1/*
2** $Id: lparser.c $
3** Lua Parser
4** See Copyright Notice in lua.h
5*/
6
7#define lparser_c
8#define LUA_CORE
9
10#include "lprefix.h"
11
12
13#include <limits.h>
14#include <string.h>
15
16#include "lua.h"
17
18#include "lcode.h"
19#include "ldebug.h"
20#include "ldo.h"
21#include "lfunc.h"
22#include "llex.h"
23#include "lmem.h"
24#include "lobject.h"
25#include "lopcodes.h"
26#include "lparser.h"
27#include "lstate.h"
28#include "lstring.h"
29#include "ltable.h"
30
31
32
33/* maximum number of local variables per function (must be smaller
34 than 250, due to the bytecode format) */
35#define MAXVARS 200
36
37
38#define hasmultret(k) ((k) == VCALL || (k) == VVARARG)
39
40
41/* because all strings are unified by the scanner, the parser
42 can use pointer equality for string equality */
43#define eqstr(a,b) ((a) == (b))
44
45
46/*
47** nodes for block list (list of active blocks)
48*/
49typedef struct BlockCnt {
50 struct BlockCnt *previous; /* chain */
51 int firstlabel; /* index of first label in this block */
52 int firstgoto; /* index of first pending goto in this block */
53 lu_byte nactvar; /* # active locals outside the block */
54 lu_byte upval; /* true if some variable in the block is an upvalue */
55 lu_byte isloop; /* true if 'block' is a loop */
56 lu_byte insidetbc; /* true if inside the scope of a to-be-closed var. */
57} BlockCnt;
58
59
60
61/*
62** prototypes for recursive non-terminal functions
63*/
64static void statement (LexState *ls);
65static void expr (LexState *ls, expdesc *v);
66
67
68static l_noret error_expected (LexState *ls, int token) {
69 luaX_syntaxerror(ls,
70 luaO_pushfstring(ls->L, "%s expected", luaX_token2str(ls, token)));
71}
72
73
74static l_noret errorlimit (FuncState *fs, int limit, const char *what) {
75 lua_State *L = fs->ls->L;
76 const char *msg;
77 int line = fs->f->linedefined;
78 const char *where = (line == 0)
79 ? "main function"
80 : luaO_pushfstring(L, "function at line %d", line);
81 msg = luaO_pushfstring(L, "too many %s (limit is %d) in %s",
82 what, limit, where);
83 luaX_syntaxerror(fs->ls, msg);
84}
85
86
87static void checklimit (FuncState *fs, int v, int l, const char *what) {
88 if (v > l) errorlimit(fs, l, what);
89}
90
91
92/*
93** Test whether next token is 'c'; if so, skip it.
94*/
95static int testnext (LexState *ls, int c) {
96 if (ls->t.token == c) {
97 luaX_next(ls);
98 return 1;
99 }
100 else return 0;
101}
102
103
104/*
105** Check that next token is 'c'.
106*/
107static void check (LexState *ls, int c) {
108 if (ls->t.token != c)
109 error_expected(ls, c);
110}
111
112
113/*
114** Check that next token is 'c' and skip it.
115*/
116static void checknext (LexState *ls, int c) {
117 check(ls, c);
118 luaX_next(ls);
119}
120
121
122#define check_condition(ls,c,msg) { if (!(c)) luaX_syntaxerror(ls, msg); }
123
124
125/*
126** Check that next token is 'what' and skip it. In case of error,
127** raise an error that the expected 'what' should match a 'who'
128** in line 'where' (if that is not the current line).
129*/
130static void check_match (LexState *ls, int what, int who, int where) {
131 if (l_unlikely(!testnext(ls, what))) {
132 if (where == ls->linenumber) /* all in the same line? */
133 error_expected(ls, what); /* do not need a complex message */
134 else {
135 luaX_syntaxerror(ls, luaO_pushfstring(ls->L,
136 "%s expected (to close %s at line %d)",
137 luaX_token2str(ls, what), luaX_token2str(ls, who), where));
138 }
139 }
140}
141
142
143static TString *str_checkname (LexState *ls) {
144 TString *ts;
145 check(ls, TK_NAME);
146 ts = ls->t.seminfo.ts;
147 luaX_next(ls);
148 return ts;
149}
150
151
152static void init_exp (expdesc *e, expkind k, int i) {
153 e->f = e->t = NO_JUMP;
154 e->k = k;
155 e->u.info = i;
156}
157
158
159static void codestring (expdesc *e, TString *s) {
160 e->f = e->t = NO_JUMP;
161 e->k = VKSTR;
162 e->u.strval = s;
163}
164
165
166static void codename (LexState *ls, expdesc *e) {
167 codestring(e, str_checkname(ls));
168}
169
170
171/*
172** Register a new local variable in the active 'Proto' (for debug
173** information).
174*/
175static int registerlocalvar (LexState *ls, FuncState *fs, TString *varname) {
176 Proto *f = fs->f;
177 int oldsize = f->sizelocvars;
178 luaM_growvector(ls->L, f->locvars, fs->ndebugvars, f->sizelocvars,
179 LocVar, SHRT_MAX, "local variables");
180 while (oldsize < f->sizelocvars)
181 f->locvars[oldsize++].varname = NULL;
182 f->locvars[fs->ndebugvars].varname = varname;
183 f->locvars[fs->ndebugvars].startpc = fs->pc;
184 luaC_objbarrier(ls->L, f, varname);
185 return fs->ndebugvars++;
186}
187
188
189/*
190** Create a new local variable with the given 'name'. Return its index
191** in the function.
192*/
193static int new_localvar (LexState *ls, TString *name) {
194 lua_State *L = ls->L;
195 FuncState *fs = ls->fs;
196 Dyndata *dyd = ls->dyd;
197 Vardesc *var;
198 checklimit(fs, dyd->actvar.n + 1 - fs->firstlocal,
199 MAXVARS, "local variables");
200 luaM_growvector(L, dyd->actvar.arr, dyd->actvar.n + 1,
201 dyd->actvar.size, Vardesc, USHRT_MAX, "local variables");
202 var = &dyd->actvar.arr[dyd->actvar.n++];
203 var->vd.kind = VDKREG; /* default */
204 var->vd.name = name;
205 return dyd->actvar.n - 1 - fs->firstlocal;
206}
207
208#define new_localvarliteral(ls,v) \
209 new_localvar(ls, \
210 luaX_newstring(ls, "" v, (sizeof(v)/sizeof(char)) - 1));
211
212
213
214/*
215** Return the "variable description" (Vardesc) of a given variable.
216** (Unless noted otherwise, all variables are referred to by their
217** compiler indices.)
218*/
219static Vardesc *getlocalvardesc (FuncState *fs, int vidx) {
220 return &fs->ls->dyd->actvar.arr[fs->firstlocal + vidx];
221}
222
223
224/*
225** Convert 'nvar', a compiler index level, to its corresponding
226** register. For that, search for the highest variable below that level
227** that is in a register and uses its register index ('ridx') plus one.
228*/
229static int reglevel (FuncState *fs, int nvar) {
230 while (nvar-- > 0) {
231 Vardesc *vd = getlocalvardesc(fs, nvar); /* get previous variable */
232 if (vd->vd.kind != RDKCTC) /* is in a register? */
233 return vd->vd.ridx + 1;
234 }
235 return 0; /* no variables in registers */
236}
237
238
239/*
240** Return the number of variables in the register stack for the given
241** function.
242*/
243int luaY_nvarstack (FuncState *fs) {
244 return reglevel(fs, fs->nactvar);
245}
246
247
248/*
249** Get the debug-information entry for current variable 'vidx'.
250*/
251static LocVar *localdebuginfo (FuncState *fs, int vidx) {
252 Vardesc *vd = getlocalvardesc(fs, vidx);
253 if (vd->vd.kind == RDKCTC)
254 return NULL; /* no debug info. for constants */
255 else {
256 int idx = vd->vd.pidx;
257 lua_assert(idx < fs->ndebugvars);
258 return &fs->f->locvars[idx];
259 }
260}
261
262
263/*
264** Create an expression representing variable 'vidx'
265*/
266static void init_var (FuncState *fs, expdesc *e, int vidx) {
267 e->f = e->t = NO_JUMP;
268 e->k = VLOCAL;
269 e->u.var.vidx = vidx;
270 e->u.var.ridx = getlocalvardesc(fs, vidx)->vd.ridx;
271}
272
273
274/*
275** Raises an error if variable described by 'e' is read only
276*/
277static void check_readonly (LexState *ls, expdesc *e) {
278 FuncState *fs = ls->fs;
279 TString *varname = NULL; /* to be set if variable is const */
280 switch (e->k) {
281 case VCONST: {
282 varname = ls->dyd->actvar.arr[e->u.info].vd.name;
283 break;
284 }
285 case VLOCAL: {
286 Vardesc *vardesc = getlocalvardesc(fs, e->u.var.vidx);
287 if (vardesc->vd.kind != VDKREG) /* not a regular variable? */
288 varname = vardesc->vd.name;
289 break;
290 }
291 case VUPVAL: {
292 Upvaldesc *up = &fs->f->upvalues[e->u.info];
293 if (up->kind != VDKREG)
294 varname = up->name;
295 break;
296 }
297 default:
298 return; /* other cases cannot be read-only */
299 }
300 if (varname) {
301 const char *msg = luaO_pushfstring(ls->L,
302 "attempt to assign to const variable '%s'", getstr(varname));
303 luaK_semerror(ls, msg); /* error */
304 }
305}
306
307
308/*
309** Start the scope for the last 'nvars' created variables.
310*/
311static void adjustlocalvars (LexState *ls, int nvars) {
312 FuncState *fs = ls->fs;
313 int reglevel = luaY_nvarstack(fs);
314 int i;
315 for (i = 0; i < nvars; i++) {
316 int vidx = fs->nactvar++;
317 Vardesc *var = getlocalvardesc(fs, vidx);
318 var->vd.ridx = reglevel++;
319 var->vd.pidx = registerlocalvar(ls, fs, var->vd.name);
320 }
321}
322
323
324/*
325** Close the scope for all variables up to level 'tolevel'.
326** (debug info.)
327*/
328static void removevars (FuncState *fs, int tolevel) {
329 fs->ls->dyd->actvar.n -= (fs->nactvar - tolevel);
330 while (fs->nactvar > tolevel) {
331 LocVar *var = localdebuginfo(fs, --fs->nactvar);
332 if (var) /* does it have debug information? */
333 var->endpc = fs->pc;
334 }
335}
336
337
338/*
339** Search the upvalues of the function 'fs' for one
340** with the given 'name'.
341*/
342static int searchupvalue (FuncState *fs, TString *name) {
343 int i;
344 Upvaldesc *up = fs->f->upvalues;
345 for (i = 0; i < fs->nups; i++) {
346 if (eqstr(up[i].name, name)) return i;
347 }
348 return -1; /* not found */
349}
350
351
352static Upvaldesc *allocupvalue (FuncState *fs) {
353 Proto *f = fs->f;
354 int oldsize = f->sizeupvalues;
355 checklimit(fs, fs->nups + 1, MAXUPVAL, "upvalues");
356 luaM_growvector(fs->ls->L, f->upvalues, fs->nups, f->sizeupvalues,
357 Upvaldesc, MAXUPVAL, "upvalues");
358 while (oldsize < f->sizeupvalues)
359 f->upvalues[oldsize++].name = NULL;
360 return &f->upvalues[fs->nups++];
361}
362
363
364static int newupvalue (FuncState *fs, TString *name, expdesc *v) {
365 Upvaldesc *up = allocupvalue(fs);
366 FuncState *prev = fs->prev;
367 if (v->k == VLOCAL) {
368 up->instack = 1;
369 up->idx = v->u.var.ridx;
370 up->kind = getlocalvardesc(prev, v->u.var.vidx)->vd.kind;
371 lua_assert(eqstr(name, getlocalvardesc(prev, v->u.var.vidx)->vd.name));
372 }
373 else {
374 up->instack = 0;
375 up->idx = cast_byte(v->u.info);
376 up->kind = prev->f->upvalues[v->u.info].kind;
377 lua_assert(eqstr(name, prev->f->upvalues[v->u.info].name));
378 }
379 up->name = name;
380 luaC_objbarrier(fs->ls->L, fs->f, name);
381 return fs->nups - 1;
382}
383
384
385/*
386** Look for an active local variable with the name 'n' in the
387** function 'fs'. If found, initialize 'var' with it and return
388** its expression kind; otherwise return -1.
389*/
390static int searchvar (FuncState *fs, TString *n, expdesc *var) {
391 int i;
392 for (i = cast_int(fs->nactvar) - 1; i >= 0; i--) {
393 Vardesc *vd = getlocalvardesc(fs, i);
394 if (eqstr(n, vd->vd.name)) { /* found? */
395 if (vd->vd.kind == RDKCTC) /* compile-time constant? */
396 init_exp(var, VCONST, fs->firstlocal + i);
397 else /* real variable */
398 init_var(fs, var, i);
399 return var->k;
400 }
401 }
402 return -1; /* not found */
403}
404
405
406/*
407** Mark block where variable at given level was defined
408** (to emit close instructions later).
409*/
410static void markupval (FuncState *fs, int level) {
411 BlockCnt *bl = fs->bl;
412 while (bl->nactvar > level)
413 bl = bl->previous;
414 bl->upval = 1;
415 fs->needclose = 1;
416}
417
418
419/*
420** Mark that current block has a to-be-closed variable.
421*/
422static void marktobeclosed (FuncState *fs) {
423 BlockCnt *bl = fs->bl;
424 bl->upval = 1;
425 bl->insidetbc = 1;
426 fs->needclose = 1;
427}
428
429
430/*
431** Find a variable with the given name 'n'. If it is an upvalue, add
432** this upvalue into all intermediate functions. If it is a global, set
433** 'var' as 'void' as a flag.
434*/
435static void singlevaraux (FuncState *fs, TString *n, expdesc *var, int base) {
436 if (fs == NULL) /* no more levels? */
437 init_exp(var, VVOID, 0); /* default is global */
438 else {
439 int v = searchvar(fs, n, var); /* look up locals at current level */
440 if (v >= 0) { /* found? */
441 if (v == VLOCAL && !base)
442 markupval(fs, var->u.var.vidx); /* local will be used as an upval */
443 }
444 else { /* not found as local at current level; try upvalues */
445 int idx = searchupvalue(fs, n); /* try existing upvalues */
446 if (idx < 0) { /* not found? */
447 singlevaraux(fs->prev, n, var, 0); /* try upper levels */
448 if (var->k == VLOCAL || var->k == VUPVAL) /* local or upvalue? */
449 idx = newupvalue(fs, n, var); /* will be a new upvalue */
450 else /* it is a global or a constant */
451 return; /* don't need to do anything at this level */
452 }
453 init_exp(var, VUPVAL, idx); /* new or old upvalue */
454 }
455 }
456}
457
458
459/*
460** Find a variable with the given name 'n', handling global variables
461** too.
462*/
463static void singlevar (LexState *ls, expdesc *var) {
464 TString *varname = str_checkname(ls);
465 FuncState *fs = ls->fs;
466 singlevaraux(fs, varname, var, 1);
467 if (var->k == VVOID) { /* global name? */
468 expdesc key;
469 singlevaraux(fs, ls->envn, var, 1); /* get environment variable */
470 lua_assert(var->k != VVOID); /* this one must exist */
471 luaK_exp2anyregup(fs, var); /* but could be a constant */
472 codestring(&key, varname); /* key is variable name */
473 luaK_indexed(fs, var, &key); /* env[varname] */
474 }
475}
476
477
478/*
479** Adjust the number of results from an expression list 'e' with 'nexps'
480** expressions to 'nvars' values.
481*/
482static void adjust_assign (LexState *ls, int nvars, int nexps, expdesc *e) {
483 FuncState *fs = ls->fs;
484 int needed = nvars - nexps; /* extra values needed */
485 if (hasmultret(e->k)) { /* last expression has multiple returns? */
486 int extra = needed + 1; /* discount last expression itself */
487 if (extra < 0)
488 extra = 0;
489 luaK_setreturns(fs, e, extra); /* last exp. provides the difference */
490 }
491 else {
492 if (e->k != VVOID) /* at least one expression? */
493 luaK_exp2nextreg(fs, e); /* close last expression */
494 if (needed > 0) /* missing values? */
495 luaK_nil(fs, fs->freereg, needed); /* complete with nils */
496 }
497 if (needed > 0)
498 luaK_reserveregs(fs, needed); /* registers for extra values */
499 else /* adding 'needed' is actually a subtraction */
500 fs->freereg += needed; /* remove extra values */
501}
502
503
504#define enterlevel(ls) luaE_incCstack(ls->L)
505
506
507#define leavelevel(ls) ((ls)->L->nCcalls--)
508
509
510/*
511** Generates an error that a goto jumps into the scope of some
512** local variable.
513*/
514static l_noret jumpscopeerror (LexState *ls, Labeldesc *gt) {
515 const char *varname = getstr(getlocalvardesc(ls->fs, gt->nactvar)->vd.name);
516 const char *msg = "<goto %s> at line %d jumps into the scope of local '%s'";
517 msg = luaO_pushfstring(ls->L, msg, getstr(gt->name), gt->line, varname);
518 luaK_semerror(ls, msg); /* raise the error */
519}
520
521
522/*
523** Solves the goto at index 'g' to given 'label' and removes it
524** from the list of pending gotos.
525** If it jumps into the scope of some variable, raises an error.
526*/
527static void solvegoto (LexState *ls, int g, Labeldesc *label) {
528 int i;
529 Labellist *gl = &ls->dyd->gt; /* list of gotos */
530 Labeldesc *gt = &gl->arr[g]; /* goto to be resolved */
531 lua_assert(eqstr(gt->name, label->name));
532 if (l_unlikely(gt->nactvar < label->nactvar)) /* enter some scope? */
533 jumpscopeerror(ls, gt);
534 luaK_patchlist(ls->fs, gt->pc, label->pc);
535 for (i = g; i < gl->n - 1; i++) /* remove goto from pending list */
536 gl->arr[i] = gl->arr[i + 1];
537 gl->n--;
538}
539
540
541/*
542** Search for an active label with the given name.
543*/
544static Labeldesc *findlabel (LexState *ls, TString *name) {
545 int i;
546 Dyndata *dyd = ls->dyd;
547 /* check labels in current function for a match */
548 for (i = ls->fs->firstlabel; i < dyd->label.n; i++) {
549 Labeldesc *lb = &dyd->label.arr[i];
550 if (eqstr(lb->name, name)) /* correct label? */
551 return lb;
552 }
553 return NULL; /* label not found */
554}
555
556
557/*
558** Adds a new label/goto in the corresponding list.
559*/
560static int newlabelentry (LexState *ls, Labellist *l, TString *name,
561 int line, int pc) {
562 int n = l->n;
563 luaM_growvector(ls->L, l->arr, n, l->size,
564 Labeldesc, SHRT_MAX, "labels/gotos");
565 l->arr[n].name = name;
566 l->arr[n].line = line;
567 l->arr[n].nactvar = ls->fs->nactvar;
568 l->arr[n].close = 0;
569 l->arr[n].pc = pc;
570 l->n = n + 1;
571 return n;
572}
573
574
575static int newgotoentry (LexState *ls, TString *name, int line, int pc) {
576 return newlabelentry(ls, &ls->dyd->gt, name, line, pc);
577}
578
579
580/*
581** Solves forward jumps. Check whether new label 'lb' matches any
582** pending gotos in current block and solves them. Return true
583** if any of the gotos need to close upvalues.
584*/
585static int solvegotos (LexState *ls, Labeldesc *lb) {
586 Labellist *gl = &ls->dyd->gt;
587 int i = ls->fs->bl->firstgoto;
588 int needsclose = 0;
589 while (i < gl->n) {
590 if (eqstr(gl->arr[i].name, lb->name)) {
591 needsclose |= gl->arr[i].close;
592 solvegoto(ls, i, lb); /* will remove 'i' from the list */
593 }
594 else
595 i++;
596 }
597 return needsclose;
598}
599
600
601/*
602** Create a new label with the given 'name' at the given 'line'.
603** 'last' tells whether label is the last non-op statement in its
604** block. Solves all pending gotos to this new label and adds
605** a close instruction if necessary.
606** Returns true iff it added a close instruction.
607*/
608static int createlabel (LexState *ls, TString *name, int line,
609 int last) {
610 FuncState *fs = ls->fs;
611 Labellist *ll = &ls->dyd->label;
612 int l = newlabelentry(ls, ll, name, line, luaK_getlabel(fs));
613 if (last) { /* label is last no-op statement in the block? */
614 /* assume that locals are already out of scope */
615 ll->arr[l].nactvar = fs->bl->nactvar;
616 }
617 if (solvegotos(ls, &ll->arr[l])) { /* need close? */
618 luaK_codeABC(fs, OP_CLOSE, luaY_nvarstack(fs), 0, 0);
619 return 1;
620 }
621 return 0;
622}
623
624
625/*
626** Adjust pending gotos to outer level of a block.
627*/
628static void movegotosout (FuncState *fs, BlockCnt *bl) {
629 int i;
630 Labellist *gl = &fs->ls->dyd->gt;
631 /* correct pending gotos to current block */
632 for (i = bl->firstgoto; i < gl->n; i++) { /* for each pending goto */
633 Labeldesc *gt = &gl->arr[i];
634 /* leaving a variable scope? */
635 if (reglevel(fs, gt->nactvar) > reglevel(fs, bl->nactvar))
636 gt->close |= bl->upval; /* jump may need a close */
637 gt->nactvar = bl->nactvar; /* update goto level */
638 }
639}
640
641
642static void enterblock (FuncState *fs, BlockCnt *bl, lu_byte isloop) {
643 bl->isloop = isloop;
644 bl->nactvar = fs->nactvar;
645 bl->firstlabel = fs->ls->dyd->label.n;
646 bl->firstgoto = fs->ls->dyd->gt.n;
647 bl->upval = 0;
648 bl->insidetbc = (fs->bl != NULL && fs->bl->insidetbc);
649 bl->previous = fs->bl;
650 fs->bl = bl;
651 lua_assert(fs->freereg == luaY_nvarstack(fs));
652}
653
654
655/*
656** generates an error for an undefined 'goto'.
657*/
658static l_noret undefgoto (LexState *ls, Labeldesc *gt) {
659 const char *msg;
660 if (eqstr(gt->name, luaS_newliteral(ls->L, "break"))) {
661 msg = "break outside loop at line %d";
662 msg = luaO_pushfstring(ls->L, msg, gt->line);
663 }
664 else {
665 msg = "no visible label '%s' for <goto> at line %d";
666 msg = luaO_pushfstring(ls->L, msg, getstr(gt->name), gt->line);
667 }
668 luaK_semerror(ls, msg);
669}
670
671
672static void leaveblock (FuncState *fs) {
673 BlockCnt *bl = fs->bl;
674 LexState *ls = fs->ls;
675 int hasclose = 0;
676 int stklevel = reglevel(fs, bl->nactvar); /* level outside the block */
677 removevars(fs, bl->nactvar); /* remove block locals */
678 lua_assert(bl->nactvar == fs->nactvar); /* back to level on entry */
679 if (bl->isloop) /* has to fix pending breaks? */
680 hasclose = createlabel(ls, luaS_newliteral(ls->L, "break"), 0, 0);
681 if (!hasclose && bl->previous && bl->upval) /* still need a 'close'? */
682 luaK_codeABC(fs, OP_CLOSE, stklevel, 0, 0);
683 fs->freereg = stklevel; /* free registers */
684 ls->dyd->label.n = bl->firstlabel; /* remove local labels */
685 fs->bl = bl->previous; /* current block now is previous one */
686 if (bl->previous) /* was it a nested block? */
687 movegotosout(fs, bl); /* update pending gotos to enclosing block */
688 else {
689 if (bl->firstgoto < ls->dyd->gt.n) /* still pending gotos? */
690 undefgoto(ls, &ls->dyd->gt.arr[bl->firstgoto]); /* error */
691 }
692}
693
694
695/*
696** adds a new prototype into list of prototypes
697*/
698static Proto *addprototype (LexState *ls) {
699 Proto *clp;
700 lua_State *L = ls->L;
701 FuncState *fs = ls->fs;
702 Proto *f = fs->f; /* prototype of current function */
703 if (fs->np >= f->sizep) {
704 int oldsize = f->sizep;
705 luaM_growvector(L, f->p, fs->np, f->sizep, Proto *, MAXARG_Bx, "functions");
706 while (oldsize < f->sizep)
707 f->p[oldsize++] = NULL;
708 }
709 f->p[fs->np++] = clp = luaF_newproto(L);
710 luaC_objbarrier(L, f, clp);
711 return clp;
712}
713
714
715/*
716** codes instruction to create new closure in parent function.
717** The OP_CLOSURE instruction uses the last available register,
718** so that, if it invokes the GC, the GC knows which registers
719** are in use at that time.
720
721*/
722static void codeclosure (LexState *ls, expdesc *v) {
723 FuncState *fs = ls->fs->prev;
724 init_exp(v, VRELOC, luaK_codeABx(fs, OP_CLOSURE, 0, fs->np - 1));
725 luaK_exp2nextreg(fs, v); /* fix it at the last register */
726}
727
728
729static void open_func (LexState *ls, FuncState *fs, BlockCnt *bl) {
730 Proto *f = fs->f;
731 fs->prev = ls->fs; /* linked list of funcstates */
732 fs->ls = ls;
733 ls->fs = fs;
734 fs->pc = 0;
735 fs->previousline = f->linedefined;
736 fs->iwthabs = 0;
737 fs->lasttarget = 0;
738 fs->freereg = 0;
739 fs->nk = 0;
740 fs->nabslineinfo = 0;
741 fs->np = 0;
742 fs->nups = 0;
743 fs->ndebugvars = 0;
744 fs->nactvar = 0;
745 fs->needclose = 0;
746 fs->firstlocal = ls->dyd->actvar.n;
747 fs->firstlabel = ls->dyd->label.n;
748 fs->bl = NULL;
749 f->source = ls->source;
750 luaC_objbarrier(ls->L, f, f->source);
751 f->maxstacksize = 2; /* registers 0/1 are always valid */
752 enterblock(fs, bl, 0);
753}
754
755
756static void close_func (LexState *ls) {
757 lua_State *L = ls->L;
758 FuncState *fs = ls->fs;
759 Proto *f = fs->f;
760 luaK_ret(fs, luaY_nvarstack(fs), 0); /* final return */
761 leaveblock(fs);
762 lua_assert(fs->bl == NULL);
763 luaK_finish(fs);
764 luaM_shrinkvector(L, f->code, f->sizecode, fs->pc, Instruction);
765 luaM_shrinkvector(L, f->lineinfo, f->sizelineinfo, fs->pc, ls_byte);
766 luaM_shrinkvector(L, f->abslineinfo, f->sizeabslineinfo,
767 fs->nabslineinfo, AbsLineInfo);
768 luaM_shrinkvector(L, f->k, f->sizek, fs->nk, TValue);
769 luaM_shrinkvector(L, f->p, f->sizep, fs->np, Proto *);
770 luaM_shrinkvector(L, f->locvars, f->sizelocvars, fs->ndebugvars, LocVar);
771 luaM_shrinkvector(L, f->upvalues, f->sizeupvalues, fs->nups, Upvaldesc);
772 ls->fs = fs->prev;
773 luaC_checkGC(L);
774}
775
776
777
778/*============================================================*/
779/* GRAMMAR RULES */
780/*============================================================*/
781
782
783/*
784** check whether current token is in the follow set of a block.
785** 'until' closes syntactical blocks, but do not close scope,
786** so it is handled in separate.
787*/
788static int block_follow (LexState *ls, int withuntil) {
789 switch (ls->t.token) {
790 case TK_ELSE: case TK_ELSEIF:
791 case TK_END: case TK_EOS:
792 return 1;
793 case TK_UNTIL: return withuntil;
794 default: return 0;
795 }
796}
797
798
799static void statlist (LexState *ls) {
800 /* statlist -> { stat [';'] } */
801 while (!block_follow(ls, 1)) {
802 if (ls->t.token == TK_RETURN) {
803 statement(ls);
804 return; /* 'return' must be last statement */
805 }
806 statement(ls);
807 }
808}
809
810
811static void fieldsel (LexState *ls, expdesc *v) {
812 /* fieldsel -> ['.' | ':'] NAME */
813 FuncState *fs = ls->fs;
814 expdesc key;
815 luaK_exp2anyregup(fs, v);
816 luaX_next(ls); /* skip the dot or colon */
817 codename(ls, &key);
818 luaK_indexed(fs, v, &key);
819}
820
821
822static void yindex (LexState *ls, expdesc *v) {
823 /* index -> '[' expr ']' */
824 luaX_next(ls); /* skip the '[' */
825 expr(ls, v);
826 luaK_exp2val(ls->fs, v);
827 checknext(ls, ']');
828}
829
830
831/*
832** {======================================================================
833** Rules for Constructors
834** =======================================================================
835*/
836
837
838typedef struct ConsControl {
839 expdesc v; /* last list item read */
840 expdesc *t; /* table descriptor */
841 int nh; /* total number of 'record' elements */
842 int na; /* number of array elements already stored */
843 int tostore; /* number of array elements pending to be stored */
844} ConsControl;
845
846
847static void recfield (LexState *ls, ConsControl *cc) {
848 /* recfield -> (NAME | '['exp']') = exp */
849 FuncState *fs = ls->fs;
850 int reg = ls->fs->freereg;
851 expdesc tab, key, val;
852 if (ls->t.token == TK_NAME) {
853 checklimit(fs, cc->nh, MAX_INT, "items in a constructor");
854 codename(ls, &key);
855 }
856 else /* ls->t.token == '[' */
857 yindex(ls, &key);
858 cc->nh++;
859 checknext(ls, '=');
860 tab = *cc->t;
861 luaK_indexed(fs, &tab, &key);
862 expr(ls, &val);
863 luaK_storevar(fs, &tab, &val);
864 fs->freereg = reg; /* free registers */
865}
866
867
868static void closelistfield (FuncState *fs, ConsControl *cc) {
869 if (cc->v.k == VVOID) return; /* there is no list item */
870 luaK_exp2nextreg(fs, &cc->v);
871 cc->v.k = VVOID;
872 if (cc->tostore == LFIELDS_PER_FLUSH) {
873 luaK_setlist(fs, cc->t->u.info, cc->na, cc->tostore); /* flush */
874 cc->na += cc->tostore;
875 cc->tostore = 0; /* no more items pending */
876 }
877}
878
879
880static void lastlistfield (FuncState *fs, ConsControl *cc) {
881 if (cc->tostore == 0) return;
882 if (hasmultret(cc->v.k)) {
883 luaK_setmultret(fs, &cc->v);
884 luaK_setlist(fs, cc->t->u.info, cc->na, LUA_MULTRET);
885 cc->na--; /* do not count last expression (unknown number of elements) */
886 }
887 else {
888 if (cc->v.k != VVOID)
889 luaK_exp2nextreg(fs, &cc->v);
890 luaK_setlist(fs, cc->t->u.info, cc->na, cc->tostore);
891 }
892 cc->na += cc->tostore;
893}
894
895
896static void listfield (LexState *ls, ConsControl *cc) {
897 /* listfield -> exp */
898 expr(ls, &cc->v);
899 cc->tostore++;
900}
901
902
903static void field (LexState *ls, ConsControl *cc) {
904 /* field -> listfield | recfield */
905 switch(ls->t.token) {
906 case TK_NAME: { /* may be 'listfield' or 'recfield' */
907 if (luaX_lookahead(ls) != '=') /* expression? */
908 listfield(ls, cc);
909 else
910 recfield(ls, cc);
911 break;
912 }
913 case '[': {
914 recfield(ls, cc);
915 break;
916 }
917 default: {
918 listfield(ls, cc);
919 break;
920 }
921 }
922}
923
924
925static void constructor (LexState *ls, expdesc *t) {
926 /* constructor -> '{' [ field { sep field } [sep] ] '}'
927 sep -> ',' | ';' */
928 FuncState *fs = ls->fs;
929 int line = ls->linenumber;
930 int pc = luaK_codeABC(fs, OP_NEWTABLE, 0, 0, 0);
931 ConsControl cc;
932 luaK_code(fs, 0); /* space for extra arg. */
933 cc.na = cc.nh = cc.tostore = 0;
934 cc.t = t;
935 init_exp(t, VNONRELOC, fs->freereg); /* table will be at stack top */
936 luaK_reserveregs(fs, 1);
937 init_exp(&cc.v, VVOID, 0); /* no value (yet) */
938 checknext(ls, '{');
939 do {
940 lua_assert(cc.v.k == VVOID || cc.tostore > 0);
941 if (ls->t.token == '}') break;
942 closelistfield(fs, &cc);
943 field(ls, &cc);
944 } while (testnext(ls, ',') || testnext(ls, ';'));
945 check_match(ls, '}', '{', line);
946 lastlistfield(fs, &cc);
947 luaK_settablesize(fs, pc, t->u.info, cc.na, cc.nh);
948}
949
950/* }====================================================================== */
951
952
953static void setvararg (FuncState *fs, int nparams) {
954 fs->f->is_vararg = 1;
955 luaK_codeABC(fs, OP_VARARGPREP, nparams, 0, 0);
956}
957
958
959static void parlist (LexState *ls) {
960 /* parlist -> [ {NAME ','} (NAME | '...') ] */
961 FuncState *fs = ls->fs;
962 Proto *f = fs->f;
963 int nparams = 0;
964 int isvararg = 0;
965 if (ls->t.token != ')') { /* is 'parlist' not empty? */
966 do {
967 switch (ls->t.token) {
968 case TK_NAME: {
969 new_localvar(ls, str_checkname(ls));
970 nparams++;
971 break;
972 }
973 case TK_DOTS: {
974 luaX_next(ls);
975 isvararg = 1;
976 break;
977 }
978 default: luaX_syntaxerror(ls, "<name> or '...' expected");
979 }
980 } while (!isvararg && testnext(ls, ','));
981 }
982 adjustlocalvars(ls, nparams);
983 f->numparams = cast_byte(fs->nactvar);
984 if (isvararg)
985 setvararg(fs, f->numparams); /* declared vararg */
986 luaK_reserveregs(fs, fs->nactvar); /* reserve registers for parameters */
987}
988
989
990static void body (LexState *ls, expdesc *e, int ismethod, int line) {
991 /* body -> '(' parlist ')' block END */
992 FuncState new_fs;
993 BlockCnt bl;
994 new_fs.f = addprototype(ls);
995 new_fs.f->linedefined = line;
996 open_func(ls, &new_fs, &bl);
997 checknext(ls, '(');
998 if (ismethod) {
999 new_localvarliteral(ls, "self"); /* create 'self' parameter */
1000 adjustlocalvars(ls, 1);
1001 }
1002 parlist(ls);
1003 checknext(ls, ')');
1004 statlist(ls);
1005 new_fs.f->lastlinedefined = ls->linenumber;
1006 check_match(ls, TK_END, TK_FUNCTION, line);
1007 codeclosure(ls, e);
1008 close_func(ls);
1009}
1010
1011
1012static int explist (LexState *ls, expdesc *v) {
1013 /* explist -> expr { ',' expr } */
1014 int n = 1; /* at least one expression */
1015 expr(ls, v);
1016 while (testnext(ls, ',')) {
1017 luaK_exp2nextreg(ls->fs, v);
1018 expr(ls, v);
1019 n++;
1020 }
1021 return n;
1022}
1023
1024
1025static void funcargs (LexState *ls, expdesc *f) {
1026 FuncState *fs = ls->fs;
1027 expdesc args;
1028 int base, nparams;
1029 int line = ls->linenumber;
1030 switch (ls->t.token) {
1031 case '(': { /* funcargs -> '(' [ explist ] ')' */
1032 luaX_next(ls);
1033 if (ls->t.token == ')') /* arg list is empty? */
1034 args.k = VVOID;
1035 else {
1036 explist(ls, &args);
1037 if (hasmultret(args.k))
1038 luaK_setmultret(fs, &args);
1039 }
1040 check_match(ls, ')', '(', line);
1041 break;
1042 }
1043 case '{': { /* funcargs -> constructor */
1044 constructor(ls, &args);
1045 break;
1046 }
1047 case TK_STRING: { /* funcargs -> STRING */
1048 codestring(&args, ls->t.seminfo.ts);
1049 luaX_next(ls); /* must use 'seminfo' before 'next' */
1050 break;
1051 }
1052 default: {
1053 luaX_syntaxerror(ls, "function arguments expected");
1054 }
1055 }
1056 lua_assert(f->k == VNONRELOC);
1057 base = f->u.info; /* base register for call */
1058 if (hasmultret(args.k))
1059 nparams = LUA_MULTRET; /* open call */
1060 else {
1061 if (args.k != VVOID)
1062 luaK_exp2nextreg(fs, &args); /* close last argument */
1063 nparams = fs->freereg - (base+1);
1064 }
1065 init_exp(f, VCALL, luaK_codeABC(fs, OP_CALL, base, nparams+1, 2));
1066 luaK_fixline(fs, line);
1067 fs->freereg = base+1; /* call removes function and arguments and leaves
1068 one result (unless changed later) */
1069}
1070
1071
1072
1073
1074/*
1075** {======================================================================
1076** Expression parsing
1077** =======================================================================
1078*/
1079
1080
1081static void primaryexp (LexState *ls, expdesc *v) {
1082 /* primaryexp -> NAME | '(' expr ')' */
1083 switch (ls->t.token) {
1084 case '(': {
1085 int line = ls->linenumber;
1086 luaX_next(ls);
1087 expr(ls, v);
1088 check_match(ls, ')', '(', line);
1089 luaK_dischargevars(ls->fs, v);
1090 return;
1091 }
1092 case TK_NAME: {
1093 singlevar(ls, v);
1094 return;
1095 }
1096 default: {
1097 luaX_syntaxerror(ls, "unexpected symbol");
1098 }
1099 }
1100}
1101
1102
1103static void suffixedexp (LexState *ls, expdesc *v) {
1104 /* suffixedexp ->
1105 primaryexp { '.' NAME | '[' exp ']' | ':' NAME funcargs | funcargs } */
1106 FuncState *fs = ls->fs;
1107 primaryexp(ls, v);
1108 for (;;) {
1109 switch (ls->t.token) {
1110 case '.': { /* fieldsel */
1111 fieldsel(ls, v);
1112 break;
1113 }
1114 case '[': { /* '[' exp ']' */
1115 expdesc key;
1116 luaK_exp2anyregup(fs, v);
1117 yindex(ls, &key);
1118 luaK_indexed(fs, v, &key);
1119 break;
1120 }
1121 case ':': { /* ':' NAME funcargs */
1122 expdesc key;
1123 luaX_next(ls);
1124 codename(ls, &key);
1125 luaK_self(fs, v, &key);
1126 funcargs(ls, v);
1127 break;
1128 }
1129 case '(': case TK_STRING: case '{': { /* funcargs */
1130 luaK_exp2nextreg(fs, v);
1131 funcargs(ls, v);
1132 break;
1133 }
1134 default: return;
1135 }
1136 }
1137}
1138
1139
1140static void simpleexp (LexState *ls, expdesc *v) {
1141 /* simpleexp -> FLT | INT | STRING | NIL | TRUE | FALSE | ... |
1142 constructor | FUNCTION body | suffixedexp */
1143 switch (ls->t.token) {
1144 case TK_FLT: {
1145 init_exp(v, VKFLT, 0);
1146 v->u.nval = ls->t.seminfo.r;
1147 break;
1148 }
1149 case TK_INT: {
1150 init_exp(v, VKINT, 0);
1151 v->u.ival = ls->t.seminfo.i;
1152 break;
1153 }
1154 case TK_STRING: {
1155 codestring(v, ls->t.seminfo.ts);
1156 break;
1157 }
1158 case TK_NIL: {
1159 init_exp(v, VNIL, 0);
1160 break;
1161 }
1162 case TK_TRUE: {
1163 init_exp(v, VTRUE, 0);
1164 break;
1165 }
1166 case TK_FALSE: {
1167 init_exp(v, VFALSE, 0);
1168 break;
1169 }
1170 case TK_DOTS: { /* vararg */
1171 FuncState *fs = ls->fs;
1172 check_condition(ls, fs->f->is_vararg,
1173 "cannot use '...' outside a vararg function");
1174 init_exp(v, VVARARG, luaK_codeABC(fs, OP_VARARG, 0, 0, 1));
1175 break;
1176 }
1177 case '{': { /* constructor */
1178 constructor(ls, v);
1179 return;
1180 }
1181 case TK_FUNCTION: {
1182 luaX_next(ls);
1183 body(ls, v, 0, ls->linenumber);
1184 return;
1185 }
1186 default: {
1187 suffixedexp(ls, v);
1188 return;
1189 }
1190 }
1191 luaX_next(ls);
1192}
1193
1194
1195static UnOpr getunopr (int op) {
1196 switch (op) {
1197 case TK_NOT: return OPR_NOT;
1198 case '-': return OPR_MINUS;
1199 case '~': return OPR_BNOT;
1200 case '#': return OPR_LEN;
1201 default: return OPR_NOUNOPR;
1202 }
1203}
1204
1205
1206static BinOpr getbinopr (int op) {
1207 switch (op) {
1208 case '+': return OPR_ADD;
1209 case '-': return OPR_SUB;
1210 case '*': return OPR_MUL;
1211 case '%': return OPR_MOD;
1212 case '^': return OPR_POW;
1213 case '/': return OPR_DIV;
1214 case TK_IDIV: return OPR_IDIV;
1215 case '&': return OPR_BAND;
1216 case '|': return OPR_BOR;
1217 case '~': return OPR_BXOR;
1218 case TK_SHL: return OPR_SHL;
1219 case TK_SHR: return OPR_SHR;
1220 case TK_CONCAT: return OPR_CONCAT;
1221 case TK_NE: return OPR_NE;
1222 case TK_EQ: return OPR_EQ;
1223 case '<': return OPR_LT;
1224 case TK_LE: return OPR_LE;
1225 case '>': return OPR_GT;
1226 case TK_GE: return OPR_GE;
1227 case TK_AND: return OPR_AND;
1228 case TK_OR: return OPR_OR;
1229 default: return OPR_NOBINOPR;
1230 }
1231}
1232
1233
1234/*
1235** Priority table for binary operators.
1236*/
1237static const struct {
1238 lu_byte left; /* left priority for each binary operator */
1239 lu_byte right; /* right priority */
1240} priority[] = { /* ORDER OPR */
1241 {10, 10}, {10, 10}, /* '+' '-' */
1242 {11, 11}, {11, 11}, /* '*' '%' */
1243 {14, 13}, /* '^' (right associative) */
1244 {11, 11}, {11, 11}, /* '/' '//' */
1245 {6, 6}, {4, 4}, {5, 5}, /* '&' '|' '~' */
1246 {7, 7}, {7, 7}, /* '<<' '>>' */
1247 {9, 8}, /* '..' (right associative) */
1248 {3, 3}, {3, 3}, {3, 3}, /* ==, <, <= */
1249 {3, 3}, {3, 3}, {3, 3}, /* ~=, >, >= */
1250 {2, 2}, {1, 1} /* and, or */
1251};
1252
1253#define UNARY_PRIORITY 12 /* priority for unary operators */
1254
1255
1256/*
1257** subexpr -> (simpleexp | unop subexpr) { binop subexpr }
1258** where 'binop' is any binary operator with a priority higher than 'limit'
1259*/
1260static BinOpr subexpr (LexState *ls, expdesc *v, int limit) {
1261 BinOpr op;
1262 UnOpr uop;
1263 enterlevel(ls);
1264 uop = getunopr(ls->t.token);
1265 if (uop != OPR_NOUNOPR) { /* prefix (unary) operator? */
1266 int line = ls->linenumber;
1267 luaX_next(ls); /* skip operator */
1268 subexpr(ls, v, UNARY_PRIORITY);
1269 luaK_prefix(ls->fs, uop, v, line);
1270 }
1271 else simpleexp(ls, v);
1272 /* expand while operators have priorities higher than 'limit' */
1273 op = getbinopr(ls->t.token);
1274 while (op != OPR_NOBINOPR && priority[op].left > limit) {
1275 expdesc v2;
1276 BinOpr nextop;
1277 int line = ls->linenumber;
1278 luaX_next(ls); /* skip operator */
1279 luaK_infix(ls->fs, op, v);
1280 /* read sub-expression with higher priority */
1281 nextop = subexpr(ls, &v2, priority[op].right);
1282 luaK_posfix(ls->fs, op, v, &v2, line);
1283 op = nextop;
1284 }
1285 leavelevel(ls);
1286 return op; /* return first untreated operator */
1287}
1288
1289
1290static void expr (LexState *ls, expdesc *v) {
1291 subexpr(ls, v, 0);
1292}
1293
1294/* }==================================================================== */
1295
1296
1297
1298/*
1299** {======================================================================
1300** Rules for Statements
1301** =======================================================================
1302*/
1303
1304
1305static void block (LexState *ls) {
1306 /* block -> statlist */
1307 FuncState *fs = ls->fs;
1308 BlockCnt bl;
1309 enterblock(fs, &bl, 0);
1310 statlist(ls);
1311 leaveblock(fs);
1312}
1313
1314
1315/*
1316** structure to chain all variables in the left-hand side of an
1317** assignment
1318*/
1319struct LHS_assign {
1320 struct LHS_assign *prev;
1321 expdesc v; /* variable (global, local, upvalue, or indexed) */
1322};
1323
1324
1325/*
1326** check whether, in an assignment to an upvalue/local variable, the
1327** upvalue/local variable is begin used in a previous assignment to a
1328** table. If so, save original upvalue/local value in a safe place and
1329** use this safe copy in the previous assignment.
1330*/
1331static void check_conflict (LexState *ls, struct LHS_assign *lh, expdesc *v) {
1332 FuncState *fs = ls->fs;
1333 int extra = fs->freereg; /* eventual position to save local variable */
1334 int conflict = 0;
1335 for (; lh; lh = lh->prev) { /* check all previous assignments */
1336 if (vkisindexed(lh->v.k)) { /* assignment to table field? */
1337 if (lh->v.k == VINDEXUP) { /* is table an upvalue? */
1338 if (v->k == VUPVAL && lh->v.u.ind.t == v->u.info) {
1339 conflict = 1; /* table is the upvalue being assigned now */
1340 lh->v.k = VINDEXSTR;
1341 lh->v.u.ind.t = extra; /* assignment will use safe copy */
1342 }
1343 }
1344 else { /* table is a register */
1345 if (v->k == VLOCAL && lh->v.u.ind.t == v->u.var.ridx) {
1346 conflict = 1; /* table is the local being assigned now */
1347 lh->v.u.ind.t = extra; /* assignment will use safe copy */
1348 }
1349 /* is index the local being assigned? */
1350 if (lh->v.k == VINDEXED && v->k == VLOCAL &&
1351 lh->v.u.ind.idx == v->u.var.ridx) {
1352 conflict = 1;
1353 lh->v.u.ind.idx = extra; /* previous assignment will use safe copy */
1354 }
1355 }
1356 }
1357 }
1358 if (conflict) {
1359 /* copy upvalue/local value to a temporary (in position 'extra') */
1360 if (v->k == VLOCAL)
1361 luaK_codeABC(fs, OP_MOVE, extra, v->u.var.ridx, 0);
1362 else
1363 luaK_codeABC(fs, OP_GETUPVAL, extra, v->u.info, 0);
1364 luaK_reserveregs(fs, 1);
1365 }
1366}
1367
1368/*
1369** Parse and compile a multiple assignment. The first "variable"
1370** (a 'suffixedexp') was already read by the caller.
1371**
1372** assignment -> suffixedexp restassign
1373** restassign -> ',' suffixedexp restassign | '=' explist
1374*/
1375static void restassign (LexState *ls, struct LHS_assign *lh, int nvars) {
1376 expdesc e;
1377 check_condition(ls, vkisvar(lh->v.k), "syntax error");
1378 check_readonly(ls, &lh->v);
1379 if (testnext(ls, ',')) { /* restassign -> ',' suffixedexp restassign */
1380 struct LHS_assign nv;
1381 nv.prev = lh;
1382 suffixedexp(ls, &nv.v);
1383 if (!vkisindexed(nv.v.k))
1384 check_conflict(ls, lh, &nv.v);
1385 enterlevel(ls); /* control recursion depth */
1386 restassign(ls, &nv, nvars+1);
1387 leavelevel(ls);
1388 }
1389 else { /* restassign -> '=' explist */
1390 int nexps;
1391 checknext(ls, '=');
1392 nexps = explist(ls, &e);
1393 if (nexps != nvars)
1394 adjust_assign(ls, nvars, nexps, &e);
1395 else {
1396 luaK_setoneret(ls->fs, &e); /* close last expression */
1397 luaK_storevar(ls->fs, &lh->v, &e);
1398 return; /* avoid default */
1399 }
1400 }
1401 init_exp(&e, VNONRELOC, ls->fs->freereg-1); /* default assignment */
1402 luaK_storevar(ls->fs, &lh->v, &e);
1403}
1404
1405
1406static int cond (LexState *ls) {
1407 /* cond -> exp */
1408 expdesc v;
1409 expr(ls, &v); /* read condition */
1410 if (v.k == VNIL) v.k = VFALSE; /* 'falses' are all equal here */
1411 luaK_goiftrue(ls->fs, &v);
1412 return v.f;
1413}
1414
1415
1416static void gotostat (LexState *ls) {
1417 FuncState *fs = ls->fs;
1418 int line = ls->linenumber;
1419 TString *name = str_checkname(ls); /* label's name */
1420 Labeldesc *lb = findlabel(ls, name);
1421 if (lb == NULL) /* no label? */
1422 /* forward jump; will be resolved when the label is declared */
1423 newgotoentry(ls, name, line, luaK_jump(fs));
1424 else { /* found a label */
1425 /* backward jump; will be resolved here */
1426 int lblevel = reglevel(fs, lb->nactvar); /* label level */
1427 if (luaY_nvarstack(fs) > lblevel) /* leaving the scope of a variable? */
1428 luaK_codeABC(fs, OP_CLOSE, lblevel, 0, 0);
1429 /* create jump and link it to the label */
1430 luaK_patchlist(fs, luaK_jump(fs), lb->pc);
1431 }
1432}
1433
1434
1435/*
1436** Break statement. Semantically equivalent to "goto break".
1437*/
1438static void breakstat (LexState *ls) {
1439 int line = ls->linenumber;
1440 luaX_next(ls); /* skip break */
1441 newgotoentry(ls, luaS_newliteral(ls->L, "break"), line, luaK_jump(ls->fs));
1442}
1443
1444
1445/*
1446** Check whether there is already a label with the given 'name'.
1447*/
1448static void checkrepeated (LexState *ls, TString *name) {
1449 Labeldesc *lb = findlabel(ls, name);
1450 if (l_unlikely(lb != NULL)) { /* already defined? */
1451 const char *msg = "label '%s' already defined on line %d";
1452 msg = luaO_pushfstring(ls->L, msg, getstr(name), lb->line);
1453 luaK_semerror(ls, msg); /* error */
1454 }
1455}
1456
1457
1458static void labelstat (LexState *ls, TString *name, int line) {
1459 /* label -> '::' NAME '::' */
1460 checknext(ls, TK_DBCOLON); /* skip double colon */
1461 while (ls->t.token == ';' || ls->t.token == TK_DBCOLON)
1462 statement(ls); /* skip other no-op statements */
1463 checkrepeated(ls, name); /* check for repeated labels */
1464 createlabel(ls, name, line, block_follow(ls, 0));
1465}
1466
1467
1468static void whilestat (LexState *ls, int line) {
1469 /* whilestat -> WHILE cond DO block END */
1470 FuncState *fs = ls->fs;
1471 int whileinit;
1472 int condexit;
1473 BlockCnt bl;
1474 luaX_next(ls); /* skip WHILE */
1475 whileinit = luaK_getlabel(fs);
1476 condexit = cond(ls);
1477 enterblock(fs, &bl, 1);
1478 checknext(ls, TK_DO);
1479 block(ls);
1480 luaK_jumpto(fs, whileinit);
1481 check_match(ls, TK_END, TK_WHILE, line);
1482 leaveblock(fs);
1483 luaK_patchtohere(fs, condexit); /* false conditions finish the loop */
1484}
1485
1486
1487static void repeatstat (LexState *ls, int line) {
1488 /* repeatstat -> REPEAT block UNTIL cond */
1489 int condexit;
1490 FuncState *fs = ls->fs;
1491 int repeat_init = luaK_getlabel(fs);
1492 BlockCnt bl1, bl2;
1493 enterblock(fs, &bl1, 1); /* loop block */
1494 enterblock(fs, &bl2, 0); /* scope block */
1495 luaX_next(ls); /* skip REPEAT */
1496 statlist(ls);
1497 check_match(ls, TK_UNTIL, TK_REPEAT, line);
1498 condexit = cond(ls); /* read condition (inside scope block) */
1499 leaveblock(fs); /* finish scope */
1500 if (bl2.upval) { /* upvalues? */
1501 int exit = luaK_jump(fs); /* normal exit must jump over fix */
1502 luaK_patchtohere(fs, condexit); /* repetition must close upvalues */
1503 luaK_codeABC(fs, OP_CLOSE, reglevel(fs, bl2.nactvar), 0, 0);
1504 condexit = luaK_jump(fs); /* repeat after closing upvalues */
1505 luaK_patchtohere(fs, exit); /* normal exit comes to here */
1506 }
1507 luaK_patchlist(fs, condexit, repeat_init); /* close the loop */
1508 leaveblock(fs); /* finish loop */
1509}
1510
1511
1512/*
1513** Read an expression and generate code to put its results in next
1514** stack slot.
1515**
1516*/
1517static void exp1 (LexState *ls) {
1518 expdesc e;
1519 expr(ls, &e);
1520 luaK_exp2nextreg(ls->fs, &e);
1521 lua_assert(e.k == VNONRELOC);
1522}
1523
1524
1525/*
1526** Fix for instruction at position 'pc' to jump to 'dest'.
1527** (Jump addresses are relative in Lua). 'back' true means
1528** a back jump.
1529*/
1530static void fixforjump (FuncState *fs, int pc, int dest, int back) {
1531 Instruction *jmp = &fs->f->code[pc];
1532 int offset = dest - (pc + 1);
1533 if (back)
1534 offset = -offset;
1535 if (l_unlikely(offset > MAXARG_Bx))
1536 luaX_syntaxerror(fs->ls, "control structure too long");
1537 SETARG_Bx(*jmp, offset);
1538}
1539
1540
1541/*
1542** Generate code for a 'for' loop.
1543*/
1544static void forbody (LexState *ls, int base, int line, int nvars, int isgen) {
1545 /* forbody -> DO block */
1546 static const OpCode forprep[2] = {OP_FORPREP, OP_TFORPREP};
1547 static const OpCode forloop[2] = {OP_FORLOOP, OP_TFORLOOP};
1548 BlockCnt bl;
1549 FuncState *fs = ls->fs;
1550 int prep, endfor;
1551 checknext(ls, TK_DO);
1552 prep = luaK_codeABx(fs, forprep[isgen], base, 0);
1553 enterblock(fs, &bl, 0); /* scope for declared variables */
1554 adjustlocalvars(ls, nvars);
1555 luaK_reserveregs(fs, nvars);
1556 block(ls);
1557 leaveblock(fs); /* end of scope for declared variables */
1558 fixforjump(fs, prep, luaK_getlabel(fs), 0);
1559 if (isgen) { /* generic for? */
1560 luaK_codeABC(fs, OP_TFORCALL, base, 0, nvars);
1561 luaK_fixline(fs, line);
1562 }
1563 endfor = luaK_codeABx(fs, forloop[isgen], base, 0);
1564 fixforjump(fs, endfor, prep + 1, 1);
1565 luaK_fixline(fs, line);
1566}
1567
1568
1569static void fornum (LexState *ls, TString *varname, int line) {
1570 /* fornum -> NAME = exp,exp[,exp] forbody */
1571 FuncState *fs = ls->fs;
1572 int base = fs->freereg;
1573 new_localvarliteral(ls, "(for state)");
1574 new_localvarliteral(ls, "(for state)");
1575 new_localvarliteral(ls, "(for state)");
1576 new_localvar(ls, varname);
1577 checknext(ls, '=');
1578 exp1(ls); /* initial value */
1579 checknext(ls, ',');
1580 exp1(ls); /* limit */
1581 if (testnext(ls, ','))
1582 exp1(ls); /* optional step */
1583 else { /* default step = 1 */
1584 luaK_int(fs, fs->freereg, 1);
1585 luaK_reserveregs(fs, 1);
1586 }
1587 adjustlocalvars(ls, 3); /* control variables */
1588 forbody(ls, base, line, 1, 0);
1589}
1590
1591
1592static void forlist (LexState *ls, TString *indexname) {
1593 /* forlist -> NAME {,NAME} IN explist forbody */
1594 FuncState *fs = ls->fs;
1595 expdesc e;
1596 int nvars = 5; /* gen, state, control, toclose, 'indexname' */
1597 int line;
1598 int base = fs->freereg;
1599 /* create control variables */
1600 new_localvarliteral(ls, "(for state)");
1601 new_localvarliteral(ls, "(for state)");
1602 new_localvarliteral(ls, "(for state)");
1603 new_localvarliteral(ls, "(for state)");
1604 /* create declared variables */
1605 new_localvar(ls, indexname);
1606 while (testnext(ls, ',')) {
1607 new_localvar(ls, str_checkname(ls));
1608 nvars++;
1609 }
1610 checknext(ls, TK_IN);
1611 line = ls->linenumber;
1612 adjust_assign(ls, 4, explist(ls, &e), &e);
1613 adjustlocalvars(ls, 4); /* control variables */
1614 marktobeclosed(fs); /* last control var. must be closed */
1615 luaK_checkstack(fs, 3); /* extra space to call generator */
1616 forbody(ls, base, line, nvars - 4, 1);
1617}
1618
1619
1620static void forstat (LexState *ls, int line) {
1621 /* forstat -> FOR (fornum | forlist) END */
1622 FuncState *fs = ls->fs;
1623 TString *varname;
1624 BlockCnt bl;
1625 enterblock(fs, &bl, 1); /* scope for loop and control variables */
1626 luaX_next(ls); /* skip 'for' */
1627 varname = str_checkname(ls); /* first variable name */
1628 switch (ls->t.token) {
1629 case '=': fornum(ls, varname, line); break;
1630 case ',': case TK_IN: forlist(ls, varname); break;
1631 default: luaX_syntaxerror(ls, "'=' or 'in' expected");
1632 }
1633 check_match(ls, TK_END, TK_FOR, line);
1634 leaveblock(fs); /* loop scope ('break' jumps to this point) */
1635}
1636
1637
1638static void test_then_block (LexState *ls, int *escapelist) {
1639 /* test_then_block -> [IF | ELSEIF] cond THEN block */
1640 BlockCnt bl;
1641 FuncState *fs = ls->fs;
1642 expdesc v;
1643 int jf; /* instruction to skip 'then' code (if condition is false) */
1644 luaX_next(ls); /* skip IF or ELSEIF */
1645 expr(ls, &v); /* read condition */
1646 checknext(ls, TK_THEN);
1647 if (ls->t.token == TK_BREAK) { /* 'if x then break' ? */
1648 int line = ls->linenumber;
1649 luaK_goiffalse(ls->fs, &v); /* will jump if condition is true */
1650 luaX_next(ls); /* skip 'break' */
1651 enterblock(fs, &bl, 0); /* must enter block before 'goto' */
1652 newgotoentry(ls, luaS_newliteral(ls->L, "break"), line, v.t);
1653 while (testnext(ls, ';')) {} /* skip semicolons */
1654 if (block_follow(ls, 0)) { /* jump is the entire block? */
1655 leaveblock(fs);
1656 return; /* and that is it */
1657 }
1658 else /* must skip over 'then' part if condition is false */
1659 jf = luaK_jump(fs);
1660 }
1661 else { /* regular case (not a break) */
1662 luaK_goiftrue(ls->fs, &v); /* skip over block if condition is false */
1663 enterblock(fs, &bl, 0);
1664 jf = v.f;
1665 }
1666 statlist(ls); /* 'then' part */
1667 leaveblock(fs);
1668 if (ls->t.token == TK_ELSE ||
1669 ls->t.token == TK_ELSEIF) /* followed by 'else'/'elseif'? */
1670 luaK_concat(fs, escapelist, luaK_jump(fs)); /* must jump over it */
1671 luaK_patchtohere(fs, jf);
1672}
1673
1674
1675static void ifstat (LexState *ls, int line) {
1676 /* ifstat -> IF cond THEN block {ELSEIF cond THEN block} [ELSE block] END */
1677 FuncState *fs = ls->fs;
1678 int escapelist = NO_JUMP; /* exit list for finished parts */
1679 test_then_block(ls, &escapelist); /* IF cond THEN block */
1680 while (ls->t.token == TK_ELSEIF)
1681 test_then_block(ls, &escapelist); /* ELSEIF cond THEN block */
1682 if (testnext(ls, TK_ELSE))
1683 block(ls); /* 'else' part */
1684 check_match(ls, TK_END, TK_IF, line);
1685 luaK_patchtohere(fs, escapelist); /* patch escape list to 'if' end */
1686}
1687
1688
1689static void localfunc (LexState *ls) {
1690 expdesc b;
1691 FuncState *fs = ls->fs;
1692 int fvar = fs->nactvar; /* function's variable index */
1693 new_localvar(ls, str_checkname(ls)); /* new local variable */
1694 adjustlocalvars(ls, 1); /* enter its scope */
1695 body(ls, &b, 0, ls->linenumber); /* function created in next register */
1696 /* debug information will only see the variable after this point! */
1697 localdebuginfo(fs, fvar)->startpc = fs->pc;
1698}
1699
1700
1701static int getlocalattribute (LexState *ls) {
1702 /* ATTRIB -> ['<' Name '>'] */
1703 if (testnext(ls, '<')) {
1704 const char *attr = getstr(str_checkname(ls));
1705 checknext(ls, '>');
1706 if (strcmp(attr, "const") == 0)
1707 return RDKCONST; /* read-only variable */
1708 else if (strcmp(attr, "close") == 0)
1709 return RDKTOCLOSE; /* to-be-closed variable */
1710 else
1711 luaK_semerror(ls,
1712 luaO_pushfstring(ls->L, "unknown attribute '%s'", attr));
1713 }
1714 return VDKREG; /* regular variable */
1715}
1716
1717
1718static void checktoclose (FuncState *fs, int level) {
1719 if (level != -1) { /* is there a to-be-closed variable? */
1720 marktobeclosed(fs);
1721 luaK_codeABC(fs, OP_TBC, reglevel(fs, level), 0, 0);
1722 }
1723}
1724
1725
1726static void localstat (LexState *ls) {
1727 /* stat -> LOCAL NAME ATTRIB { ',' NAME ATTRIB } ['=' explist] */
1728 FuncState *fs = ls->fs;
1729 int toclose = -1; /* index of to-be-closed variable (if any) */
1730 Vardesc *var; /* last variable */
1731 int vidx, kind; /* index and kind of last variable */
1732 int nvars = 0;
1733 int nexps;
1734 expdesc e;
1735 do {
1736 vidx = new_localvar(ls, str_checkname(ls));
1737 kind = getlocalattribute(ls);
1738 getlocalvardesc(fs, vidx)->vd.kind = kind;
1739 if (kind == RDKTOCLOSE) { /* to-be-closed? */
1740 if (toclose != -1) /* one already present? */
1741 luaK_semerror(ls, "multiple to-be-closed variables in local list");
1742 toclose = fs->nactvar + nvars;
1743 }
1744 nvars++;
1745 } while (testnext(ls, ','));
1746 if (testnext(ls, '='))
1747 nexps = explist(ls, &e);
1748 else {
1749 e.k = VVOID;
1750 nexps = 0;
1751 }
1752 var = getlocalvardesc(fs, vidx); /* get last variable */
1753 if (nvars == nexps && /* no adjustments? */
1754 var->vd.kind == RDKCONST && /* last variable is const? */
1755 luaK_exp2const(fs, &e, &var->k)) { /* compile-time constant? */
1756 var->vd.kind = RDKCTC; /* variable is a compile-time constant */
1757 adjustlocalvars(ls, nvars - 1); /* exclude last variable */
1758 fs->nactvar++; /* but count it */
1759 }
1760 else {
1761 adjust_assign(ls, nvars, nexps, &e);
1762 adjustlocalvars(ls, nvars);
1763 }
1764 checktoclose(fs, toclose);
1765}
1766
1767
1768static int funcname (LexState *ls, expdesc *v) {
1769 /* funcname -> NAME {fieldsel} [':' NAME] */
1770 int ismethod = 0;
1771 singlevar(ls, v);
1772 while (ls->t.token == '.')
1773 fieldsel(ls, v);
1774 if (ls->t.token == ':') {
1775 ismethod = 1;
1776 fieldsel(ls, v);
1777 }
1778 return ismethod;
1779}
1780
1781
1782static void funcstat (LexState *ls, int line) {
1783 /* funcstat -> FUNCTION funcname body */
1784 int ismethod;
1785 expdesc v, b;
1786 luaX_next(ls); /* skip FUNCTION */
1787 ismethod = funcname(ls, &v);
1788 body(ls, &b, ismethod, line);
1789 check_readonly(ls, &v);
1790 luaK_storevar(ls->fs, &v, &b);
1791 luaK_fixline(ls->fs, line); /* definition "happens" in the first line */
1792}
1793
1794
1795static void exprstat (LexState *ls) {
1796 /* stat -> func | assignment */
1797 FuncState *fs = ls->fs;
1798 struct LHS_assign v;
1799 suffixedexp(ls, &v.v);
1800 if (ls->t.token == '=' || ls->t.token == ',') { /* stat -> assignment ? */
1801 v.prev = NULL;
1802 restassign(ls, &v, 1);
1803 }
1804 else { /* stat -> func */
1805 Instruction *inst;
1806 check_condition(ls, v.v.k == VCALL, "syntax error");
1807 inst = &getinstruction(fs, &v.v);
1808 SETARG_C(*inst, 1); /* call statement uses no results */
1809 }
1810}
1811
1812
1813static void retstat (LexState *ls) {
1814 /* stat -> RETURN [explist] [';'] */
1815 FuncState *fs = ls->fs;
1816 expdesc e;
1817 int nret; /* number of values being returned */
1818 int first = luaY_nvarstack(fs); /* first slot to be returned */
1819 if (block_follow(ls, 1) || ls->t.token == ';')
1820 nret = 0; /* return no values */
1821 else {
1822 nret = explist(ls, &e); /* optional return values */
1823 if (hasmultret(e.k)) {
1824 luaK_setmultret(fs, &e);
1825 if (e.k == VCALL && nret == 1 && !fs->bl->insidetbc) { /* tail call? */
1826 SET_OPCODE(getinstruction(fs,&e), OP_TAILCALL);
1827 lua_assert(GETARG_A(getinstruction(fs,&e)) == luaY_nvarstack(fs));
1828 }
1829 nret = LUA_MULTRET; /* return all values */
1830 }
1831 else {
1832 if (nret == 1) /* only one single value? */
1833 first = luaK_exp2anyreg(fs, &e); /* can use original slot */
1834 else { /* values must go to the top of the stack */
1835 luaK_exp2nextreg(fs, &e);
1836 lua_assert(nret == fs->freereg - first);
1837 }
1838 }
1839 }
1840 luaK_ret(fs, first, nret);
1841 testnext(ls, ';'); /* skip optional semicolon */
1842}
1843
1844
1845static void statement (LexState *ls) {
1846 int line = ls->linenumber; /* may be needed for error messages */
1847 enterlevel(ls);
1848 switch (ls->t.token) {
1849 case ';': { /* stat -> ';' (empty statement) */
1850 luaX_next(ls); /* skip ';' */
1851 break;
1852 }
1853 case TK_IF: { /* stat -> ifstat */
1854 ifstat(ls, line);
1855 break;
1856 }
1857 case TK_WHILE: { /* stat -> whilestat */
1858 whilestat(ls, line);
1859 break;
1860 }
1861 case TK_DO: { /* stat -> DO block END */
1862 luaX_next(ls); /* skip DO */
1863 block(ls);
1864 check_match(ls, TK_END, TK_DO, line);
1865 break;
1866 }
1867 case TK_FOR: { /* stat -> forstat */
1868 forstat(ls, line);
1869 break;
1870 }
1871 case TK_REPEAT: { /* stat -> repeatstat */
1872 repeatstat(ls, line);
1873 break;
1874 }
1875 case TK_FUNCTION: { /* stat -> funcstat */
1876 funcstat(ls, line);
1877 break;
1878 }
1879 case TK_LOCAL: { /* stat -> localstat */
1880 luaX_next(ls); /* skip LOCAL */
1881 if (testnext(ls, TK_FUNCTION)) /* local function? */
1882 localfunc(ls);
1883 else
1884 localstat(ls);
1885 break;
1886 }
1887 case TK_DBCOLON: { /* stat -> label */
1888 luaX_next(ls); /* skip double colon */
1889 labelstat(ls, str_checkname(ls), line);
1890 break;
1891 }
1892 case TK_RETURN: { /* stat -> retstat */
1893 luaX_next(ls); /* skip RETURN */
1894 retstat(ls);
1895 break;
1896 }
1897 case TK_BREAK: { /* stat -> breakstat */
1898 breakstat(ls);
1899 break;
1900 }
1901 case TK_GOTO: { /* stat -> 'goto' NAME */
1902 luaX_next(ls); /* skip 'goto' */
1903 gotostat(ls);
1904 break;
1905 }
1906 default: { /* stat -> func | assignment */
1907 exprstat(ls);
1908 break;
1909 }
1910 }
1911 lua_assert(ls->fs->f->maxstacksize >= ls->fs->freereg &&
1912 ls->fs->freereg >= luaY_nvarstack(ls->fs));
1913 ls->fs->freereg = luaY_nvarstack(ls->fs); /* free registers */
1914 leavelevel(ls);
1915}
1916
1917/* }====================================================================== */
1918
1919
1920/*
1921** compiles the main function, which is a regular vararg function with an
1922** upvalue named LUA_ENV
1923*/
1924static void mainfunc (LexState *ls, FuncState *fs) {
1925 BlockCnt bl;
1926 Upvaldesc *env;
1927 open_func(ls, fs, &bl);
1928 setvararg(fs, 0); /* main function is always declared vararg */
1929 env = allocupvalue(fs); /* ...set environment upvalue */
1930 env->instack = 1;
1931 env->idx = 0;
1932 env->kind = VDKREG;
1933 env->name = ls->envn;
1934 luaC_objbarrier(ls->L, fs->f, env->name);
1935 luaX_next(ls); /* read first token */
1936 statlist(ls); /* parse main body */
1937 check(ls, TK_EOS);
1938 close_func(ls);
1939}
1940
1941
1942LClosure *luaY_parser (lua_State *L, ZIO *z, Mbuffer *buff,
1943 Dyndata *dyd, const char *name, int firstchar) {
1944 LexState lexstate;
1945 FuncState funcstate;
1946 LClosure *cl = luaF_newLclosure(L, 1); /* create main closure */
1947 setclLvalue2s(L, L->top.p, cl); /* anchor it (to avoid being collected) */
1948 luaD_inctop(L);
1949 lexstate.h = luaH_new(L); /* create table for scanner */
1950 sethvalue2s(L, L->top.p, lexstate.h); /* anchor it */
1951 luaD_inctop(L);
1952 funcstate.f = cl->p = luaF_newproto(L);
1953 luaC_objbarrier(L, cl, cl->p);
1954 funcstate.f->source = luaS_new(L, name); /* create and anchor TString */
1955 luaC_objbarrier(L, funcstate.f, funcstate.f->source);
1956 lexstate.buff = buff;
1957 lexstate.dyd = dyd;
1958 dyd->actvar.n = dyd->gt.n = dyd->label.n = 0;
1959 luaX_setinput(L, &lexstate, z, funcstate.f->source, firstchar);
1960 mainfunc(&lexstate, &funcstate);
1961 lua_assert(!funcstate.prev && funcstate.nups == 1 && !lexstate.fs);
1962 /* all scopes should be correctly finished */
1963 lua_assert(dyd->actvar.n == 0 && dyd->gt.n == 0 && dyd->label.n == 0);
1964 L->top.p--; /* remove scanner's table */
1965 return cl; /* closure is on the stack, too */
1966}
1967