/*

  * Copyright 2007-2008 The Kuali Foundation

  * 

  * Licensed under the Educational Community 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.opensource.org/licenses/ecl2.php

  * 

  * 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.

  */

 package org.kuali.rice.ken.util;

 import java.util.ArrayList;

 import java.util.Iterator;

 import java.util.List;

 import javax.xml.namespace.NamespaceContext;

 /**

  * XPath NamespaceContext implementation that delegates in sequence to a list of NamespaceContexts,

  * returning the first match. 

  * @author Kuali Rice Team (rice.collab@kuali.org)

  */

 public class CompoundNamespaceContext implements NamespaceContext {

     private final List<NamespaceContext> contexts;

     /**

      * Constructs a CompoundNamespaceContext.java.

      * @param first

      * @param second

      */

     public CompoundNamespaceContext(NamespaceContext first, NamespaceContext second) {

         this.contexts = new ArrayList<NamespaceContext>(2);

         this.contexts.add(first);

         this.contexts.add(second);

     }

     /**

      * Constructs a CompoundNamespaceContext.java.

      * @param contexts

      */

     public CompoundNamespaceContext(List<NamespaceContext> contexts) {

         this.contexts = contexts;

     }

     /**

      * @see javax.xml.namespace.NamespaceContext#getNamespaceURI(java.lang.String)

      */

     public String getNamespaceURI(String prefix) {

         if (prefix == null) {

             throw new IllegalArgumentException("The prefix cannot be null.");

         }

         for (NamespaceContext nc: contexts) {

             String uri = nc.getNamespaceURI(prefix);

             if (uri != null) {

                 return uri;

             }

         }

         return null;

     }

     /**

      * @see javax.xml.namespace.NamespaceContext#getPrefix(java.lang.String)

      */

     public String getPrefix(String namespaceURI) {

         if (namespaceURI == null) {

             throw new IllegalArgumentException("The namespace uri cannot be null.");

         }

         for (NamespaceContext nc: contexts) {

             String prefix = nc.getPrefix(namespaceURI);

             if (prefix != null) {

                 return prefix;

             }

         }

         return null;

     }

     /**

      * @see javax.xml.namespace.NamespaceContext#getPrefixes(java.lang.String)

      */

     public Iterator getPrefixes(String namespaceURI) {

         if (namespaceURI == null) {

             throw new IllegalArgumentException("The namespace uri cannot be null.");

         }

         for (NamespaceContext nc: contexts) {

             Iterator prefixes = nc.getPrefixes(namespaceURI);

             if (prefixes != null) {

                 return prefixes;

             }

         }

         return null;

     }

 }