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The Waikato Environment for Knowledge Analysis (WEKA), a machine learning workbench. This version represents the developer version, the "bleeding edge" of development, you could say. New functionality gets added to this version.

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/*
 *   This program is free software: you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation, either version 3 of the License, or
 *   (at your option) any later version.
 *
 *   This program is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *   GNU General Public License for more details.
 *
 *   You should have received a copy of the GNU General Public License
 *   along with this program.  If not, see .
 */

/*
 * AlphabeticStringTokenizer.java
 * Copyright (C) 2003-2012 University of Waikato, Hamilton, New Zealand
 */

package weka.core.tokenizers;

import java.util.NoSuchElementException;

import weka.core.RevisionUtils;

/**
 *  Alphabetic string tokenizer, tokens are to be
 * formed only from contiguous alphabetic sequences.
 * 
 * 
 * 
 * @author Asrhaf M. Kibriya ([email protected])
 * @author FracPete (fracpete at waikato dot ac dot nz)
 * @version $Revision: 10203 $
 */
public class AlphabeticTokenizer extends Tokenizer {

  /** for serialization */
  private static final long serialVersionUID = 6705199562609861697L;

  /** the characters of the string */
  protected char[] m_Str;

  /** the current position */
  protected int m_CurrentPos;

  /**
   * Returns a string describing the stemmer
   * 
   * @return a description suitable for displaying in the explorer/experimenter
   *         gui
   */
  @Override
  public String globalInfo() {
    return "Alphabetic string tokenizer, tokens are to be formed only from "
      + "contiguous alphabetic sequences.";
  }

  /**
   * returns whether there are more elements still
   * 
   * @return true if there are still more elements
   */
  @Override
  public boolean hasMoreElements() {
    int beginpos = m_CurrentPos;

    while ((beginpos < m_Str.length)
      && ((m_Str[beginpos] < 'a') || (m_Str[beginpos] > 'z'))
      && ((m_Str[beginpos] < 'A') || (m_Str[beginpos] > 'Z'))) {
      beginpos++;
    }
    m_CurrentPos = beginpos;

    if ((beginpos < m_Str.length)
      && (((m_Str[beginpos] >= 'a') && (m_Str[beginpos] <= 'z')) || ((m_Str[beginpos] >= 'A') && (m_Str[beginpos] <= 'Z')))) {
      return true;
    } else {
      return false;
    }
  }

  /**
   * returns the next element
   * 
   * @return the next element
   */
  @Override
  public String nextElement() {
    int beginpos, endpos;

    beginpos = m_CurrentPos;

    while ((beginpos < m_Str.length)
      && ((m_Str[beginpos] < 'a') && (m_Str[beginpos] > 'z'))
      && ((m_Str[beginpos] < 'A') && (m_Str[beginpos] > 'Z'))) {
      beginpos++;
    }
    m_CurrentPos = endpos = beginpos;

    if (beginpos >= m_Str.length) {
      throw new NoSuchElementException("No more tokens present");
    }

    while ((endpos < m_Str.length)
      && (((m_Str[endpos] >= 'a') && (m_Str[endpos] <= 'z')) || ((m_Str[endpos] >= 'A') && (m_Str[endpos] <= 'Z')))) {
      endpos++;
    }

    String s = new String(m_Str, beginpos, endpos - m_CurrentPos);
    m_CurrentPos = endpos;

    return s;
  }

  /**
   * Sets the string to tokenize. Tokenization happens immediately.
   * 
   * @param s the string to tokenize
   */
  @Override
  public void tokenize(String s) {
    m_CurrentPos = 0;
    m_Str = new char[s.length()];
    s.getChars(0, s.length(), m_Str, 0);
  }

  /**
   * Returns the revision string.
   * 
   * @return the revision
   */
  @Override
  public String getRevision() {
    return RevisionUtils.extract("$Revision: 10203 $");
  }

  /**
   * Runs the tokenizer with the given options and strings to tokenize. The
   * tokens are printed to stdout.
   * 
   * @param args the commandline options and strings to tokenize
   */
  public static void main(String[] args) {
    runTokenizer(new AlphabeticTokenizer(), args);
  }
}