com.groupbyinc.common.apache.commons.text.translate.LookupTranslator Maven / Gradle / Ivy
/*
* 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.HashMap;
import java.util.HashSet;
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 lookupMap;
/** The first character of each key in the lookupMap. */
private final HashSet 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 lookupMap) {
if (lookupMap == null) {
throw new InvalidParameterException("lookupMap cannot be null");
}
this.lookupMap = new HashMap<>();
this.prefixSet = new HashSet<>();
int currentShortest = Integer.MAX_VALUE;
int currentLongest = 0;
for (final Map.Entry pair : lookupMap.entrySet()) {
this.lookupMap.put(pair.getKey().toString(), pair.getValue().toString());
this.prefixSet.add(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.contains(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;
}
}