No longer used.
[dragonfly.git] / 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 1.3 2003/11/12 14:53:54 eirikn 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 (char *, int);
82 static char     *rxp__expand (int);
83 static int       rxp__match (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 }