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Lucene example source code file (CompositeBreakIterator.java)

This example Lucene source code file (CompositeBreakIterator.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Lucene tags/keywords

breakiteratorwrapper, breakiteratorwrapper, compositebreakiterator, compositebreakiterator, icutokenizerconfig, icutokenizerconfig, scriptiterator, scriptiterator

The Lucene CompositeBreakIterator.java source code

package org.apache.lucene.analysis.icu.segmentation;

/**
 * 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 com.ibm.icu.lang.UScript;
import com.ibm.icu.text.BreakIterator;

/**
 * An internal BreakIterator for multilingual text, following recommendations
 * from: UAX #29: Unicode Text Segmentation. (http://unicode.org/reports/tr29/)
 * <p>
 * See http://unicode.org/reports/tr29/#Tailoring for the motivation of this
 * design.
 * <p>
 * Text is first divided into script boundaries. The processing is then
 * delegated to the appropriate break iterator for that specific script.
 * <p>
 * This break iterator also allows you to retrieve the ISO 15924 script code
 * associated with a piece of text.
 * <p>
 * See also UAX #29, UTR #24
 * @lucene.experimental
 */
final class CompositeBreakIterator {
  private final ICUTokenizerConfig config;
  private final BreakIteratorWrapper wordBreakers[] = new BreakIteratorWrapper[UScript.CODE_LIMIT];

  private BreakIteratorWrapper rbbi;
  private final ScriptIterator scriptIterator = new ScriptIterator();

  private char text[];

  CompositeBreakIterator(ICUTokenizerConfig config) {
    this.config = config;
  }

  /**
   * Retrieve the next break position. If the RBBI range is exhausted within the
   * script boundary, examine the next script boundary.
   * 
   * @return the next break position or BreakIterator.DONE
   */
  int next() {
    int next = rbbi.next();
    while (next == BreakIterator.DONE && scriptIterator.next()) {
      rbbi = getBreakIterator(scriptIterator.getScriptCode());
      rbbi.setText(text, scriptIterator.getScriptStart(), 
          scriptIterator.getScriptLimit() - scriptIterator.getScriptStart());
      next = rbbi.next();
    }
    return (next == BreakIterator.DONE) ? BreakIterator.DONE : next
        + scriptIterator.getScriptStart();
  }

  /**
   * Retrieve the current break position.
   * 
   * @return the current break position or BreakIterator.DONE
   */
  int current() {
    final int current = rbbi.current();
    return (current == BreakIterator.DONE) ? BreakIterator.DONE : current
        + scriptIterator.getScriptStart();
  }

  /**
   * Retrieve the rule status code (token type) from the underlying break
   * iterator
   * 
   * @return rule status code (see RuleBasedBreakIterator constants)
   */
  int getRuleStatus() {
    return rbbi.getRuleStatus();
  }

  /**
   * Retrieve the UScript script code for the current token. This code can be
   * decoded with UScript into a name or ISO 15924 code.
   * 
   * @return UScript script code for the current token.
   */
  int getScriptCode() {
    return scriptIterator.getScriptCode();
  }

  /**
   * Set a new region of text to be examined by this iterator
   * 
   * @param text buffer of text
   * @param start offset into buffer
   * @param length maximum length to examine
   */
  void setText(final char text[], int start, int length) {
    this.text = text;
    scriptIterator.setText(text, start, length);
    if (scriptIterator.next()) {
      rbbi = getBreakIterator(scriptIterator.getScriptCode());
      rbbi.setText(text, scriptIterator.getScriptStart(), 
          scriptIterator.getScriptLimit() - scriptIterator.getScriptStart());
    } else {
      rbbi = getBreakIterator(UScript.COMMON);
      rbbi.setText(text, 0, 0);
    }
  }
  
  private BreakIteratorWrapper getBreakIterator(int scriptCode) {
    if (wordBreakers[scriptCode] == null)
      wordBreakers[scriptCode] = BreakIteratorWrapper.wrap(config.getBreakIterator(scriptCode));
    return wordBreakers[scriptCode];
  }
}

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