/**
* Copyright (C) 2010 Orbeon, Inc.
*
* This program is free software; you can redistribute it and/or modify it under the terms of the
* GNU Lesser General Public License as published by the Free Software Foundation; either version
* 2.1 of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
* without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
* See the GNU Lesser General Public License for more details.
*
* The full text of the license is available at http://www.gnu.org/copyleft/lesser.html
*/
package org.orbeon.oxf.xml;
import org.orbeon.oxf.common.OXFException;
import org.orbeon.oxf.util.NumberUtils;
import org.orbeon.oxf.util.SecureUtils;
import java.security.MessageDigest;
import java.util.*;
/**
* Optimized namespace mapping that includes a hash.
*
* This helps with memory use and with getting XPath expressions from cache. For optimal use, the mappings should be
* kept around so the hash doesn't have to be recomputed over and over.
*/
public class NamespaceMapping {
public static NamespaceMapping EMPTY_MAPPING = new NamespaceMapping(Collections.<String, String> emptyMap());
public final String hash;
public final Map<String, String> mapping;
// NOTE: mapping MUST already be sorted
public NamespaceMapping(String hash, Map<String, String> mapping) {
assert hash != null;
assert mapping != null;
this.hash = hash;
this.mapping = mapping;
}
public NamespaceMapping(Map<String, String> mapping) {
assert mapping != null;
final TreeMap<String, String> sortedMapping = new TreeMap<String, String>();
sortedMapping.putAll(mapping);
this.hash = NamespaceMapping.hashMapping(sortedMapping);
this.mapping = sortedMapping;
}
public static String hashMapping(Map<String, String> sortedMapping) {
try {
final MessageDigest digest = SecureUtils.defaultMessageDigest();
for (final Map.Entry<String, String> sortedEntry : sortedMapping.entrySet()) {
digest.update(sortedEntry.getKey().getBytes("UTF-8"));
digest.update((byte) ' ');
digest.update(sortedEntry.getValue().getBytes("UTF-8"));
digest.update((byte) ' ');
}
return NumberUtils.toHexString(digest.digest());
} catch (Exception e) {
throw new OXFException(e);
}
}
}