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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.standard;


import java.io.IOException;

import org.apache.lucene.analysis.Tokenizer;
import org.apache.lucene.analysis.tokenattributes.OffsetAttribute;
import org.apache.lucene.analysis.tokenattributes.PositionIncrementAttribute;
import org.apache.lucene.analysis.tokenattributes.CharTermAttribute;
import org.apache.lucene.analysis.tokenattributes.TypeAttribute;
import org.apache.lucene.util.AttributeFactory;

/**
 * This class implements Word Break rules from the Unicode Text Segmentation 
 * algorithm, as specified in 
 * Unicode Standard Annex #29 
 * URLs and email addresses are also tokenized according to the relevant RFCs.
 * 
 * Tokens produced are of the following types:
 * 

 *   <ALPHANUM>: A sequence of alphabetic and numeric characters
 *   <NUM>: A number
 *   <URL>: A URL
 *   <EMAIL>: An email address
 *   <SOUTHEAST_ASIAN>: A sequence of characters from South and Southeast
 *       Asian languages, including Thai, Lao, Myanmar, and Khmer
 *   <IDEOGRAPHIC>: A single CJKV ideographic character
 *   <HIRAGANA>: A single hiragana character
 * 
 */

public final class UAX29URLEmailTokenizer extends Tokenizer {
  /** A private instance of the JFlex-constructed scanner */
  private final UAX29URLEmailTokenizerImpl scanner;
  
  public static final int ALPHANUM          = 0;
  public static final int NUM               = 1;
  public static final int SOUTHEAST_ASIAN   = 2;
  public static final int IDEOGRAPHIC       = 3;
  public static final int HIRAGANA          = 4;
  public static final int KATAKANA          = 5;
  public static final int HANGUL            = 6;
  public static final int URL               = 7;
  public static final int EMAIL             = 8;

  /** String token types that correspond to token type int constants */
  public static final String [] TOKEN_TYPES = new String [] {
    StandardTokenizer.TOKEN_TYPES[StandardTokenizer.ALPHANUM],
    StandardTokenizer.TOKEN_TYPES[StandardTokenizer.NUM],
    StandardTokenizer.TOKEN_TYPES[StandardTokenizer.SOUTHEAST_ASIAN],
    StandardTokenizer.TOKEN_TYPES[StandardTokenizer.IDEOGRAPHIC],
    StandardTokenizer.TOKEN_TYPES[StandardTokenizer.HIRAGANA],
    StandardTokenizer.TOKEN_TYPES[StandardTokenizer.KATAKANA],
    StandardTokenizer.TOKEN_TYPES[StandardTokenizer.HANGUL],
    "",
    "",
  };
  
  private int skippedPositions;

  private int maxTokenLength = StandardAnalyzer.DEFAULT_MAX_TOKEN_LENGTH;

  /** Set the max allowed token length.  Any token longer
   *  than this is skipped. */
  public void setMaxTokenLength(int length) {
    if (length < 1) {
      throw new IllegalArgumentException("maxTokenLength must be greater than zero");
    }
    this.maxTokenLength = length;
    scanner.setBufferSize(Math.min(length, 1024 * 1024)); // limit buffer size to 1M chars
  }

  /** @see #setMaxTokenLength */
  public int getMaxTokenLength() {
    return maxTokenLength;
  }

  /**
   * Creates a new instance of the UAX29URLEmailTokenizer.  Attaches
   * the input to the newly created JFlex scanner.

   */
  public UAX29URLEmailTokenizer() {
    this.scanner = getScanner();
  }

  /**
   * Creates a new UAX29URLEmailTokenizer with a given {@link AttributeFactory} 
   */
  public UAX29URLEmailTokenizer(AttributeFactory factory) {
    super(factory);
    this.scanner = getScanner();
  }

  private UAX29URLEmailTokenizerImpl getScanner() {
    return new UAX29URLEmailTokenizerImpl(input);
  }

  // this tokenizer generates three attributes:
  // term offset, positionIncrement and type
  private final CharTermAttribute termAtt = addAttribute(CharTermAttribute.class);
  private final OffsetAttribute offsetAtt = addAttribute(OffsetAttribute.class);
  private final PositionIncrementAttribute posIncrAtt = addAttribute(PositionIncrementAttribute.class);
  private final TypeAttribute typeAtt = addAttribute(TypeAttribute.class);

  @Override
  public final boolean incrementToken() throws IOException {
    clearAttributes();
    skippedPositions = 0;

    while(true) {
      int tokenType = scanner.getNextToken();

      if (tokenType == UAX29URLEmailTokenizerImpl.YYEOF) {
        return false;
      }

      if (scanner.yylength() <= maxTokenLength) {
        posIncrAtt.setPositionIncrement(skippedPositions+1);
        scanner.getText(termAtt);
        final int start = scanner.yychar();
        offsetAtt.setOffset(correctOffset(start), correctOffset(start+termAtt.length()));
        typeAtt.setType(TOKEN_TYPES[tokenType]);
        return true;
      } else
        // When we skip a too-long term, we still increment the
        // position increment
        skippedPositions++;
    }
  }
  
  @Override
  public final void end() throws IOException {
    super.end();
    // set final offset
    int finalOffset = correctOffset(scanner.yychar() + scanner.yylength());
    offsetAtt.setOffset(finalOffset, finalOffset);
    // adjust any skipped tokens
    posIncrAtt.setPositionIncrement(posIncrAtt.getPositionIncrement()+skippedPositions);
  }
  
  @Override
  public void close() throws IOException {
    super.close();
    scanner.yyreset(input);
  }

  @Override
  public void reset() throws IOException {
    super.reset();
    scanner.yyreset(input);
    skippedPositions = 0;
  }
}