| /* |
| * Licensed to the Apache Software Foundation (ASF) under one or more |
| * contributor license agreements. See the NOTICE file distributed with |
| * this work for additional information regarding copyright ownership. |
| * The ASF licenses this file to You under 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.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| package org.apache.commons.text.translate; |
| |
| import java.io.IOException; |
| import java.io.Writer; |
| import java.security.InvalidParameterException; |
| import java.util.BitSet; |
| import java.util.HashMap; |
| import java.util.Map; |
| |
| /** |
| * Translates a value using a lookup table. |
| * |
| * @since 1.0 |
| */ |
| public class LookupTranslator extends CharSequenceTranslator { |
| |
| /** The mapping to be used in translation. */ |
| private final Map<String, String> lookupMap; |
| /** The first character of each key in the lookupMap. */ |
| private final BitSet prefixSet; |
| /** The length of the shortest key in the lookupMap. */ |
| private final int shortest; |
| /** The length of the longest key in the lookupMap. */ |
| private final int longest; |
| |
| /** |
| * Define the lookup table to be used in translation |
| * |
| * Note that, as of Lang 3.1 (the origin of this code), the key to the lookup |
| * table is converted to a java.lang.String. This is because we need the key |
| * to support hashCode and equals(Object), allowing it to be the key for a |
| * HashMap. See LANG-882. |
| * |
| * @param lookupMap Map<CharSequence, CharSequence> table of translator |
| * mappings |
| */ |
| public LookupTranslator(final Map<CharSequence, CharSequence> lookupMap) { |
| if (lookupMap == null) { |
| throw new InvalidParameterException("lookupMap cannot be null"); |
| } |
| this.lookupMap = new HashMap<>(); |
| this.prefixSet = new BitSet(); |
| int currentShortest = Integer.MAX_VALUE; |
| int currentLongest = 0; |
| |
| for (final Map.Entry<CharSequence, CharSequence> pair : lookupMap.entrySet()) { |
| this.lookupMap.put(pair.getKey().toString(), pair.getValue().toString()); |
| this.prefixSet.set(pair.getKey().charAt(0)); |
| final int sz = pair.getKey().length(); |
| if (sz < currentShortest) { |
| currentShortest = sz; |
| } |
| if (sz > currentLongest) { |
| currentLongest = sz; |
| } |
| } |
| this.shortest = currentShortest; |
| this.longest = currentLongest; |
| } |
| |
| /** |
| * {@inheritDoc} |
| */ |
| @Override |
| public int translate(final CharSequence input, final int index, final Writer out) throws IOException { |
| // check if translation exists for the input at position index |
| if (prefixSet.get(input.charAt(index))) { |
| int max = longest; |
| if (index + longest > input.length()) { |
| max = input.length() - index; |
| } |
| // implement greedy algorithm by trying maximum match first |
| for (int i = max; i >= shortest; i--) { |
| final CharSequence subSeq = input.subSequence(index, index + i); |
| final String result = lookupMap.get(subSeq.toString()); |
| |
| if (result != null) { |
| out.write(result); |
| return i; |
| } |
| } |
| } |
| return 0; |
| } |
| } |