pylucene 3.5.0-3

[pylucene.git] / lucene-java-3.5.0 / lucene / contrib / icu / src / java / org / apache / lucene / analysis / icu / ICUNormalizer2Filter.java

diff --git a/lucene-java-3.5.0/lucene/contrib/icu/src/java/org/apache/lucene/analysis/icu/ICUNormalizer2Filter.java b/lucene-java-3.5.0/lucene/contrib/icu/src/java/org/apache/lucene/analysis/icu/ICUNormalizer2Filter.java
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+++ b/lucene-java-3.5.0/lucene/contrib/icu/src/java/org/apache/lucene/analysis/icu/ICUNormalizer2Filter.java
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+package org.apache.lucene.analysis.icu;
+
+/**
+ * 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 org.apache.lucene.analysis.TokenFilter;
+import org.apache.lucene.analysis.TokenStream;
+import org.apache.lucene.analysis.tokenattributes.CharTermAttribute;
+
+import com.ibm.icu.text.Normalizer;
+import com.ibm.icu.text.Normalizer2;
+
+/**
+ * Normalize token text with ICU's {@link com.ibm.icu.text.Normalizer2}
+ * <p>
+ * With this filter, you can normalize text in the following ways:
+ * <ul>
+ *  <li> NFKC Normalization, Case Folding, and removing Ignorables (the default)
+ *  <li> Using a standard Normalization mode (NFC, NFD, NFKC, NFKD)
+ *  <li> Based on rules from a custom normalization mapping.
+ * </ul>
+ * <p>
+ * If you use the defaults, this filter is a simple way to standardize Unicode text
+ * in a language-independent way for search:
+ * <ul>
+ *  <li> The case folding that it does can be seen as a replacement for
+ *  LowerCaseFilter: For example, it handles cases such as the Greek sigma, so that
+ * "Μάϊος" and "ΜΆΪΟΣ" will match correctly.
+ *  <li> The normalization will standardizes different forms of the same 
+ *  character in Unicode. For example, CJK full-width numbers will be standardized
+ *  to their ASCII forms.
+ *  <li> Ignorables such as Zero-Width Joiner and Variation Selectors are removed.
+ *  These are typically modifier characters that affect display.
+ * </ul>
+ * 
+ * @see com.ibm.icu.text.Normalizer2
+ * @see com.ibm.icu.text.FilteredNormalizer2
+ */
+public class ICUNormalizer2Filter extends TokenFilter {
+  private final CharTermAttribute termAtt = addAttribute(CharTermAttribute.class);
+  private final Normalizer2 normalizer;
+  private final StringBuilder buffer = new StringBuilder();
+
+  /**
+   * Create a new Normalizer2Filter that combines NFKC normalization, Case
+   * Folding, and removes Default Ignorables (NFKC_Casefold)
+   */
+  public ICUNormalizer2Filter(TokenStream input) {
+    this(input, Normalizer2.getInstance(null, "nfkc_cf", Normalizer2.Mode.COMPOSE));
+  }
+
+  /**
+   * Create a new Normalizer2Filter with the specified Normalizer2
+   * @param input stream
+   * @param normalizer normalizer to use
+   */
+  public ICUNormalizer2Filter(TokenStream input, Normalizer2 normalizer) {
+    super(input);
+    this.normalizer = normalizer;
+  }
+
+  @Override
+  public final boolean incrementToken() throws IOException {
+    if (input.incrementToken()) {
+      if (normalizer.quickCheck(termAtt) != Normalizer.YES) {
+        buffer.setLength(0);
+        normalizer.normalize(termAtt, buffer);
+        termAtt.setEmpty().append(buffer);
+      }
+      return true;
+    } else {
+      return false;
+    }
+  }
+}