Commit | Line | Data |
---|---|---|
189d0003 C |
1 | /* |
2 | * regcomp and regexec -- regsub and regerror are elsewhere | |
3 | * | |
4 | * Copyright (c) 1986 by University of Toronto. | |
5 | * Written by Henry Spencer. Not derived from licensed software. | |
6 | * | |
7 | * Permission is granted to anyone to use this software for any | |
8 | * purpose on any computer system, and to redistribute it freely, | |
9 | * subject to the following restrictions: | |
10 | * | |
11 | * 1. The author is not responsible for the consequences of use of | |
12 | * this software, no matter how awful, even if they arise | |
13 | * from defects in it. | |
14 | * | |
15 | * 2. The origin of this software must not be misrepresented, either | |
16 | * by explicit claim or by omission. | |
17 | * | |
18 | * 3. Altered versions must be plainly marked as such, and must not | |
19 | * be misrepresented as being the original software. | |
20 | *** THIS IS AN ALTERED VERSION. It was altered by John Gilmore, | |
21 | *** hoptoad!gnu, on 27 Dec 1986, to add \n as an alternative to | | |
22 | *** to assist in implementing egrep. | |
23 | *** THIS IS AN ALTERED VERSION. It was altered by John Gilmore, | |
24 | *** hoptoad!gnu, on 27 Dec 1986, to add \< and \> for word-matching | |
25 | *** as in BSD grep and ex. | |
26 | *** THIS IS AN ALTERED VERSION. It was altered by John Gilmore, | |
27 | *** hoptoad!gnu, on 28 Dec 1986, to optimize characters quoted with \. | |
28 | *** THIS IS AN ALTERED VERSION. It was altered by James A. Woods, | |
29 | *** ames!jaw, on 19 June 1987, to quash a regcomp() redundancy. | |
30 | * | |
31 | * Beware that some of this code is subtly aware of the way operator | |
32 | * precedence is structured in regular expressions. Serious changes in | |
33 | * regular-expression syntax might require a total rethink. | |
34 | */ | |
35 | #include <stdio.h> | |
36 | #include <ctype.h> | |
37 | #include <regexp.h> | |
38 | #include "regmagic.h" | |
39 | ||
40 | /* | |
41 | * The "internal use only" fields in regexp.h are present to pass info from | |
42 | * compile to execute that permits the execute phase to run lots faster on | |
43 | * simple cases. They are: | |
44 | * | |
45 | * regstart char that must begin a match; '\0' if none obvious | |
46 | * reganch is the match anchored (at beginning-of-line only)? | |
47 | * regmust string (pointer into program) that match must include, or NULL | |
48 | * regmlen length of regmust string | |
49 | * | |
50 | * Regstart and reganch permit very fast decisions on suitable starting points | |
51 | * for a match, cutting down the work a lot. Regmust permits fast rejection | |
52 | * of lines that cannot possibly match. The regmust tests are costly enough | |
53 | * that regcomp() supplies a regmust only if the r.e. contains something | |
54 | * potentially expensive (at present, the only such thing detected is * or + | |
55 | * at the start of the r.e., which can involve a lot of backup). Regmlen is | |
56 | * supplied because the test in regexec() needs it and regcomp() is computing | |
57 | * it anyway. | |
58 | */ | |
59 | ||
60 | /* | |
61 | * Structure for regexp "program". This is essentially a linear encoding | |
62 | * of a nondeterministic finite-state machine (aka syntax charts or | |
63 | * "railroad normal form" in parsing technology). Each node is an opcode | |
64 | * plus a "next" pointer, possibly plus an operand. "Next" pointers of | |
65 | * all nodes except BRANCH implement concatenation; a "next" pointer with | |
66 | * a BRANCH on both ends of it is connecting two alternatives. (Here we | |
67 | * have one of the subtle syntax dependencies: an individual BRANCH (as | |
68 | * opposed to a collection of them) is never concatenated with anything | |
69 | * because of operator precedence.) The operand of some types of node is | |
70 | * a literal string; for others, it is a node leading into a sub-FSM. In | |
71 | * particular, the operand of a BRANCH node is the first node of the branch. | |
72 | * (NB this is *not* a tree structure: the tail of the branch connects | |
73 | * to the thing following the set of BRANCHes.) The opcodes are: | |
74 | */ | |
75 | ||
76 | /* definition number opnd? meaning */ | |
77 | #define END 0 /* no End of program. */ | |
78 | #define BOL 1 /* no Match "" at beginning of line. */ | |
79 | #define EOL 2 /* no Match "" at end of line. */ | |
80 | #define ANY 3 /* no Match any one character. */ | |
81 | #define ANYOF 4 /* str Match any character in this string. */ | |
82 | #define ANYBUT 5 /* str Match any character not in this string. */ | |
83 | #define BRANCH 6 /* node Match this alternative, or the next... */ | |
84 | #define BACK 7 /* no Match "", "next" ptr points backward. */ | |
85 | #define EXACTLY 8 /* str Match this string. */ | |
86 | #define NOTHING 9 /* no Match empty string. */ | |
87 | #define STAR 10 /* node Match this (simple) thing 0 or more times. */ | |
88 | #define PLUS 11 /* node Match this (simple) thing 1 or more times. */ | |
89 | #define WORDA 12 /* no Match "" at wordchar, where prev is nonword */ | |
90 | #define WORDZ 13 /* no Match "" at nonwordchar, where prev is word */ | |
91 | #define OPEN 20 /* no Mark this point in input as start of #n. */ | |
92 | /* OPEN+1 is number 1, etc. */ | |
93 | #define CLOSE 30 /* no Analogous to OPEN. */ | |
94 | ||
95 | /* | |
96 | * Opcode notes: | |
97 | * | |
98 | * BRANCH The set of branches constituting a single choice are hooked | |
99 | * together with their "next" pointers, since precedence prevents | |
100 | * anything being concatenated to any individual branch. The | |
101 | * "next" pointer of the last BRANCH in a choice points to the | |
102 | * thing following the whole choice. This is also where the | |
103 | * final "next" pointer of each individual branch points; each | |
104 | * branch starts with the operand node of a BRANCH node. | |
105 | * | |
106 | * BACK Normal "next" pointers all implicitly point forward; BACK | |
107 | * exists to make loop structures possible. | |
108 | * | |
109 | * STAR,PLUS '?', and complex '*' and '+', are implemented as circular | |
110 | * BRANCH structures using BACK. Simple cases (one character | |
111 | * per match) are implemented with STAR and PLUS for speed | |
112 | * and to minimize recursive plunges. | |
113 | * | |
114 | * OPEN,CLOSE ...are numbered at compile time. | |
115 | */ | |
116 | ||
117 | /* | |
118 | * A node is one char of opcode followed by two chars of "next" pointer. | |
119 | * "Next" pointers are stored as two 8-bit pieces, high order first. The | |
120 | * value is a positive offset from the opcode of the node containing it. | |
121 | * An operand, if any, simply follows the node. (Note that much of the | |
122 | * code generation knows about this implicit relationship.) | |
123 | * | |
124 | * Using two bytes for the "next" pointer is vast overkill for most things, | |
125 | * but allows patterns to get big without disasters. | |
126 | */ | |
127 | #define OP(p) (*(p)) | |
128 | #define NEXT(p) (((*((p)+1)&0377)<<8) + (*((p)+2)&0377)) | |
129 | #define OPERAND(p) ((p) + 3) | |
130 | ||
131 | /* | |
132 | * See regmagic.h for one further detail of program structure. | |
133 | */ | |
134 | ||
135 | ||
136 | /* | |
137 | * Utility definitions. | |
138 | */ | |
139 | #ifndef CHARBITS | |
140 | #define UCHARAT(p) ((int)*(unsigned char *)(p)) | |
141 | #else | |
142 | #define UCHARAT(p) ((int)*(p)&CHARBITS) | |
143 | #endif | |
144 | ||
145 | #define FAIL(m) { regerror(m); return(NULL); } | |
146 | #define ISMULT(c) ((c) == '*' || (c) == '+' || (c) == '?') | |
147 | ||
148 | /* | |
149 | * Flags to be passed up and down. | |
150 | */ | |
151 | #define HASWIDTH 01 /* Known never to match null string. */ | |
152 | #define SIMPLE 02 /* Simple enough to be STAR/PLUS operand. */ | |
153 | #define SPSTART 04 /* Starts with * or +. */ | |
154 | #define WORST 0 /* Worst case. */ | |
155 | ||
156 | /* | |
157 | * Global work variables for regcomp(). | |
158 | */ | |
159 | static char *regparse; /* Input-scan pointer. */ | |
160 | static int regnpar; /* () count. */ | |
161 | static char regdummy; | |
162 | static char *regcode; /* Code-emit pointer; ®dummy = don't. */ | |
163 | static long regsize; /* Code size. */ | |
164 | ||
165 | /* | |
166 | * Forward declarations for regcomp()'s friends. | |
167 | */ | |
168 | #ifndef STATIC | |
169 | #define STATIC static | |
170 | #endif | |
171 | STATIC char *reg(); | |
172 | STATIC char *regbranch(); | |
173 | STATIC char *regpiece(); | |
174 | STATIC char *regatom(); | |
175 | STATIC char *regnode(); | |
176 | STATIC char *regnext(); | |
177 | STATIC void regc(); | |
178 | STATIC void reginsert(); | |
179 | STATIC void regtail(); | |
180 | STATIC void regoptail(); | |
181 | #ifdef STRCSPN | |
182 | STATIC int strcspn(); | |
183 | #endif | |
184 | ||
185 | /* | |
186 | - regcomp - compile a regular expression into internal code | |
187 | * | |
188 | * We can't allocate space until we know how big the compiled form will be, | |
189 | * but we can't compile it (and thus know how big it is) until we've got a | |
190 | * place to put the code. So we cheat: we compile it twice, once with code | |
191 | * generation turned off and size counting turned on, and once "for real". | |
192 | * This also means that we don't allocate space until we are sure that the | |
193 | * thing really will compile successfully, and we never have to move the | |
194 | * code and thus invalidate pointers into it. (Note that it has to be in | |
195 | * one piece because free() must be able to free it all.) | |
196 | * | |
197 | * Beware that the optimization-preparation code in here knows about some | |
198 | * of the structure of the compiled regexp. | |
199 | */ | |
200 | regexp * | |
201 | regcomp(exp) | |
202 | char *exp; | |
203 | { | |
204 | register regexp *r; | |
205 | register char *scan; | |
206 | register char *longest; | |
207 | register int len; | |
208 | int flags; | |
209 | extern char *malloc(); | |
210 | ||
211 | if (exp == NULL) | |
212 | FAIL("NULL argument"); | |
213 | ||
214 | /* First pass: determine size, legality. */ | |
215 | if (exp[0] == '.' && exp[1] == '*') exp += 2; /* aid grep */ | |
216 | regparse = exp; | |
217 | regnpar = 1; | |
218 | regsize = 0L; | |
219 | regcode = ®dummy; | |
220 | regc(MAGIC); | |
221 | if (reg(0, &flags) == NULL) | |
222 | return(NULL); | |
223 | ||
224 | /* Small enough for pointer-storage convention? */ | |
225 | if (regsize >= 32767L) /* Probably could be 65535L. */ | |
226 | FAIL("regexp too big"); | |
227 | ||
228 | /* Allocate space. */ | |
229 | r = (regexp *)malloc(sizeof(regexp) + (unsigned)regsize); | |
230 | if (r == NULL) | |
231 | FAIL("out of space"); | |
232 | ||
233 | /* Second pass: emit code. */ | |
234 | regparse = exp; | |
235 | regnpar = 1; | |
236 | regcode = r->program; | |
237 | regc(MAGIC); | |
238 | if (reg(0, &flags) == NULL) | |
239 | return(NULL); | |
240 | ||
241 | /* Dig out information for optimizations. */ | |
242 | r->regstart = '\0'; /* Worst-case defaults. */ | |
243 | r->reganch = 0; | |
244 | r->regmust = NULL; | |
245 | r->regmlen = 0; | |
246 | scan = r->program+1; /* First BRANCH. */ | |
247 | if (OP(regnext(scan)) == END) { /* Only one top-level choice. */ | |
248 | scan = OPERAND(scan); | |
249 | ||
250 | /* Starting-point info. */ | |
251 | if (OP(scan) == EXACTLY) | |
252 | r->regstart = *OPERAND(scan); | |
253 | else if (OP(scan) == BOL) | |
254 | r->reganch++; | |
255 | ||
256 | /* | |
257 | * If there's something expensive in the r.e., find the | |
258 | * longest literal string that must appear and make it the | |
259 | * regmust. Resolve ties in favor of later strings, since | |
260 | * the regstart check works with the beginning of the r.e. | |
261 | * and avoiding duplication strengthens checking. Not a | |
262 | * strong reason, but sufficient in the absence of others. | |
263 | */ | |
264 | if (flags&SPSTART) { | |
265 | longest = NULL; | |
266 | len = 0; | |
267 | for (; scan != NULL; scan = regnext(scan)) | |
268 | if (OP(scan) == EXACTLY && strlen(OPERAND(scan)) >= len) { | |
269 | longest = OPERAND(scan); | |
270 | len = strlen(OPERAND(scan)); | |
271 | } | |
272 | r->regmust = longest; | |
273 | r->regmlen = len; | |
274 | } | |
275 | } | |
276 | ||
277 | return(r); | |
278 | } | |
279 | ||
280 | /* | |
281 | - reg - regular expression, i.e. main body or parenthesized thing | |
282 | * | |
283 | * Caller must absorb opening parenthesis. | |
284 | * | |
285 | * Combining parenthesis handling with the base level of regular expression | |
286 | * is a trifle forced, but the need to tie the tails of the branches to what | |
287 | * follows makes it hard to avoid. | |
288 | */ | |
289 | static char * | |
290 | reg(paren, flagp) | |
291 | int paren; /* Parenthesized? */ | |
292 | int *flagp; | |
293 | { | |
294 | register char *ret; | |
295 | register char *br; | |
296 | register char *ender; | |
297 | register int parno; | |
298 | int flags; | |
299 | ||
300 | *flagp = HASWIDTH; /* Tentatively. */ | |
301 | ||
302 | /* Make an OPEN node, if parenthesized. */ | |
303 | if (paren) { | |
304 | if (regnpar >= NSUBEXP) | |
305 | FAIL("too many ()"); | |
306 | parno = regnpar; | |
307 | regnpar++; | |
308 | ret = regnode(OPEN+parno); | |
309 | } else | |
310 | ret = NULL; | |
311 | ||
312 | /* Pick up the branches, linking them together. */ | |
313 | br = regbranch(&flags); | |
314 | if (br == NULL) | |
315 | return(NULL); | |
316 | if (ret != NULL) | |
317 | regtail(ret, br); /* OPEN -> first. */ | |
318 | else | |
319 | ret = br; | |
320 | if (!(flags&HASWIDTH)) | |
321 | *flagp &= ~HASWIDTH; | |
322 | *flagp |= flags&SPSTART; | |
323 | while (*regparse == '|' || *regparse == '\n') { | |
324 | regparse++; | |
325 | br = regbranch(&flags); | |
326 | if (br == NULL) | |
327 | return(NULL); | |
328 | regtail(ret, br); /* BRANCH -> BRANCH. */ | |
329 | if (!(flags&HASWIDTH)) | |
330 | *flagp &= ~HASWIDTH; | |
331 | *flagp |= flags&SPSTART; | |
332 | } | |
333 | ||
334 | /* Make a closing node, and hook it on the end. */ | |
335 | ender = regnode((paren) ? CLOSE+parno : END); | |
336 | regtail(ret, ender); | |
337 | ||
338 | /* Hook the tails of the branches to the closing node. */ | |
339 | for (br = ret; br != NULL; br = regnext(br)) | |
340 | regoptail(br, ender); | |
341 | ||
342 | /* Check for proper termination. */ | |
343 | if (paren && *regparse++ != ')') { | |
344 | FAIL("unmatched ()"); | |
345 | } else if (!paren && *regparse != '\0') { | |
346 | if (*regparse == ')') { | |
347 | FAIL("unmatched ()"); | |
348 | } else | |
349 | FAIL("junk on end"); /* "Can't happen". */ | |
350 | /* NOTREACHED */ | |
351 | } | |
352 | ||
353 | return(ret); | |
354 | } | |
355 | ||
356 | /* | |
357 | - regbranch - one alternative of an | operator | |
358 | * | |
359 | * Implements the concatenation operator. | |
360 | */ | |
361 | static char * | |
362 | regbranch(flagp) | |
363 | int *flagp; | |
364 | { | |
365 | register char *ret; | |
366 | register char *chain; | |
367 | register char *latest; | |
368 | int flags; | |
369 | ||
370 | *flagp = WORST; /* Tentatively. */ | |
371 | ||
372 | ret = regnode(BRANCH); | |
373 | chain = NULL; | |
374 | while (*regparse != '\0' && *regparse != ')' && | |
375 | *regparse != '\n' && *regparse != '|') { | |
376 | latest = regpiece(&flags); | |
377 | if (latest == NULL) | |
378 | return(NULL); | |
379 | *flagp |= flags&HASWIDTH; | |
380 | if (chain == NULL) /* First piece. */ | |
381 | *flagp |= flags&SPSTART; | |
382 | else | |
383 | regtail(chain, latest); | |
384 | chain = latest; | |
385 | } | |
386 | if (chain == NULL) /* Loop ran zero times. */ | |
387 | (void) regnode(NOTHING); | |
388 | ||
389 | return(ret); | |
390 | } | |
391 | ||
392 | /* | |
393 | - regpiece - something followed by possible [*+?] | |
394 | * | |
395 | * Note that the branching code sequences used for ? and the general cases | |
396 | * of * and + are somewhat optimized: they use the same NOTHING node as | |
397 | * both the endmarker for their branch list and the body of the last branch. | |
398 | * It might seem that this node could be dispensed with entirely, but the | |
399 | * endmarker role is not redundant. | |
400 | */ | |
401 | static char * | |
402 | regpiece(flagp) | |
403 | int *flagp; | |
404 | { | |
405 | register char *ret; | |
406 | register char op; | |
407 | register char *next; | |
408 | int flags; | |
409 | ||
410 | ret = regatom(&flags); | |
411 | if (ret == NULL) | |
412 | return(NULL); | |
413 | ||
414 | op = *regparse; | |
415 | if (!ISMULT(op)) { | |
416 | *flagp = flags; | |
417 | return(ret); | |
418 | } | |
419 | ||
420 | if (!(flags&HASWIDTH) && op != '?') | |
421 | FAIL("*+ operand could be empty"); | |
422 | *flagp = (op != '+') ? (WORST|SPSTART) : (WORST|HASWIDTH); | |
423 | ||
424 | if (op == '*' && (flags&SIMPLE)) | |
425 | reginsert(STAR, ret); | |
426 | else if (op == '*') { | |
427 | /* Emit x* as (x&|), where & means "self". */ | |
428 | reginsert(BRANCH, ret); /* Either x */ | |
429 | regoptail(ret, regnode(BACK)); /* and loop */ | |
430 | regoptail(ret, ret); /* back */ | |
431 | regtail(ret, regnode(BRANCH)); /* or */ | |
432 | regtail(ret, regnode(NOTHING)); /* null. */ | |
433 | } else if (op == '+' && (flags&SIMPLE)) | |
434 | reginsert(PLUS, ret); | |
435 | else if (op == '+') { | |
436 | /* Emit x+ as x(&|), where & means "self". */ | |
437 | next = regnode(BRANCH); /* Either */ | |
438 | regtail(ret, next); | |
439 | regtail(regnode(BACK), ret); /* loop back */ | |
440 | regtail(next, regnode(BRANCH)); /* or */ | |
441 | regtail(ret, regnode(NOTHING)); /* null. */ | |
442 | } else if (op == '?') { | |
443 | /* Emit x? as (x|) */ | |
444 | reginsert(BRANCH, ret); /* Either x */ | |
445 | regtail(ret, regnode(BRANCH)); /* or */ | |
446 | next = regnode(NOTHING); /* null. */ | |
447 | regtail(ret, next); | |
448 | regoptail(ret, next); | |
449 | } | |
450 | regparse++; | |
451 | if (ISMULT(*regparse)) | |
452 | FAIL("nested *?+"); | |
453 | ||
454 | return(ret); | |
455 | } | |
456 | ||
457 | /* | |
458 | - regatom - the lowest level | |
459 | * | |
460 | * Optimization: gobbles an entire sequence of ordinary characters so that | |
461 | * it can turn them into a single node, which is smaller to store and | |
462 | * faster to run. Backslashed characters are exceptions, each becoming a | |
463 | * separate node; the code is simpler that way and it's not worth fixing. | |
464 | */ | |
465 | static char * | |
466 | regatom(flagp) | |
467 | int *flagp; | |
468 | { | |
469 | register char *ret; | |
470 | int flags; | |
471 | ||
472 | *flagp = WORST; /* Tentatively. */ | |
473 | ||
474 | switch (*regparse++) { | |
475 | /* FIXME: these chars only have meaning at beg/end of pat? */ | |
476 | case '^': | |
477 | ret = regnode(BOL); | |
478 | break; | |
479 | case '$': | |
480 | ret = regnode(EOL); | |
481 | break; | |
482 | case '.': | |
483 | ret = regnode(ANY); | |
484 | *flagp |= HASWIDTH|SIMPLE; | |
485 | break; | |
486 | case '[': { | |
487 | register int class; | |
488 | register int classend; | |
489 | ||
490 | if (*regparse == '^') { /* Complement of range. */ | |
491 | ret = regnode(ANYBUT); | |
492 | regparse++; | |
493 | } else | |
494 | ret = regnode(ANYOF); | |
495 | if (*regparse == ']' || *regparse == '-') | |
496 | regc(*regparse++); | |
497 | while (*regparse != '\0' && *regparse != ']') { | |
498 | if (*regparse == '-') { | |
499 | regparse++; | |
500 | if (*regparse == ']' || *regparse == '\0') | |
501 | regc('-'); | |
502 | else { | |
503 | class = UCHARAT(regparse-2)+1; | |
504 | classend = UCHARAT(regparse); | |
505 | if (class > classend+1) | |
506 | FAIL("invalid [] range"); | |
507 | for (; class <= classend; class++) | |
508 | regc(class); | |
509 | regparse++; | |
510 | } | |
511 | } else | |
512 | regc(*regparse++); | |
513 | } | |
514 | regc('\0'); | |
515 | if (*regparse != ']') | |
516 | FAIL("unmatched []"); | |
517 | regparse++; | |
518 | *flagp |= HASWIDTH|SIMPLE; | |
519 | } | |
520 | break; | |
521 | case '(': | |
522 | ret = reg(1, &flags); | |
523 | if (ret == NULL) | |
524 | return(NULL); | |
525 | *flagp |= flags&(HASWIDTH|SPSTART); | |
526 | break; | |
527 | case '\0': | |
528 | case '|': | |
529 | case '\n': | |
530 | case ')': | |
531 | FAIL("internal urp"); /* Supposed to be caught earlier. */ | |
532 | break; | |
533 | case '?': | |
534 | case '+': | |
535 | case '*': | |
536 | FAIL("?+* follows nothing"); | |
537 | break; | |
538 | case '\\': | |
539 | switch (*regparse++) { | |
540 | case '\0': | |
541 | FAIL("trailing \\"); | |
542 | break; | |
543 | case '<': | |
544 | ret = regnode(WORDA); | |
545 | break; | |
546 | case '>': | |
547 | ret = regnode(WORDZ); | |
548 | break; | |
549 | /* FIXME: Someday handle \1, \2, ... */ | |
550 | default: | |
551 | /* Handle general quoted chars in exact-match routine */ | |
552 | goto de_fault; | |
553 | } | |
554 | break; | |
555 | de_fault: | |
556 | default: | |
557 | /* | |
558 | * Encode a string of characters to be matched exactly. | |
559 | * | |
560 | * This is a bit tricky due to quoted chars and due to | |
561 | * '*', '+', and '?' taking the SINGLE char previous | |
562 | * as their operand. | |
563 | * | |
564 | * On entry, the char at regparse[-1] is going to go | |
565 | * into the string, no matter what it is. (It could be | |
566 | * following a \ if we are entered from the '\' case.) | |
567 | * | |
568 | * Basic idea is to pick up a good char in ch and | |
569 | * examine the next char. If it's *+? then we twiddle. | |
570 | * If it's \ then we frozzle. If it's other magic char | |
571 | * we push ch and terminate the string. If none of the | |
572 | * above, we push ch on the string and go around again. | |
573 | * | |
574 | * regprev is used to remember where "the current char" | |
575 | * starts in the string, if due to a *+? we need to back | |
576 | * up and put the current char in a separate, 1-char, string. | |
577 | * When regprev is NULL, ch is the only char in the | |
578 | * string; this is used in *+? handling, and in setting | |
579 | * flags |= SIMPLE at the end. | |
580 | */ | |
581 | { | |
582 | char *regprev; | |
583 | register char ch; | |
584 | ||
585 | regparse--; /* Look at cur char */ | |
586 | ret = regnode(EXACTLY); | |
587 | for ( regprev = 0 ; ; ) { | |
588 | ch = *regparse++; /* Get current char */ | |
589 | switch (*regparse) { /* look at next one */ | |
590 | ||
591 | default: | |
592 | regc(ch); /* Add cur to string */ | |
593 | break; | |
594 | ||
595 | case '.': case '[': case '(': | |
596 | case ')': case '|': case '\n': | |
597 | case '$': case '^': | |
598 | case '\0': | |
599 | /* FIXME, $ and ^ should not always be magic */ | |
600 | magic: | |
601 | regc(ch); /* dump cur char */ | |
602 | goto done; /* and we are done */ | |
603 | ||
604 | case '?': case '+': case '*': | |
605 | if (!regprev) /* If just ch in str, */ | |
606 | goto magic; /* use it */ | |
607 | /* End mult-char string one early */ | |
608 | regparse = regprev; /* Back up parse */ | |
609 | goto done; | |
610 | ||
611 | case '\\': | |
612 | regc(ch); /* Cur char OK */ | |
613 | switch (regparse[1]){ /* Look after \ */ | |
614 | case '\0': | |
615 | case '<': | |
616 | case '>': | |
617 | /* FIXME: Someday handle \1, \2, ... */ | |
618 | goto done; /* Not quoted */ | |
619 | default: | |
620 | /* Backup point is \, scan * point is after it. */ | |
621 | regprev = regparse; | |
622 | regparse++; | |
623 | continue; /* NOT break; */ | |
624 | } | |
625 | } | |
626 | regprev = regparse; /* Set backup point */ | |
627 | } | |
628 | done: | |
629 | regc('\0'); | |
630 | *flagp |= HASWIDTH; | |
631 | if (!regprev) /* One char? */ | |
632 | *flagp |= SIMPLE; | |
633 | } | |
634 | break; | |
635 | } | |
636 | ||
637 | return(ret); | |
638 | } | |
639 | ||
640 | /* | |
641 | - regnode - emit a node | |
642 | */ | |
643 | static char * /* Location. */ | |
644 | regnode(op) | |
645 | char op; | |
646 | { | |
647 | register char *ret; | |
648 | register char *ptr; | |
649 | ||
650 | ret = regcode; | |
651 | if (ret == ®dummy) { | |
652 | regsize += 3; | |
653 | return(ret); | |
654 | } | |
655 | ||
656 | ptr = ret; | |
657 | *ptr++ = op; | |
658 | *ptr++ = '\0'; /* Null "next" pointer. */ | |
659 | *ptr++ = '\0'; | |
660 | regcode = ptr; | |
661 | ||
662 | return(ret); | |
663 | } | |
664 | ||
665 | /* | |
666 | - regc - emit (if appropriate) a byte of code | |
667 | */ | |
668 | static void | |
669 | regc(b) | |
670 | char b; | |
671 | { | |
672 | if (regcode != ®dummy) | |
673 | *regcode++ = b; | |
674 | else | |
675 | regsize++; | |
676 | } | |
677 | ||
678 | /* | |
679 | - reginsert - insert an operator in front of already-emitted operand | |
680 | * | |
681 | * Means relocating the operand. | |
682 | */ | |
683 | static void | |
684 | reginsert(op, opnd) | |
685 | char op; | |
686 | char *opnd; | |
687 | { | |
688 | register char *src; | |
689 | register char *dst; | |
690 | register char *place; | |
691 | ||
692 | if (regcode == ®dummy) { | |
693 | regsize += 3; | |
694 | return; | |
695 | } | |
696 | ||
697 | src = regcode; | |
698 | regcode += 3; | |
699 | dst = regcode; | |
700 | while (src > opnd) | |
701 | *--dst = *--src; | |
702 | ||
703 | place = opnd; /* Op node, where operand used to be. */ | |
704 | *place++ = op; | |
705 | *place++ = '\0'; | |
706 | *place++ = '\0'; | |
707 | } | |
708 | ||
709 | /* | |
710 | - regtail - set the next-pointer at the end of a node chain | |
711 | */ | |
712 | static void | |
713 | regtail(p, val) | |
714 | char *p; | |
715 | char *val; | |
716 | { | |
717 | register char *scan; | |
718 | register char *temp; | |
719 | register int offset; | |
720 | ||
721 | if (p == ®dummy) | |
722 | return; | |
723 | ||
724 | /* Find last node. */ | |
725 | scan = p; | |
726 | for (;;) { | |
727 | temp = regnext(scan); | |
728 | if (temp == NULL) | |
729 | break; | |
730 | scan = temp; | |
731 | } | |
732 | ||
733 | if (OP(scan) == BACK) | |
734 | offset = scan - val; | |
735 | else | |
736 | offset = val - scan; | |
737 | *(scan+1) = (offset>>8)&0377; | |
738 | *(scan+2) = offset&0377; | |
739 | } | |
740 | ||
741 | /* | |
742 | - regoptail - regtail on operand of first argument; nop if operandless | |
743 | */ | |
744 | static void | |
745 | regoptail(p, val) | |
746 | char *p; | |
747 | char *val; | |
748 | { | |
749 | /* "Operandless" and "op != BRANCH" are synonymous in practice. */ | |
750 | if (p == NULL || p == ®dummy || OP(p) != BRANCH) | |
751 | return; | |
752 | regtail(OPERAND(p), val); | |
753 | } | |
754 | ||
755 | /* | |
756 | * regexec and friends | |
757 | */ | |
758 | ||
759 | /* | |
760 | * Global work variables for regexec(). | |
761 | */ | |
762 | static char *reginput; /* String-input pointer. */ | |
763 | static char *regbol; /* Beginning of input, for ^ check. */ | |
764 | static char **regstartp; /* Pointer to startp array. */ | |
765 | static char **regendp; /* Ditto for endp. */ | |
766 | ||
767 | /* | |
768 | * Forwards. | |
769 | */ | |
770 | STATIC int regtry(); | |
771 | STATIC int regmatch(); | |
772 | STATIC int regrepeat(); | |
773 | ||
774 | #ifdef DEBUG | |
775 | int regnarrate = 0; | |
776 | void regdump(); | |
777 | STATIC char *regprop(); | |
778 | #endif | |
779 | ||
780 | /* | |
781 | - regexec - match a regexp against a string | |
782 | */ | |
783 | int | |
784 | regexec(prog, string) | |
785 | register regexp *prog; | |
786 | register char *string; | |
787 | { | |
788 | register char *s; | |
789 | extern char *strchr(); | |
790 | ||
791 | /* Be paranoid... */ | |
792 | if (prog == NULL || string == NULL) { | |
793 | regerror("NULL parameter"); | |
794 | return(0); | |
795 | } | |
796 | ||
797 | /* Check validity of program. */ | |
798 | if (UCHARAT(prog->program) != MAGIC) { | |
799 | regerror("corrupted program"); | |
800 | return(0); | |
801 | } | |
802 | ||
803 | /* If there is a "must appear" string, look for it. */ | |
804 | if (prog->regmust != NULL) { | |
805 | s = string; | |
806 | while ((s = strchr(s, prog->regmust[0])) != NULL) { | |
807 | if (strncmp(s, prog->regmust, prog->regmlen) == 0) | |
808 | break; /* Found it. */ | |
809 | s++; | |
810 | } | |
811 | if (s == NULL) /* Not present. */ | |
812 | return(0); | |
813 | } | |
814 | ||
815 | /* Mark beginning of line for ^ . */ | |
816 | regbol = string; | |
817 | ||
818 | /* Simplest case: anchored match need be tried only once. */ | |
819 | if (prog->reganch) | |
820 | return(regtry(prog, string)); | |
821 | ||
822 | /* Messy cases: unanchored match. */ | |
823 | s = string; | |
824 | if (prog->regstart != '\0') | |
825 | /* We know what char it must start with. */ | |
826 | while ((s = strchr(s, prog->regstart)) != NULL) { | |
827 | if (regtry(prog, s)) | |
828 | return(1); | |
829 | s++; | |
830 | } | |
831 | else | |
832 | /* We don't -- general case. */ | |
833 | do { | |
834 | if (regtry(prog, s)) | |
835 | return(1); | |
836 | } while (*s++ != '\0'); | |
837 | ||
838 | /* Failure. */ | |
839 | return(0); | |
840 | } | |
841 | ||
842 | /* | |
843 | - regtry - try match at specific point | |
844 | */ | |
845 | static int /* 0 failure, 1 success */ | |
846 | regtry(prog, string) | |
847 | regexp *prog; | |
848 | char *string; | |
849 | { | |
850 | register int i; | |
851 | register char **sp; | |
852 | register char **ep; | |
853 | ||
854 | reginput = string; | |
855 | regstartp = prog->startp; | |
856 | regendp = prog->endp; | |
857 | ||
858 | sp = prog->startp; | |
859 | ep = prog->endp; | |
860 | for (i = NSUBEXP; i > 0; i--) { | |
861 | *sp++ = NULL; | |
862 | *ep++ = NULL; | |
863 | } | |
864 | if (regmatch(prog->program + 1)) { | |
865 | prog->startp[0] = string; | |
866 | prog->endp[0] = reginput; | |
867 | return(1); | |
868 | } else | |
869 | return(0); | |
870 | } | |
871 | ||
872 | /* | |
873 | - regmatch - main matching routine | |
874 | * | |
875 | * Conceptually the strategy is simple: check to see whether the current | |
876 | * node matches, call self recursively to see whether the rest matches, | |
877 | * and then act accordingly. In practice we make some effort to avoid | |
878 | * recursion, in particular by going through "ordinary" nodes (that don't | |
879 | * need to know whether the rest of the match failed) by a loop instead of | |
880 | * by recursion. | |
881 | */ | |
882 | static int /* 0 failure, 1 success */ | |
883 | regmatch(prog) | |
884 | char *prog; | |
885 | { | |
886 | register char *scan; /* Current node. */ | |
887 | char *next; /* Next node. */ | |
888 | extern char *strchr(); | |
889 | ||
890 | scan = prog; | |
891 | #ifdef DEBUG | |
892 | if (scan != NULL && regnarrate) | |
893 | fprintf(stderr, "%s(\n", regprop(scan)); | |
894 | #endif | |
895 | while (scan != NULL) { | |
896 | #ifdef DEBUG | |
897 | if (regnarrate) | |
898 | fprintf(stderr, "%s...\n", regprop(scan)); | |
899 | #endif | |
900 | next = regnext(scan); | |
901 | ||
902 | switch (OP(scan)) { | |
903 | case BOL: | |
904 | if (reginput != regbol) | |
905 | return(0); | |
906 | break; | |
907 | case EOL: | |
908 | if (*reginput != '\0') | |
909 | return(0); | |
910 | break; | |
911 | case WORDA: | |
912 | /* Must be looking at a letter, digit, or _ */ | |
913 | if ((!isalnum(*reginput)) && *reginput != '_') | |
914 | return(0); | |
915 | /* Prev must be BOL or nonword */ | |
916 | if (reginput > regbol && | |
917 | (isalnum(reginput[-1]) || reginput[-1] == '_')) | |
918 | return(0); | |
919 | break; | |
920 | case WORDZ: | |
921 | /* Must be looking at non letter, digit, or _ */ | |
922 | if (isalnum(*reginput) || *reginput == '_') | |
923 | return(0); | |
924 | /* We don't care what the previous char was */ | |
925 | break; | |
926 | case ANY: | |
927 | if (*reginput == '\0') | |
928 | return(0); | |
929 | reginput++; | |
930 | break; | |
931 | case EXACTLY: { | |
932 | register int len; | |
933 | register char *opnd; | |
934 | ||
935 | opnd = OPERAND(scan); | |
936 | /* Inline the first character, for speed. */ | |
937 | if (*opnd != *reginput) | |
938 | return(0); | |
939 | len = strlen(opnd); | |
940 | if (len > 1 && strncmp(opnd, reginput, len) != 0) | |
941 | return(0); | |
942 | reginput += len; | |
943 | } | |
944 | break; | |
945 | case ANYOF: | |
946 | if (*reginput == '\0' || strchr(OPERAND(scan), *reginput) == NULL) | |
947 | return(0); | |
948 | reginput++; | |
949 | break; | |
950 | case ANYBUT: | |
951 | if (*reginput == '\0' || strchr(OPERAND(scan), *reginput) != NULL) | |
952 | return(0); | |
953 | reginput++; | |
954 | break; | |
955 | case NOTHING: | |
956 | break; | |
957 | case BACK: | |
958 | break; | |
959 | case OPEN+1: | |
960 | case OPEN+2: | |
961 | case OPEN+3: | |
962 | case OPEN+4: | |
963 | case OPEN+5: | |
964 | case OPEN+6: | |
965 | case OPEN+7: | |
966 | case OPEN+8: | |
967 | case OPEN+9: { | |
968 | register int no; | |
969 | register char *save; | |
970 | ||
971 | no = OP(scan) - OPEN; | |
972 | save = reginput; | |
973 | ||
974 | if (regmatch(next)) { | |
975 | /* | |
976 | * Don't set startp if some later | |
977 | * invocation of the same parentheses | |
978 | * already has. | |
979 | */ | |
980 | if (regstartp[no] == NULL) | |
981 | regstartp[no] = save; | |
982 | return(1); | |
983 | } else | |
984 | return(0); | |
985 | } | |
986 | break; | |
987 | case CLOSE+1: | |
988 | case CLOSE+2: | |
989 | case CLOSE+3: | |
990 | case CLOSE+4: | |
991 | case CLOSE+5: | |
992 | case CLOSE+6: | |
993 | case CLOSE+7: | |
994 | case CLOSE+8: | |
995 | case CLOSE+9: { | |
996 | register int no; | |
997 | register char *save; | |
998 | ||
999 | no = OP(scan) - CLOSE; | |
1000 | save = reginput; | |
1001 | ||
1002 | if (regmatch(next)) { | |
1003 | /* | |
1004 | * Don't set endp if some later | |
1005 | * invocation of the same parentheses | |
1006 | * already has. | |
1007 | */ | |
1008 | if (regendp[no] == NULL) | |
1009 | regendp[no] = save; | |
1010 | return(1); | |
1011 | } else | |
1012 | return(0); | |
1013 | } | |
1014 | break; | |
1015 | case BRANCH: { | |
1016 | register char *save; | |
1017 | ||
1018 | if (OP(next) != BRANCH) /* No choice. */ | |
1019 | next = OPERAND(scan); /* Avoid recursion. */ | |
1020 | else { | |
1021 | do { | |
1022 | save = reginput; | |
1023 | if (regmatch(OPERAND(scan))) | |
1024 | return(1); | |
1025 | reginput = save; | |
1026 | scan = regnext(scan); | |
1027 | } while (scan != NULL && OP(scan) == BRANCH); | |
1028 | return(0); | |
1029 | /* NOTREACHED */ | |
1030 | } | |
1031 | } | |
1032 | break; | |
1033 | case STAR: | |
1034 | case PLUS: { | |
1035 | register char nextch; | |
1036 | register int no; | |
1037 | register char *save; | |
1038 | register int min; | |
1039 | ||
1040 | /* | |
1041 | * Lookahead to avoid useless match attempts | |
1042 | * when we know what character comes next. | |
1043 | */ | |
1044 | nextch = '\0'; | |
1045 | if (OP(next) == EXACTLY) | |
1046 | nextch = *OPERAND(next); | |
1047 | min = (OP(scan) == STAR) ? 0 : 1; | |
1048 | save = reginput; | |
1049 | no = regrepeat(OPERAND(scan)); | |
1050 | while (no >= min) { | |
1051 | /* If it could work, try it. */ | |
1052 | if (nextch == '\0' || *reginput == nextch) | |
1053 | if (regmatch(next)) | |
1054 | return(1); | |
1055 | /* Couldn't or didn't -- back up. */ | |
1056 | no--; | |
1057 | reginput = save + no; | |
1058 | } | |
1059 | return(0); | |
1060 | } | |
1061 | break; | |
1062 | case END: | |
1063 | return(1); /* Success! */ | |
1064 | break; | |
1065 | default: | |
1066 | regerror("memory corruption"); | |
1067 | return(0); | |
1068 | break; | |
1069 | } | |
1070 | ||
1071 | scan = next; | |
1072 | } | |
1073 | ||
1074 | /* | |
1075 | * We get here only if there's trouble -- normally "case END" is | |
1076 | * the terminating point. | |
1077 | */ | |
1078 | regerror("corrupted pointers"); | |
1079 | return(0); | |
1080 | } | |
1081 | ||
1082 | /* | |
1083 | - regrepeat - repeatedly match something simple, report how many | |
1084 | */ | |
1085 | static int | |
1086 | regrepeat(p) | |
1087 | char *p; | |
1088 | { | |
1089 | register int count = 0; | |
1090 | register char *scan; | |
1091 | register char *opnd; | |
1092 | ||
1093 | scan = reginput; | |
1094 | opnd = OPERAND(p); | |
1095 | switch (OP(p)) { | |
1096 | case ANY: | |
1097 | count = strlen(scan); | |
1098 | scan += count; | |
1099 | break; | |
1100 | case EXACTLY: | |
1101 | while (*opnd == *scan) { | |
1102 | count++; | |
1103 | scan++; | |
1104 | } | |
1105 | break; | |
1106 | case ANYOF: | |
1107 | while (*scan != '\0' && strchr(opnd, *scan) != NULL) { | |
1108 | count++; | |
1109 | scan++; | |
1110 | } | |
1111 | break; | |
1112 | case ANYBUT: | |
1113 | while (*scan != '\0' && strchr(opnd, *scan) == NULL) { | |
1114 | count++; | |
1115 | scan++; | |
1116 | } | |
1117 | break; | |
1118 | default: /* Oh dear. Called inappropriately. */ | |
1119 | regerror("internal foulup"); | |
1120 | count = 0; /* Best compromise. */ | |
1121 | break; | |
1122 | } | |
1123 | reginput = scan; | |
1124 | ||
1125 | return(count); | |
1126 | } | |
1127 | ||
1128 | /* | |
1129 | - regnext - dig the "next" pointer out of a node | |
1130 | */ | |
1131 | static char * | |
1132 | regnext(p) | |
1133 | register char *p; | |
1134 | { | |
1135 | register int offset; | |
1136 | ||
1137 | if (p == ®dummy) | |
1138 | return(NULL); | |
1139 | ||
1140 | offset = NEXT(p); | |
1141 | if (offset == 0) | |
1142 | return(NULL); | |
1143 | ||
1144 | if (OP(p) == BACK) | |
1145 | return(p-offset); | |
1146 | else | |
1147 | return(p+offset); | |
1148 | } | |
1149 | ||
1150 | #ifdef DEBUG | |
1151 | ||
1152 | STATIC char *regprop(); | |
1153 | ||
1154 | /* | |
1155 | - regdump - dump a regexp onto stdout in vaguely comprehensible form | |
1156 | */ | |
1157 | void | |
1158 | regdump(r) | |
1159 | regexp *r; | |
1160 | { | |
1161 | register char *s; | |
1162 | register char op = EXACTLY; /* Arbitrary non-END op. */ | |
1163 | register char *next; | |
1164 | extern char *strchr(); | |
1165 | ||
1166 | ||
1167 | s = r->program + 1; | |
1168 | while (op != END) { /* While that wasn't END last time... */ | |
1169 | op = OP(s); | |
1170 | printf("%2d%s", s-r->program, regprop(s)); /* Where, what. */ | |
1171 | next = regnext(s); | |
1172 | if (next == NULL) /* Next ptr. */ | |
1173 | printf("(0)"); | |
1174 | else | |
1175 | printf("(%d)", (s-r->program)+(next-s)); | |
1176 | s += 3; | |
1177 | if (op == ANYOF || op == ANYBUT || op == EXACTLY) { | |
1178 | /* Literal string, where present. */ | |
1179 | while (*s != '\0') { | |
1180 | putchar(*s); | |
1181 | s++; | |
1182 | } | |
1183 | s++; | |
1184 | } | |
1185 | putchar('\n'); | |
1186 | } | |
1187 | ||
1188 | /* Header fields of interest. */ | |
1189 | if (r->regstart != '\0') | |
1190 | printf("start `%c' ", r->regstart); | |
1191 | if (r->reganch) | |
1192 | printf("anchored "); | |
1193 | if (r->regmust != NULL) | |
1194 | printf("must have \"%s\"", r->regmust); | |
1195 | printf("\n"); | |
1196 | } | |
1197 | ||
1198 | /* | |
1199 | - regprop - printable representation of opcode | |
1200 | */ | |
1201 | static char * | |
1202 | regprop(op) | |
1203 | char *op; | |
1204 | { | |
1205 | register char *p; | |
1206 | static char buf[50]; | |
1207 | ||
1208 | (void) strcpy(buf, ":"); | |
1209 | ||
1210 | switch (OP(op)) { | |
1211 | case BOL: | |
1212 | p = "BOL"; | |
1213 | break; | |
1214 | case EOL: | |
1215 | p = "EOL"; | |
1216 | break; | |
1217 | case ANY: | |
1218 | p = "ANY"; | |
1219 | break; | |
1220 | case ANYOF: | |
1221 | p = "ANYOF"; | |
1222 | break; | |
1223 | case ANYBUT: | |
1224 | p = "ANYBUT"; | |
1225 | break; | |
1226 | case BRANCH: | |
1227 | p = "BRANCH"; | |
1228 | break; | |
1229 | case EXACTLY: | |
1230 | p = "EXACTLY"; | |
1231 | break; | |
1232 | case NOTHING: | |
1233 | p = "NOTHING"; | |
1234 | break; | |
1235 | case BACK: | |
1236 | p = "BACK"; | |
1237 | break; | |
1238 | case END: | |
1239 | p = "END"; | |
1240 | break; | |
1241 | case OPEN+1: | |
1242 | case OPEN+2: | |
1243 | case OPEN+3: | |
1244 | case OPEN+4: | |
1245 | case OPEN+5: | |
1246 | case OPEN+6: | |
1247 | case OPEN+7: | |
1248 | case OPEN+8: | |
1249 | case OPEN+9: | |
1250 | sprintf(buf+strlen(buf), "OPEN%d", OP(op)-OPEN); | |
1251 | p = NULL; | |
1252 | break; | |
1253 | case CLOSE+1: | |
1254 | case CLOSE+2: | |
1255 | case CLOSE+3: | |
1256 | case CLOSE+4: | |
1257 | case CLOSE+5: | |
1258 | case CLOSE+6: | |
1259 | case CLOSE+7: | |
1260 | case CLOSE+8: | |
1261 | case CLOSE+9: | |
1262 | sprintf(buf+strlen(buf), "CLOSE%d", OP(op)-CLOSE); | |
1263 | p = NULL; | |
1264 | break; | |
1265 | case STAR: | |
1266 | p = "STAR"; | |
1267 | break; | |
1268 | case PLUS: | |
1269 | p = "PLUS"; | |
1270 | break; | |
1271 | case WORDA: | |
1272 | p = "WORDA"; | |
1273 | break; | |
1274 | case WORDZ: | |
1275 | p = "WORDZ"; | |
1276 | break; | |
1277 | default: | |
1278 | regerror("corrupted opcode"); | |
1279 | break; | |
1280 | } | |
1281 | if (p != NULL) | |
1282 | (void) strcat(buf, p); | |
1283 | return(buf); | |
1284 | } | |
1285 | #endif | |
1286 | ||
1287 | /* | |
1288 | * The following is provided for those people who do not have strcspn() in | |
1289 | * their C libraries. They should get off their butts and do something | |
1290 | * about it; at least one public-domain implementation of those (highly | |
1291 | * useful) string routines has been published on Usenet. | |
1292 | */ | |
1293 | #ifdef STRCSPN | |
1294 | /* | |
1295 | * strcspn - find length of initial segment of s1 consisting entirely | |
1296 | * of characters not from s2 | |
1297 | */ | |
1298 | ||
1299 | static int | |
1300 | strcspn(s1, s2) | |
1301 | char *s1; | |
1302 | char *s2; | |
1303 | { | |
1304 | register char *scan1; | |
1305 | register char *scan2; | |
1306 | register int count; | |
1307 | ||
1308 | count = 0; | |
1309 | for (scan1 = s1; *scan1 != '\0'; scan1++) { | |
1310 | for (scan2 = s2; *scan2 != '\0';) /* ++ moved down. */ | |
1311 | if (*scan1 == *scan2++) | |
1312 | return(count); | |
1313 | count++; | |
1314 | } | |
1315 | return(count); | |
1316 | } | |
1317 | #endif |