pylucene 3.5.0-3

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

diff --git a/lucene-java-3.5.0/lucene/contrib/analyzers/common/src/java/org/apache/lucene/analysis/hunspell/HunspellStemFilter.java b/lucene-java-3.5.0/lucene/contrib/analyzers/common/src/java/org/apache/lucene/analysis/hunspell/HunspellStemFilter.java
new file mode 100644 (file)
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+++ b/lucene-java-3.5.0/lucene/contrib/analyzers/common/src/java/org/apache/lucene/analysis/hunspell/HunspellStemFilter.java
@@ -0,0 +1,112 @@
+package org.apache.lucene.analysis.hunspell;
+
+/**
+ * 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.List;
+
+import org.apache.lucene.analysis.TokenFilter;
+import org.apache.lucene.analysis.TokenStream;
+import org.apache.lucene.analysis.hunspell.HunspellStemmer.Stem;
+import org.apache.lucene.analysis.tokenattributes.CharTermAttribute;
+import org.apache.lucene.analysis.tokenattributes.PositionIncrementAttribute;
+
+/**
+ * TokenFilter that uses hunspell affix rules and words to stem tokens.  Since hunspell supports a word having multiple
+ * stems, this filter can emit multiple tokens for each consumed token
+ */
+public final class HunspellStemFilter extends TokenFilter {
+  
+  private final CharTermAttribute termAtt = addAttribute(CharTermAttribute.class);
+  private final PositionIncrementAttribute posIncAtt = addAttribute(PositionIncrementAttribute.class);
+  private final HunspellStemmer stemmer;
+  
+  private List<Stem> buffer;
+  private State savedState;
+  
+  private final boolean dedup;
+
+  /**
+   * Creates a new HunspellStemFilter that will stem tokens from the given TokenStream using affix rules in the provided
+   * HunspellDictionary
+   *
+   * @param input TokenStream whose tokens will be stemmed
+   * @param dictionary HunspellDictionary containing the affix rules and words that will be used to stem the tokens
+   */
+  public HunspellStemFilter(TokenStream input, HunspellDictionary dictionary) {
+    this(input, dictionary, true);
+  }
+  
+  /**
+   * Creates a new HunspellStemFilter that will stem tokens from the given TokenStream using affix rules in the provided
+   * HunspellDictionary
+   *
+   * @param input TokenStream whose tokens will be stemmed
+   * @param dictionary HunspellDictionary containing the affix rules and words that will be used to stem the tokens
+   * @param dedup true if only unique terms should be output.
+   */
+  public HunspellStemFilter(TokenStream input, HunspellDictionary dictionary, boolean dedup) {
+    super(input);
+    this.dedup = dedup;
+    this.stemmer = new HunspellStemmer(dictionary);
+  }
+
+  /**
+   * {@inheritDoc}
+   */
+  @Override
+  public boolean incrementToken() throws IOException {
+    if (buffer != null && !buffer.isEmpty()) {
+      Stem nextStem = buffer.remove(0);
+      restoreState(savedState);
+      posIncAtt.setPositionIncrement(0);
+      termAtt.copyBuffer(nextStem.getStem(), 0, nextStem.getStemLength());
+      termAtt.setLength(nextStem.getStemLength());
+      return true;
+    }
+    
+    if (!input.incrementToken()) {
+      return false;
+    }
+    
+    buffer = dedup ? stemmer.uniqueStems(termAtt.buffer(), termAtt.length()) : stemmer.stem(termAtt.buffer(), termAtt.length());
+
+    if (buffer.isEmpty()) { // we do not know this word, return it unchanged
+      return true;
+    }     
+
+    Stem stem = buffer.remove(0);
+    termAtt.copyBuffer(stem.getStem(), 0, stem.getStemLength());
+    termAtt.setLength(stem.getStemLength());
+
+    if (!buffer.isEmpty()) {
+      savedState = captureState();
+    }
+
+    return true;
+  }
+
+  /**
+   * {@inheritDoc}
+   */
+  @Override
+  public void reset() throws IOException {
+    super.reset();
+    buffer = null;
+  }
+}