pylucene 3.5.0-3

[pylucene.git] / lucene-java-3.5.0 / lucene / contrib / analyzers / smartcn / src / java / org / apache / lucene / analysis / cn / smart / WordSegmenter.java

diff --git a/lucene-java-3.5.0/lucene/contrib/analyzers/smartcn/src/java/org/apache/lucene/analysis/cn/smart/WordSegmenter.java b/lucene-java-3.5.0/lucene/contrib/analyzers/smartcn/src/java/org/apache/lucene/analysis/cn/smart/WordSegmenter.java
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+++ b/lucene-java-3.5.0/lucene/contrib/analyzers/smartcn/src/java/org/apache/lucene/analysis/cn/smart/WordSegmenter.java
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+/**
+ * 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.lucene.analysis.cn.smart;
+
+import java.util.Collections;
+import java.util.List;
+
+import org.apache.lucene.analysis.cn.smart.hhmm.HHMMSegmenter;
+import org.apache.lucene.analysis.cn.smart.hhmm.SegToken;
+import org.apache.lucene.analysis.cn.smart.hhmm.SegTokenFilter;
+
+/**
+ * Segment a sentence of Chinese text into words.
+ * @lucene.experimental
+ */
+class WordSegmenter {
+
+  private HHMMSegmenter hhmmSegmenter = new HHMMSegmenter();
+
+  private SegTokenFilter tokenFilter = new SegTokenFilter();
+
+  /**
+   * Segment a sentence into words with {@link HHMMSegmenter}
+   * 
+   * @param sentence input sentence
+   * @param startOffset start offset of sentence
+   * @return {@link List} of {@link SegToken}
+   */
+  public List<SegToken> segmentSentence(String sentence, int startOffset) {
+
+    List<SegToken> segTokenList = hhmmSegmenter.process(sentence);
+    // tokens from sentence, excluding WordType.SENTENCE_BEGIN and WordType.SENTENCE_END
+    List<SegToken> result = Collections.emptyList();
+    
+    if (segTokenList.size() > 2) // if its not an empty sentence
+      result = segTokenList.subList(1, segTokenList.size() - 1);
+    
+    for (SegToken st : result)
+      convertSegToken(st, sentence, startOffset);
+    
+    return result;
+  }
+
+  /**
+   * Process a {@link SegToken} so that it is ready for indexing.
+   * 
+   * This method calculates offsets and normalizes the token with {@link SegTokenFilter}.
+   * 
+   * @param st input {@link SegToken}
+   * @param sentence associated Sentence
+   * @param sentenceStartOffset offset into sentence
+   * @return Lucene {@link SegToken}
+   */
+  public SegToken convertSegToken(SegToken st, String sentence,
+      int sentenceStartOffset) {
+
+    switch (st.wordType) {
+      case WordType.STRING:
+      case WordType.NUMBER:
+      case WordType.FULLWIDTH_NUMBER:
+      case WordType.FULLWIDTH_STRING:
+        st.charArray = sentence.substring(st.startOffset, st.endOffset)
+            .toCharArray();
+        break;
+      default:
+        break;
+    }
+
+    st = tokenFilter.filter(st);
+    st.startOffset += sentenceStartOffset;
+    st.endOffset += sentenceStartOffset;
+    return st;
+  }
+}