currentnodelistiterator.java

java1.6众多例子参考

/*
 * 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: CurrentNodeListIterator.java,v 1.2.4.1 2005/09/06 06:04:45 pvedula Exp $
 */

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

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

/**
 * Iterators of this kind use a CurrentNodeListFilter to filter a subset of 
 * nodes from a source iterator. For each node from the source, the boolean 
 * method CurrentNodeListFilter.test() is called. 
 *
 * All nodes from the source are read into an array upon calling setStartNode() 
 * (this is needed to determine the value of last, a parameter to 
 * CurrentNodeListFilter.test()). The method getLast() returns the last element 
 * after applying the filter.
 * @author Jacek Ambroziak
 * @author Santiago Pericas-Geertsen
 * @author Morten Jorgensen
 */

public final class CurrentNodeListIterator extends DTMAxisIteratorBase {
    /**
     * A flag indicating if nodes are returned in document order.
     */
    private boolean _docOrder;

    /**
     * The source for this iterator.
     */
    private DTMAxisIterator _source;

    /**
     * A reference to a filter object.
     */
    private final CurrentNodeListFilter _filter;

    /**
     * An integer array to store nodes from source iterator.
     */
    private IntegerArray _nodes = new IntegerArray();
	
    /**
     * Index in _nodes of the next node to filter.
     */
    private int _currentIndex;
	
    /**
     * The current node in the stylesheet at the time of evaluation.
     */
    private final int _currentNode;

    /**
     * A reference to the translet.
     */
    private AbstractTranslet _translet;

    public CurrentNodeListIterator(DTMAxisIterator source, 
				   CurrentNodeListFilter filter,
				   int currentNode,
				   AbstractTranslet translet) 
    {
	this(source, !source.isReverse(), filter, currentNode, translet);
    }

    public CurrentNodeListIterator(DTMAxisIterator source, boolean docOrder,
				   CurrentNodeListFilter filter,
				   int currentNode,
				   AbstractTranslet translet) 
    {
	_source = source;
	_filter = filter;
	_translet = translet;
	_docOrder = docOrder;
	_currentNode = currentNode;
    }

    public DTMAxisIterator forceNaturalOrder() {
	_docOrder = true;
	return this;
    }

    public void setRestartable(boolean isRestartable) {
	_isRestartable = isRestartable;
	_source.setRestartable(isRestartable);
    }

    public boolean isReverse() {
	return !_docOrder;
    }

    public DTMAxisIterator cloneIterator() {
	try {
	    final CurrentNodeListIterator clone =
		(CurrentNodeListIterator) super.clone();
	    clone._nodes = (IntegerArray) _nodes.clone();
	    clone._source = _source.cloneIterator();
	    clone._isRestartable = false;
	    return clone.reset();
	}
	catch (CloneNotSupportedException e) {
	    BasisLibrary.runTimeError(BasisLibrary.ITERATOR_CLONE_ERR,
				      e.toString());
	    return null;
	}
    }
    
    public DTMAxisIterator reset() {
	_currentIndex = 0;
	return resetPosition();
    }

    public int next() {
	final int last = _nodes.cardinality();
	final int currentNode = _currentNode;
	final AbstractTranslet translet = _translet;

	for (int index = _currentIndex; index < last; ) {
	    final int position = _docOrder ? index + 1 : last - index;
	    final int node = _nodes.at(index++); 	// note increment

	    if (_filter.test(node, position, last, currentNode, translet,
                             this)) {
		_currentIndex = index;
		return returnNode(node);
	    }
	}
	return END;
    }

    public DTMAxisIterator setStartNode(int node) {
	if (_isRestartable) {
	    _source.setStartNode(_startNode = node);

	    _nodes.clear();
	    while ((node = _source.next()) != END) {
		_nodes.add(node);
	    }
	    _currentIndex = 0;
	    resetPosition();
	}
	return this;
    }
	
    public int getLast() {
	if (_last == -1) {
	    _last = computePositionOfLast();
	}
	return _last;
    }

    public void setMark() {
	_markedNode = _currentIndex;
    }

    public void gotoMark() {
	_currentIndex = _markedNode;
    }

    private int computePositionOfLast() {
        final int last = _nodes.cardinality();
        final int currNode = _currentNode;
	final AbstractTranslet translet = _translet;

	int lastPosition = _position;
	for (int index = _currentIndex; index < last; ) {
	    final int position = _docOrder ? index + 1 : last - index;
            int nodeIndex = _nodes.at(index++); 	// note increment

            if (_filter.test(nodeIndex, position, last, currNode, translet,
                             this)) {
                lastPosition++;
            }
        }
	return lastPosition;
    }
}