CheckingTokenStream.java

package org.cdlib.xtf.util;


/**
 * Copyright (c) 2004, Regents of the University of California
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * - Redistributions of source code must retain the above copyright notice,
 *   this list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright notice,
 *   this list of conditions and the following disclaimer in the documentation
 *   and/or other materials provided with the distribution.
 * - Neither the name of the University of California nor the names of its
 *   contributors may be used to endorse or promote products derived from this
 *   software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */
import java.io.IOException;
import org.apache.lucene.analysis.Token;
import org.apache.lucene.analysis.TokenStream;
import org.apache.lucene.analysis.standard.StandardTokenizerConstants;

/**
 * Used for debugging optimized FastTokenStream, this class checks the main
 * TokenStream against a reference one for equality. Any difference is flagged
 * with an assertion failure.
 *
 * @author Martin Haye
 */
public class CheckingTokenStream extends TokenStream 
{
  /** Main token stream that is being checked */
  TokenStream main;

  /** Reference stream to check the main one against */
  TokenStream ref;

  /** Token type for words containing apostrophes */
  private static final String APOSTROPHE_TYPE = StandardTokenizerConstants.tokenImage[StandardTokenizerConstants.APOSTROPHE];

  /** Token type for acronyms */
  private static final String ACRONYM_TYPE = StandardTokenizerConstants.tokenImage[StandardTokenizerConstants.ACRONYM];

  /** Construct a CheckingTokenStream */
  public CheckingTokenStream(TokenStream main, TokenStream ref) 
  {
    this.main = main;
    this.ref = ref;

    // Assertions must be enabled!
    boolean flag = false;
    assert (flag = true) == true;
    if (!flag)
      throw new RuntimeException(
        "CheckingTokenStream requires assertions to be enabled");
  } // constructor

  /**
   * Get the next token from the main stream. Checks that this token matches
   * the next one in the reference stream.
   */
  public Token next()
    throws IOException 
  {
    Token t1 = main.next();
    Token t2 = ref.next();
    if (t1 == null || t2 == null)
      assert t1 == t2;
    else {
      assert t1.termText().equals(t2.termText());
      assert t1.startOffset() == t2.startOffset();
      assert t1.endOffset() == t2.endOffset();
      assert t1.getPositionIncrement() == t2.getPositionIncrement();
      assert idType(t1.type()).equals(idType(t2.type()));
    }
    return t1;
  }

  /** Map the type to apostrophe, acronym, or other */
  private String idType(String type) {
    if (type.equals(APOSTROPHE_TYPE))
      return APOSTROPHE_TYPE;
    if (type.equals(ACRONYM_TYPE))
      return ACRONYM_TYPE;
    return "other";
  }

  /** Close the token stream */
  public void close()
    throws IOException 
  {
    main.close();
    ref.close();
  }
} // class CheckingTokenizer