org.lockss.util.OneToOneNamespaceContext.java Source code

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Here is the source code for org.lockss.util.OneToOneNamespaceContext.java

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/*
 * $Id$
 */

/*
    
Copyright (c) 2000-2015 Board of Trustees of Leland Stanford Jr. University,
all rights reserved.
    
Permission is hereby granted, free of charge, to any person obtaining a copy
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copies of the Software, and to permit persons to whom the Software is
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The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.
    
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IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
STANFORD UNIVERSITY BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
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*/

package org.lockss.util;

import java.util.*;

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

import org.apache.commons.collections4.bidimap.DualHashBidiMap;
import org.apache.commons.collections4.iterators.SingletonIterator;
import org.apache.commons.collections4.BidiMap;

/**
 * <p>
 * Provides a concrete implementation of {@link NamespaceContext} (as none are
 * readily available from the JDK or Apache Commons) that encapsulates a
 * one-to-one mapping between prefixes and namespace URIs.
 * </p>
 * <p>
 * The {@link #put(String, String)} and {@link #remove(String)} methods return
 * the instance itself so that calls can be chained to quickly build an instance
 * without a prior map.
 * </p>
 * 
 * @author Thib Guicherd-Callin
 * @since 1.67.5
 */
public class OneToOneNamespaceContext implements NamespaceContext {

    /**
     * @since 1.67.5
     */
    protected BidiMap<String, String> bidiMap;

    /**
     * <p>
     * Builds a new instance that initially maps
     * {@link XMLConstants#DEFAULT_NS_PREFIX} to {@link XMLConstants#NULL_NS_URI}.
     * </p>
     * 
     * @since 1.67.5
     */
    public OneToOneNamespaceContext() {
        this.bidiMap = new DualHashBidiMap<String, String>();
        put(XMLConstants.DEFAULT_NS_PREFIX, XMLConstants.NULL_NS_URI);
    }

    /**
     * <p>
     * Builds a new instance that initially has the same mappings as the given
     * map, and adds a mapping from {@link XMLConstants#DEFAULT_NS_PREFIX} to
     * {@link XMLConstants#NULL_NS_URI} if there is no mapping for it initially.
     * </p>
     * 
     * @param map
     *          An initial mapping of prefixes to namespace URIs.
     * @since 1.67.5
     */
    public OneToOneNamespaceContext(Map<String, String> map) {
        this.bidiMap = new DualHashBidiMap<String, String>(map);
        if (!bidiMap.containsKey(XMLConstants.DEFAULT_NS_PREFIX)) {
            put(XMLConstants.DEFAULT_NS_PREFIX, XMLConstants.NULL_NS_URI);
        }
    }

    /**
     * @since 1.67.5
     */
    public OneToOneNamespaceContext put(String prefix, String namespaceURI) {
        bidiMap.put(prefix, namespaceURI);
        return this;
    }

    /**
     * @since 1.67.5
     */
    public OneToOneNamespaceContext remove(String prefix) {
        bidiMap.remove(prefix);
        return this;
    }

    @Override
    public String getNamespaceURI(String prefix) {
        return bidiMap.get(prefix);
    }

    @Override
    public String getPrefix(String namespaceURI) {
        return bidiMap.getKey(namespaceURI);
    }

    @Override
    public Iterator<String> getPrefixes(String namespaceURI) {
        return new SingletonIterator<String>(getPrefix(namespaceURI));
    }

}