nodeiteratorbase.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: NodeIteratorBase.java,v 1.2.4.1 2005/09/06 09:37:02 pvedula Exp $
 */

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

import com.sun.org.apache.xalan.internal.xsltc.NodeIterator;
import com.sun.org.apache.xalan.internal.xsltc.runtime.BasisLibrary;

/**
 * @author Jacek Ambroziak
 * @author Santiago Pericas-Geertsen
 * @author Morten Jorgensen
 */
public abstract class NodeIteratorBase implements NodeIterator {

    /**
     * Cached computed value of last().
     */
    protected int _last = -1;

    /**
     * Value of position() in this iterator. Incremented in
     * returnNode().
     */
    protected int _position = 0;

    /**
     * Store node in call to setMark().
     */
    protected int _markedNode;

    /**
     * Store node in call to setStartNode().
     */
    protected int _startNode = NodeIterator.END;

    /** 
     * Flag indicating if "self" should be returned.
     */
    protected boolean _includeSelf = false;

    /**
     * Flag indicating if iterator can be restarted.
     */
    protected boolean _isRestartable = true;

    /**
     * Setter for _isRestartable flag. 
     */
    public void setRestartable(boolean isRestartable) {
	_isRestartable = isRestartable;
    }

    /**
     * Initialize iterator using a node. If iterator is not
     * restartable, then do nothing. If node is equal to END then
     * subsequent calls to next() must return END.
     */
    abstract public NodeIterator setStartNode(int node);

    /**
     * Reset this iterator using state from last call to
     * setStartNode().
     */
    public NodeIterator reset() {
	final boolean temp = _isRestartable;
	_isRestartable = true;
	// Must adjust _startNode if self is included
	setStartNode(_includeSelf ? _startNode + 1 : _startNode);
	_isRestartable = temp;
	return this;
    }

    /**
     * Setter for _includeSelf flag.
     */
    public NodeIterator includeSelf() {
	_includeSelf = true;
	return this;
    }

    /**
     * Default implementation of getLast(). Stores current position
     * and current node, resets the iterator, counts all nodes and
     * restores iterator to original state.
     */
    public int getLast() {
	if (_last == -1) {
	    final int temp = _position;
	    setMark();
	    reset();
	    do {
		_last++;
	    } while (next() != END);
	    gotoMark();
	    _position = temp;
	}
	return _last;
    }

    /**
     * Returns the position() in this iterator.
     */
    public int getPosition() {
	return _position == 0 ? 1 : _position;
    }

    /**
     * Indicates if position in this iterator is computed in reverse
     * document order. Note that nodes are always returned in document
     * order.
     */
    public boolean isReverse() {
	return false;
    }
    
    /**
     * Clones and resets this iterator. Note that the cloned iterator is 
     * not restartable. This is because cloning is needed for variable 
     * references, and the context node of the original variable 
     * declaration must be preserved.
     */
    public NodeIterator cloneIterator() {
	try {
	    final NodeIteratorBase clone = (NodeIteratorBase)super.clone();
	    clone._isRestartable = false;
	    return clone.reset();
	}
	catch (CloneNotSupportedException e) {
	    BasisLibrary.runTimeError(BasisLibrary.ITERATOR_CLONE_ERR,
				      e.toString());
	    return null;
	}
    }
    
    /**
     * Utility method that increments position and returns its
     * argument.
     */
    protected final int returnNode(final int node) {
	_position++;
	return node;
    }
    
    /**
     * Reset the position in this iterator.
     */
    protected final NodeIterator resetPosition() {
	_position = 0;
	return this;
    }
}