pylucene 3.5.0-3

[pylucene.git] / lucene-java-3.5.0 / lucene / contrib / analyzers / common / src / java / org / apache / lucene / analysis / miscellaneous / StemmerOverrideFilter.java

diff --git a/lucene-java-3.5.0/lucene/contrib/analyzers/common/src/java/org/apache/lucene/analysis/miscellaneous/StemmerOverrideFilter.java b/lucene-java-3.5.0/lucene/contrib/analyzers/common/src/java/org/apache/lucene/analysis/miscellaneous/StemmerOverrideFilter.java
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+++ b/lucene-java-3.5.0/lucene/contrib/analyzers/common/src/java/org/apache/lucene/analysis/miscellaneous/StemmerOverrideFilter.java
@@ -0,0 +1,70 @@
+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;
+    }
+  }
+}