1 /*
2 ** $Id: lparser.c,v 2.130.1.1 2013/04/12 18:48:47 roberto Exp $
3 ** Lua Parser
4 ** See Copyright Notice in lua.h
5 */
6 
7 
8 #include <string.h>
9 
10 #define lparser_c
11 #define LUA_CORE
12 
13 #include "lua.h"
14 
15 #include "lcode.h"
16 #include "ldebug.h"
17 #include "ldo.h"
18 #include "lfunc.h"
19 #include "llex.h"
20 #include "lmem.h"
21 #include "lobject.h"
22 #include "lopcodes.h"
23 #include "lparser.h"
24 #include "lstate.h"
25 #include "lstring.h"
26 #include "ltable.h"
27 
28 
29 
30 /* maximum number of local variables per function (must be smaller
31    than 250, due to the bytecode format) */
32 #define MAXVARS     200
33 
34 
35 #define hasmultret(k)       ((k) == VCALL || (k) == VVARARG)
36 
37 
38 
39 /*
40 ** nodes for block list (list of active blocks)
41 */
42 typedef struct BlockCnt {
43   struct BlockCnt *previous;  /* chain */
44   short firstlabel;  /* index of first label in this block */
45   short firstgoto;  /* index of first pending goto in this block */
46   lu_byte nactvar;  /* # active locals outside the block */
47   lu_byte upval;  /* true if some variable in the block is an upvalue */
48   lu_byte isloop;  /* true if `block' is a loop */
49 } BlockCnt;
50 
51 
52 
53 /*
54 ** prototypes for recursive non-terminal functions
55 */
56 static void statement (LexState *ls);
57 static void expr (LexState *ls, expdesc *v);
58 
59 
anchor_token(LexState * ls)60 static void anchor_token (LexState *ls) {
61   /* last token from outer function must be EOS */
62   lua_assert(ls->fs != NULL || ls->t.token == TK_EOS);
63   if (ls->t.token == TK_NAME || ls->t.token == TK_STRING) {
64     TString *ts = ls->t.seminfo.ts;
65     luaX_newstring(ls, getstr(ts), ts->tsv.len);
66   }
67 }
68 
69 
70 /* semantic error */
semerror(LexState * ls,const char * msg)71 static l_noret semerror (LexState *ls, const char *msg) {
72   ls->t.token = 0;  /* remove 'near to' from final message */
73   luaX_syntaxerror(ls, msg);
74 }
75 
76 
error_expected(LexState * ls,int token)77 static l_noret error_expected (LexState *ls, int token) {
78   luaX_syntaxerror(ls,
79       luaO_pushfstring(ls->L, "%s expected", luaX_token2str(ls, token)));
80 }
81 
82 
errorlimit(FuncState * fs,int limit,const char * what)83 static l_noret errorlimit (FuncState *fs, int limit, const char *what) {
84   lua_State *L = fs->ls->L;
85   const char *msg;
86   int line = fs->f->linedefined;
87   const char *where = (line == 0)
88                       ? "main function"
89                       : luaO_pushfstring(L, "function at line %d", line);
90   msg = luaO_pushfstring(L, "too many %s (limit is %d) in %s",
91                              what, limit, where);
92   luaX_syntaxerror(fs->ls, msg);
93 }
94 
95 
checklimit(FuncState * fs,int v,int l,const char * what)96 static void checklimit (FuncState *fs, int v, int l, const char *what) {
97   if (v > l) errorlimit(fs, l, what);
98 }
99 
100 
testnext(LexState * ls,int c)101 static int testnext (LexState *ls, int c) {
102   if (ls->t.token == c) {
103     luaX_next(ls);
104     return 1;
105   }
106   else return 0;
107 }
108 
109 
check(LexState * ls,int c)110 static void check (LexState *ls, int c) {
111   if (ls->t.token != c)
112     error_expected(ls, c);
113 }
114 
115 
checknext(LexState * ls,int c)116 static 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 
check_match(LexState * ls,int what,int who,int where)126 static void check_match (LexState *ls, int what, int who, int where) {
127   if (!testnext(ls, what)) {
128     if (where == ls->linenumber)
129       error_expected(ls, what);
130     else {
131       luaX_syntaxerror(ls, luaO_pushfstring(ls->L,
132              "%s expected (to close %s at line %d)",
133               luaX_token2str(ls, what), luaX_token2str(ls, who), where));
134     }
135   }
136 }
137 
138 
str_checkname(LexState * ls)139 static TString *str_checkname (LexState *ls) {
140   TString *ts;
141   check(ls, TK_NAME);
142   ts = ls->t.seminfo.ts;
143   luaX_next(ls);
144   return ts;
145 }
146 
147 
init_exp(expdesc * e,expkind k,int i)148 static void init_exp (expdesc *e, expkind k, int i) {
149   e->f = e->t = NO_JUMP;
150   e->k = k;
151   e->u.info = i;
152 }
153 
154 
codestring(LexState * ls,expdesc * e,TString * s)155 static void codestring (LexState *ls, expdesc *e, TString *s) {
156   init_exp(e, VK, luaK_stringK(ls->fs, s));
157 }
158 
159 
checkname(LexState * ls,expdesc * e)160 static void checkname (LexState *ls, expdesc *e) {
161   codestring(ls, e, str_checkname(ls));
162 }
163 
164 
registerlocalvar(LexState * ls,TString * varname)165 static int registerlocalvar (LexState *ls, TString *varname) {
166   FuncState *fs = ls->fs;
167   Proto *f = fs->f;
168   int oldsize = f->sizelocvars;
169   luaM_growvector(ls->L, f->locvars, fs->nlocvars, f->sizelocvars,
170                   LocVar, SHRT_MAX, "local variables");
171   while (oldsize < f->sizelocvars) f->locvars[oldsize++].varname = NULL;
172   f->locvars[fs->nlocvars].varname = varname;
173   luaC_objbarrier(ls->L, f, varname);
174   return fs->nlocvars++;
175 }
176 
177 
new_localvar(LexState * ls,TString * name)178 static void new_localvar (LexState *ls, TString *name) {
179   FuncState *fs = ls->fs;
180   Dyndata *dyd = ls->dyd;
181   int reg = registerlocalvar(ls, name);
182   checklimit(fs, dyd->actvar.n + 1 - fs->firstlocal,
183                   MAXVARS, "local variables");
184   luaM_growvector(ls->L, dyd->actvar.arr, dyd->actvar.n + 1,
185                   dyd->actvar.size, Vardesc, MAX_INT, "local variables");
186   dyd->actvar.arr[dyd->actvar.n++].idx = cast(short, reg);
187 }
188 
189 
new_localvarliteral_(LexState * ls,const char * name,size_t sz)190 static void new_localvarliteral_ (LexState *ls, const char *name, size_t sz) {
191   new_localvar(ls, luaX_newstring(ls, name, sz));
192 }
193 
194 #define new_localvarliteral(ls,v) \
195     new_localvarliteral_(ls, "" v, (sizeof(v)/sizeof(char))-1)
196 
197 
getlocvar(FuncState * fs,int i)198 static LocVar *getlocvar (FuncState *fs, int i) {
199   int idx = fs->ls->dyd->actvar.arr[fs->firstlocal + i].idx;
200   lua_assert(idx < fs->nlocvars);
201   return &fs->f->locvars[idx];
202 }
203 
204 
adjustlocalvars(LexState * ls,int nvars)205 static void adjustlocalvars (LexState *ls, int nvars) {
206   FuncState *fs = ls->fs;
207   fs->nactvar = cast_byte(fs->nactvar + nvars);
208   for (; nvars; nvars--) {
209     getlocvar(fs, fs->nactvar - nvars)->startpc = fs->pc;
210   }
211 }
212 
213 
removevars(FuncState * fs,int tolevel)214 static void removevars (FuncState *fs, int tolevel) {
215   fs->ls->dyd->actvar.n -= (fs->nactvar - tolevel);
216   while (fs->nactvar > tolevel)
217     getlocvar(fs, --fs->nactvar)->endpc = fs->pc;
218 }
219 
220 
searchupvalue(FuncState * fs,TString * name)221 static int searchupvalue (FuncState *fs, TString *name) {
222   int i;
223   Upvaldesc *up = fs->f->upvalues;
224   for (i = 0; i < fs->nups; i++) {
225     if (luaS_eqstr(up[i].name, name)) return i;
226   }
227   return -1;  /* not found */
228 }
229 
230 
newupvalue(FuncState * fs,TString * name,expdesc * v)231 static int newupvalue (FuncState *fs, TString *name, expdesc *v) {
232   Proto *f = fs->f;
233   int oldsize = f->sizeupvalues;
234   checklimit(fs, fs->nups + 1, MAXUPVAL, "upvalues");
235   luaM_growvector(fs->ls->L, f->upvalues, fs->nups, f->sizeupvalues,
236                   Upvaldesc, MAXUPVAL, "upvalues");
237   while (oldsize < f->sizeupvalues) f->upvalues[oldsize++].name = NULL;
238   f->upvalues[fs->nups].instack = (v->k == VLOCAL);
239   f->upvalues[fs->nups].idx = cast_byte(v->u.info);
240   f->upvalues[fs->nups].name = name;
241   luaC_objbarrier(fs->ls->L, f, name);
242   return fs->nups++;
243 }
244 
245 
searchvar(FuncState * fs,TString * n)246 static int searchvar (FuncState *fs, TString *n) {
247   int i;
248   for (i = cast_int(fs->nactvar) - 1; i >= 0; i--) {
249     if (luaS_eqstr(n, getlocvar(fs, i)->varname))
250       return i;
251   }
252   return -1;  /* not found */
253 }
254 
255 
256 /*
257   Mark block where variable at given level was defined
258   (to emit close instructions later).
259 */
markupval(FuncState * fs,int level)260 static void markupval (FuncState *fs, int level) {
261   BlockCnt *bl = fs->bl;
262   while (bl->nactvar > level) bl = bl->previous;
263   bl->upval = 1;
264 }
265 
266 
267 /*
268   Find variable with given name 'n'. If it is an upvalue, add this
269   upvalue into all intermediate functions.
270 */
singlevaraux(FuncState * fs,TString * n,expdesc * var,int base)271 static int singlevaraux (FuncState *fs, TString *n, expdesc *var, int base) {
272   if (fs == NULL)  /* no more levels? */
273     return VVOID;  /* default is global */
274   else {
275     int v = searchvar(fs, n);  /* look up locals at current level */
276     if (v >= 0) {  /* found? */
277       init_exp(var, VLOCAL, v);  /* variable is local */
278       if (!base)
279         markupval(fs, v);  /* local will be used as an upval */
280       return VLOCAL;
281     }
282     else {  /* not found as local at current level; try upvalues */
283       int idx = searchupvalue(fs, n);  /* try existing upvalues */
284       if (idx < 0) {  /* not found? */
285         if (singlevaraux(fs->prev, n, var, 0) == VVOID) /* try upper levels */
286           return VVOID;  /* not found; is a global */
287         /* else was LOCAL or UPVAL */
288         idx  = newupvalue(fs, n, var);  /* will be a new upvalue */
289       }
290       init_exp(var, VUPVAL, idx);
291       return VUPVAL;
292     }
293   }
294 }
295 
296 
singlevar(LexState * ls,expdesc * var)297 static void singlevar (LexState *ls, expdesc *var) {
298   TString *varname = str_checkname(ls);
299   FuncState *fs = ls->fs;
300   if (singlevaraux(fs, varname, var, 1) == VVOID) {  /* global name? */
301     expdesc key;
302     singlevaraux(fs, ls->envn, var, 1);  /* get environment variable */
303     lua_assert(var->k == VLOCAL || var->k == VUPVAL);
304     codestring(ls, &key, varname);  /* key is variable name */
305     luaK_indexed(fs, var, &key);  /* env[varname] */
306   }
307 }
308 
309 
adjust_assign(LexState * ls,int nvars,int nexps,expdesc * e)310 static void adjust_assign (LexState *ls, int nvars, int nexps, expdesc *e) {
311   FuncState *fs = ls->fs;
312   int extra = nvars - nexps;
313   if (hasmultret(e->k)) {
314     extra++;  /* includes call itself */
315     if (extra < 0) extra = 0;
316     luaK_setreturns(fs, e, extra);  /* last exp. provides the difference */
317     if (extra > 1) luaK_reserveregs(fs, extra-1);
318   }
319   else {
320     if (e->k != VVOID) luaK_exp2nextreg(fs, e);  /* close last expression */
321     if (extra > 0) {
322       int reg = fs->freereg;
323       luaK_reserveregs(fs, extra);
324       luaK_nil(fs, reg, extra);
325     }
326   }
327 }
328 
329 
enterlevel(LexState * ls)330 static void enterlevel (LexState *ls) {
331   lua_State *L = ls->L;
332   ++L->nCcalls;
333   checklimit(ls->fs, L->nCcalls, LUAI_MAXCCALLS, "C levels");
334 }
335 
336 
337 #define leavelevel(ls)  ((ls)->L->nCcalls--)
338 
339 
closegoto(LexState * ls,int g,Labeldesc * label)340 static void closegoto (LexState *ls, int g, Labeldesc *label) {
341   int i;
342   FuncState *fs = ls->fs;
343   Labellist *gl = &ls->dyd->gt;
344   Labeldesc *gt = &gl->arr[g];
345   lua_assert(luaS_eqstr(gt->name, label->name));
346   if (gt->nactvar < label->nactvar) {
347     TString *vname = getlocvar(fs, gt->nactvar)->varname;
348     const char *msg = luaO_pushfstring(ls->L,
349       "<goto %s> at line %d jumps into the scope of local " LUA_QS,
350       getstr(gt->name), gt->line, getstr(vname));
351     semerror(ls, msg);
352   }
353   luaK_patchlist(fs, gt->pc, label->pc);
354   /* remove goto from pending list */
355   for (i = g; i < gl->n - 1; i++)
356     gl->arr[i] = gl->arr[i + 1];
357   gl->n--;
358 }
359 
360 
361 /*
362 ** try to close a goto with existing labels; this solves backward jumps
363 */
findlabel(LexState * ls,int g)364 static int findlabel (LexState *ls, int g) {
365   int i;
366   BlockCnt *bl = ls->fs->bl;
367   Dyndata *dyd = ls->dyd;
368   Labeldesc *gt = &dyd->gt.arr[g];
369   /* check labels in current block for a match */
370   for (i = bl->firstlabel; i < dyd->label.n; i++) {
371     Labeldesc *lb = &dyd->label.arr[i];
372     if (luaS_eqstr(lb->name, gt->name)) {  /* correct label? */
373       if (gt->nactvar > lb->nactvar &&
374           (bl->upval || dyd->label.n > bl->firstlabel))
375         luaK_patchclose(ls->fs, gt->pc, lb->nactvar);
376       closegoto(ls, g, lb);  /* close it */
377       return 1;
378     }
379   }
380   return 0;  /* label not found; cannot close goto */
381 }
382 
383 
newlabelentry(LexState * ls,Labellist * l,TString * name,int line,int pc)384 static int newlabelentry (LexState *ls, Labellist *l, TString *name,
385                           int line, int pc) {
386   int n = l->n;
387   luaM_growvector(ls->L, l->arr, n, l->size,
388                   Labeldesc, SHRT_MAX, "labels/gotos");
389   l->arr[n].name = name;
390   l->arr[n].line = line;
391   l->arr[n].nactvar = ls->fs->nactvar;
392   l->arr[n].pc = pc;
393   l->n++;
394   return n;
395 }
396 
397 
398 /*
399 ** check whether new label 'lb' matches any pending gotos in current
400 ** block; solves forward jumps
401 */
findgotos(LexState * ls,Labeldesc * lb)402 static void findgotos (LexState *ls, Labeldesc *lb) {
403   Labellist *gl = &ls->dyd->gt;
404   int i = ls->fs->bl->firstgoto;
405   while (i < gl->n) {
406     if (luaS_eqstr(gl->arr[i].name, lb->name))
407       closegoto(ls, i, lb);
408     else
409       i++;
410   }
411 }
412 
413 
414 /*
415 ** "export" pending gotos to outer level, to check them against
416 ** outer labels; if the block being exited has upvalues, and
417 ** the goto exits the scope of any variable (which can be the
418 ** upvalue), close those variables being exited.
419 */
movegotosout(FuncState * fs,BlockCnt * bl)420 static void movegotosout (FuncState *fs, BlockCnt *bl) {
421   int i = bl->firstgoto;
422   Labellist *gl = &fs->ls->dyd->gt;
423   /* correct pending gotos to current block and try to close it
424      with visible labels */
425   while (i < gl->n) {
426     Labeldesc *gt = &gl->arr[i];
427     if (gt->nactvar > bl->nactvar) {
428       if (bl->upval)
429         luaK_patchclose(fs, gt->pc, bl->nactvar);
430       gt->nactvar = bl->nactvar;
431     }
432     if (!findlabel(fs->ls, i))
433       i++;  /* move to next one */
434   }
435 }
436 
437 
enterblock(FuncState * fs,BlockCnt * bl,lu_byte isloop)438 static void enterblock (FuncState *fs, BlockCnt *bl, lu_byte isloop) {
439   bl->isloop = isloop;
440   bl->nactvar = fs->nactvar;
441   bl->firstlabel = (short)fs->ls->dyd->label.n;
442   bl->firstgoto = (short)fs->ls->dyd->gt.n;
443   bl->upval = 0;
444   bl->previous = fs->bl;
445   fs->bl = bl;
446   lua_assert(fs->freereg == fs->nactvar);
447 }
448 
449 
450 /*
451 ** create a label named "break" to resolve break statements
452 */
breaklabel(LexState * ls)453 static void breaklabel (LexState *ls) {
454   TString *n = luaS_new(ls->L, "break");
455   int l = newlabelentry(ls, &ls->dyd->label, n, 0, ls->fs->pc);
456   findgotos(ls, &ls->dyd->label.arr[l]);
457 }
458 
459 /*
460 ** generates an error for an undefined 'goto'; choose appropriate
461 ** message when label name is a reserved word (which can only be 'break')
462 */
undefgoto(LexState * ls,Labeldesc * gt)463 static l_noret undefgoto (LexState *ls, Labeldesc *gt) {
464   const char *msg = isreserved(gt->name)
465                     ? "<%s> at line %d not inside a loop"
466                     : "no visible label " LUA_QS " for <goto> at line %d";
467   msg = luaO_pushfstring(ls->L, msg, getstr(gt->name), gt->line);
468   semerror(ls, msg);
469 }
470 
471 
leaveblock(FuncState * fs)472 static void leaveblock (FuncState *fs) {
473   BlockCnt *bl = fs->bl;
474   LexState *ls = fs->ls;
475   if (bl->previous && bl->upval) {
476     /* create a 'jump to here' to close upvalues */
477     int j = luaK_jump(fs);
478     luaK_patchclose(fs, j, bl->nactvar);
479     luaK_patchtohere(fs, j);
480   }
481   if (bl->isloop)
482     breaklabel(ls);  /* close pending breaks */
483   fs->bl = bl->previous;
484   removevars(fs, bl->nactvar);
485   lua_assert(bl->nactvar == fs->nactvar);
486   fs->freereg = fs->nactvar;  /* free registers */
487   ls->dyd->label.n = bl->firstlabel;  /* remove local labels */
488   if (bl->previous)  /* inner block? */
489     movegotosout(fs, bl);  /* update pending gotos to outer block */
490   else if (bl->firstgoto < ls->dyd->gt.n)  /* pending gotos in outer block? */
491     undefgoto(ls, &ls->dyd->gt.arr[bl->firstgoto]);  /* error */
492 }
493 
494 
495 /*
496 ** adds a new prototype into list of prototypes
497 */
addprototype(LexState * ls)498 static Proto *addprototype (LexState *ls) {
499   Proto *clp;
500   lua_State *L = ls->L;
501   FuncState *fs = ls->fs;
502   Proto *f = fs->f;  /* prototype of current function */
503   if (fs->np >= f->sizep) {
504     int oldsize = f->sizep;
505     luaM_growvector(L, f->p, fs->np, f->sizep, Proto *, MAXARG_Bx, "functions");
506     while (oldsize < f->sizep) f->p[oldsize++] = NULL;
507   }
508   f->p[fs->np++] = clp = luaF_newproto(L);
509   luaC_objbarrier(L, f, clp);
510   return clp;
511 }
512 
513 
514 /*
515 ** codes instruction to create new closure in parent function.
516 ** The OP_CLOSURE instruction must use the last available register,
517 ** so that, if it invokes the GC, the GC knows which registers
518 ** are in use at that time.
519 */
codeclosure(LexState * ls,expdesc * v)520 static void codeclosure (LexState *ls, expdesc *v) {
521   FuncState *fs = ls->fs->prev;
522   init_exp(v, VRELOCABLE, luaK_codeABx(fs, OP_CLOSURE, 0, fs->np - 1));
523   luaK_exp2nextreg(fs, v);  /* fix it at the last register */
524 }
525 
526 
open_func(LexState * ls,FuncState * fs,BlockCnt * bl)527 static void open_func (LexState *ls, FuncState *fs, BlockCnt *bl) {
528   lua_State *L = ls->L;
529   Proto *f;
530   fs->prev = ls->fs;  /* linked list of funcstates */
531   fs->ls = ls;
532   ls->fs = fs;
533   fs->pc = 0;
534   fs->lasttarget = 0;
535   fs->jpc = NO_JUMP;
536   fs->freereg = 0;
537   fs->nk = 0;
538   fs->np = 0;
539   fs->nups = 0;
540   fs->nlocvars = 0;
541   fs->nactvar = 0;
542   fs->firstlocal = ls->dyd->actvar.n;
543   fs->bl = NULL;
544   f = fs->f;
545   f->source = ls->source;
546   f->maxstacksize = 2;  /* registers 0/1 are always valid */
547   fs->h = luaH_new(L);
548   /* anchor table of constants (to avoid being collected) */
549   sethvalue2s(L, L->top, fs->h);
550   incr_top(L);
551   enterblock(fs, bl, 0);
552 }
553 
554 
close_func(LexState * ls)555 static void close_func (LexState *ls) {
556   lua_State *L = ls->L;
557   FuncState *fs = ls->fs;
558   Proto *f = fs->f;
559   luaK_ret(fs, 0, 0);  /* final return */
560   leaveblock(fs);
561   luaM_reallocvector(L, f->code, f->sizecode, fs->pc, Instruction);
562   f->sizecode = fs->pc;
563   luaM_reallocvector(L, f->lineinfo, f->sizelineinfo, fs->pc, int);
564   f->sizelineinfo = fs->pc;
565   luaM_reallocvector(L, f->k, f->sizek, fs->nk, TValue);
566   f->sizek = fs->nk;
567   luaM_reallocvector(L, f->p, f->sizep, fs->np, Proto *);
568   f->sizep = fs->np;
569   luaM_reallocvector(L, f->locvars, f->sizelocvars, fs->nlocvars, LocVar);
570   f->sizelocvars = fs->nlocvars;
571   luaM_reallocvector(L, f->upvalues, f->sizeupvalues, fs->nups, Upvaldesc);
572   f->sizeupvalues = fs->nups;
573   lua_assert(fs->bl == NULL);
574   ls->fs = fs->prev;
575   /* last token read was anchored in defunct function; must re-anchor it */
576   anchor_token(ls);
577   L->top--;  /* pop table of constants */
578   luaC_checkGC(L);
579 }
580 
581 
582 
583 /*============================================================*/
584 /* GRAMMAR RULES */
585 /*============================================================*/
586 
587 
588 /*
589 ** check whether current token is in the follow set of a block.
590 ** 'until' closes syntactical blocks, but do not close scope,
591 ** so it handled in separate.
592 */
block_follow(LexState * ls,int withuntil)593 static int block_follow (LexState *ls, int withuntil) {
594   switch (ls->t.token) {
595     case TK_ELSE: case TK_ELSEIF:
596     case TK_END: case TK_EOS:
597       return 1;
598     case TK_UNTIL: return withuntil;
599     default: return 0;
600   }
601 }
602 
603 
statlist(LexState * ls)604 static void statlist (LexState *ls) {
605   /* statlist -> { stat [`;'] } */
606   while (!block_follow(ls, 1)) {
607     if (ls->t.token == TK_RETURN) {
608       statement(ls);
609       return;  /* 'return' must be last statement */
610     }
611     statement(ls);
612   }
613 }
614 
615 
fieldsel(LexState * ls,expdesc * v)616 static void fieldsel (LexState *ls, expdesc *v) {
617   /* fieldsel -> ['.' | ':'] NAME */
618   FuncState *fs = ls->fs;
619   expdesc key;
620   luaK_exp2anyregup(fs, v);
621   luaX_next(ls);  /* skip the dot or colon */
622   checkname(ls, &key);
623   luaK_indexed(fs, v, &key);
624 }
625 
626 
yindex(LexState * ls,expdesc * v)627 static void yindex (LexState *ls, expdesc *v) {
628   /* index -> '[' expr ']' */
629   luaX_next(ls);  /* skip the '[' */
630   expr(ls, v);
631   luaK_exp2val(ls->fs, v);
632   checknext(ls, ']');
633 }
634 
635 
636 /*
637 ** {======================================================================
638 ** Rules for Constructors
639 ** =======================================================================
640 */
641 
642 
643 struct ConsControl {
644   expdesc v;  /* last list item read */
645   expdesc *t;  /* table descriptor */
646   int nh;  /* total number of `record' elements */
647   int na;  /* total number of array elements */
648   int tostore;  /* number of array elements pending to be stored */
649 };
650 
651 
recfield(LexState * ls,struct ConsControl * cc)652 static void recfield (LexState *ls, struct ConsControl *cc) {
653   /* recfield -> (NAME | `['exp1`]') = exp1 */
654   FuncState *fs = ls->fs;
655   int reg = ls->fs->freereg;
656   expdesc key, val;
657   int rkkey;
658   if (ls->t.token == TK_NAME) {
659     checklimit(fs, cc->nh, MAX_INT, "items in a constructor");
660     checkname(ls, &key);
661   }
662   else  /* ls->t.token == '[' */
663     yindex(ls, &key);
664   cc->nh++;
665   checknext(ls, '=');
666   rkkey = luaK_exp2RK(fs, &key);
667   expr(ls, &val);
668   luaK_codeABC(fs, OP_SETTABLE, cc->t->u.info, rkkey, luaK_exp2RK(fs, &val));
669   fs->freereg = (lu_byte)reg;  /* free registers */
670 }
671 
672 
closelistfield(FuncState * fs,struct ConsControl * cc)673 static void closelistfield (FuncState *fs, struct ConsControl *cc) {
674   if (cc->v.k == VVOID) return;  /* there is no list item */
675   luaK_exp2nextreg(fs, &cc->v);
676   cc->v.k = VVOID;
677   if (cc->tostore == LFIELDS_PER_FLUSH) {
678     luaK_setlist(fs, cc->t->u.info, cc->na, cc->tostore);  /* flush */
679     cc->tostore = 0;  /* no more items pending */
680   }
681 }
682 
683 
lastlistfield(FuncState * fs,struct ConsControl * cc)684 static void lastlistfield (FuncState *fs, struct ConsControl *cc) {
685   if (cc->tostore == 0) return;
686   if (hasmultret(cc->v.k)) {
687     luaK_setmultret(fs, &cc->v);
688     luaK_setlist(fs, cc->t->u.info, cc->na, LUA_MULTRET);
689     cc->na--;  /* do not count last expression (unknown number of elements) */
690   }
691   else {
692     if (cc->v.k != VVOID)
693       luaK_exp2nextreg(fs, &cc->v);
694     luaK_setlist(fs, cc->t->u.info, cc->na, cc->tostore);
695   }
696 }
697 
698 
listfield(LexState * ls,struct ConsControl * cc)699 static void listfield (LexState *ls, struct ConsControl *cc) {
700   /* listfield -> exp */
701   expr(ls, &cc->v);
702   checklimit(ls->fs, cc->na, MAX_INT, "items in a constructor");
703   cc->na++;
704   cc->tostore++;
705 }
706 
707 
field(LexState * ls,struct ConsControl * cc)708 static void field (LexState *ls, struct ConsControl *cc) {
709   /* field -> listfield | recfield */
710   switch(ls->t.token) {
711     case TK_NAME: {  /* may be 'listfield' or 'recfield' */
712       if (luaX_lookahead(ls) != '=')  /* expression? */
713         listfield(ls, cc);
714       else
715         recfield(ls, cc);
716       break;
717     }
718     case '[': {
719       recfield(ls, cc);
720       break;
721     }
722     default: {
723       listfield(ls, cc);
724       break;
725     }
726   }
727 }
728 
729 
constructor(LexState * ls,expdesc * t)730 static void constructor (LexState *ls, expdesc *t) {
731   /* constructor -> '{' [ field { sep field } [sep] ] '}'
732      sep -> ',' | ';' */
733   FuncState *fs = ls->fs;
734   int line = ls->linenumber;
735   int pc = luaK_codeABC(fs, OP_NEWTABLE, 0, 0, 0);
736   struct ConsControl cc;
737   cc.na = cc.nh = cc.tostore = 0;
738   cc.t = t;
739   init_exp(t, VRELOCABLE, pc);
740   init_exp(&cc.v, VVOID, 0);  /* no value (yet) */
741   luaK_exp2nextreg(ls->fs, t);  /* fix it at stack top */
742   checknext(ls, '{');
743   do {
744     lua_assert(cc.v.k == VVOID || cc.tostore > 0);
745     if (ls->t.token == '}') break;
746     closelistfield(fs, &cc);
747     field(ls, &cc);
748   } while (testnext(ls, ',') || testnext(ls, ';'));
749   check_match(ls, '}', '{', line);
750   lastlistfield(fs, &cc);
751   SETARG_B(fs->f->code[pc], luaO_int2fb(cc.na)); /* set initial array size */
752   SETARG_C(fs->f->code[pc], luaO_int2fb(cc.nh));  /* set initial table size */
753 }
754 
755 /* }====================================================================== */
756 
757 
758 
parlist(LexState * ls)759 static void parlist (LexState *ls) {
760   /* parlist -> [ param { `,' param } ] */
761   FuncState *fs = ls->fs;
762   Proto *f = fs->f;
763   int nparams = 0;
764   f->is_vararg = 0;
765   if (ls->t.token != ')') {  /* is `parlist' not empty? */
766     do {
767       switch (ls->t.token) {
768         case TK_NAME: {  /* param -> NAME */
769           new_localvar(ls, str_checkname(ls));
770           nparams++;
771           break;
772         }
773         case TK_DOTS: {  /* param -> `...' */
774           luaX_next(ls);
775           f->is_vararg = 1;
776           break;
777         }
778         default: luaX_syntaxerror(ls, "<name> or " LUA_QL("...") " expected");
779       }
780     } while (!f->is_vararg && testnext(ls, ','));
781   }
782   adjustlocalvars(ls, nparams);
783   f->numparams = cast_byte(fs->nactvar);
784   luaK_reserveregs(fs, fs->nactvar);  /* reserve register for parameters */
785 }
786 
787 
body(LexState * ls,expdesc * e,int ismethod,int line)788 static void body (LexState *ls, expdesc *e, int ismethod, int line) {
789   /* body ->  `(' parlist `)' block END */
790   FuncState new_fs;
791   BlockCnt bl;
792   new_fs.f = addprototype(ls);
793   new_fs.f->linedefined = line;
794   open_func(ls, &new_fs, &bl);
795   checknext(ls, '(');
796   if (ismethod) {
797     new_localvarliteral(ls, "self");  /* create 'self' parameter */
798     adjustlocalvars(ls, 1);
799   }
800   parlist(ls);
801   checknext(ls, ')');
802   statlist(ls);
803   new_fs.f->lastlinedefined = ls->linenumber;
804   check_match(ls, TK_END, TK_FUNCTION, line);
805   codeclosure(ls, e);
806   close_func(ls);
807 }
808 
809 
explist(LexState * ls,expdesc * v)810 static int explist (LexState *ls, expdesc *v) {
811   /* explist -> expr { `,' expr } */
812   int n = 1;  /* at least one expression */
813   expr(ls, v);
814   while (testnext(ls, ',')) {
815     luaK_exp2nextreg(ls->fs, v);
816     expr(ls, v);
817     n++;
818   }
819   return n;
820 }
821 
822 
funcargs(LexState * ls,expdesc * f,int line)823 static void funcargs (LexState *ls, expdesc *f, int line) {
824   FuncState *fs = ls->fs;
825   expdesc args;
826   int base, nparams;
827   switch (ls->t.token) {
828     case '(': {  /* funcargs -> `(' [ explist ] `)' */
829       luaX_next(ls);
830       if (ls->t.token == ')')  /* arg list is empty? */
831         args.k = VVOID;
832       else {
833         explist(ls, &args);
834         luaK_setmultret(fs, &args);
835       }
836       check_match(ls, ')', '(', line);
837       break;
838     }
839     case '{': {  /* funcargs -> constructor */
840       constructor(ls, &args);
841       break;
842     }
843     case TK_STRING: {  /* funcargs -> STRING */
844       codestring(ls, &args, ls->t.seminfo.ts);
845       luaX_next(ls);  /* must use `seminfo' before `next' */
846       break;
847     }
848     default: {
849       luaX_syntaxerror(ls, "function arguments expected");
850     }
851   }
852   lua_assert(f->k == VNONRELOC);
853   base = f->u.info;  /* base register for call */
854   if (hasmultret(args.k))
855     nparams = LUA_MULTRET;  /* open call */
856   else {
857     if (args.k != VVOID)
858       luaK_exp2nextreg(fs, &args);  /* close last argument */
859     nparams = fs->freereg - (base+1);
860   }
861   init_exp(f, VCALL, luaK_codeABC(fs, OP_CALL, base, nparams+1, 2));
862   luaK_fixline(fs, line);
863   fs->freereg = (lu_byte)base + 1;  /* call remove function and arguments and leaves
864                               (unless changed) one result */
865 }
866 
867 
868 
869 
870 /*
871 ** {======================================================================
872 ** Expression parsing
873 ** =======================================================================
874 */
875 
876 
primaryexp(LexState * ls,expdesc * v)877 static void primaryexp (LexState *ls, expdesc *v) {
878   /* primaryexp -> NAME | '(' expr ')' */
879   switch (ls->t.token) {
880     case '(': {
881       int line = ls->linenumber;
882       luaX_next(ls);
883       expr(ls, v);
884       check_match(ls, ')', '(', line);
885       luaK_dischargevars(ls->fs, v);
886       return;
887     }
888     case TK_NAME: {
889       singlevar(ls, v);
890       return;
891     }
892     default: {
893       luaX_syntaxerror(ls, "unexpected symbol");
894     }
895   }
896 }
897 
898 
suffixedexp(LexState * ls,expdesc * v)899 static void suffixedexp (LexState *ls, expdesc *v) {
900   /* suffixedexp ->
901        primaryexp { '.' NAME | '[' exp ']' | ':' NAME funcargs | funcargs } */
902   FuncState *fs = ls->fs;
903   int line = ls->linenumber;
904   primaryexp(ls, v);
905   for (;;) {
906     switch (ls->t.token) {
907       case '.': {  /* fieldsel */
908         fieldsel(ls, v);
909         break;
910       }
911       case '[': {  /* `[' exp1 `]' */
912         expdesc key;
913         luaK_exp2anyregup(fs, v);
914         yindex(ls, &key);
915         luaK_indexed(fs, v, &key);
916         break;
917       }
918       case ':': {  /* `:' NAME funcargs */
919         expdesc key;
920         luaX_next(ls);
921         checkname(ls, &key);
922         luaK_self(fs, v, &key);
923         funcargs(ls, v, line);
924         break;
925       }
926       case '(': case TK_STRING: case '{': {  /* funcargs */
927         luaK_exp2nextreg(fs, v);
928         funcargs(ls, v, line);
929         break;
930       }
931       default: return;
932     }
933   }
934 }
935 
936 
simpleexp(LexState * ls,expdesc * v)937 static void simpleexp (LexState *ls, expdesc *v) {
938   /* simpleexp -> NUMBER | STRING | NIL | TRUE | FALSE | ... |
939                   constructor | FUNCTION body | suffixedexp */
940   switch (ls->t.token) {
941     case TK_NUMBER: {
942       init_exp(v, VKNUM, 0);
943       v->u.nval = ls->t.seminfo.r;
944       break;
945     }
946     case TK_STRING: {
947       codestring(ls, v, ls->t.seminfo.ts);
948       break;
949     }
950     case TK_NIL: {
951       init_exp(v, VNIL, 0);
952       break;
953     }
954     case TK_TRUE: {
955       init_exp(v, VTRUE, 0);
956       break;
957     }
958     case TK_FALSE: {
959       init_exp(v, VFALSE, 0);
960       break;
961     }
962     case TK_DOTS: {  /* vararg */
963       FuncState *fs = ls->fs;
964       check_condition(ls, fs->f->is_vararg,
965                       "cannot use " LUA_QL("...") " outside a vararg function");
966       init_exp(v, VVARARG, luaK_codeABC(fs, OP_VARARG, 0, 1, 0));
967       break;
968     }
969     case '{': {  /* constructor */
970       constructor(ls, v);
971       return;
972     }
973     case TK_FUNCTION: {
974       luaX_next(ls);
975       body(ls, v, 0, ls->linenumber);
976       return;
977     }
978     default: {
979       suffixedexp(ls, v);
980       return;
981     }
982   }
983   luaX_next(ls);
984 }
985 
986 
getunopr(int op)987 static UnOpr getunopr (int op) {
988   switch (op) {
989     case TK_NOT: return OPR_NOT;
990     case '-': return OPR_MINUS;
991     case '#': return OPR_LEN;
992     default: return OPR_NOUNOPR;
993   }
994 }
995 
996 
getbinopr(int op)997 static BinOpr getbinopr (int op) {
998   switch (op) {
999     case '+': return OPR_ADD;
1000     case '-': return OPR_SUB;
1001     case '*': return OPR_MUL;
1002     case '/': return OPR_DIV;
1003     case '%': return OPR_MOD;
1004     case '^': return OPR_POW;
1005     case TK_CONCAT: return OPR_CONCAT;
1006     case TK_NE: return OPR_NE;
1007     case TK_EQ: return OPR_EQ;
1008     case '<': return OPR_LT;
1009     case TK_LE: return OPR_LE;
1010     case '>': return OPR_GT;
1011     case TK_GE: return OPR_GE;
1012     case TK_AND: return OPR_AND;
1013     case TK_OR: return OPR_OR;
1014     default: return OPR_NOBINOPR;
1015   }
1016 }
1017 
1018 
1019 static const struct {
1020   lu_byte left;  /* left priority for each binary operator */
1021   lu_byte right; /* right priority */
1022 } priority[] = {  /* ORDER OPR */
1023    {6, 6}, {6, 6}, {7, 7}, {7, 7}, {7, 7},  /* `+' `-' `*' `/' `%' */
1024    {10, 9}, {5, 4},                 /* ^, .. (right associative) */
1025    {3, 3}, {3, 3}, {3, 3},          /* ==, <, <= */
1026    {3, 3}, {3, 3}, {3, 3},          /* ~=, >, >= */
1027    {2, 2}, {1, 1}                   /* and, or */
1028 };
1029 
1030 #define UNARY_PRIORITY  8  /* priority for unary operators */
1031 
1032 
1033 /*
1034 ** subexpr -> (simpleexp | unop subexpr) { binop subexpr }
1035 ** where `binop' is any binary operator with a priority higher than `limit'
1036 */
subexpr(LexState * ls,expdesc * v,int limit)1037 static BinOpr subexpr (LexState *ls, expdesc *v, int limit) {
1038   BinOpr op;
1039   UnOpr uop;
1040   enterlevel(ls);
1041   uop = getunopr(ls->t.token);
1042   if (uop != OPR_NOUNOPR) {
1043     int line = ls->linenumber;
1044     luaX_next(ls);
1045     subexpr(ls, v, UNARY_PRIORITY);
1046     luaK_prefix(ls->fs, uop, v, line);
1047   }
1048   else simpleexp(ls, v);
1049   /* expand while operators have priorities higher than `limit' */
1050   op = getbinopr(ls->t.token);
1051   while (op != OPR_NOBINOPR && priority[op].left > limit) {
1052     expdesc v2;
1053     BinOpr nextop;
1054     int line = ls->linenumber;
1055     luaX_next(ls);
1056     luaK_infix(ls->fs, op, v);
1057     /* read sub-expression with higher priority */
1058     nextop = subexpr(ls, &v2, priority[op].right);
1059     luaK_posfix(ls->fs, op, v, &v2, line);
1060     op = nextop;
1061   }
1062   leavelevel(ls);
1063   return op;  /* return first untreated operator */
1064 }
1065 
1066 
expr(LexState * ls,expdesc * v)1067 static void expr (LexState *ls, expdesc *v) {
1068   subexpr(ls, v, 0);
1069 }
1070 
1071 /* }==================================================================== */
1072 
1073 
1074 
1075 /*
1076 ** {======================================================================
1077 ** Rules for Statements
1078 ** =======================================================================
1079 */
1080 
1081 
block(LexState * ls)1082 static void block (LexState *ls) {
1083   /* block -> statlist */
1084   FuncState *fs = ls->fs;
1085   BlockCnt bl;
1086   enterblock(fs, &bl, 0);
1087   statlist(ls);
1088   leaveblock(fs);
1089 }
1090 
1091 
1092 /*
1093 ** structure to chain all variables in the left-hand side of an
1094 ** assignment
1095 */
1096 struct LHS_assign {
1097   struct LHS_assign *prev;
1098   expdesc v;  /* variable (global, local, upvalue, or indexed) */
1099 };
1100 
1101 
1102 /*
1103 ** check whether, in an assignment to an upvalue/local variable, the
1104 ** upvalue/local variable is begin used in a previous assignment to a
1105 ** table. If so, save original upvalue/local value in a safe place and
1106 ** use this safe copy in the previous assignment.
1107 */
check_conflict(LexState * ls,struct LHS_assign * lh,expdesc * v)1108 static void check_conflict (LexState *ls, struct LHS_assign *lh, expdesc *v) {
1109   FuncState *fs = ls->fs;
1110   int extra = fs->freereg;  /* eventual position to save local variable */
1111   int conflict = 0;
1112   for (; lh; lh = lh->prev) {  /* check all previous assignments */
1113     if (lh->v.k == VINDEXED) {  /* assigning to a table? */
1114       /* table is the upvalue/local being assigned now? */
1115       if (lh->v.u.ind.vt == v->k && lh->v.u.ind.t == v->u.info) {
1116         conflict = 1;
1117         lh->v.u.ind.vt = VLOCAL;
1118         lh->v.u.ind.t = (lu_byte)extra;  /* previous assignment will use safe copy */
1119       }
1120       /* index is the local being assigned? (index cannot be upvalue) */
1121       if (v->k == VLOCAL && lh->v.u.ind.idx == v->u.info) {
1122         conflict = 1;
1123         lh->v.u.ind.idx = (short)extra;  /* previous assignment will use safe copy */
1124       }
1125     }
1126   }
1127   if (conflict) {
1128     /* copy upvalue/local value to a temporary (in position 'extra') */
1129     OpCode op = (v->k == VLOCAL) ? OP_MOVE : OP_GETUPVAL;
1130     luaK_codeABC(fs, op, extra, v->u.info, 0);
1131     luaK_reserveregs(fs, 1);
1132   }
1133 }
1134 
1135 
assignment(LexState * ls,struct LHS_assign * lh,int nvars)1136 static void assignment (LexState *ls, struct LHS_assign *lh, int nvars) {
1137   expdesc e;
1138   check_condition(ls, vkisvar(lh->v.k), "syntax error");
1139   if (testnext(ls, ',')) {  /* assignment -> ',' suffixedexp assignment */
1140     struct LHS_assign nv;
1141     nv.prev = lh;
1142     suffixedexp(ls, &nv.v);
1143     if (nv.v.k != VINDEXED)
1144       check_conflict(ls, lh, &nv.v);
1145     checklimit(ls->fs, nvars + ls->L->nCcalls, LUAI_MAXCCALLS,
1146                     "C levels");
1147     assignment(ls, &nv, nvars+1);
1148   }
1149   else {  /* assignment -> `=' explist */
1150     int nexps;
1151     checknext(ls, '=');
1152     nexps = explist(ls, &e);
1153     if (nexps != nvars) {
1154       adjust_assign(ls, nvars, nexps, &e);
1155       if (nexps > nvars)
1156           ls->fs->freereg -= (lu_byte)(nexps - nvars);  /* remove extra values */
1157     }
1158     else {
1159       luaK_setoneret(ls->fs, &e);  /* close last expression */
1160       luaK_storevar(ls->fs, &lh->v, &e);
1161       return;  /* avoid default */
1162     }
1163   }
1164   init_exp(&e, VNONRELOC, ls->fs->freereg-1);  /* default assignment */
1165   luaK_storevar(ls->fs, &lh->v, &e);
1166 }
1167 
1168 
cond(LexState * ls)1169 static int cond (LexState *ls) {
1170   /* cond -> exp */
1171   expdesc v;
1172   expr(ls, &v);  /* read condition */
1173   if (v.k == VNIL) v.k = VFALSE;  /* `falses' are all equal here */
1174   luaK_goiftrue(ls->fs, &v);
1175   return v.f;
1176 }
1177 
1178 
gotostat(LexState * ls,int pc)1179 static void gotostat (LexState *ls, int pc) {
1180   int line = ls->linenumber;
1181   TString *label;
1182   int g;
1183   if (testnext(ls, TK_GOTO))
1184     label = str_checkname(ls);
1185   else {
1186     luaX_next(ls);  /* skip break */
1187     label = luaS_new(ls->L, "break");
1188   }
1189   g = newlabelentry(ls, &ls->dyd->gt, label, line, pc);
1190   findlabel(ls, g);  /* close it if label already defined */
1191 }
1192 
1193 
1194 /* check for repeated labels on the same block */
checkrepeated(FuncState * fs,Labellist * ll,TString * label)1195 static void checkrepeated (FuncState *fs, Labellist *ll, TString *label) {
1196   int i;
1197   for (i = fs->bl->firstlabel; i < ll->n; i++) {
1198     if (luaS_eqstr(label, ll->arr[i].name)) {
1199       const char *msg = luaO_pushfstring(fs->ls->L,
1200                           "label " LUA_QS " already defined on line %d",
1201                           getstr(label), ll->arr[i].line);
1202       semerror(fs->ls, msg);
1203     }
1204   }
1205 }
1206 
1207 
1208 /* skip no-op statements */
skipnoopstat(LexState * ls)1209 static void skipnoopstat (LexState *ls) {
1210   while (ls->t.token == ';' || ls->t.token == TK_DBCOLON)
1211     statement(ls);
1212 }
1213 
1214 
labelstat(LexState * ls,TString * label,int line)1215 static void labelstat (LexState *ls, TString *label, int line) {
1216   /* label -> '::' NAME '::' */
1217   FuncState *fs = ls->fs;
1218   Labellist *ll = &ls->dyd->label;
1219   int l;  /* index of new label being created */
1220   checkrepeated(fs, ll, label);  /* check for repeated labels */
1221   checknext(ls, TK_DBCOLON);  /* skip double colon */
1222   /* create new entry for this label */
1223   l = newlabelentry(ls, ll, label, line, fs->pc);
1224   skipnoopstat(ls);  /* skip other no-op statements */
1225   if (block_follow(ls, 0)) {  /* label is last no-op statement in the block? */
1226     /* assume that locals are already out of scope */
1227     ll->arr[l].nactvar = fs->bl->nactvar;
1228   }
1229   findgotos(ls, &ll->arr[l]);
1230 }
1231 
1232 
whilestat(LexState * ls,int line)1233 static void whilestat (LexState *ls, int line) {
1234   /* whilestat -> WHILE cond DO block END */
1235   FuncState *fs = ls->fs;
1236   int whileinit;
1237   int condexit;
1238   BlockCnt bl;
1239   luaX_next(ls);  /* skip WHILE */
1240   whileinit = luaK_getlabel(fs);
1241   condexit = cond(ls);
1242   enterblock(fs, &bl, 1);
1243   checknext(ls, TK_DO);
1244   block(ls);
1245   luaK_jumpto(fs, whileinit);
1246   check_match(ls, TK_END, TK_WHILE, line);
1247   leaveblock(fs);
1248   luaK_patchtohere(fs, condexit);  /* false conditions finish the loop */
1249 }
1250 
1251 
repeatstat(LexState * ls,int line)1252 static void repeatstat (LexState *ls, int line) {
1253   /* repeatstat -> REPEAT block UNTIL cond */
1254   int condexit;
1255   FuncState *fs = ls->fs;
1256   int repeat_init = luaK_getlabel(fs);
1257   BlockCnt bl1, bl2;
1258   enterblock(fs, &bl1, 1);  /* loop block */
1259   enterblock(fs, &bl2, 0);  /* scope block */
1260   luaX_next(ls);  /* skip REPEAT */
1261   statlist(ls);
1262   check_match(ls, TK_UNTIL, TK_REPEAT, line);
1263   condexit = cond(ls);  /* read condition (inside scope block) */
1264   if (bl2.upval)  /* upvalues? */
1265     luaK_patchclose(fs, condexit, bl2.nactvar);
1266   leaveblock(fs);  /* finish scope */
1267   luaK_patchlist(fs, condexit, repeat_init);  /* close the loop */
1268   leaveblock(fs);  /* finish loop */
1269 }
1270 
1271 
exp1(LexState * ls)1272 static int exp1 (LexState *ls) {
1273   expdesc e;
1274   int reg;
1275   expr(ls, &e);
1276   luaK_exp2nextreg(ls->fs, &e);
1277   lua_assert(e.k == VNONRELOC);
1278   reg = e.u.info;
1279   return reg;
1280 }
1281 
1282 
forbody(LexState * ls,int base,int line,int nvars,int isnum)1283 static void forbody (LexState *ls, int base, int line, int nvars, int isnum) {
1284   /* forbody -> DO block */
1285   BlockCnt bl;
1286   FuncState *fs = ls->fs;
1287   int prep, endfor;
1288   adjustlocalvars(ls, 3);  /* control variables */
1289   checknext(ls, TK_DO);
1290   prep = isnum ? luaK_codeAsBx(fs, OP_FORPREP, base, NO_JUMP) : luaK_jump(fs);
1291   enterblock(fs, &bl, 0);  /* scope for declared variables */
1292   adjustlocalvars(ls, nvars);
1293   luaK_reserveregs(fs, nvars);
1294   block(ls);
1295   leaveblock(fs);  /* end of scope for declared variables */
1296   luaK_patchtohere(fs, prep);
1297   if (isnum)  /* numeric for? */
1298     endfor = luaK_codeAsBx(fs, OP_FORLOOP, base, NO_JUMP);
1299   else {  /* generic for */
1300     luaK_codeABC(fs, OP_TFORCALL, base, 0, nvars);
1301     luaK_fixline(fs, line);
1302     endfor = luaK_codeAsBx(fs, OP_TFORLOOP, base + 2, NO_JUMP);
1303   }
1304   luaK_patchlist(fs, endfor, prep + 1);
1305   luaK_fixline(fs, line);
1306 }
1307 
1308 
fornum(LexState * ls,TString * varname,int line)1309 static void fornum (LexState *ls, TString *varname, int line) {
1310   /* fornum -> NAME = exp1,exp1[,exp1] forbody */
1311   FuncState *fs = ls->fs;
1312   int base = fs->freereg;
1313   new_localvarliteral(ls, "(for index)");
1314   new_localvarliteral(ls, "(for limit)");
1315   new_localvarliteral(ls, "(for step)");
1316   new_localvar(ls, varname);
1317   checknext(ls, '=');
1318   exp1(ls);  /* initial value */
1319   checknext(ls, ',');
1320   exp1(ls);  /* limit */
1321   if (testnext(ls, ','))
1322     exp1(ls);  /* optional step */
1323   else {  /* default step = 1 */
1324     luaK_codek(fs, fs->freereg, luaK_numberK(fs, 1));
1325     luaK_reserveregs(fs, 1);
1326   }
1327   forbody(ls, base, line, 1, 1);
1328 }
1329 
1330 
forlist(LexState * ls,TString * indexname)1331 static void forlist (LexState *ls, TString *indexname) {
1332   /* forlist -> NAME {,NAME} IN explist forbody */
1333   FuncState *fs = ls->fs;
1334   expdesc e;
1335   int nvars = 4;  /* gen, state, control, plus at least one declared var */
1336   int line;
1337   int base = fs->freereg;
1338   /* create control variables */
1339   new_localvarliteral(ls, "(for generator)");
1340   new_localvarliteral(ls, "(for state)");
1341   new_localvarliteral(ls, "(for control)");
1342   /* create declared variables */
1343   new_localvar(ls, indexname);
1344   while (testnext(ls, ',')) {
1345     new_localvar(ls, str_checkname(ls));
1346     nvars++;
1347   }
1348   checknext(ls, TK_IN);
1349   line = ls->linenumber;
1350   adjust_assign(ls, 3, explist(ls, &e), &e);
1351   luaK_checkstack(fs, 3);  /* extra space to call generator */
1352   forbody(ls, base, line, nvars - 3, 0);
1353 }
1354 
1355 
forstat(LexState * ls,int line)1356 static void forstat (LexState *ls, int line) {
1357   /* forstat -> FOR (fornum | forlist) END */
1358   FuncState *fs = ls->fs;
1359   TString *varname;
1360   BlockCnt bl;
1361   enterblock(fs, &bl, 1);  /* scope for loop and control variables */
1362   luaX_next(ls);  /* skip `for' */
1363   varname = str_checkname(ls);  /* first variable name */
1364   switch (ls->t.token) {
1365     case '=': fornum(ls, varname, line); break;
1366     case ',': case TK_IN: forlist(ls, varname); break;
1367     default: luaX_syntaxerror(ls, LUA_QL("=") " or " LUA_QL("in") " expected");
1368   }
1369   check_match(ls, TK_END, TK_FOR, line);
1370   leaveblock(fs);  /* loop scope (`break' jumps to this point) */
1371 }
1372 
1373 
test_then_block(LexState * ls,int * escapelist)1374 static void test_then_block (LexState *ls, int *escapelist) {
1375   /* test_then_block -> [IF | ELSEIF] cond THEN block */
1376   BlockCnt bl;
1377   FuncState *fs = ls->fs;
1378   expdesc v;
1379   int jf;  /* instruction to skip 'then' code (if condition is false) */
1380   luaX_next(ls);  /* skip IF or ELSEIF */
1381   expr(ls, &v);  /* read condition */
1382   checknext(ls, TK_THEN);
1383   if (ls->t.token == TK_GOTO || ls->t.token == TK_BREAK) {
1384     luaK_goiffalse(ls->fs, &v);  /* will jump to label if condition is true */
1385     enterblock(fs, &bl, 0);  /* must enter block before 'goto' */
1386     gotostat(ls, v.t);  /* handle goto/break */
1387     skipnoopstat(ls);  /* skip other no-op statements */
1388     if (block_follow(ls, 0)) {  /* 'goto' is the entire block? */
1389       leaveblock(fs);
1390       return;  /* and that is it */
1391     }
1392     else  /* must skip over 'then' part if condition is false */
1393       jf = luaK_jump(fs);
1394   }
1395   else {  /* regular case (not goto/break) */
1396     luaK_goiftrue(ls->fs, &v);  /* skip over block if condition is false */
1397     enterblock(fs, &bl, 0);
1398     jf = v.f;
1399   }
1400   statlist(ls);  /* `then' part */
1401   leaveblock(fs);
1402   if (ls->t.token == TK_ELSE ||
1403       ls->t.token == TK_ELSEIF)  /* followed by 'else'/'elseif'? */
1404     luaK_concat(fs, escapelist, luaK_jump(fs));  /* must jump over it */
1405   luaK_patchtohere(fs, jf);
1406 }
1407 
1408 
ifstat(LexState * ls,int line)1409 static void ifstat (LexState *ls, int line) {
1410   /* ifstat -> IF cond THEN block {ELSEIF cond THEN block} [ELSE block] END */
1411   FuncState *fs = ls->fs;
1412   int escapelist = NO_JUMP;  /* exit list for finished parts */
1413   test_then_block(ls, &escapelist);  /* IF cond THEN block */
1414   while (ls->t.token == TK_ELSEIF)
1415     test_then_block(ls, &escapelist);  /* ELSEIF cond THEN block */
1416   if (testnext(ls, TK_ELSE))
1417     block(ls);  /* `else' part */
1418   check_match(ls, TK_END, TK_IF, line);
1419   luaK_patchtohere(fs, escapelist);  /* patch escape list to 'if' end */
1420 }
1421 
1422 
localfunc(LexState * ls)1423 static void localfunc (LexState *ls) {
1424   expdesc b;
1425   FuncState *fs = ls->fs;
1426   new_localvar(ls, str_checkname(ls));  /* new local variable */
1427   adjustlocalvars(ls, 1);  /* enter its scope */
1428   body(ls, &b, 0, ls->linenumber);  /* function created in next register */
1429   /* debug information will only see the variable after this point! */
1430   getlocvar(fs, b.u.info)->startpc = fs->pc;
1431 }
1432 
1433 
localstat(LexState * ls)1434 static void localstat (LexState *ls) {
1435   /* stat -> LOCAL NAME {`,' NAME} [`=' explist] */
1436   int nvars = 0;
1437   int nexps;
1438   expdesc e;
1439   do {
1440     new_localvar(ls, str_checkname(ls));
1441     nvars++;
1442   } while (testnext(ls, ','));
1443   if (testnext(ls, '='))
1444     nexps = explist(ls, &e);
1445   else {
1446     e.k = VVOID;
1447     nexps = 0;
1448   }
1449   adjust_assign(ls, nvars, nexps, &e);
1450   adjustlocalvars(ls, nvars);
1451 }
1452 
1453 
funcname(LexState * ls,expdesc * v)1454 static int funcname (LexState *ls, expdesc *v) {
1455   /* funcname -> NAME {fieldsel} [`:' NAME] */
1456   int ismethod = 0;
1457   singlevar(ls, v);
1458   while (ls->t.token == '.')
1459     fieldsel(ls, v);
1460   if (ls->t.token == ':') {
1461     ismethod = 1;
1462     fieldsel(ls, v);
1463   }
1464   return ismethod;
1465 }
1466 
1467 
funcstat(LexState * ls,int line)1468 static void funcstat (LexState *ls, int line) {
1469   /* funcstat -> FUNCTION funcname body */
1470   int ismethod;
1471   expdesc v, b;
1472   luaX_next(ls);  /* skip FUNCTION */
1473   ismethod = funcname(ls, &v);
1474   body(ls, &b, ismethod, line);
1475   luaK_storevar(ls->fs, &v, &b);
1476   luaK_fixline(ls->fs, line);  /* definition `happens' in the first line */
1477 }
1478 
1479 
exprstat(LexState * ls)1480 static void exprstat (LexState *ls) {
1481   /* stat -> func | assignment */
1482   FuncState *fs = ls->fs;
1483   struct LHS_assign v;
1484   suffixedexp(ls, &v.v);
1485   if (ls->t.token == '=' || ls->t.token == ',') { /* stat -> assignment ? */
1486     v.prev = NULL;
1487     assignment(ls, &v, 1);
1488   }
1489   else {  /* stat -> func */
1490     check_condition(ls, v.v.k == VCALL, "syntax error");
1491     SETARG_C(getcode(fs, &v.v), 1);  /* call statement uses no results */
1492   }
1493 }
1494 
1495 
retstat(LexState * ls)1496 static void retstat (LexState *ls) {
1497   /* stat -> RETURN [explist] [';'] */
1498   FuncState *fs = ls->fs;
1499   expdesc e;
1500   int first, nret;  /* registers with returned values */
1501   if (block_follow(ls, 1) || ls->t.token == ';')
1502     first = nret = 0;  /* return no values */
1503   else {
1504     nret = explist(ls, &e);  /* optional return values */
1505     if (hasmultret(e.k)) {
1506       luaK_setmultret(fs, &e);
1507       if (e.k == VCALL && nret == 1) {  /* tail call? */
1508         SET_OPCODE(getcode(fs,&e), OP_TAILCALL);
1509         lua_assert(GETARG_A(getcode(fs,&e)) == fs->nactvar);
1510       }
1511       first = fs->nactvar;
1512       nret = LUA_MULTRET;  /* return all values */
1513     }
1514     else {
1515       if (nret == 1)  /* only one single value? */
1516         first = luaK_exp2anyreg(fs, &e);
1517       else {
1518         luaK_exp2nextreg(fs, &e);  /* values must go to the `stack' */
1519         first = fs->nactvar;  /* return all `active' values */
1520         lua_assert(nret == fs->freereg - first);
1521       }
1522     }
1523   }
1524   luaK_ret(fs, first, nret);
1525   testnext(ls, ';');  /* skip optional semicolon */
1526 }
1527 
1528 
statement(LexState * ls)1529 static void statement (LexState *ls) {
1530   int line = ls->linenumber;  /* may be needed for error messages */
1531   enterlevel(ls);
1532   switch (ls->t.token) {
1533     case ';': {  /* stat -> ';' (empty statement) */
1534       luaX_next(ls);  /* skip ';' */
1535       break;
1536     }
1537     case TK_IF: {  /* stat -> ifstat */
1538       ifstat(ls, line);
1539       break;
1540     }
1541     case TK_WHILE: {  /* stat -> whilestat */
1542       whilestat(ls, line);
1543       break;
1544     }
1545     case TK_DO: {  /* stat -> DO block END */
1546       luaX_next(ls);  /* skip DO */
1547       block(ls);
1548       check_match(ls, TK_END, TK_DO, line);
1549       break;
1550     }
1551     case TK_FOR: {  /* stat -> forstat */
1552       forstat(ls, line);
1553       break;
1554     }
1555     case TK_REPEAT: {  /* stat -> repeatstat */
1556       repeatstat(ls, line);
1557       break;
1558     }
1559     case TK_FUNCTION: {  /* stat -> funcstat */
1560       funcstat(ls, line);
1561       break;
1562     }
1563     case TK_LOCAL: {  /* stat -> localstat */
1564       luaX_next(ls);  /* skip LOCAL */
1565       if (testnext(ls, TK_FUNCTION))  /* local function? */
1566         localfunc(ls);
1567       else
1568         localstat(ls);
1569       break;
1570     }
1571     case TK_DBCOLON: {  /* stat -> label */
1572       luaX_next(ls);  /* skip double colon */
1573       labelstat(ls, str_checkname(ls), line);
1574       break;
1575     }
1576     case TK_RETURN: {  /* stat -> retstat */
1577       luaX_next(ls);  /* skip RETURN */
1578       retstat(ls);
1579       break;
1580     }
1581     case TK_BREAK:   /* stat -> breakstat */
1582     case TK_GOTO: {  /* stat -> 'goto' NAME */
1583       gotostat(ls, luaK_jump(ls->fs));
1584       break;
1585     }
1586     default: {  /* stat -> func | assignment */
1587       exprstat(ls);
1588       break;
1589     }
1590   }
1591   lua_assert(ls->fs->f->maxstacksize >= ls->fs->freereg &&
1592              ls->fs->freereg >= ls->fs->nactvar);
1593   ls->fs->freereg = ls->fs->nactvar;  /* free registers */
1594   leavelevel(ls);
1595 }
1596 
1597 /* }====================================================================== */
1598 
1599 
1600 /*
1601 ** compiles the main function, which is a regular vararg function with an
1602 ** upvalue named LUA_ENV
1603 */
mainfunc(LexState * ls,FuncState * fs)1604 static void mainfunc (LexState *ls, FuncState *fs) {
1605   BlockCnt bl;
1606   expdesc v;
1607   open_func(ls, fs, &bl);
1608   fs->f->is_vararg = 1;  /* main function is always vararg */
1609   init_exp(&v, VLOCAL, 0);  /* create and... */
1610   newupvalue(fs, ls->envn, &v);  /* ...set environment upvalue */
1611   luaX_next(ls);  /* read first token */
1612   statlist(ls);  /* parse main body */
1613   check(ls, TK_EOS);
1614   close_func(ls);
1615 }
1616 
1617 
luaY_parser(lua_State * L,ZIO * z,Mbuffer * buff,Dyndata * dyd,const char * name,int firstchar)1618 Closure *luaY_parser (lua_State *L, ZIO *z, Mbuffer *buff,
1619                       Dyndata *dyd, const char *name, int firstchar) {
1620   LexState lexstate;
1621   FuncState funcstate;
1622   Closure *cl = luaF_newLclosure(L, 1);  /* create main closure */
1623   /* anchor closure (to avoid being collected) */
1624   setclLvalue(L, L->top, cl);
1625   incr_top(L);
1626   funcstate.f = cl->l.p = luaF_newproto(L);
1627   funcstate.f->source = luaS_new(L, name);  /* create and anchor TString */
1628   lexstate.buff = buff;
1629   lexstate.dyd = dyd;
1630   dyd->actvar.n = dyd->gt.n = dyd->label.n = 0;
1631   luaX_setinput(L, &lexstate, z, funcstate.f->source, firstchar);
1632   mainfunc(&lexstate, &funcstate);
1633   lua_assert(!funcstate.prev && funcstate.nups == 1 && !lexstate.fs);
1634   /* all scopes should be correctly finished */
1635   lua_assert(dyd->actvar.n == 0 && dyd->gt.n == 0 && dyd->label.n == 0);
1636   return cl;  /* it's on the stack too */
1637 }
1638 
1639