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