games/quiz/rxp.c

   1 /*-
   2  * Copyright (c) 1991, 1993
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * This code is derived from software contributed to Berkeley by
   6  * Jim R. Oldroyd at The Instruction Set and Keith Gabryelski at
   7  * Commodore Business Machines.
   8  *
   9  * Redistribution and use in source and binary forms, with or without
  10  * modification, are permitted provided that the following conditions
  11  * are met:
  12  * 1. Redistributions of source code must retain the above copyright
  13  *    notice, this list of conditions and the following disclaimer.
  14  * 2. Redistributions in binary form must reproduce the above copyright
  15  *    notice, this list of conditions and the following disclaimer in the
  16  *    documentation and/or other materials provided with the distribution.
  17  * 3. All advertising materials mentioning features or use of this software
  18  *    must display the following acknowledgement:
  19  *      This product includes software developed by the University of
  20  *      California, Berkeley and its contributors.
  21  * 4. Neither the name of the University nor the names of its contributors
  22  *    may be used to endorse or promote products derived from this software
  23  *    without specific prior written permission.
  24  *
  25  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  26  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  27  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  28  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  29  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  30  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  31  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  32  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  33  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  34  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  35  * SUCH DAMAGE.
  36  *
  37  * @(#)rxp.c    8.1 (Berkeley) 5/31/93
  38  * $FreeBSD: src/games/quiz/rxp.c,v 1.5 1999/12/12 02:29:54 billf Exp $
  39  * $DragonFly: src/games/quiz/rxp.c,v 1.2 2003/06/17 04:25:24 dillon Exp $
  40  */
  41
  42 /*
  43  * regular expression parser
  44  *
  45  * external functions and return values are:
  46  * rxp_compile(s)
  47  *      TRUE    success
  48  *      FALSE   parse failure; error message will be in char rxperr[]
  49  * metas are:
  50  *      {...}   optional pattern, equialent to [...|]
  51  *      |       alternate pattern
  52  *      [...]   pattern delimiters
  53  *
  54  * rxp_match(s)
  55  *      TRUE    string s matches compiled pattern
  56  *      FALSE   match failure or regexp error
  57  *
  58  * rxp_expand()
  59  *      char *  reverse-engineered regular expression string
  60  *      NULL    regexp error
  61  */
  62
  63 #include <stdio.h>
  64 #include <ctype.h>
  65 #include "quiz.h"
  66                                         /* regexp tokens,       arg */
  67 #define LIT     (-1)                    /* literal character,   char */
  68 #define SOT     (-2)                    /* start text anchor,   - */
  69 #define EOT     (-3)                    /* end text anchor,     - */
  70 #define GRP_S   (-4)                    /* start alternate grp, ptr_to_end */
  71 #define GRP_E   (-5)                    /* end group,           - */
  72 #define ALT_S   (-6)                    /* alternate starts,    ptr_to_next */
  73 #define ALT_E   (-7)                    /* alternate ends,      - */
  74 #define END     (-8)                    /* end of regexp,       - */
  75
  76 typedef short Rxp_t;                    /* type for regexp tokens */
  77
  78 static Rxp_t rxpbuf[RXP_LINE_SZ];       /* compiled regular expression buffer */
  79 char rxperr[128];                       /* parser error message */
  80
  81 static int       rxp__compile __P((char *, int));
  82 static char     *rxp__expand __P((int));
  83 static int       rxp__match __P((char *, int, Rxp_t *, Rxp_t *, char *));
  84
  85 int
  86 rxp_compile(s)
  87         char *  s;
  88 {
  89         return (rxp__compile(s, TRUE));
  90 }
  91
  92 static int
  93 rxp__compile(s, first)
  94         char *s;
  95         int first;
  96 {
  97         static Rxp_t *rp;
  98         static char *sp;
  99         Rxp_t *grp_ptr;
 100         Rxp_t *alt_ptr;
 101         int esc, err;
 102
 103         esc = 0;
 104         if (first) {
 105                 rp = rxpbuf;
 106                 sp = s;
 107                 *rp++ = SOT;    /* auto-anchor: pat is really ^pat$ */
 108                 *rp++ = GRP_S;  /* auto-group: ^pat$ is really ^[pat]$ */
 109                 *rp++ = 0;
 110         }
 111         *rp++ = ALT_S;
 112         alt_ptr = rp;
 113         *rp++ = 0;
 114         for (; *sp; ++sp) {
 115                 if (rp - rxpbuf >= RXP_LINE_SZ - 4) {
 116                         (void)snprintf(rxperr, sizeof(rxperr),
 117                             "regular expression too long %s", s);
 118                         return (FALSE);
 119                 }
 120                 if (*sp == ':' && !esc)
 121                         break;
 122                 if (esc) {
 123                         *rp++ = LIT;
 124                         *rp++ = *sp;
 125                         esc = 0;
 126                 }
 127                 else switch (*sp) {
 128                 case '\\':
 129                         esc = 1;
 130                         break;
 131                 case '{':
 132                 case '[':
 133                         *rp++ = GRP_S;
 134                         grp_ptr = rp;
 135                         *rp++ = 0;
 136                         sp++;
 137                         if ((err = rxp__compile(s, FALSE)) != TRUE)
 138                                 return (err);
 139                         *rp++ = GRP_E;
 140                         *grp_ptr = rp - rxpbuf;
 141                         break;
 142                 case '}':
 143                 case ']':
 144                 case '|':
 145                         *rp++ = ALT_E;
 146                         *alt_ptr = rp - rxpbuf;
 147                         if (*sp != ']') {
 148                                 *rp++ = ALT_S;
 149                                 alt_ptr = rp;
 150                                 *rp++ = 0;
 151                         }
 152                         if (*sp != '|') {
 153                                 if (*sp != ']') {
 154                                         *rp++ = ALT_E;
 155                                         *alt_ptr = rp - rxpbuf;
 156                                 }
 157                                 if (first) {
 158                                         (void)snprintf(rxperr, sizeof(rxperr),
 159                                             "unmatched alternator in regexp %s",
 160                                              s);
 161                                         return (FALSE);
 162                                 }
 163                                 return (TRUE);
 164                         }
 165                         break;
 166                 default:
 167                         *rp++ = LIT;
 168                         *rp++ = *sp;
 169                         esc = 0;
 170                         break;
 171                 }
 172         }
 173         if (!first) {
 174                 (void)snprintf(rxperr, sizeof(rxperr),
 175                     "unmatched alternator in regexp %s", s);
 176                 return (FALSE);
 177         }
 178         *rp++ = ALT_E;
 179         *alt_ptr = rp - rxpbuf;
 180         *rp++ = GRP_E;
 181         *(rxpbuf + 2) = rp - rxpbuf;
 182         *rp++ = EOT;
 183         *rp = END;
 184         return (TRUE);
 185 }
 186
 187 /*
 188  * match string against compiled regular expression
 189  */
 190 int
 191 rxp_match(s)
 192         char *  s;
 193 {
 194         return (rxp__match(s, TRUE, NULL, NULL, NULL));
 195 }
 196
 197 static int
 198 rxp__match(s, first, j_succ, j_fail, sp_fail)
 199         char *s;
 200         int first;
 201         Rxp_t *j_succ;          /* jump here on successful alt match */
 202         Rxp_t *j_fail;          /* jump here on failed match */
 203         char *sp_fail;          /* reset sp to here on failed match */
 204 {
 205         static Rxp_t *rp;
 206         static char *sp;
 207         int ch;
 208         Rxp_t *grp_end;
 209         int err;
 210
 211         grp_end = NULL;
 212         if (first) {
 213                 rp = rxpbuf;
 214                 sp = s;
 215         }
 216         while (rp < rxpbuf + RXP_LINE_SZ && *rp != END)
 217                 switch(*rp) {
 218                 case LIT:
 219                         rp++;
 220                         ch = isascii(*rp) && isupper(*rp) ? tolower(*rp) : *rp;
 221                         if (ch != *sp++) {
 222                                 rp = j_fail;
 223                                 sp = sp_fail;
 224                                 return (TRUE);
 225                         }
 226                         rp++;
 227                         break;
 228                 case SOT:
 229                         if (sp != s)
 230                                 return (FALSE);
 231                         rp++;
 232                         break;
 233                 case EOT:
 234                         if (*sp != 0)
 235                                 return (FALSE);
 236                         rp++;
 237                         break;
 238                 case GRP_S:
 239                         rp++;
 240                         grp_end = rxpbuf + *rp++;
 241                         break;
 242                 case ALT_S:
 243                         rp++;
 244                         if ((err = rxp__match(sp,
 245                             FALSE, grp_end, rxpbuf + *rp++, sp)) != TRUE)
 246                                 return (err);
 247                         break;
 248                 case ALT_E:
 249                         rp = j_succ;
 250                         return (TRUE);
 251                 case GRP_E:
 252                 default:
 253                         return (FALSE);
 254                 }
 255         return (*rp != END ? FALSE : TRUE);
 256 }
 257
 258 /*
 259  * Reverse engineer the regular expression, by picking first of all alternates.
 260  */
 261 char *
 262 rxp_expand()
 263 {
 264         return (rxp__expand(TRUE));
 265 }
 266
 267 static char *
 268 rxp__expand(first)
 269         int first;
 270 {
 271         static char buf[RXP_LINE_SZ/2];
 272         static Rxp_t *rp;
 273         static char *bp;
 274         Rxp_t *grp_ptr;
 275         char *err;
 276
 277         if (first) {
 278                 rp = rxpbuf;
 279                 bp = buf;
 280         }
 281         while (rp < rxpbuf + RXP_LINE_SZ && *rp != END)
 282                 switch(*rp) {
 283                 case LIT:
 284                         rp++;
 285                         *bp++ = *rp++;
 286                         break;
 287                 case GRP_S:
 288                         rp++;
 289                         grp_ptr = rxpbuf + *rp;
 290                         rp++;
 291                         if ((err = rxp__expand(FALSE)) == NULL)
 292                                 return (err);
 293                         rp = grp_ptr;
 294                         break;
 295                 case ALT_E:
 296                         return (buf);
 297                 case ALT_S:
 298                         rp++;
 299                         /* FALLTHROUGH */
 300                 case SOT:
 301                 case EOT:
 302                 case GRP_E:
 303                         rp++;
 304                         break;
 305                 default:
 306                         return (NULL);
 307                 }
 308         if (first) {
 309                 if (*rp != END)
 310                         return (NULL);
 311                 *bp = '\0';
 312         }
 313         return (buf);
 314 }