/*
* This file is part of the DiffX library.
*
* For licensing information please see the file license.txt included in the release.
* A copy of this licence can also be found at
* http://www.opensource.org/licenses/artistic-license-2.0.php
*/
package com.topologi.diffx.sequence;
import java.util.Collections;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.Map;
/**
* Provides a mapping of namespace URIs to prefixes.
*
* <p>This class can be used to reconstruct the qualified element or attribute names.
*
* <p>Note that for each namespace URI there can only be one prefix.
*
* @author Christophe Lauret
* @version 12 May 2010
*
* @since 0.7
*/
public final class PrefixMapping {
/**
* Maps namespace URIs to prefixes.
*/
private final Map<String, String> mappings = new HashMap<String, String>();
/**
* Add the specified mapping if the namespace URI has not been mapped before.
*
* <p>This method will ensure that the mapping is actually unique, that is that
* the namespace URI correspond to one and only one prefix and that the prefix only
* corresponds to one and only one namespace URI.
*
* @param uri The namespace URI to map.
* @param prefix The prefix to use.
*
* @throws NullPointerException if the URI or prefix is <code>null</code>
*/
public void add(String uri, String prefix) throws NullPointerException {
if (!this.mappings.containsKey(uri)) {
int count = 0;
String actualPrefix = prefix;
while (this.mappings.containsValue(actualPrefix)) {
actualPrefix = prefix + count++;
}
this.mappings.put(uri, actualPrefix);
}
}
/**
* Returns an enumeration of the namespace URIs used in this mapping.
*
* @return An enumeration of the namespace URIs used in this mapping.
*/
public Enumeration<String> getURIs() {
return Collections.enumeration(this.mappings.keySet());
}
/**
* Returns the prefix corresponding to the given namespace URI.
*
* @param uri The namespace URI to map.
*
* @return The corresponding prefix.
*/
public String getPrefix(String uri) {
return uri == null? "" : this.mappings.get(uri);
}
}