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The Fedora Client is a Java Library that allows API access to a Fedora Repository. The client is typically one part of a full Fedora installation.
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/*
 * -----------------------------------------------------------------------------
 *
 * License and Copyright: The contents of this file are subject to 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.fedora-commons.org/licenses.
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License for
 * the specific language governing rights and limitations under the License.
 *
 * The entire file consists of original code.
 * Copyright © 2008 Fedora Commons, Inc.

 * 
Copyright © 2002-2007 The Rector and Visitors of the University of 
 * Virginia and Cornell University
 
 * All rights reserved.
 *
 * -----------------------------------------------------------------------------
 */
/* The contents of this file are subject to the license and copyright terms
 * detailed in the license directory at the root of the source tree (also 
 * available online at http://www.fedora.info/license/).
 */
package fedora.utilities;

import java.util.ArrayList;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;

import javax.xml.XMLConstants;
import javax.xml.namespace.NamespaceContext;


/**
 * An implementation of {@link NamespaceContext NamespaceContext} that provides
 * an addNamespace method.
 * 
 * @author Edwin Shin
 * @version $Id: NamespaceContextImpl.java 7438 2008-07-08 06:41:33Z pangloss $
 */
public class NamespaceContextImpl
        implements NamespaceContext {
    /**
     * Namespace URI to use to represent that there is no Namespace. 
     * Defined by the Namespace specification to be "".
     */
    private static final String NULL_NS_URI = "";
    
    private Map prefix2ns = new ConcurrentHashMap();
    
    public NamespaceContextImpl() {
        prefix2ns.put(XMLConstants.XML_NS_PREFIX, XMLConstants.XML_NS_URI);
        prefix2ns.put(XMLConstants.XMLNS_ATTRIBUTE, XMLConstants.XMLNS_ATTRIBUTE_NS_URI);
    }
    
    public NamespaceContextImpl(String prefix, String namespaceURI) {
        this();
        this.addNamespace(prefix, namespaceURI);
    }
    
    /**
     * Constructor that takes a Map of prefix to namespaces.
     * 
     * @param prefix2ns a mapping of prefixes to namespaces.
     * @throws IllegalArgumentException if prefix2ns contains 
     * {@value XMLConstants.XML_NS_URI} or {@value XMLConstants.XMLNS_ATTRIBUTE_NS_URI}
     */
    public NamespaceContextImpl(Map prefix2ns) {
        this();
        for (String prefix : prefix2ns.keySet()) {
            addNamespace(prefix, prefix2ns.get(prefix));
        }
    }
    
    /**
     * {@inheritDoc}
     */
    public String getNamespaceURI(String prefix) {
        if (prefix == null) {
            throw new IllegalArgumentException("null prefix not allowed.");
        }
        if (prefix2ns.containsKey(prefix)) {
            return prefix2ns.get(prefix);
        }
        return NULL_NS_URI;
    }

    /**
     * {@inheritDoc}
     */
    public String getPrefix(String namespaceURI) {
        if (namespaceURI == null) {
            throw new IllegalArgumentException("null namespaceURI not allowed.");
        }
        for (String prefix : prefix2ns.keySet()) {
            if (prefix2ns.get(prefix).equals(namespaceURI)) {
                return prefix;
            }
        }
        return null;
    }

    /**
     * {@inheritDoc}
     */
    public Iterator getPrefixes(String namespaceURI) {
        List prefixes = new ArrayList();
        for (String prefix : prefix2ns.keySet()) {
            if (prefix2ns.containsKey(prefix) && 
                    prefix2ns.get(prefix).equals(namespaceURI)) {
                prefixes.add(prefix);
            }
        }
        return Collections.unmodifiableList(prefixes).iterator();
    }
    
    /**
     * Add a prefix to namespace mapping.
     * 
     * @param prefix
     * @param namespaceURI
     * @throws IllegalArgumentException if namespaceURI is one of 
     * {@value XMLConstants.XML_NS_URI} or {@value XMLConstants.XMLNS_ATTRIBUTE_NS_URI}
     */
    public void addNamespace(String prefix, String namespaceURI) {
        if (prefix == null || namespaceURI == null) {
            throw new IllegalArgumentException("null arguments not allowed.");
        }
        if (namespaceURI.equals(XMLConstants.XML_NS_URI)) {
            throw new IllegalArgumentException("Adding a new namespace for " +
                XMLConstants.XML_NS_URI + "not allowed.");
        } else if (namespaceURI.equals(XMLConstants.XMLNS_ATTRIBUTE_NS_URI)) {
            throw new IllegalArgumentException("Adding a new namespace for " +
                XMLConstants.XMLNS_ATTRIBUTE_NS_URI + "not allowed.");
        }
        prefix2ns.put(prefix, namespaceURI);
    }

}