pylucene 3.5.0-3

[pylucene.git] / lucene-java-3.5.0 / lucene / src / java / org / apache / lucene / analysis / StopAnalyzer.java

diff --git a/lucene-java-3.5.0/lucene/src/java/org/apache/lucene/analysis/StopAnalyzer.java b/lucene-java-3.5.0/lucene/src/java/org/apache/lucene/analysis/StopAnalyzer.java
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+package org.apache.lucene.analysis;
+
+/**
+ * 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.File;
+import java.io.IOException;
+import java.io.Reader;
+import java.util.Arrays;
+import java.util.Set;
+import java.util.List;
+
+import org.apache.lucene.util.IOUtils;
+import org.apache.lucene.util.Version;
+
+/** Filters {@link LetterTokenizer} with {@link LowerCaseFilter} and {@link StopFilter}.
+ *
+ * <a name="version"/>
+ * <p>You must specify the required {@link Version}
+ * compatibility when creating StopAnalyzer:
+ * <ul>
+ *    <li> As of 3.1, StopFilter correctly handles Unicode 4.0
+ *         supplementary characters in stopwords
+ *   <li> As of 2.9, position increments are preserved
+ * </ul>
+*/
+
+public final class StopAnalyzer extends StopwordAnalyzerBase {
+  
+  /** An unmodifiable set containing some common English words that are not usually useful
+  for searching.*/
+  public static final Set<?> ENGLISH_STOP_WORDS_SET;
+  
+  static {
+    final List<String> stopWords = Arrays.asList(
+      "a", "an", "and", "are", "as", "at", "be", "but", "by",
+      "for", "if", "in", "into", "is", "it",
+      "no", "not", "of", "on", "or", "such",
+      "that", "the", "their", "then", "there", "these",
+      "they", "this", "to", "was", "will", "with"
+    );
+    final CharArraySet stopSet = new CharArraySet(Version.LUCENE_CURRENT, 
+        stopWords.size(), false);
+    stopSet.addAll(stopWords);  
+    ENGLISH_STOP_WORDS_SET = CharArraySet.unmodifiableSet(stopSet); 
+  }
+  
+  /** Builds an analyzer which removes words in
+   *  {@link #ENGLISH_STOP_WORDS_SET}.
+   * @param matchVersion See <a href="#version">above</a>
+   */
+  public StopAnalyzer(Version matchVersion) {
+    this(matchVersion, ENGLISH_STOP_WORDS_SET);
+  }
+
+  /** Builds an analyzer with the stop words from the given set.
+   * @param matchVersion See <a href="#version">above</a>
+   * @param stopWords Set of stop words */
+  public StopAnalyzer(Version matchVersion, Set<?> stopWords) {
+    super(matchVersion, stopWords);
+  }
+
+  /** Builds an analyzer with the stop words from the given file.
+   * @see WordlistLoader#getWordSet(Reader, Version)
+   * @param matchVersion See <a href="#version">above</a>
+   * @param stopwordsFile File to load stop words from */
+  public StopAnalyzer(Version matchVersion, File stopwordsFile) throws IOException {
+    this(matchVersion, WordlistLoader.getWordSet(IOUtils.getDecodingReader(stopwordsFile,
+        IOUtils.CHARSET_UTF_8), matchVersion));
+  }
+
+  /** Builds an analyzer with the stop words from the given reader.
+   * @see WordlistLoader#getWordSet(Reader, Version)
+   * @param matchVersion See <a href="#version">above</a>
+   * @param stopwords Reader to load stop words from */
+  public StopAnalyzer(Version matchVersion, Reader stopwords) throws IOException {
+    this(matchVersion, WordlistLoader.getWordSet(stopwords, matchVersion));
+  }
+
+  /**
+   * Creates
+   * {@link org.apache.lucene.analysis.ReusableAnalyzerBase.TokenStreamComponents}
+   * used to tokenize all the text in the provided {@link Reader}.
+   * 
+   * @return {@link org.apache.lucene.analysis.ReusableAnalyzerBase.TokenStreamComponents}
+   *         built from a {@link LowerCaseTokenizer} filtered with
+   *         {@link StopFilter}
+   */
+  @Override
+  protected TokenStreamComponents createComponents(String fieldName,
+      Reader reader) {
+    final Tokenizer source = new LowerCaseTokenizer(matchVersion, reader);
+    return new TokenStreamComponents(source, new StopFilter(matchVersion,
+          source, stopwords));
+  }
+}
+