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
  38 #ifndef lint
  39 #if 0
  40 static char sccsid[] = "@(#)rxp.c       8.1 (Berkeley) 5/31/93";
  41 #endif
  42 static const char rcsid[] =
  43  "$FreeBSD: src/games/quiz/rxp.c,v 1.5 1999/12/12 02:29:54 billf Exp $";
  44 #endif /* not lint */
  45
  46 /*
  47  * regular expression parser
  48  *
  49  * external functions and return values are:
  50  * rxp_compile(s)
  51  *      TRUE    success
  52  *      FALSE   parse failure; error message will be in char rxperr[]
  53  * metas are:
  54  *      {...}   optional pattern, equialent to [...|]
  55  *      |       alternate pattern
  56  *      [...]   pattern delimiters
  57  *
  58  * rxp_match(s)
  59  *      TRUE    string s matches compiled pattern
  60  *      FALSE   match failure or regexp error
  61  *
  62  * rxp_expand()
  63  *      char *  reverse-engineered regular expression string
  64  *      NULL    regexp error
  65  */
  66
  67 #include <stdio.h>
  68 #include <ctype.h>
  69 #include "quiz.h"
  70                                         /* regexp tokens,       arg */
  71 #define LIT     (-1)                    /* literal character,   char */
  72 #define SOT     (-2)                    /* start text anchor,   - */
  73 #define EOT     (-3)                    /* end text anchor,     - */
  74 #define GRP_S   (-4)                    /* start alternate grp, ptr_to_end */
  75 #define GRP_E   (-5)                    /* end group,           - */
  76 #define ALT_S   (-6)                    /* alternate starts,    ptr_to_next */
  77 #define ALT_E   (-7)                    /* alternate ends,      - */
  78 #define END     (-8)                    /* end of regexp,       - */
  79
  80 typedef short Rxp_t;                    /* type for regexp tokens */
  81
  82 static Rxp_t rxpbuf[RXP_LINE_SZ];       /* compiled regular expression buffer */
  83 char rxperr[128];                       /* parser error message */
  84
  85 static int       rxp__compile __P((char *, int));
  86 static char     *rxp__expand __P((int));
  87 static int       rxp__match __P((char *, int, Rxp_t *, Rxp_t *, char *));
  88
  89 int
  90 rxp_compile(s)
  91         char *  s;
  92 {
  93         return (rxp__compile(s, TRUE));
  94 }
  95
  96 static int
  97 rxp__compile(s, first)
  98         char *s;
  99         int first;
 100 {
 101         static Rxp_t *rp;
 102         static char *sp;
 103         Rxp_t *grp_ptr;
 104         Rxp_t *alt_ptr;
 105         int esc, err;
 106
 107         esc = 0;
 108         if (first) {
 109                 rp = rxpbuf;
 110                 sp = s;
 111                 *rp++ = SOT;    /* auto-anchor: pat is really ^pat$ */
 112                 *rp++ = GRP_S;  /* auto-group: ^pat$ is really ^[pat]$ */
 113                 *rp++ = 0;
 114         }
 115         *rp++ = ALT_S;
 116         alt_ptr = rp;
 117         *rp++ = 0;
 118         for (; *sp; ++sp) {
 119                 if (rp - rxpbuf >= RXP_LINE_SZ - 4) {
 120                         (void)snprintf(rxperr, sizeof(rxperr),
 121                             "regular expression too long %s", s);
 122                         return (FALSE);
 123                 }
 124                 if (*sp == ':' && !esc)
 125                         break;
 126                 if (esc) {
 127                         *rp++ = LIT;
 128                         *rp++ = *sp;
 129                         esc = 0;
 130                 }
 131                 else switch (*sp) {
 132                 case '\\':
 133                         esc = 1;
 134                         break;
 135                 case '{':
 136                 case '[':
 137                         *rp++ = GRP_S;
 138                         grp_ptr = rp;
 139                         *rp++ = 0;
 140                         sp++;
 141                         if ((err = rxp__compile(s, FALSE)) != TRUE)
 142                                 return (err);
 143                         *rp++ = GRP_E;
 144                         *grp_ptr = rp - rxpbuf;
 145                         break;
 146                 case '}':
 147                 case ']':
 148                 case '|':
 149                         *rp++ = ALT_E;
 150                         *alt_ptr = rp - rxpbuf;
 151                         if (*sp != ']') {
 152                                 *rp++ = ALT_S;
 153                                 alt_ptr = rp;
 154                                 *rp++ = 0;
 155                         }
 156                         if (*sp != '|') {
 157                                 if (*sp != ']') {
 158                                         *rp++ = ALT_E;
 159                                         *alt_ptr = rp - rxpbuf;
 160                                 }
 161                                 if (first) {
 162                                         (void)snprintf(rxperr, sizeof(rxperr),
 163                                             "unmatched alternator in regexp %s",
 164                                              s);
 165                                         return (FALSE);
 166                                 }
 167                                 return (TRUE);
 168                         }
 169                         break;
 170                 default:
 171                         *rp++ = LIT;
 172                         *rp++ = *sp;
 173                         esc = 0;
 174                         break;
 175                 }
 176         }
 177         if (!first) {
 178                 (void)snprintf(rxperr, sizeof(rxperr),
 179                     "unmatched alternator in regexp %s", s);
 180                 return (FALSE);
 181         }
 182         *rp++ = ALT_E;
 183         *alt_ptr = rp - rxpbuf;
 184         *rp++ = GRP_E;
 185         *(rxpbuf + 2) = rp - rxpbuf;
 186         *rp++ = EOT;
 187         *rp = END;
 188         return (TRUE);
 189 }
 190
 191 /*
 192  * match string against compiled regular expression
 193  */
 194 int
 195 rxp_match(s)
 196         char *  s;
 197 {
 198         return (rxp__match(s, TRUE, NULL, NULL, NULL));
 199 }
 200
 201 static int
 202 rxp__match(s, first, j_succ, j_fail, sp_fail)
 203         char *s;
 204         int first;
 205         Rxp_t *j_succ;          /* jump here on successful alt match */
 206         Rxp_t *j_fail;          /* jump here on failed match */
 207         char *sp_fail;          /* reset sp to here on failed match */
 208 {
 209         static Rxp_t *rp;
 210         static char *sp;
 211         int ch;
 212         Rxp_t *grp_end;
 213         int err;
 214
 215         grp_end = NULL;
 216         if (first) {
 217                 rp = rxpbuf;
 218                 sp = s;
 219         }
 220         while (rp < rxpbuf + RXP_LINE_SZ && *rp != END)
 221                 switch(*rp) {
 222                 case LIT:
 223                         rp++;
 224                         ch = isascii(*rp) && isupper(*rp) ? tolower(*rp) : *rp;
 225                         if (ch != *sp++) {
 226                                 rp = j_fail;
 227                                 sp = sp_fail;
 228                                 return (TRUE);
 229                         }
 230                         rp++;
 231                         break;
 232                 case SOT:
 233                         if (sp != s)
 234                                 return (FALSE);
 235                         rp++;
 236                         break;
 237                 case EOT:
 238                         if (*sp != 0)
 239                                 return (FALSE);
 240                         rp++;
 241                         break;
 242                 case GRP_S:
 243                         rp++;
 244                         grp_end = rxpbuf + *rp++;
 245                         break;
 246                 case ALT_S:
 247                         rp++;
 248                         if ((err = rxp__match(sp,
 249                             FALSE, grp_end, rxpbuf + *rp++, sp)) != TRUE)
 250                                 return (err);
 251                         break;
 252                 case ALT_E:
 253                         rp = j_succ;
 254                         return (TRUE);
 255                 case GRP_E:
 256                 default:
 257                         return (FALSE);
 258                 }
 259         return (*rp != END ? FALSE : TRUE);
 260 }
 261
 262 /*
 263  * Reverse engineer the regular expression, by picking first of all alternates.
 264  */
 265 char *
 266 rxp_expand()
 267 {
 268         return (rxp__expand(TRUE));
 269 }
 270
 271 static char *
 272 rxp__expand(first)
 273         int first;
 274 {
 275         static char buf[RXP_LINE_SZ/2];
 276         static Rxp_t *rp;
 277         static char *bp;
 278         Rxp_t *grp_ptr;
 279         char *err;
 280
 281         if (first) {
 282                 rp = rxpbuf;
 283                 bp = buf;
 284         }
 285         while (rp < rxpbuf + RXP_LINE_SZ && *rp != END)
 286                 switch(*rp) {
 287                 case LIT:
 288                         rp++;
 289                         *bp++ = *rp++;
 290                         break;
 291                 case GRP_S:
 292                         rp++;
 293                         grp_ptr = rxpbuf + *rp;
 294                         rp++;
 295                         if ((err = rxp__expand(FALSE)) == NULL)
 296                                 return (err);
 297                         rp = grp_ptr;
 298                         break;
 299                 case ALT_E:
 300                         return (buf);
 301                 case ALT_S:
 302                         rp++;
 303                         /* FALLTHROUGH */
 304                 case SOT:
 305                 case EOT:
 306                 case GRP_E:
 307                         rp++;
 308                         break;
 309                 default:
 310                         return (NULL);
 311                 }
 312         if (first) {
 313                 if (*rp != END)
 314                         return (NULL);
 315                 *bp = '\0';
 316         }
 317         return (buf);
 318 }