001 /*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements. See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License. You may obtain a copy of the License at
008 *
009 * http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017 package org.apache.commons.lang3.text.translate;
018
019 import java.io.IOException;
020 import java.io.Writer;
021 import java.util.HashMap;
022
023 /**
024 * Translates a value using a lookup table.
025 *
026 * @author Apache Software Foundation
027 * @since 3.0
028 * @version $Id: LookupTranslator.java 967237 2010-07-23 20:08:57Z mbenson $
029 */
030 // TODO: Replace with a RegexLookup? Performance test.
031 public class LookupTranslator extends CharSequenceTranslator {
032
033 private final HashMap<CharSequence, CharSequence> lookupMap;
034 private final int shortest;
035 private final int longest;
036
037 /**
038 * Define the lookup table to be used in translation
039 *
040 * @param lookup CharSequence[][] table of size [*][2]
041 */
042 public LookupTranslator(CharSequence[][] lookup) {
043 lookupMap = new HashMap<CharSequence, CharSequence>();
044 int _shortest = Integer.MAX_VALUE;
045 int _longest = 0;
046 for(CharSequence[] seq : lookup) {
047 this.lookupMap.put(seq[0], seq[1]);
048 int sz = seq[0].length();
049 if(sz < _shortest) {
050 _shortest = sz;
051 }
052 if(sz > _longest) {
053 _longest = sz;
054 }
055 }
056 shortest = _shortest;
057 longest = _longest;
058 }
059
060 /**
061 * {@inheritDoc}
062 */
063 @Override
064 public int translate(CharSequence input, int index, Writer out) throws IOException {
065 int max = longest;
066 if(index + longest > input.length()) {
067 max = input.length() - index;
068 }
069 // descend so as to get a greedy algorithm
070 for(int i=max; i >= shortest; i--) {
071 CharSequence subSeq = input.subSequence(index, index + i);
072 CharSequence result = lookupMap.get(subSeq);
073 if(result != null) {
074 out.write(result.toString());
075 return i;
076 }
077 }
078 return 0;
079 }
080 }