Commons JXPath example source code file (PrecedingOrFollowingContext.java)

This example Commons JXPath source code file (PrecedingOrFollowingContext.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

evalcontext, evalcontext, nodeiterator, nodeiterator, nodepointer, nodepointer, nodetest, nodetest, precedingorfollowingcontext, stack, util

The Commons JXPath PrecedingOrFollowingContext.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.Stack;

import org.apache.commons.jxpath.ri.EvalContext;
import org.apache.commons.jxpath.ri.compiler.NodeTest;
import org.apache.commons.jxpath.ri.model.NodeIterator;
import org.apache.commons.jxpath.ri.model.NodePointer;

/**
 * EvalContext that walks the "preceding::" and "following::" axes.
 *
 * @author Dmitri Plotnikov
 * @version $Revision: 670727 $ $Date: 2008-06-23 15:10:38 -0500 (Mon, 23 Jun 2008) $
 */
public class PrecedingOrFollowingContext extends EvalContext {
    private NodeTest nodeTest;
    private boolean setStarted = false;
    private Stack stack = null;
    private NodePointer currentNodePointer;
    private NodePointer currentRootLocation;
    private boolean reverse;

    /**
     * Create a new PrecedingOrFollowingContext.
     * @param parentContext parent context
     * @param nodeTest test
     * @param reverse whether to iterate in reverse order
     */
    public PrecedingOrFollowingContext(
        EvalContext parentContext,
        NodeTest nodeTest,
        boolean reverse) {
        super(parentContext);
        this.nodeTest = nodeTest;
        this.reverse = reverse;
    }

    public NodePointer getCurrentNodePointer() {
        return currentNodePointer;
    }

    public int getDocumentOrder() {
        return reverse ? -1 : 1;
    }

    public void reset() {
        super.reset();
        setStarted = false;
    }

    public boolean setPosition(int position) {
        if (position < this.position) {
            reset();
        }

        while (this.position < position) {
            if (!nextNode()) {
                return false;
            }
        }
        return true;
    }

    public boolean nextNode() {
        if (!setStarted) {
            setStarted = true;
            if (stack == null) {
                stack = new Stack();
            }
            else {
                stack.clear();
            }
            currentRootLocation = parentContext.getCurrentNodePointer();
            NodePointer parent = currentRootLocation.getParent();
            if (parent != null) {
                // TBD: check type
                stack.push(
                    parent.childIterator(null, reverse, currentRootLocation));
            }
        }

        while (true) {
            if (stack.isEmpty()) {
                currentRootLocation = currentRootLocation.getParent();

                if (currentRootLocation == null
                    || currentRootLocation.isRoot()) {
                    break;
                }

                NodePointer parent = currentRootLocation.getParent();
                if (parent != null) {
                    stack.push(
                        parent.childIterator(
                            null,
                            reverse,
                            currentRootLocation));
                }
            }

            while (!stack.isEmpty()) {
                if (!reverse) {
                    NodeIterator it = (NodeIterator) stack.peek();
                    if (it.setPosition(it.getPosition() + 1)) {
                        currentNodePointer = it.getNodePointer();
                        if (!currentNodePointer.isLeaf()) {
                            stack.push(
                                currentNodePointer.childIterator(
                                    null,
                                    reverse,
                                    null));
                        }
                        if (currentNodePointer.testNode(nodeTest)) {
                            super.setPosition(getCurrentPosition() + 1);
                            return true;
                        }
                    }
                    else {
                        // We get here only if the name test failed
                        // and the iterator ended
                        stack.pop();
                    }
                }
                else {
                    NodeIterator it = (NodeIterator) stack.peek();
                    if (it.setPosition(it.getPosition() + 1)) {
                        currentNodePointer = it.getNodePointer();
                        if (!currentNodePointer.isLeaf()) {
                            stack.push(
                                currentNodePointer.childIterator(
                                    null,
                                    reverse,
                                    null));
                        }
                        else if (currentNodePointer.testNode(nodeTest)) {
                            super.setPosition(getCurrentPosition() + 1);
                            return true;
                        }
                    }
                    else {
                        stack.pop();
                        if (!stack.isEmpty()) {
                            it = (NodeIterator) stack.peek();
                            currentNodePointer = it.getNodePointer();
                            if (currentNodePointer.testNode(nodeTest)) {
                                super.setPosition(getCurrentPosition() + 1);
                                return true;
                            }
                        }
                    }
                }
            }
        }
        return false;
    }
}