--- /dev/null
+package org.apache.lucene.analysis.miscellaneous;
+
+/**
+ * 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.
+ */
+
+import java.io.IOException;
+import java.util.Map;
+
+import org.apache.lucene.analysis.CharArrayMap;
+import org.apache.lucene.analysis.TokenFilter;
+import org.apache.lucene.analysis.TokenStream;
+import org.apache.lucene.analysis.tokenattributes.KeywordAttribute;
+import org.apache.lucene.analysis.tokenattributes.CharTermAttribute;
+import org.apache.lucene.util.Version;
+
+/**
+ * Provides the ability to override any {@link KeywordAttribute} aware stemmer
+ * with custom dictionary-based stemming.
+ */
+public final class StemmerOverrideFilter extends TokenFilter {
+ private final CharArrayMap<String> dictionary;
+
+ private final CharTermAttribute termAtt = addAttribute(CharTermAttribute.class);
+ private final KeywordAttribute keywordAtt = addAttribute(KeywordAttribute.class);
+
+ /**
+ * Create a new StemmerOverrideFilter, performing dictionary-based stemming
+ * with the provided <code>dictionary</code>.
+ * <p>
+ * Any dictionary-stemmed terms will be marked with {@link KeywordAttribute}
+ * so that they will not be stemmed with stemmers down the chain.
+ * </p>
+ */
+ public StemmerOverrideFilter(Version matchVersion, TokenStream input,
+ Map<?,String> dictionary) {
+ super(input);
+ this.dictionary = dictionary instanceof CharArrayMap ?
+ (CharArrayMap<String>) dictionary : CharArrayMap.copy(matchVersion, dictionary);
+ }
+
+ @Override
+ public boolean incrementToken() throws IOException {
+ if (input.incrementToken()) {
+ if (!keywordAtt.isKeyword()) { // don't muck with already-keyworded terms
+ String stem = dictionary.get(termAtt.buffer(), 0, termAtt.length());
+ if (stem != null) {
+ termAtt.setEmpty().append(stem);
+ keywordAtt.setKeyword(true);
+ }
+ }
+ return true;
+ } else {
+ return false;
+ }
+ }
+}