1/*
2** $Id: lptree.c,v 1.22 2016/09/13 18:10:22 roberto Exp $
3** Copyright 2013, Lua.org & PUC-Rio (see 'lpeg.html' for license)
4*/
5
6#include <ctype.h>
7#include <limits.h>
8#include <string.h>
9
10
11#include "lua.h"
12#include "lauxlib.h"
13
14#include "lptypes.h"
15#include "lpcap.h"
16#include "lpcode.h"
17#include "lpprint.h"
18#include "lptree.h"
19
20
21/* number of siblings for each tree */
22const byte numsiblings[] = {
23 0, 0, 0, /* char, set, any */
24 0, 0, /* true, false */
25 1, /* rep */
26 2, 2, /* seq, choice */
27 1, 1, /* not, and */
28 0, 0, 2, 1, /* call, opencall, rule, grammar */
29 1, /* behind */
30 1, 1 /* capture, runtime capture */
31};
32
33
34static TTree *newgrammar (lua_State *L, int arg);
35
36
37/*
38** returns a reasonable name for value at index 'idx' on the stack
39*/
40static const char *val2str (lua_State *L, int idx) {
41 const char *k = lua_tostring(L, idx);
42 if (k != NULL)
43 return lua_pushfstring(L, "%s", k);
44 else
45 return lua_pushfstring(L, "(a %s)", luaL_typename(L, idx));
46}
47
48
49/*
50** Fix a TOpenCall into a TCall node, using table 'postable' to
51** translate a key to its rule address in the tree. Raises an
52** error if key does not exist.
53*/
54static void fixonecall (lua_State *L, int postable, TTree *g, TTree *t) {
55 int n;
56 lua_rawgeti(L, -1, t->key); /* get rule's name */
57 lua_gettable(L, postable); /* query name in position table */
58 n = lua_tonumber(L, -1); /* get (absolute) position */
59 lua_pop(L, 1); /* remove position */
60 if (n == 0) { /* no position? */
61 lua_rawgeti(L, -1, t->key); /* get rule's name again */
62 luaL_error(L, "rule '%s' undefined in given grammar", val2str(L, -1));
63 }
64 t->tag = TCall;
65 t->u.ps = n - (t - g); /* position relative to node */
66 assert(sib2(t)->tag == TRule);
67 sib2(t)->key = t->key; /* fix rule's key */
68}
69
70
71/*
72** Transform left associative constructions into right
73** associative ones, for sequence and choice; that is:
74** (t11 + t12) + t2 => t11 + (t12 + t2)
75** (t11 * t12) * t2 => t11 * (t12 * t2)
76** (that is, Op (Op t11 t12) t2 => Op t11 (Op t12 t2))
77*/
78static void correctassociativity (TTree *tree) {
79 TTree *t1 = sib1(tree);
80 assert(tree->tag == TChoice || tree->tag == TSeq);
81 while (t1->tag == tree->tag) {
82 int n1size = tree->u.ps - 1; /* t1 == Op t11 t12 */
83 int n11size = t1->u.ps - 1;
84 int n12size = n1size - n11size - 1;
85 memmove(sib1(tree), sib1(t1), n11size * sizeof(TTree)); /* move t11 */
86 tree->u.ps = n11size + 1;
87 sib2(tree)->tag = tree->tag;
88 sib2(tree)->u.ps = n12size + 1;
89 }
90}
91
92
93/*
94** Make final adjustments in a tree. Fix open calls in tree 't',
95** making them refer to their respective rules or raising appropriate
96** errors (if not inside a grammar). Correct associativity of associative
97** constructions (making them right associative). Assume that tree's
98** ktable is at the top of the stack (for error messages).
99*/
100static void finalfix (lua_State *L, int postable, TTree *g, TTree *t) {
101 tailcall:
102 switch (t->tag) {
103 case TGrammar: /* subgrammars were already fixed */
104 return;
105 case TOpenCall: {
106 if (g != NULL) /* inside a grammar? */
107 fixonecall(L, postable, g, t);
108 else { /* open call outside grammar */
109 lua_rawgeti(L, -1, t->key);
110 luaL_error(L, "rule '%s' used outside a grammar", val2str(L, -1));
111 }
112 break;
113 }
114 case TSeq: case TChoice:
115 correctassociativity(t);
116 break;
117 }
118 switch (numsiblings[t->tag]) {
119 case 1: /* finalfix(L, postable, g, sib1(t)); */
120 t = sib1(t); goto tailcall;
121 case 2:
122 finalfix(L, postable, g, sib1(t));
123 t = sib2(t); goto tailcall; /* finalfix(L, postable, g, sib2(t)); */
124 default: assert(numsiblings[t->tag] == 0); break;
125 }
126}
127
128
129
130/*
131** {===================================================================
132** KTable manipulation
133**
134** - The ktable of a pattern 'p' can be shared by other patterns that
135** contain 'p' and no other constants. Because of this sharing, we
136** should not add elements to a 'ktable' unless it was freshly created
137** for the new pattern.
138**
139** - The maximum index in a ktable is USHRT_MAX, because trees and
140** patterns use unsigned shorts to store those indices.
141** ====================================================================
142*/
143
144/*
145** Create a new 'ktable' to the pattern at the top of the stack.
146*/
147static void newktable (lua_State *L, int n) {
148 lua_createtable(L, n, 0); /* create a fresh table */
149 lua_setuservalue(L, -2); /* set it as 'ktable' for pattern */
150}
151
152
153/*
154** Add element 'idx' to 'ktable' of pattern at the top of the stack;
155** Return index of new element.
156** If new element is nil, does not add it to table (as it would be
157** useless) and returns 0, as ktable[0] is always nil.
158*/
159static int addtoktable (lua_State *L, int idx) {
160 if (lua_isnil(L, idx)) /* nil value? */
161 return 0;
162 else {
163 int n;
164 lua_getuservalue(L, -1); /* get ktable from pattern */
165 n = lua_rawlen(L, -1);
166 if (n >= USHRT_MAX)
167 luaL_error(L, "too many Lua values in pattern");
168 lua_pushvalue(L, idx); /* element to be added */
169 lua_rawseti(L, -2, ++n);
170 lua_pop(L, 1); /* remove 'ktable' */
171 return n;
172 }
173}
174
175
176/*
177** Return the number of elements in the ktable at 'idx'.
178** In Lua 5.2/5.3, default "environment" for patterns is nil, not
179** a table. Treat it as an empty table. In Lua 5.1, assumes that
180** the environment has no numeric indices (len == 0)
181*/
182static int ktablelen (lua_State *L, int idx) {
183 if (!lua_istable(L, idx)) return 0;
184 else return lua_rawlen(L, idx);
185}
186
187
188/*
189** Concatentate the contents of table 'idx1' into table 'idx2'.
190** (Assume that both indices are negative.)
191** Return the original length of table 'idx2' (or 0, if no
192** element was added, as there is no need to correct any index).
193*/
194static int concattable (lua_State *L, int idx1, int idx2) {
195 int i;
196 int n1 = ktablelen(L, idx1);
197 int n2 = ktablelen(L, idx2);
198 if (n1 + n2 > USHRT_MAX)
199 luaL_error(L, "too many Lua values in pattern");
200 if (n1 == 0) return 0; /* nothing to correct */
201 for (i = 1; i <= n1; i++) {
202 lua_rawgeti(L, idx1, i);
203 lua_rawseti(L, idx2 - 1, n2 + i); /* correct 'idx2' */
204 }
205 return n2;
206}
207
208
209/*
210** When joining 'ktables', constants from one of the subpatterns must
211** be renumbered; 'correctkeys' corrects their indices (adding 'n'
212** to each of them)
213*/
214static void correctkeys (TTree *tree, int n) {
215 if (n == 0) return; /* no correction? */
216 tailcall:
217 switch (tree->tag) {
218 case TOpenCall: case TCall: case TRunTime: case TRule: {
219 if (tree->key > 0)
220 tree->key += n;
221 break;
222 }
223 case TCapture: {
224 if (tree->key > 0 && tree->cap != Carg && tree->cap != Cnum)
225 tree->key += n;
226 break;
227 }
228 default: break;
229 }
230 switch (numsiblings[tree->tag]) {
231 case 1: /* correctkeys(sib1(tree), n); */
232 tree = sib1(tree); goto tailcall;
233 case 2:
234 correctkeys(sib1(tree), n);
235 tree = sib2(tree); goto tailcall; /* correctkeys(sib2(tree), n); */
236 default: assert(numsiblings[tree->tag] == 0); break;
237 }
238}
239
240
241/*
242** Join the ktables from p1 and p2 the ktable for the new pattern at the
243** top of the stack, reusing them when possible.
244*/
245static void joinktables (lua_State *L, int p1, TTree *t2, int p2) {
246 int n1, n2;
247 lua_getuservalue(L, p1); /* get ktables */
248 lua_getuservalue(L, p2);
249 n1 = ktablelen(L, -2);
250 n2 = ktablelen(L, -1);
251 if (n1 == 0 && n2 == 0) /* are both tables empty? */
252 lua_pop(L, 2); /* nothing to be done; pop tables */
253 else if (n2 == 0 || lp_equal(L, -2, -1)) { /* 2nd table empty or equal? */
254 lua_pop(L, 1); /* pop 2nd table */
255 lua_setuservalue(L, -2); /* set 1st ktable into new pattern */
256 }
257 else if (n1 == 0) { /* first table is empty? */
258 lua_setuservalue(L, -3); /* set 2nd table into new pattern */
259 lua_pop(L, 1); /* pop 1st table */
260 }
261 else {
262 lua_createtable(L, n1 + n2, 0); /* create ktable for new pattern */
263 /* stack: new p; ktable p1; ktable p2; new ktable */
264 concattable(L, -3, -1); /* from p1 into new ktable */
265 concattable(L, -2, -1); /* from p2 into new ktable */
266 lua_setuservalue(L, -4); /* new ktable becomes 'p' environment */
267 lua_pop(L, 2); /* pop other ktables */
268 correctkeys(t2, n1); /* correction for indices from p2 */
269 }
270}
271
272
273/*
274** copy 'ktable' of element 'idx' to new tree (on top of stack)
275*/
276static void copyktable (lua_State *L, int idx) {
277 lua_getuservalue(L, idx);
278 lua_setuservalue(L, -2);
279}
280
281
282/*
283** merge 'ktable' from 'stree' at stack index 'idx' into 'ktable'
284** from tree at the top of the stack, and correct corresponding
285** tree.
286*/
287static void mergektable (lua_State *L, int idx, TTree *stree) {
288 int n;
289 lua_getuservalue(L, -1); /* get ktables */
290 lua_getuservalue(L, idx);
291 n = concattable(L, -1, -2);
292 lua_pop(L, 2); /* remove both ktables */
293 correctkeys(stree, n);
294}
295
296
297/*
298** Create a new 'ktable' to the pattern at the top of the stack, adding
299** all elements from pattern 'p' (if not 0) plus element 'idx' to it.
300** Return index of new element.
301*/
302static int addtonewktable (lua_State *L, int p, int idx) {
303 newktable(L, 1);
304 if (p)
305 mergektable(L, p, NULL);
306 return addtoktable(L, idx);
307}
308
309/* }====================================================== */
310
311
312/*
313** {======================================================
314** Tree generation
315** =======================================================
316*/
317
318/*
319** In 5.2, could use 'luaL_testudata'...
320*/
321static int testpattern (lua_State *L, int idx) {
322 if (lua_touserdata(L, idx)) { /* value is a userdata? */
323 if (lua_getmetatable(L, idx)) { /* does it have a metatable? */
324 luaL_getmetatable(L, PATTERN_T);
325 if (lua_rawequal(L, -1, -2)) { /* does it have the correct mt? */
326 lua_pop(L, 2); /* remove both metatables */
327 return 1;
328 }
329 }
330 }
331 return 0;
332}
333
334
335static Pattern *getpattern (lua_State *L, int idx) {
336 return (Pattern *)luaL_checkudata(L, idx, PATTERN_T);
337}
338
339
340static int getsize (lua_State *L, int idx) {
341 return (lua_rawlen(L, idx) - sizeof(Pattern)) / sizeof(TTree) + 1;
342}
343
344
345static TTree *gettree (lua_State *L, int idx, int *len) {
346 Pattern *p = getpattern(L, idx);
347 if (len)
348 *len = getsize(L, idx);
349 return p->tree;
350}
351
352
353/*
354** create a pattern. Set its uservalue (the 'ktable') equal to its
355** metatable. (It could be any empty sequence; the metatable is at
356** hand here, so we use it.)
357*/
358static TTree *newtree (lua_State *L, int len) {
359 size_t size = (len - 1) * sizeof(TTree) + sizeof(Pattern);
360 Pattern *p = (Pattern *)lua_newuserdata(L, size);
361 luaL_getmetatable(L, PATTERN_T);
362 lua_pushvalue(L, -1);
363 lua_setuservalue(L, -3);
364 lua_setmetatable(L, -2);
365 p->code = NULL; p->codesize = 0;
366 return p->tree;
367}
368
369
370static TTree *newleaf (lua_State *L, int tag) {
371 TTree *tree = newtree(L, 1);
372 tree->tag = tag;
373 return tree;
374}
375
376
377static TTree *newcharset (lua_State *L) {
378 TTree *tree = newtree(L, bytes2slots(CHARSETSIZE) + 1);
379 tree->tag = TSet;
380 loopset(i, treebuffer(tree)[i] = 0);
381 return tree;
382}
383
384
385/*
386** add to tree a sequence where first sibling is 'sib' (with size
387** 'sibsize'); returns position for second sibling
388*/
389static TTree *seqaux (TTree *tree, TTree *sib, int sibsize) {
390 tree->tag = TSeq; tree->u.ps = sibsize + 1;
391 memcpy(sib1(tree), sib, sibsize * sizeof(TTree));
392 return sib2(tree);
393}
394
395
396/*
397** Build a sequence of 'n' nodes, each with tag 'tag' and 'u.n' got
398** from the array 's' (or 0 if array is NULL). (TSeq is binary, so it
399** must build a sequence of sequence of sequence...)
400*/
401static void fillseq (TTree *tree, int tag, int n, const char *s) {
402 int i;
403 for (i = 0; i < n - 1; i++) { /* initial n-1 copies of Seq tag; Seq ... */
404 tree->tag = TSeq; tree->u.ps = 2;
405 sib1(tree)->tag = tag;
406 sib1(tree)->u.n = s ? (byte)s[i] : 0;
407 tree = sib2(tree);
408 }
409 tree->tag = tag; /* last one does not need TSeq */
410 tree->u.n = s ? (byte)s[i] : 0;
411}
412
413
414/*
415** Numbers as patterns:
416** 0 == true (always match); n == TAny repeated 'n' times;
417** -n == not (TAny repeated 'n' times)
418*/
419static TTree *numtree (lua_State *L, int n) {
420 if (n == 0)
421 return newleaf(L, TTrue);
422 else {
423 TTree *tree, *nd;
424 if (n > 0)
425 tree = nd = newtree(L, 2 * n - 1);
426 else { /* negative: code it as !(-n) */
427 n = -n;
428 tree = newtree(L, 2 * n);
429 tree->tag = TNot;
430 nd = sib1(tree);
431 }
432 fillseq(nd, TAny, n, NULL); /* sequence of 'n' any's */
433 return tree;
434 }
435}
436
437
438/*
439** Convert value at index 'idx' to a pattern
440*/
441static TTree *getpatt (lua_State *L, int idx, int *len) {
442 TTree *tree;
443 switch (lua_type(L, idx)) {
444 case LUA_TSTRING: {
445 size_t slen;
446 const char *s = lua_tolstring(L, idx, &slen); /* get string */
447 if (slen == 0) /* empty? */
448 tree = newleaf(L, TTrue); /* always match */
449 else {
450 tree = newtree(L, 2 * (slen - 1) + 1);
451 fillseq(tree, TChar, slen, s); /* sequence of 'slen' chars */
452 }
453 break;
454 }
455 case LUA_TNUMBER: {
456 int n = lua_tointeger(L, idx);
457 tree = numtree(L, n);
458 break;
459 }
460 case LUA_TBOOLEAN: {
461 tree = (lua_toboolean(L, idx) ? newleaf(L, TTrue) : newleaf(L, TFalse));
462 break;
463 }
464 case LUA_TTABLE: {
465 tree = newgrammar(L, idx);
466 break;
467 }
468 case LUA_TFUNCTION: {
469 tree = newtree(L, 2);
470 tree->tag = TRunTime;
471 tree->key = addtonewktable(L, 0, idx);
472 sib1(tree)->tag = TTrue;
473 break;
474 }
475 default: {
476 return gettree(L, idx, len);
477 }
478 }
479 lua_replace(L, idx); /* put new tree into 'idx' slot */
480 if (len)
481 *len = getsize(L, idx);
482 return tree;
483}
484
485
486/*
487** create a new tree, whith a new root and one sibling.
488** Sibling must be on the Lua stack, at index 1.
489*/
490static TTree *newroot1sib (lua_State *L, int tag) {
491 int s1;
492 TTree *tree1 = getpatt(L, 1, &s1);
493 TTree *tree = newtree(L, 1 + s1); /* create new tree */
494 tree->tag = tag;
495 memcpy(sib1(tree), tree1, s1 * sizeof(TTree));
496 copyktable(L, 1);
497 return tree;
498}
499
500
501/*
502** create a new tree, whith a new root and 2 siblings.
503** Siblings must be on the Lua stack, first one at index 1.
504*/
505static TTree *newroot2sib (lua_State *L, int tag) {
506 int s1, s2;
507 TTree *tree1 = getpatt(L, 1, &s1);
508 TTree *tree2 = getpatt(L, 2, &s2);
509 TTree *tree = newtree(L, 1 + s1 + s2); /* create new tree */
510 tree->tag = tag;
511 tree->u.ps = 1 + s1;
512 memcpy(sib1(tree), tree1, s1 * sizeof(TTree));
513 memcpy(sib2(tree), tree2, s2 * sizeof(TTree));
514 joinktables(L, 1, sib2(tree), 2);
515 return tree;
516}
517
518
519static int lp_P (lua_State *L) {
520 luaL_checkany(L, 1);
521 getpatt(L, 1, NULL);
522 lua_settop(L, 1);
523 return 1;
524}
525
526
527/*
528** sequence operator; optimizations:
529** false x => false, x true => x, true x => x
530** (cannot do x . false => false because x may have runtime captures)
531*/
532static int lp_seq (lua_State *L) {
533 TTree *tree1 = getpatt(L, 1, NULL);
534 TTree *tree2 = getpatt(L, 2, NULL);
535 if (tree1->tag == TFalse || tree2->tag == TTrue)
536 lua_pushvalue(L, 1); /* false . x == false, x . true = x */
537 else if (tree1->tag == TTrue)
538 lua_pushvalue(L, 2); /* true . x = x */
539 else
540 newroot2sib(L, TSeq);
541 return 1;
542}
543
544
545/*
546** choice operator; optimizations:
547** charset / charset => charset
548** true / x => true, x / false => x, false / x => x
549** (x / true is not equivalent to true)
550*/
551static int lp_choice (lua_State *L) {
552 Charset st1, st2;
553 TTree *t1 = getpatt(L, 1, NULL);
554 TTree *t2 = getpatt(L, 2, NULL);
555 if (tocharset(t1, &st1) && tocharset(t2, &st2)) {
556 TTree *t = newcharset(L);
557 loopset(i, treebuffer(t)[i] = st1.cs[i] | st2.cs[i]);
558 }
559 else if (nofail(t1) || t2->tag == TFalse)
560 lua_pushvalue(L, 1); /* true / x => true, x / false => x */
561 else if (t1->tag == TFalse)
562 lua_pushvalue(L, 2); /* false / x => x */
563 else
564 newroot2sib(L, TChoice);
565 return 1;
566}
567
568
569/*
570** p^n
571*/
572static int lp_star (lua_State *L) {
573 int size1;
574 int n = (int)luaL_checkinteger(L, 2);
575 TTree *tree1 = getpatt(L, 1, &size1);
576 if (n >= 0) { /* seq tree1 (seq tree1 ... (seq tree1 (rep tree1))) */
577 TTree *tree = newtree(L, (n + 1) * (size1 + 1));
578 if (nullable(tree1))
579 luaL_error(L, "loop body may accept empty string");
580 while (n--) /* repeat 'n' times */
581 tree = seqaux(tree, tree1, size1);
582 tree->tag = TRep;
583 memcpy(sib1(tree), tree1, size1 * sizeof(TTree));
584 }
585 else { /* choice (seq tree1 ... choice tree1 true ...) true */
586 TTree *tree;
587 n = -n;
588 /* size = (choice + seq + tree1 + true) * n, but the last has no seq */
589 tree = newtree(L, n * (size1 + 3) - 1);
590 for (; n > 1; n--) { /* repeat (n - 1) times */
591 tree->tag = TChoice; tree->u.ps = n * (size1 + 3) - 2;
592 sib2(tree)->tag = TTrue;
593 tree = sib1(tree);
594 tree = seqaux(tree, tree1, size1);
595 }
596 tree->tag = TChoice; tree->u.ps = size1 + 1;
597 sib2(tree)->tag = TTrue;
598 memcpy(sib1(tree), tree1, size1 * sizeof(TTree));
599 }
600 copyktable(L, 1);
601 return 1;
602}
603
604
605/*
606** #p == &p
607*/
608static int lp_and (lua_State *L) {
609 newroot1sib(L, TAnd);
610 return 1;
611}
612
613
614/*
615** -p == !p
616*/
617static int lp_not (lua_State *L) {
618 newroot1sib(L, TNot);
619 return 1;
620}
621
622
623/*
624** [t1 - t2] == Seq (Not t2) t1
625** If t1 and t2 are charsets, make their difference.
626*/
627static int lp_sub (lua_State *L) {
628 Charset st1, st2;
629 int s1, s2;
630 TTree *t1 = getpatt(L, 1, &s1);
631 TTree *t2 = getpatt(L, 2, &s2);
632 if (tocharset(t1, &st1) && tocharset(t2, &st2)) {
633 TTree *t = newcharset(L);
634 loopset(i, treebuffer(t)[i] = st1.cs[i] & ~st2.cs[i]);
635 }
636 else {
637 TTree *tree = newtree(L, 2 + s1 + s2);
638 tree->tag = TSeq; /* sequence of... */
639 tree->u.ps = 2 + s2;
640 sib1(tree)->tag = TNot; /* ...not... */
641 memcpy(sib1(sib1(tree)), t2, s2 * sizeof(TTree)); /* ...t2 */
642 memcpy(sib2(tree), t1, s1 * sizeof(TTree)); /* ... and t1 */
643 joinktables(L, 1, sib1(tree), 2);
644 }
645 return 1;
646}
647
648
649static int lp_set (lua_State *L) {
650 size_t l;
651 const char *s = luaL_checklstring(L, 1, &l);
652 TTree *tree = newcharset(L);
653 while (l--) {
654 setchar(treebuffer(tree), (byte)(*s));
655 s++;
656 }
657 return 1;
658}
659
660
661static int lp_range (lua_State *L) {
662 int arg;
663 int top = lua_gettop(L);
664 TTree *tree = newcharset(L);
665 for (arg = 1; arg <= top; arg++) {
666 int c;
667 size_t l;
668 const char *r = luaL_checklstring(L, arg, &l);
669 luaL_argcheck(L, l == 2, arg, "range must have two characters");
670 for (c = (byte)r[0]; c <= (byte)r[1]; c++)
671 setchar(treebuffer(tree), c);
672 }
673 return 1;
674}
675
676
677/*
678** Look-behind predicate
679*/
680static int lp_behind (lua_State *L) {
681 TTree *tree;
682 TTree *tree1 = getpatt(L, 1, NULL);
683 int n = fixedlen(tree1);
684 luaL_argcheck(L, n >= 0, 1, "pattern may not have fixed length");
685 luaL_argcheck(L, !hascaptures(tree1), 1, "pattern have captures");
686 luaL_argcheck(L, n <= MAXBEHIND, 1, "pattern too long to look behind");
687 tree = newroot1sib(L, TBehind);
688 tree->u.n = n;
689 return 1;
690}
691
692
693/*
694** Create a non-terminal
695*/
696static int lp_V (lua_State *L) {
697 TTree *tree = newleaf(L, TOpenCall);
698 luaL_argcheck(L, !lua_isnoneornil(L, 1), 1, "non-nil value expected");
699 tree->key = addtonewktable(L, 0, 1);
700 return 1;
701}
702
703
704/*
705** Create a tree for a non-empty capture, with a body and
706** optionally with an associated Lua value (at index 'labelidx' in the
707** stack)
708*/
709static int capture_aux (lua_State *L, int cap, int labelidx) {
710 TTree *tree = newroot1sib(L, TCapture);
711 tree->cap = cap;
712 tree->key = (labelidx == 0) ? 0 : addtonewktable(L, 1, labelidx);
713 return 1;
714}
715
716
717/*
718** Fill a tree with an empty capture, using an empty (TTrue) sibling.
719*/
720static TTree *auxemptycap (TTree *tree, int cap) {
721 tree->tag = TCapture;
722 tree->cap = cap;
723 sib1(tree)->tag = TTrue;
724 return tree;
725}
726
727
728/*
729** Create a tree for an empty capture
730*/
731static TTree *newemptycap (lua_State *L, int cap) {
732 return auxemptycap(newtree(L, 2), cap);
733}
734
735
736/*
737** Create a tree for an empty capture with an associated Lua value
738*/
739static TTree *newemptycapkey (lua_State *L, int cap, int idx) {
740 TTree *tree = auxemptycap(newtree(L, 2), cap);
741 tree->key = addtonewktable(L, 0, idx);
742 return tree;
743}
744
745
746/*
747** Captures with syntax p / v
748** (function capture, query capture, string capture, or number capture)
749*/
750static int lp_divcapture (lua_State *L) {
751 switch (lua_type(L, 2)) {
752 case LUA_TFUNCTION: return capture_aux(L, Cfunction, 2);
753 case LUA_TTABLE: return capture_aux(L, Cquery, 2);
754 case LUA_TSTRING: return capture_aux(L, Cstring, 2);
755 case LUA_TNUMBER: {
756 int n = lua_tointeger(L, 2);
757 TTree *tree = newroot1sib(L, TCapture);
758 luaL_argcheck(L, 0 <= n && n <= SHRT_MAX, 1, "invalid number");
759 tree->cap = Cnum;
760 tree->key = n;
761 return 1;
762 }
763 default: return luaL_argerror(L, 2, "invalid replacement value");
764 }
765}
766
767
768static int lp_substcapture (lua_State *L) {
769 return capture_aux(L, Csubst, 0);
770}
771
772
773static int lp_tablecapture (lua_State *L) {
774 return capture_aux(L, Ctable, 0);
775}
776
777
778static int lp_groupcapture (lua_State *L) {
779 if (lua_isnoneornil(L, 2))
780 return capture_aux(L, Cgroup, 0);
781 else
782 return capture_aux(L, Cgroup, 2);
783}
784
785
786static int lp_foldcapture (lua_State *L) {
787 luaL_checktype(L, 2, LUA_TFUNCTION);
788 return capture_aux(L, Cfold, 2);
789}
790
791
792static int lp_simplecapture (lua_State *L) {
793 return capture_aux(L, Csimple, 0);
794}
795
796
797static int lp_poscapture (lua_State *L) {
798 newemptycap(L, Cposition);
799 return 1;
800}
801
802
803static int lp_argcapture (lua_State *L) {
804 int n = (int)luaL_checkinteger(L, 1);
805 TTree *tree = newemptycap(L, Carg);
806 tree->key = n;
807 luaL_argcheck(L, 0 < n && n <= SHRT_MAX, 1, "invalid argument index");
808 return 1;
809}
810
811
812static int lp_backref (lua_State *L) {
813 luaL_checkany(L, 1);
814 newemptycapkey(L, Cbackref, 1);
815 return 1;
816}
817
818
819/*
820** Constant capture
821*/
822static int lp_constcapture (lua_State *L) {
823 int i;
824 int n = lua_gettop(L); /* number of values */
825 if (n == 0) /* no values? */
826 newleaf(L, TTrue); /* no capture */
827 else if (n == 1)
828 newemptycapkey(L, Cconst, 1); /* single constant capture */
829 else { /* create a group capture with all values */
830 TTree *tree = newtree(L, 1 + 3 * (n - 1) + 2);
831 newktable(L, n); /* create a 'ktable' for new tree */
832 tree->tag = TCapture;
833 tree->cap = Cgroup;
834 tree->key = 0;
835 tree = sib1(tree);
836 for (i = 1; i <= n - 1; i++) {
837 tree->tag = TSeq;
838 tree->u.ps = 3; /* skip TCapture and its sibling */
839 auxemptycap(sib1(tree), Cconst);
840 sib1(tree)->key = addtoktable(L, i);
841 tree = sib2(tree);
842 }
843 auxemptycap(tree, Cconst);
844 tree->key = addtoktable(L, i);
845 }
846 return 1;
847}
848
849
850static int lp_matchtime (lua_State *L) {
851 TTree *tree;
852 luaL_checktype(L, 2, LUA_TFUNCTION);
853 tree = newroot1sib(L, TRunTime);
854 tree->key = addtonewktable(L, 1, 2);
855 return 1;
856}
857
858/* }====================================================== */
859
860
861/*
862** {======================================================
863** Grammar - Tree generation
864** =======================================================
865*/
866
867/*
868** push on the stack the index and the pattern for the
869** initial rule of grammar at index 'arg' in the stack;
870** also add that index into position table.
871*/
872static void getfirstrule (lua_State *L, int arg, int postab) {
873 lua_rawgeti(L, arg, 1); /* access first element */
874 if (lua_isstring(L, -1)) { /* is it the name of initial rule? */
875 lua_pushvalue(L, -1); /* duplicate it to use as key */
876 lua_gettable(L, arg); /* get associated rule */
877 }
878 else {
879 lua_pushinteger(L, 1); /* key for initial rule */
880 lua_insert(L, -2); /* put it before rule */
881 }
882 if (!testpattern(L, -1)) { /* initial rule not a pattern? */
883 if (lua_isnil(L, -1))
884 luaL_error(L, "grammar has no initial rule");
885 else
886 luaL_error(L, "initial rule '%s' is not a pattern", lua_tostring(L, -2));
887 }
888 lua_pushvalue(L, -2); /* push key */
889 lua_pushinteger(L, 1); /* push rule position (after TGrammar) */
890 lua_settable(L, postab); /* insert pair at position table */
891}
892
893/*
894** traverse grammar at index 'arg', pushing all its keys and patterns
895** into the stack. Create a new table (before all pairs key-pattern) to
896** collect all keys and their associated positions in the final tree
897** (the "position table").
898** Return the number of rules and (in 'totalsize') the total size
899** for the new tree.
900*/
901static int collectrules (lua_State *L, int arg, int *totalsize) {
902 int n = 1; /* to count number of rules */
903 int postab = lua_gettop(L) + 1; /* index of position table */
904 int size; /* accumulator for total size */
905 lua_newtable(L); /* create position table */
906 getfirstrule(L, arg, postab);
907 size = 2 + getsize(L, postab + 2); /* TGrammar + TRule + rule */
908 lua_pushnil(L); /* prepare to traverse grammar table */
909 while (lua_next(L, arg) != 0) {
910 if (lua_tonumber(L, -2) == 1 ||
911 lp_equal(L, -2, postab + 1)) { /* initial rule? */
912 lua_pop(L, 1); /* remove value (keep key for lua_next) */
913 continue;
914 }
915 if (!testpattern(L, -1)) /* value is not a pattern? */
916 luaL_error(L, "rule '%s' is not a pattern", val2str(L, -2));
917 luaL_checkstack(L, LUA_MINSTACK, "grammar has too many rules");
918 lua_pushvalue(L, -2); /* push key (to insert into position table) */
919 lua_pushinteger(L, size);
920 lua_settable(L, postab);
921 size += 1 + getsize(L, -1); /* update size */
922 lua_pushvalue(L, -2); /* push key (for next lua_next) */
923 n++;
924 }
925 *totalsize = size + 1; /* TTrue to finish list of rules */
926 return n;
927}
928
929
930static void buildgrammar (lua_State *L, TTree *grammar, int frule, int n) {
931 int i;
932 TTree *nd = sib1(grammar); /* auxiliary pointer to traverse the tree */
933 for (i = 0; i < n; i++) { /* add each rule into new tree */
934 int ridx = frule + 2*i + 1; /* index of i-th rule */
935 int rulesize;
936 TTree *rn = gettree(L, ridx, &rulesize);
937 nd->tag = TRule;
938 nd->key = 0; /* will be fixed when rule is used */
939 nd->cap = i; /* rule number */
940 nd->u.ps = rulesize + 1; /* point to next rule */
941 memcpy(sib1(nd), rn, rulesize * sizeof(TTree)); /* copy rule */
942 mergektable(L, ridx, sib1(nd)); /* merge its ktable into new one */
943 nd = sib2(nd); /* move to next rule */
944 }
945 nd->tag = TTrue; /* finish list of rules */
946}
947
948
949/*
950** Check whether a tree has potential infinite loops
951*/
952static int checkloops (TTree *tree) {
953 tailcall:
954 if (tree->tag == TRep && nullable(sib1(tree)))
955 return 1;
956 else if (tree->tag == TGrammar)
957 return 0; /* sub-grammars already checked */
958 else {
959 switch (numsiblings[tree->tag]) {
960 case 1: /* return checkloops(sib1(tree)); */
961 tree = sib1(tree); goto tailcall;
962 case 2:
963 if (checkloops(sib1(tree))) return 1;
964 /* else return checkloops(sib2(tree)); */
965 tree = sib2(tree); goto tailcall;
966 default: assert(numsiblings[tree->tag] == 0); return 0;
967 }
968 }
969}
970
971
972/*
973** Give appropriate error message for 'verifyrule'. If a rule appears
974** twice in 'passed', there is path from it back to itself without
975** advancing the subject.
976*/
977static int verifyerror (lua_State *L, int *passed, int npassed) {
978 int i, j;
979 for (i = npassed - 1; i >= 0; i--) { /* search for a repetition */
980 for (j = i - 1; j >= 0; j--) {
981 if (passed[i] == passed[j]) {
982 lua_rawgeti(L, -1, passed[i]); /* get rule's key */
983 return luaL_error(L, "rule '%s' may be left recursive", val2str(L, -1));
984 }
985 }
986 }
987 return luaL_error(L, "too many left calls in grammar");
988}
989
990
991/*
992** Check whether a rule can be left recursive; raise an error in that
993** case; otherwise return 1 iff pattern is nullable.
994** The return value is used to check sequences, where the second pattern
995** is only relevant if the first is nullable.
996** Parameter 'nb' works as an accumulator, to allow tail calls in
997** choices. ('nb' true makes function returns true.)
998** Parameter 'passed' is a list of already visited rules, 'npassed'
999** counts the elements in 'passed'.
1000** Assume ktable at the top of the stack.
1001*/
1002static int verifyrule (lua_State *L, TTree *tree, int *passed, int npassed,
1003 int nb) {
1004 tailcall:
1005 switch (tree->tag) {
1006 case TChar: case TSet: case TAny:
1007 case TFalse:
1008 return nb; /* cannot pass from here */
1009 case TTrue:
1010 case TBehind: /* look-behind cannot have calls */
1011 return 1;
1012 case TNot: case TAnd: case TRep:
1013 /* return verifyrule(L, sib1(tree), passed, npassed, 1); */
1014 tree = sib1(tree); nb = 1; goto tailcall;
1015 case TCapture: case TRunTime:
1016 /* return verifyrule(L, sib1(tree), passed, npassed, nb); */
1017 tree = sib1(tree); goto tailcall;
1018 case TCall:
1019 /* return verifyrule(L, sib2(tree), passed, npassed, nb); */
1020 tree = sib2(tree); goto tailcall;
1021 case TSeq: /* only check 2nd child if first is nb */
1022 if (!verifyrule(L, sib1(tree), passed, npassed, 0))
1023 return nb;
1024 /* else return verifyrule(L, sib2(tree), passed, npassed, nb); */
1025 tree = sib2(tree); goto tailcall;
1026 case TChoice: /* must check both children */
1027 nb = verifyrule(L, sib1(tree), passed, npassed, nb);
1028 /* return verifyrule(L, sib2(tree), passed, npassed, nb); */
1029 tree = sib2(tree); goto tailcall;
1030 case TRule:
1031 if (npassed >= MAXRULES)
1032 return verifyerror(L, passed, npassed);
1033 else {
1034 passed[npassed++] = tree->key;
1035 /* return verifyrule(L, sib1(tree), passed, npassed); */
1036 tree = sib1(tree); goto tailcall;
1037 }
1038 case TGrammar:
1039 return nullable(tree); /* sub-grammar cannot be left recursive */
1040 default: assert(0); return 0;
1041 }
1042}
1043
1044
1045static void verifygrammar (lua_State *L, TTree *grammar) {
1046 int passed[MAXRULES];
1047 TTree *rule;
1048 /* check left-recursive rules */
1049 for (rule = sib1(grammar); rule->tag == TRule; rule = sib2(rule)) {
1050 if (rule->key == 0) continue; /* unused rule */
1051 verifyrule(L, sib1(rule), passed, 0, 0);
1052 }
1053 assert(rule->tag == TTrue);
1054 /* check infinite loops inside rules */
1055 for (rule = sib1(grammar); rule->tag == TRule; rule = sib2(rule)) {
1056 if (rule->key == 0) continue; /* unused rule */
1057 if (checkloops(sib1(rule))) {
1058 lua_rawgeti(L, -1, rule->key); /* get rule's key */
1059 luaL_error(L, "empty loop in rule '%s'", val2str(L, -1));
1060 }
1061 }
1062 assert(rule->tag == TTrue);
1063}
1064
1065
1066/*
1067** Give a name for the initial rule if it is not referenced
1068*/
1069static void initialrulename (lua_State *L, TTree *grammar, int frule) {
1070 if (sib1(grammar)->key == 0) { /* initial rule is not referenced? */
1071 int n = lua_rawlen(L, -1) + 1; /* index for name */
1072 lua_pushvalue(L, frule); /* rule's name */
1073 lua_rawseti(L, -2, n); /* ktable was on the top of the stack */
1074 sib1(grammar)->key = n;
1075 }
1076}
1077
1078
1079static TTree *newgrammar (lua_State *L, int arg) {
1080 int treesize;
1081 int frule = lua_gettop(L) + 2; /* position of first rule's key */
1082 int n = collectrules(L, arg, &treesize);
1083 TTree *g = newtree(L, treesize);
1084 luaL_argcheck(L, n <= MAXRULES, arg, "grammar has too many rules");
1085 g->tag = TGrammar; g->u.n = n;
1086 lua_newtable(L); /* create 'ktable' */
1087 lua_setuservalue(L, -2);
1088 buildgrammar(L, g, frule, n);
1089 lua_getuservalue(L, -1); /* get 'ktable' for new tree */
1090 finalfix(L, frule - 1, g, sib1(g));
1091 initialrulename(L, g, frule);
1092 verifygrammar(L, g);
1093 lua_pop(L, 1); /* remove 'ktable' */
1094 lua_insert(L, -(n * 2 + 2)); /* move new table to proper position */
1095 lua_pop(L, n * 2 + 1); /* remove position table + rule pairs */
1096 return g; /* new table at the top of the stack */
1097}
1098
1099/* }====================================================== */
1100
1101
1102static Instruction *prepcompile (lua_State *L, Pattern *p, int idx) {
1103 lua_getuservalue(L, idx); /* push 'ktable' (may be used by 'finalfix') */
1104 finalfix(L, 0, NULL, p->tree);
1105 lua_pop(L, 1); /* remove 'ktable' */
1106 return compile(L, p);
1107}
1108
1109
1110static int lp_printtree (lua_State *L) {
1111 TTree *tree = getpatt(L, 1, NULL);
1112 int c = lua_toboolean(L, 2);
1113 if (c) {
1114 lua_getuservalue(L, 1); /* push 'ktable' (may be used by 'finalfix') */
1115 finalfix(L, 0, NULL, tree);
1116 lua_pop(L, 1); /* remove 'ktable' */
1117 }
1118 printktable(L, 1);
1119 printtree(tree, 0);
1120 return 0;
1121}
1122
1123
1124static int lp_printcode (lua_State *L) {
1125 Pattern *p = getpattern(L, 1);
1126 printktable(L, 1);
1127 if (p->code == NULL) /* not compiled yet? */
1128 prepcompile(L, p, 1);
1129 printpatt(p->code, p->codesize);
1130 return 0;
1131}
1132
1133
1134/*
1135** Get the initial position for the match, interpreting negative
1136** values from the end of the subject
1137*/
1138static size_t initposition (lua_State *L, size_t len) {
1139 lua_Integer ii = luaL_optinteger(L, 3, 1);
1140 if (ii > 0) { /* positive index? */
1141 if ((size_t)ii <= len) /* inside the string? */
1142 return (size_t)ii - 1; /* return it (corrected to 0-base) */
1143 else return len; /* crop at the end */
1144 }
1145 else { /* negative index */
1146 if ((size_t)(-ii) <= len) /* inside the string? */
1147 return len - ((size_t)(-ii)); /* return position from the end */
1148 else return 0; /* crop at the beginning */
1149 }
1150}
1151
1152
1153/*
1154** Main match function
1155*/
1156static int lp_match (lua_State *L) {
1157 Capture capture[INITCAPSIZE];
1158 const char *r;
1159 size_t l;
1160 Pattern *p = (getpatt(L, 1, NULL), getpattern(L, 1));
1161 Instruction *code = (p->code != NULL) ? p->code : prepcompile(L, p, 1);
1162 const char *s = luaL_checklstring(L, SUBJIDX, &l);
1163 size_t i = initposition(L, l);
1164 int ptop = lua_gettop(L);
1165 lua_pushnil(L); /* initialize subscache */
1166 lua_pushlightuserdata(L, capture); /* initialize caplistidx */
1167 lua_getuservalue(L, 1); /* initialize penvidx */
1168 r = match(L, s, s + i, s + l, code, capture, ptop);
1169 if (r == NULL) {
1170 lua_pushnil(L);
1171 return 1;
1172 }
1173 return getcaptures(L, s, r, ptop);
1174}
1175
1176
1177
1178/*
1179** {======================================================
1180** Library creation and functions not related to matching
1181** =======================================================
1182*/
1183
1184/* maximum limit for stack size */
1185#define MAXLIM (INT_MAX / 100)
1186
1187static int lp_setmax (lua_State *L) {
1188 lua_Integer lim = luaL_checkinteger(L, 1);
1189 luaL_argcheck(L, 0 < lim && lim <= MAXLIM, 1, "out of range");
1190 lua_settop(L, 1);
1191 lua_setfield(L, LUA_REGISTRYINDEX, MAXSTACKIDX);
1192 return 0;
1193}
1194
1195
1196static int lp_version (lua_State *L) {
1197 lua_pushstring(L, VERSION);
1198 return 1;
1199}
1200
1201
1202static int lp_type (lua_State *L) {
1203 if (testpattern(L, 1))
1204 lua_pushliteral(L, "pattern");
1205 else
1206 lua_pushnil(L);
1207 return 1;
1208}
1209
1210
1211int lp_gc (lua_State *L) {
1212 Pattern *p = getpattern(L, 1);
1213 realloccode(L, p, 0); /* delete code block */
1214 return 0;
1215}
1216
1217
1218static void createcat (lua_State *L, const char *catname, int (catf) (int)) {
1219 TTree *t = newcharset(L);
1220 int i;
1221 for (i = 0; i <= UCHAR_MAX; i++)
1222 if (catf(i)) setchar(treebuffer(t), i);
1223 lua_setfield(L, -2, catname);
1224}
1225
1226
1227static int lp_locale (lua_State *L) {
1228 if (lua_isnoneornil(L, 1)) {
1229 lua_settop(L, 0);
1230 lua_createtable(L, 0, 12);
1231 }
1232 else {
1233 luaL_checktype(L, 1, LUA_TTABLE);
1234 lua_settop(L, 1);
1235 }
1236 createcat(L, "alnum", isalnum);
1237 createcat(L, "alpha", isalpha);
1238 createcat(L, "cntrl", iscntrl);
1239 createcat(L, "digit", isdigit);
1240 createcat(L, "graph", isgraph);
1241 createcat(L, "lower", islower);
1242 createcat(L, "print", isprint);
1243 createcat(L, "punct", ispunct);
1244 createcat(L, "space", isspace);
1245 createcat(L, "upper", isupper);
1246 createcat(L, "xdigit", isxdigit);
1247 return 1;
1248}
1249
1250
1251static struct luaL_Reg pattreg[] = {
1252 {"ptree", lp_printtree},
1253 {"pcode", lp_printcode},
1254 {"match", lp_match},
1255 {"B", lp_behind},
1256 {"V", lp_V},
1257 {"C", lp_simplecapture},
1258 {"Cc", lp_constcapture},
1259 {"Cmt", lp_matchtime},
1260 {"Cb", lp_backref},
1261 {"Carg", lp_argcapture},
1262 {"Cp", lp_poscapture},
1263 {"Cs", lp_substcapture},
1264 {"Ct", lp_tablecapture},
1265 {"Cf", lp_foldcapture},
1266 {"Cg", lp_groupcapture},
1267 {"P", lp_P},
1268 {"S", lp_set},
1269 {"R", lp_range},
1270 {"locale", lp_locale},
1271 {"version", lp_version},
1272 {"setmaxstack", lp_setmax},
1273 {"type", lp_type},
1274 {NULL, NULL}
1275};
1276
1277
1278static struct luaL_Reg metareg[] = {
1279 {"__mul", lp_seq},
1280 {"__add", lp_choice},
1281 {"__pow", lp_star},
1282 {"__gc", lp_gc},
1283 {"__len", lp_and},
1284 {"__div", lp_divcapture},
1285 {"__unm", lp_not},
1286 {"__sub", lp_sub},
1287 {NULL, NULL}
1288};
1289
1290
1291int luaopen_lpeg (lua_State *L);
1292int luaopen_lpeg (lua_State *L) {
1293 luaL_newmetatable(L, PATTERN_T);
1294 lua_pushnumber(L, MAXBACK); /* initialize maximum backtracking */
1295 lua_setfield(L, LUA_REGISTRYINDEX, MAXSTACKIDX);
1296 luaL_setfuncs(L, metareg, 0);
1297 luaL_newlib(L, pattreg);
1298 lua_pushvalue(L, -1);
1299 lua_setfield(L, -3, "__index");
1300 return 1;
1301}
1302
1303/* }====================================================== */
1304