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Java example source code file (SortingIterator.java)

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

Learn more about this Java project at its project page.

Java - Java tags/keywords

clonenotsupportedexception, dtmaxisiterator, dtmaxisiteratorbase, end, init_data_size, nodesortrecord, nodesortrecordfactory, sortingiterator

The SortingIterator.java Java example source code

/*
 * reserved comment block
 * DO NOT REMOVE OR ALTER!
 */
/*
 * Copyright 2001-2004 The Apache Software Foundation.
 *
 * Licensed 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.
 */
/*
 * $Id: SortingIterator.java,v 1.2.4.1 2005/09/06 10:23:32 pvedula Exp $
 */

package com.sun.org.apache.xalan.internal.xsltc.dom;

import com.sun.org.apache.xalan.internal.xsltc.runtime.BasisLibrary;
import com.sun.org.apache.xml.internal.dtm.DTMAxisIterator;
import com.sun.org.apache.xml.internal.dtm.ref.DTMAxisIteratorBase;

/**
 * @author Jacek Ambroziak
 * @author Santiago Pericas-Geertsen
 * @author Morten Jorgensen
 */
public final class SortingIterator extends DTMAxisIteratorBase {
    private final static int INIT_DATA_SIZE = 16;

    private DTMAxisIterator _source;
    private NodeSortRecordFactory _factory;

    private NodeSortRecord[] _data;
    private int _free = 0;
    private int _current;       // index in _nodes of the next node to try

    public SortingIterator(DTMAxisIterator source,
                           NodeSortRecordFactory factory) {
        _source = source;
        _factory = factory;
    }

    public int next() {
        return _current < _free ? _data[_current++].getNode() : END;
    }

    public DTMAxisIterator setStartNode(int node) {
        try {
            _source.setStartNode(_startNode = node);
            _data = new NodeSortRecord[INIT_DATA_SIZE];
            _free = 0;

            // gather all nodes from the source iterator
            while ((node = _source.next()) != END) {
                addRecord(_factory.makeNodeSortRecord(node,_free));
            }
            // now sort the records
            quicksort(0, _free - 1);

            _current = 0;
            return this;
        }
        catch (Exception e) {
            return this;
        }
    }

    public int getPosition() {
        return _current == 0 ? 1 : _current;
    }

    public int getLast() {
        return _free;
    }

    public void setMark() {
        _source.setMark();
        _markedNode = _current;
    }

    public void gotoMark() {
        _source.gotoMark();
        _current = _markedNode;
    }

    /**
     * Clone a <code>SortingIterator by cloning its source
     * iterator and then sharing the factory and the array of
     * <code>NodeSortRecords.
     */
    public DTMAxisIterator cloneIterator() {
        try {
            final SortingIterator clone = (SortingIterator) super.clone();
            clone._source = _source.cloneIterator();
            clone._factory = _factory;          // shared between clones
            clone._data = _data;                // shared between clones
            clone._free = _free;
            clone._current = _current;
            clone.setRestartable(false);
            return clone.reset();
        }
        catch (CloneNotSupportedException e) {
            BasisLibrary.runTimeError(BasisLibrary.ITERATOR_CLONE_ERR,
                                      e.toString());
            return null;
        }
    }

    private void addRecord(NodeSortRecord record) {
        if (_free == _data.length) {
            NodeSortRecord[] newArray = new NodeSortRecord[_data.length * 2];
            System.arraycopy(_data, 0, newArray, 0, _free);
            _data = newArray;
        }
        _data[_free++] = record;
    }

    private void quicksort(int p, int r) {
        while (p < r) {
            final int q = partition(p, r);
            quicksort(p, q);
            p = q + 1;
        }
    }

    private int partition(int p, int r) {
        final NodeSortRecord x = _data[(p + r) >>> 1];
        int i = p - 1;
        int j = r + 1;
        while (true) {
            while (x.compareTo(_data[--j]) < 0);
            while (x.compareTo(_data[++i]) > 0);
            if (i < j) {
                final NodeSortRecord t = _data[i];
                _data[i] = _data[j];
                _data[j] = t;
            }
            else {
                return(j);
            }
        }
    }
}

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