xpathresultimpl.java

java1.6众多例子参考

/*
 * Copyright 2002-2005 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: XPathResultImpl.java,v 1.2.4.1 2005/09/10 04:18:54 jeffsuttor Exp $
 */


package com.sun.org.apache.xpath.internal.domapi;

import javax.xml.transform.TransformerException;

import com.sun.org.apache.xpath.internal.XPath;
import com.sun.org.apache.xpath.internal.objects.XObject;
import com.sun.org.apache.xpath.internal.res.XPATHErrorResources;
import com.sun.org.apache.xpath.internal.res.XPATHMessages;
import org.w3c.dom.DOMException;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import org.w3c.dom.events.Event;
import org.w3c.dom.events.EventListener;
import org.w3c.dom.events.EventTarget;
import org.w3c.dom.traversal.NodeIterator;
import org.w3c.dom.xpath.XPathException;
import org.w3c.dom.xpath.XPathResult;

/**
 *
 * The class provides an implementation XPathResult according 
 * to the DOM L3 XPath Specification, Working Group Note 26 February 2004.
 *
 * <p>See also the <a href='http://www.w3.org/TR/2004/NOTE-DOM-Level-3-XPath-20040226'>Document Object Model (DOM) Level 3 XPath Specification</a>.</p>
 * 
 * <p>The <code>XPathResult</code> interface represents the result of the 
 * evaluation of an XPath expression within the context of a particular 
 * node. Since evaluation of an XPath expression can result in various 
 * result types, this object makes it possible to discover and manipulate 
 * the type and value of the result.</p>
 * 
 * <p>This implementation wraps an <code>XObject</code>.
 * 
 * @see com.sun.org.apache.xpath.internal.objects.XObject
 * @see org.w3c.dom.xpath.XPathResult
 * 
 * @xsl.usage internal
 */
class XPathResultImpl implements XPathResult, EventListener {

	/**
     *  The wrapped XObject
     */
	final private XObject m_resultObj;
	
	/**
	 * The xpath object that wraps the expression used for this result.
	 */
	final private XPath m_xpath;
		
	/**
     *  This the type specified by the user during construction.  Typically
	 *  the constructor will be called by com.sun.org.apache.xpath.internal.XPath.evaluate().
     */
	final private short m_resultType; 
	
	private boolean m_isInvalidIteratorState = false;
	
    /**
     * Only used to attach a mutation event handler when specified
     * type is an iterator type.
     */
	final private Node m_contextNode;
	
	/**
     *  The iterator, if this is an iterator type.
     */
	private NodeIterator m_iterator = null;;
	
	/**
     *  The list, if this is a snapshot type.
     */
	private NodeList m_list = null;
	

	/**
	 * Constructor for XPathResultImpl.
     * 
     * For internal use only.
	 */
	 XPathResultImpl(short type, XObject result, Node contextNode, XPath xpath) {
		// Check that the type is valid
		if (!isValidType(type)) {
            String fmsg = XPATHMessages.createXPATHMessage(XPATHErrorResources.ER_INVALID_XPATH_TYPE, new Object[] {new Integer(type)});       
            throw new XPathException(XPathException.TYPE_ERR,fmsg); // Invalid XPath type argument: {0}           
		}

        // Result object should never be null!
        if (null == result) {
            String fmsg = XPATHMessages.createXPATHMessage(XPATHErrorResources.ER_EMPTY_XPATH_RESULT, null);       
            throw new XPathException(XPathException.INVALID_EXPRESSION_ERR,fmsg); // Empty XPath result object
        }
        
        this.m_resultObj = result;
        this.m_contextNode = contextNode;
        this.m_xpath = xpath;

        // If specified result was ANY_TYPE, determine XObject type
        if (type == ANY_TYPE) {
            this.m_resultType = getTypeFromXObject(result);
        } else {
            this.m_resultType = type;
        }
		
        // If the context node supports DOM Events and the type is one of the iterator
        // types register this result as an event listener
        if (((m_resultType == XPathResult.ORDERED_NODE_ITERATOR_TYPE) ||
            (m_resultType == XPathResult.UNORDERED_NODE_ITERATOR_TYPE))) {
            	addEventListener();
                
        }// else can we handle iterator types if contextNode doesn't support EventTarget??
    				
        // If this is an iterator type get the iterator
        if ((m_resultType == ORDERED_NODE_ITERATOR_TYPE) ||
            (m_resultType == UNORDERED_NODE_ITERATOR_TYPE) ||
            (m_resultType == ANY_UNORDERED_NODE_TYPE) ||
            (m_resultType == FIRST_ORDERED_NODE_TYPE))  {
    
            try {
                m_iterator = m_resultObj.nodeset();
            } catch (TransformerException te) {
                // probably not a node type
				String fmsg = XPATHMessages.createXPATHMessage(XPATHErrorResources.ER_INCOMPATIBLE_TYPES, new Object[] {m_xpath.getPatternString(), getTypeString(getTypeFromXObject(m_resultObj)),getTypeString(m_resultType)});       
  			    throw new XPathException(XPathException.TYPE_ERR, fmsg);  // "The XPathResult of XPath expression {0} has an XPathResultType of {1} which cannot be coerced into the specified XPathResultType of {2}."},
           }
    
                // If user requested ordered nodeset and result is unordered 
                // need to sort...TODO
    //            if ((m_resultType == ORDERED_NODE_ITERATOR_TYPE) &&
    //                (!(((DTMNodeIterator)m_iterator).getDTMIterator().isDocOrdered()))) {
    // 
    //            }
    
        // If it's a snapshot type, get the nodelist
        } else if ((m_resultType == UNORDERED_NODE_SNAPSHOT_TYPE) ||
                   (m_resultType == ORDERED_NODE_SNAPSHOT_TYPE)) {
            try {       	
        	   m_list = m_resultObj.nodelist();
            } catch (TransformerException te) {
        		// probably not a node type 
				String fmsg = XPATHMessages.createXPATHMessage(XPATHErrorResources.ER_INCOMPATIBLE_TYPES, new Object[] {m_xpath.getPatternString(), getTypeString(getTypeFromXObject(m_resultObj)),getTypeString(m_resultType)});       
				throw new XPathException(XPathException.TYPE_ERR, fmsg); // "The XPathResult of XPath expression {0} has an XPathResultType of {1} which cannot be coerced into the specified XPathResultType of {2}."},
            }
    	}	    	 
	}

	/**
	 * @see org.w3c.dom.xpath.XPathResult#getResultType()
	 */
	public short getResultType() {
		return m_resultType;
	}

	/**
	 *  The value of this number result.
     * @exception XPathException
     *   TYPE_ERR: raised if <code>resultType</code> is not 
     *   <code>NUMBER_TYPE</code>.
	 * @see org.w3c.dom.xpath.XPathResult#getNumberValue()
	 */
	public double getNumberValue() throws XPathException {
		if (getResultType() != NUMBER_TYPE) {
			String fmsg = XPATHMessages.createXPATHMessage(XPATHErrorResources.ER_CANT_CONVERT_XPATHRESULTTYPE_TO_NUMBER, new Object[] {m_xpath.getPatternString(), getTypeString(m_resultType)});		
			throw new XPathException(XPathException.TYPE_ERR,fmsg);
//		"The XPathResult of XPath expression {0} has an XPathResultType of {1} which cannot be converted to a number"
		} else {
			try {
			   return m_resultObj.num();
			} catch (Exception e) {
				// Type check above should prevent this exception from occurring.
				throw new XPathException(XPathException.TYPE_ERR,e.getMessage());
			}
		}		
	}

	/**
	 * The value of this string result.
     * @exception XPathException
     *   TYPE_ERR: raised if <code>resultType</code> is not 
     *   <code>STRING_TYPE</code>.
     * 
	 * @see org.w3c.dom.xpath.XPathResult#getStringValue()
	 */
	public String getStringValue() throws XPathException {
		if (getResultType() != STRING_TYPE) {
			String fmsg = XPATHMessages.createXPATHMessage(XPATHErrorResources.ER_CANT_CONVERT_TO_STRING, new Object[] {m_xpath.getPatternString(), m_resultObj.getTypeString()});		
			throw new XPathException(XPathException.TYPE_ERR,fmsg);
//		"The XPathResult of XPath expression {0} has an XPathResultType of {1} which cannot be converted to a string."
		} else {
			try {
			   return m_resultObj.str();
			} catch (Exception e) {
				// Type check above should prevent this exception from occurring.
				throw new XPathException(XPathException.TYPE_ERR,e.getMessage());
			}
		}
	}

	/**
	 * @see org.w3c.dom.xpath.XPathResult#getBooleanValue()
	 */
	public boolean getBooleanValue() throws XPathException {
		if (getResultType() != BOOLEAN_TYPE) {
			String fmsg = XPATHMessages.createXPATHMessage(XPATHErrorResources.ER_CANT_CONVERT_TO_BOOLEAN, new Object[] {m_xpath.getPatternString(), getTypeString(m_resultType)});		
			throw new XPathException(XPathException.TYPE_ERR,fmsg);
//		"The XPathResult of XPath expression {0} has an XPathResultType of {1} which cannot be converted to a boolean."			
		} else {
			try {
			   return m_resultObj.bool();
			} catch (TransformerException e) {
				// Type check above should prevent this exception from occurring.
				throw new XPathException(XPathException.TYPE_ERR,e.getMessage());
			}
		}
	}

	/**
	 * The value of this single node result, which may be <code>null</code>.
     * @exception XPathException
     *   TYPE_ERR: raised if <code>resultType</code> is not 
     *   <code>ANY_UNORDERED_NODE_TYPE</code> or 
     *   <code>FIRST_ORDERED_NODE_TYPE</code>.
     * 
	 * @see org.w3c.dom.xpath.XPathResult#getSingleNodeValue()
	 */
	public Node getSingleNodeValue() throws XPathException {
		
		if ((m_resultType != ANY_UNORDERED_NODE_TYPE) &&
		    (m_resultType != FIRST_ORDERED_NODE_TYPE)) {
				String fmsg = XPATHMessages.createXPATHMessage(XPATHErrorResources.ER_CANT_CONVERT_TO_SINGLENODE, new Object[] {m_xpath.getPatternString(), getTypeString(m_resultType)});                        
				throw new XPathException(XPathException.TYPE_ERR,fmsg);
//				"The XPathResult of XPath expression {0} has an XPathResultType of {1} which cannot be converted to a single node. 
//				 This method applies only to types ANY_UNORDERED_NODE_TYPE and FIRST_ORDERED_NODE_TYPE."
	    }