/*
* $Header: /home/projects/jaxen/scm/jaxen/src/java/main/org/jaxen/function/IdFunction.java,v 1.13 2006/02/05 21:47:41 elharo Exp $
* $Revision: 1.13 $
* $Date: 2006/02/05 21:47:41 $
*
* ====================================================================
*
* Copyright 2000-2002 bob mcwhirter & James Strachan.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* * Neither the name of the Jaxen Project nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
* IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
* PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
* OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* ====================================================================
* This software consists of voluntary contributions made by many
* individuals on behalf of the Jaxen Project and was originally
* created by bob mcwhirter <bob@werken.com> and
* James Strachan <jstrachan@apache.org>. For more information on the
* Jaxen Project, please see <http://www.jaxen.org/>.
*
* $Id: IdFunction.java,v 1.13 2006/02/05 21:47:41 elharo Exp $
*/
package org.orbeon.jaxen.function;
import org.orbeon.jaxen.Context;
import org.orbeon.jaxen.Function;
import org.orbeon.jaxen.FunctionCallException;
import org.orbeon.jaxen.Navigator;
import java.util.*;
/**
* <p><b>4.1</b> <code><i>node-set</i> id(<i>object</i>)</code> </p>
*
* <p>The <b>id</b> function returns a <code>List</code>
* of all the elements in the context document that have an ID
* matching one of a specified list of IDs. How an attribute is determined
* to be of type ID depends on the navigator, but it normally requires that
* the attribute be declared to have type ID in the DTD.
* </p>
*
* <p>
* There should be no more than one element in any document with a
* certain ID. However, if there are multiple such elements--i.e. if
* there are duplicate IDs--then this function selects only the first element
* in document order with the specified ID.
* </p>
*
* @author Erwin Bolwidt (ejb @ klomp.org)
* @author J\u00e9r\u00f4me N\u00e8gre (jerome.negre @ e-xmlmedia.fr)
*
* @see <a href="http://www.w3.org/TR/xpath#function-id" target="_top">Section 4.1 of the XPath Specification</a>
*/
public class IdFunction implements Function
{
/**
* Create a new <code>IdFunction</code> object.
*/
public IdFunction() {}
/**
* Returns a list of the nodes with the specified IDs.
*
* @param context the context at the point in the
* expression when the function is called
* @param args a list with exactly one item which is either a string
* a node-set
*
* @return a <code>List</code> containing the first node in document
* with each of the specified IDs; or
* an empty list if there are no such nodes
*
* @throws FunctionCallException if <code>args</code> has more or less than one item
*/
public Object call(Context context, List args) throws FunctionCallException
{
if ( args.size() == 1 ) {
return evaluate( context.getNodeSet(),
args.get(0), context.getNavigator() );
}
throw new FunctionCallException( "id() requires one argument" );
}
/**
* Returns a list of the nodes with the specified IDs.
*
* @param contextNodes the context node-set. The first item in this list
* determines the document in which the search is performed.
* @param arg the ID or IDs to search for
* @param nav the navigator used to calculate string-values and search
* by ID
*
* @return a <code>List</code> containing the first node in document
* with each of the specified IDs; or
* an empty list if there are no such nodes
*
*/
public static List evaluate(List contextNodes, Object arg, Navigator nav)
{
if (contextNodes.size() == 0) return Collections.EMPTY_LIST;
List nodes = new ArrayList();
Object contextNode = contextNodes.get(0);
if (arg instanceof List) {
Iterator iter = ((List)arg).iterator();
while (iter.hasNext()) {
String id = StringFunction.evaluate(iter.next(), nav);
nodes.addAll( evaluate( contextNodes, id, nav ) );
}
}
else {
String ids = StringFunction.evaluate(arg, nav);
StringTokenizer tok = new StringTokenizer(ids, " \t\n\r");
while (tok.hasMoreTokens()) {
String id = tok.nextToken();
Object node = nav.getElementById(contextNode, id);
if (node != null) {
nodes.add(node);
}
}
}
return nodes;
}
}