCurrentNodePointer();
                        if (!pointers.contains(ptr)) {
                            pointers.add(ptr);
                        }
                    }
                }
            }
            sortPointers(pointers);

            for (Iterator it = pointers.iterator(); it.hasNext();) {
                nodeSet.add((Pointer) it.next());
            }
        }
        return super.setPosition(position);
    }
}