awkmatcher.java

jakarta-oro-2.0.8 正则表达式 引擎 源代码

/*
 * $Id: AwkMatcher.java,v 1.11 2003/11/07 20:16:24 dfs Exp $
 *
 * ====================================================================
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 2000 The Apache Software Foundation.  All rights
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. 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.
 *
 * 3. The end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "Apache" and "Apache Software Foundation", "Jakarta-Oro" 
 *    must not be used to endorse or promote products derived from this
 *    software without prior written permission. For written
 *    permission, please contact [e-mail].
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 * 5. Products derived from this software may not be called "Apache" 
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 * SUCH DAMAGE.
 * ====================================================================
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 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 */


package org.apache.oro.text.awk;

import java.io.*;

import org.apache.oro.text.regex.*;

/**
 * The AwkMatcher class is used to match regular expressions
 * (conforming to the Awk regular expression syntax) generated by
 * AwkCompiler.  AwkMatcher only supports 8-bit ASCII.  Any attempt
 * to match Unicode values greater than 255 will result in undefined
 * behavior.  AwkMatcher finds true leftmost-longest matches, so
 * you must take care with how you formulate your regular expression
 * to avoid matching more than you really want.
 * <p>
 * It is important for you to remember that AwkMatcher does not save
 * parenthesized sub-group information.  Therefore the number of groups
 * saved in a MatchResult produced by AwkMatcher will always be 1.
 *
 * @version @version@
 * @since 1.0
 * @see org.apache.oro.text.regex.PatternMatcher
 * @see AwkCompiler
 */
public final class AwkMatcher implements PatternMatcher {
  private int __lastMatchedBufferOffset;
  private AwkMatchResult __lastMatchResult = null;
  private AwkStreamInput __scratchBuffer, __streamSearchBuffer;
  private AwkPattern __awkPattern;
  private int __offsets[] = new int[2];

  /**
   * A kluge variable to make PatternMatcherInput matches work when
   * their begin offset is non-zero.  This kluge is caused by the
   * misguided notion that AwkStreamInput could be overloaded to do
   * both stream and fixed buffer matches.  The whole input representation
   * scheme has to be scrapped and redone. -- dfs 2001/07/10
   */
  private int __beginOffset;

  public AwkMatcher() {
    __scratchBuffer = new AwkStreamInput();
    __scratchBuffer._endOfStreamReached = true;
  }

  /**
   * Determines if a prefix of a string (represented as a char[])
   * matches a given pattern, starting from a given offset into the string.
   * If a prefix of the string matches the pattern, a MatchResult instance
   * representing the match is made accesible via
   * {@link #getMatch()}.
   * <p>
   * This method is useful for certain common token identification tasks
   * that are made more difficult without this functionality.
   * <p>
   * @param input  The char[] to test for a prefix match.
   * @param pattern  The Pattern to be matched.
   * @param offset The offset at which to start searching for the prefix.
   * @return True if input matches pattern, false otherwise.
   */
  // I reimplemented this method in terms of streammatchesPrefix
  // to reduce the code size.  This is not very elegant and
  // reduces performance by a small degree.
  public boolean matchesPrefix(char[] input, Pattern pattern, int offset){
    int result = -1;

    __awkPattern = (AwkPattern)pattern;

    __scratchBuffer._buffer       = input;
    __scratchBuffer._bufferSize   = input.length;
    __scratchBuffer._bufferOffset = __beginOffset = 0;
    __scratchBuffer._endOfStreamReached = true;
    __streamSearchBuffer = __scratchBuffer;
    __offsets[0] = offset;
    try {
      result = __streamMatchPrefix();
    } catch(IOException e){
      // Don't do anything because we're not doing any I/O
      result = -1;
    }

    if(result < 0) {
      __lastMatchResult = null;
      return false;
    }

    __lastMatchResult =
      new AwkMatchResult(new String(input, 0, result), offset);

    return true;
  }


  /**
   * Determines if a prefix of a string (represented as a char[])
   * matches a given pattern.
   * If a prefix of the string matches the pattern, a MatchResult instance
   * representing the match is made accesible via
   * {@link #getMatch()}.
   * <p>
   * This method is useful for certain common token identification tasks
   * that are made more difficult without this functionality.
   * <p>
   * @param input  The char[] to test for a prefix match.
   * @param pattern  The Pattern to be matched.
   * @return True if input matches pattern, false otherwise.
   */
  public boolean matchesPrefix(char[] input, Pattern pattern){
    return matchesPrefix(input, pattern, 0);
  }


  /**
   * Determines if a prefix of a string matches a given pattern.
   * If a prefix of the string matches the pattern, a MatchResult instance
   * representing the match is made accesible via
   * {@link #getMatch()}.
   * <p>
   * This method is useful for certain common token identification tasks
   * that are made more difficult without this functionality.
   * <p>
   * @param input  The String to test for a prefix match.
   * @param pattern  The Pattern to be matched.
   * @return True if input matches pattern, false otherwise.
   */
  public boolean matchesPrefix(String input, Pattern pattern) {
    return matchesPrefix(input.toCharArray(), pattern, 0);
  }


  /**
   * Determines if a prefix of a PatternMatcherInput instance
   * matches a given pattern.  If there is a match, a MatchResult instance
   * representing the match is made accesible via
   * {@link #getMatch()}.  Unlike the
   * {@link #contains(PatternMatcherInput, Pattern)}
   * method, the current offset of the PatternMatcherInput argument
   * is not updated.  You should remember that the region starting
   * from the begin offset of the PatternMatcherInput will be
   * tested for a prefix match.
   * <p>
   * This method is useful for certain common token identification tasks
   * that are made more difficult without this functionality.
   * <p>
   * @param input  The PatternMatcherInput to test for a prefix match.
   * @param pattern  The Pattern to be matched.
   * @return True if input matches pattern, false otherwise.
   */
  public boolean matchesPrefix(PatternMatcherInput input, Pattern pattern){
    int result = -1;

    __awkPattern = (AwkPattern)pattern;
    __scratchBuffer._buffer       = input.getBuffer();
    __scratchBuffer._bufferOffset = __beginOffset = input.getBeginOffset();
    __offsets[0] = input.getCurrentOffset();

    __scratchBuffer._bufferSize   = input.length();
    __scratchBuffer._endOfStreamReached = true;
    __streamSearchBuffer = __scratchBuffer;
    try {
      result = __streamMatchPrefix();
    } catch(IOException e) {
      // Don't do anything because we're not doing any I/O
      result = -1;
    }

    if(result < 0) {
      __lastMatchResult = null;
      return false;
    }

    __lastMatchResult =
      new AwkMatchResult(new String(__scratchBuffer._buffer, __offsets[0],
				    result), __offsets[0]);

    return true;
  }



  /**
   * Determines if a string (represented as a char[]) exactly 
   * matches a given pattern.  If
   * there is an exact match, a MatchResult instance
   * representing the match is made accesible via
   * {@link #getMatch()}.  The pattern must be
   * an AwkPattern instance, otherwise a ClassCastException will
   * be thrown.  You are not required to, and indeed should NOT try to
   * (for performance reasons), catch a ClassCastException because it
   * will never be thrown as long as you use an AwkPattern as the pattern
   * parameter.
   * <p>
   * @param input  The char[] to test for an exact match.
   * @param pattern  The AwkPattern to be matched.
   * @return True if input matches pattern, false otherwise.
   * @exception ClassCastException If a Pattern instance other than an
   *         AwkPattern is passed as the pattern parameter.
   */
  public boolean matches(char[] input, Pattern pattern) {
    int result = -1;

    __awkPattern = (AwkPattern)pattern;
    __scratchBuffer._buffer       = input;
    __scratchBuffer._bufferSize   = input.length;
    __scratchBuffer._bufferOffset = __beginOffset = 0;
    __scratchBuffer._endOfStreamReached = true;
    __streamSearchBuffer = __scratchBuffer;
    __offsets[0] = 0;
    try {
      result = __streamMatchPrefix();
    } catch(IOException e){
      // Don't do anything because we're not doing any I/O
      result = -1;
    }

    if(result != input.length) {
      __lastMatchResult = null;
      return false;
    }

    __lastMatchResult =
      new AwkMatchResult(new String(input, 0, result), 0);

    return true;
  }




  /**
   * Determines if a string exactly matches a given pattern.  If
   * there is an exact match, a MatchResult instance
   * representing the match is made accesible via
   * {@link #getMatch()}.  The pattern must be
   * a AwkPattern instance, otherwise a ClassCastException will
   * be thrown.  You are not required to, and indeed should NOT try to
   * (for performance reasons), catch a ClassCastException because it
   * will never be thrown as long as you use an AwkPattern as the pattern
   * parameter.
   * <p>
   * @param input  The String to test for an exact match.
   * @param pattern  The AwkPattern to be matched.
   * @return True if input matches pattern, false otherwise.
   * @exception ClassCastException If a Pattern instance other than an
   *         AwkPattern is passed as the pattern parameter.
   */
  public boolean matches(String input, Pattern pattern){
    return matches(input.toCharArray(), pattern);
  }


  /**
   * Determines if the contents of a PatternMatcherInput instance
   * exactly matches a given pattern.  If
   * there is an exact match, a MatchResult instance
   * representing the match is made accesible via
   * {@link #getMatch()}.  Unlike the
   * {@link #contains(PatternMatcherInput, Pattern)}
   * method, the current offset of the PatternMatcherInput argument
   * is not updated.  You should remember that the region between
   * the begin and end offsets of the PatternMatcherInput will be
   * tested for an exact match.
   * <p>
   * The pattern must be an AwkPattern instance, otherwise a
   * ClassCastException will be thrown.  You are not required to, and 
   * indeed should NOT try to (for performance reasons), catch a
   * ClassCastException because it will never be thrown as long as you use
   * an AwkPattern as the pattern parameter.
   * <p>
   * @param input  The PatternMatcherInput to test for a match.
   * @param pattern  The AwkPattern to be matched.
   * @return True if input matches pattern, false otherwise.
   * @exception ClassCastException If a Pattern instance other than an
   *         AwkPattern is passed as the pattern parameter.
   */
  public boolean matches(PatternMatcherInput input, Pattern pattern){
    int result = -1;

    __awkPattern = (AwkPattern)pattern;
    __scratchBuffer._buffer       = input.getBuffer();
    __scratchBuffer._bufferSize   = input.length();
    __scratchBuffer._bufferOffset = __beginOffset = input.getBeginOffset();
    __offsets[0] = input.getBeginOffset();
    __scratchBuffer._endOfStreamReached = true;
    __streamSearchBuffer = __scratchBuffer;
    try {
      result = __streamMatchPrefix();
    } catch(IOException e){
      // Don't do anything because we're not doing any I/O
      result = -1;
    }

    if(result != __scratchBuffer._bufferSize) {
      __lastMatchResult = null;
      return false;
    }

    __lastMatchResult =
      new AwkMatchResult(new String(__scratchBuffer._buffer, __offsets[0],
			     __scratchBuffer._bufferSize), __offsets[0]);

    return true;
  }



  /**
   * Determines if a string (represented as a char[]) contains a pattern.
   * If the pattern is
   * matched by some substring of the input, a MatchResult instance
   * representing the <b> first </b> such match is made acessible via 
   * {@link #getMatch()}.  If you want to access
   * subsequent matches you should either use a PatternMatcherInput object
   * or use the offset information in the MatchResult to create a substring
   * representing the remaining input.  Using the MatchResult offset 
   * information is the recommended method of obtaining the parts of the
   * string preceeding the match and following the match.
   * <p>
   * The pattern must be an AwkPattern instance, otherwise a
   * ClassCastException will be thrown.  You are not required to, and 
   * indeed should NOT try to (for performance reasons), catch a
   * ClassCastException because it will never be thrown as long as you use