match.c

C语言库函数的源代码,是C语言学习参考的好文档。

                                 then bad pattern */

                              if (range_end == '\0' || range_end == ']')
                                    return MATCH_PATTERN;

                              /* special character range end */
                              if (range_end == '\\')
                              {
                                    range_end = *++p;

                                    /* if end of text then
                                       we have a bad pattern */
                                    if (!range_end)
                                          return MATCH_PATTERN;
                              }

                              /* move just beyond this range */
                              p++;
                        }

                        /* if the text character is in range then match found.
                           make sure the range letters have the proper
                           relationship to one another before comparison */

                        if (range_start < range_end)
                        {
                              if (*t >= range_start && *t <= range_end)
                              {
                                    member_match = TRUE;
                                    loop = FALSE;
                              }
                        }
                        else
                        {
                              if (*t >= range_end && *t <= range_start)
                              {
                                    member_match = TRUE;
                                    loop = FALSE;
                              }
                        }
                  }

                  /* if there was a match in an exclusion set then no match */
                  /* if there was no match in a member set then no match */

                  if ((invert && member_match) || !(invert || member_match))
                        return MATCH_RANGE;

                  /* if this is not an exclusion then skip the rest of
                     the [...] construct that already matched. */

                  if (member_match)
                  {
                        while (*p != ']')
                        {
                              /* bad pattern (Missing ']') */
                              if (!*p)
                                    return MATCH_PATTERN;

                              /* skip exact match */
                              if (*p == '\\')
                              {
                                    p++;

                                    /* if end of text then
                                       we have a bad pattern */

                                    if (!*p)
                                          return MATCH_PATTERN;
                              }

                              /* move to next pattern char */

                              p++;
                        }
                  }
                  break;
            }
            case '\\':  /* next character is quoted and must match exactly */

                  /* move pattern pointer to quoted char and fall through */

                  p++;

                  /* if end of text then we have a bad pattern */

                  if (!*p)
                        return MATCH_PATTERN;

                  /* must match this character exactly */

            default:
                  if (*p != *t)
                        return MATCH_LITERAL;
            }
      }
      /* if end of text not reached then the pattern fails */

      if (*t)
            return MATCH_END;
      else  return MATCH_VALID;
}


/*----------------------------------------------------------------------------
*
* recursively call matche() with final segment of PATTERN and of TEXT.
*
----------------------------------------------------------------------------*/

int matche_after_star (register char *p, register char *t)
{
      register int match = 0;
      register nextp;

      /* pass over existing ? and * in pattern */

      while ( *p == '?' || *p == '*' )
      {
            /* take one char for each ? and + */

            if (*p == '?')
            {
                  /* if end of text then no match */
                  if (!*t++)
                        return MATCH_ABORT;
            }

            /* move to next char in pattern */

            p++;
      }

      /* if end of pattern we have matched regardless of text left */

      if (!*p)
            return MATCH_VALID;

      /* get the next character to match which must be a literal or '[' */

      nextp = *p;
      if (nextp == '\\')
      {
            nextp = p[1];

            /* if end of text then we have a bad pattern */

            if (!nextp)
                  return MATCH_PATTERN;
      }

      /* Continue until we run out of text or definite result seen */

      do
      {
            /* a precondition for matching is that the next character
               in the pattern match the next character in the text or that
               the next pattern char is the beginning of a range.  Increment
               text pointer as we go here */

            if (nextp == *t || nextp == '[')
                  match = matche(p, t);

            /* if the end of text is reached then no match */

            if (!*t++)
                  match = MATCH_ABORT;

      } while ( match != MATCH_VALID && 
                match != MATCH_ABORT &&
                match != MATCH_PATTERN);

      /* return result */

      return match;
}


/*----------------------------------------------------------------------------
*
* match() is a shell to matche() to return only BOOLEAN values.
*
----------------------------------------------------------------------------*/

BOOLEAN match( char *p, char *t )
{
      int error_type;

      error_type = matche(p,t);
      return (error_type == MATCH_VALID ) ? TRUE : FALSE;
}


#ifdef TEST

/*
** This test main expects as first arg the pattern and as second arg
** the match string.  Output is yea or nay on match.  If nay on
** match then the error code is parsed and written.
*/

#include <stdio.h>

int main(int argc, char *argv[])
{
      int error;
      int is_valid_error;

      if (argc != 3)
            printf("Usage:  MATCH Pattern Text\n");
      else
      {
            printf("Pattern: %s\n", argv[1]);
            printf("Text   : %s\n", argv[2]);

            if (!is_pattern(argv[1]))
                  printf("    First Argument Is Not A Pattern\n");
            else
            {
                  error = matche(argv[1],argv[2]);
                  is_valid_pattern(argv[1],&is_valid_error);

                  switch (error)
                  {
                  case MATCH_VALID:
                        printf("    Match Successful");
                        if (is_valid_error != PATTERN_VALID)
                              printf(" -- is_valid_pattern() "
                                    "is complaining\n");
                        else  printf("\n");
                        break;

                  case MATCH_LITERAL:
                        printf("    Match Failed on Literal\n");
                        break;

                  case MATCH_RANGE:
                        printf("    Match Failed on [..]\n");
                        break;

                  case MATCH_ABORT:
                        printf("    Match Failed on Early "
                              "Text Termination\n");
                        break;

                  case MATCH_END:
                        printf("    Match Failed on Early "
                              "Pattern Termination\n");
                        break;

                  case MATCH_PATTERN:
                        switch (is_valid_error)
                        {
                        case PATTERN_VALID:
                              printf("    Internal Disagreement "
                                    "On Pattern\n");
                              break;

                        case PATTERN_ESC:
                              printf("    Literal Escape at "
                                    "End of Pattern\n");
                              break;


                        case PATTERN_RANGE:
                              printf("    No End of Range in "
                                    "[..] Construct\n");
                              break;

                        case PATTERN_CLOSE:
                              printf("    [..] Construct is Open\n");
                              break;

                        case PATTERN_EMPTY:
                              printf("    [..] Construct is Empty\n");
                              break;

                        default:
                              printf("    Internal Error in "
                                    "is_valid_pattern()\n");
                        }
                        break;

                  default:
                        printf("    Internal Error in matche()\n");
                        break;
                  }
            }
      }
      return(0);
}

#endif /* TEST */