/*
 * $Id: Perl5MatchResult.java,v 1.8 2003/11/07 20:16:25 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 apache@apache.org.
 *
 * 5. Products derived from this software may not be called "Apache" 
 *    or "Jakarta-Oro", nor may "Apache" or "Jakarta-Oro" appear in their 
 *    name, without prior written permission of the Apache Software Foundation.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED 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 APACHE SOFTWARE FOUNDATION OR
 * ITS 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.
 * ====================================================================
 *
 * 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.regex;


/**
 * A class used to store and access the results of a Perl5Pattern match.
 *
 * @version @version@
 * @since 1.0
 * @see PatternMatcher
 * @see Perl5Matcher
 */
final class Perl5MatchResult implements MatchResult {
  /**
   * The character offset into the line or stream where the match
   * begins.  Pattern matching methods that look for matches a line at
   * a time should use this field as the offset into the line
   * of the match.  Methods that look for matches independent of line
   * boundaries should use this field as the offset into the entire
   * text stream.
   */
   int _matchBeginOffset;


  /**
   * Arrays containing the beginning and end offsets of the pattern
   * groups matched within the actual matched pattern contained in the 
   * variable <code>match</code>.
   * Pattern matching methods that do not match subgroups, will only contain
   * entries for group 0, which always refers to the entire pattern.
   * <code>beginGroupOffset</code> contains the start offset of the groups,
   * indexed by group number, which will always be 0 for group 0.
   * <code>endGroupOffset</code> contains the ending offset + 1 of the groups.
   * A group matching the null string will have  <code>beginGroupOffset</code>
   * and <code>endGroupOffset</code> entries of equal value.  Following a
   * convention established by the GNU regular expression library for the
   * C language, groups that are not part of a match contain -1 as their
   * begin and end offsets.
   */
   int[] _beginGroupOffset, _endGroupOffset;


  /**
   * The entire string that matched the pattern.
   */
   String _match;


  /**
   * Constructs a MatchResult able to store match information for
   * a number of subpattern groups.
   * <p>
   * @param groups  The number of groups this MatchResult can store.
   *        Only postitive values greater than or equal to 1 make any
   *        sense.  At minimum, a MatchResult stores one group which
   *        represents the entire pattern matched including all subparts.
   */
  Perl5MatchResult(int groups){
    _beginGroupOffset = new int[groups];
    _endGroupOffset   = new int[groups];
  }


  /**
   * @return The length of the match.
   */
  public int length(){
    int length;

    length = (_endGroupOffset[0] - _beginGroupOffset[0]);

    return (length > 0 ? length : 0);
  }


  /**
   * @return The number of groups contained in the result.  This number
   *         includes the 0th group.  In other words, the result refers
   *         to the number of parenthesized subgroups plus the entire match
   *         itself.
   */
  public int groups(){
    return _beginGroupOffset.length;
  }

  /**
   * @param group The pattern subgroup to return.
   * @return A string containing the indicated pattern subgroup.  Group
   *         0 always refers to the entire match.  If a group was never
   *         matched, it returns null.  This is not to be confused with
   *         a group matching the null string, which will return a String
   *         of length 0.
   */
  public String group(int group){
    int begin, end, length;

    if(group < _beginGroupOffset.length){
      begin  = _beginGroupOffset[group];
      end    = _endGroupOffset[group];
      length = _match.length();

      if(begin >= 0 && end >= 0) {
	if(begin < length && end <= length && end > begin)
	  return _match.substring(begin, end);
	else if(begin <= end)
	  return "";
      }
    }

    return null;
  }

  /**
   * @param group The pattern subgroup.
   * @return The offset into group 0 of the first token in the indicated
   *         pattern subgroup.  If a group was never matched or does
   *         not exist, returns -1.
   */
  public int begin(int group){
    int begin, end;//, length;
    if(group < _beginGroupOffset.length){
      begin  = _beginGroupOffset[group];
      end    = _endGroupOffset[group];
      //length = _match.length();
      if(begin >= 0 && end >= 0)// && begin < length && end <= length)
	//return _beginGroupOffset[group];
	return begin;
    }

    return -1;
  }

  /**
   * @param group The pattern subgroup.
   * @return Returns one plus the offset into group 0 of the last token in
   *         the indicated pattern subgroup.  If a group was never matched
   *         or does not exist, returns -1.  A group matching the null
   *         string will return its start offset.
   */
  public int end(int group){
    int begin, end; //, length;
    if(group < _beginGroupOffset.length){
      begin  = _beginGroupOffset[group];
      end    = _endGroupOffset[group];
      //length = _match.length();
      if(begin >= 0 && end >= 0)// && begin < length && end <= length)
	//return _endGroupOffset[group];
	return end;
    }
    return -1;
  }

  /**
   * Returns an offset marking the beginning of the pattern match
   * relative to the beginning of the input.
   * <p>
   * @param group The pattern subgroup.
   * @return The offset of the first token in the indicated
   *         pattern subgroup.  If a group was never matched or does
   *         not exist, returns -1.
   */
  public int beginOffset(int group){
    int begin, end;//, length;
    if(group < _beginGroupOffset.length){
      begin  = _beginGroupOffset[group];
      end    = _endGroupOffset[group];
      //length = _match.length();
      if(begin >= 0 && end >= 0)// && begin < length && end <= length)
	//return _matchBeginOffset + _beginGroupOffset[group];
	return _matchBeginOffset + begin;
    }
    return -1;
  }

  /**
   * Returns an offset marking the end of the pattern match 
   * relative to the beginning of the input.
   * <p>
   * @param group The pattern subgroup.
   * @return Returns one plus the offset of the last token in
   *         the indicated pattern subgroup.  If a group was never matched
   *         or does not exist, returns -1.  A group matching the null
   *         string will return its start offset.
   */
  public int endOffset(int group){
    int begin, end;//, length;
    if(group < _endGroupOffset.length){
      begin  = _beginGroupOffset[group];
      end    = _endGroupOffset[group];
      //length = _match.length();
      if(begin >= 0 && end >= 0)// && begin < length && end <= length)
	//return _matchBeginOffset + _endGroupOffset[group];
	return _matchBeginOffset + end;
    }
    return -1;
  }


  /**
   * The same as group(0).
   *
   * @return A string containing the entire match.
   */
  public String toString() {
    return group(0);
  }
}
