root/src/lua-5.1.3/src/lparser.c

Revision 5c8778c4361d2ad3adc94ef98d804c6fa9e6ba7c, 35.8 kB (checked in by Theo Schlossnagle <jesus@omniti.com>, 10 years ago)

import lua... I'd like to write checkers in lua

  • Property mode set to 100644
Line 
1 /*
2 ** $Id: lparser.c,v 2.42.1.3 2007/12/28 15:32:23 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 #define hasmultret(k)           ((k) == VCALL || (k) == VVARARG)
31
32 #define getlocvar(fs, i)        ((fs)->f->locvars[(fs)->actvar[i]])
33
34 #define luaY_checklimit(fs,v,l,m)       if ((v)>(l)) errorlimit(fs,l,m)
35
36
37 /*
38 ** nodes for block list (list of active blocks)
39 */
40 typedef struct BlockCnt {
41   struct BlockCnt *previous;  /* chain */
42   int breaklist;  /* list of jumps out of this loop */
43   lu_byte nactvar;  /* # active locals outside the breakable structure */
44   lu_byte upval;  /* true if some variable in the block is an upvalue */
45   lu_byte isbreakable;  /* true if `block' is a loop */
46 } BlockCnt;
47
48
49
50 /*
51 ** prototypes for recursive non-terminal functions
52 */
53 static void chunk (LexState *ls);
54 static void expr (LexState *ls, expdesc *v);
55
56
57 static void anchor_token (LexState *ls) {
58   if (ls->t.token == TK_NAME || ls->t.token == TK_STRING) {
59     TString *ts = ls->t.seminfo.ts;
60     luaX_newstring(ls, getstr(ts), ts->tsv.len);
61   }
62 }
63
64
65 static void error_expected (LexState *ls, int token) {
66   luaX_syntaxerror(ls,
67       luaO_pushfstring(ls->L, LUA_QS " expected", luaX_token2str(ls, token)));
68 }
69
70
71 static void errorlimit (FuncState *fs, int limit, const char *what) {
72   const char *msg = (fs->f->linedefined == 0) ?
73     luaO_pushfstring(fs->L, "main function has more than %d %s", limit, what) :
74     luaO_pushfstring(fs->L, "function at line %d has more than %d %s",
75                             fs->f->linedefined, limit, what);
76   luaX_lexerror(fs->ls, msg, 0);
77 }
78
79
80 static int testnext (LexState *ls, int c) {
81   if (ls->t.token == c) {
82     luaX_next(ls);
83     return 1;
84   }
85   else return 0;
86 }
87
88
89 static void check (LexState *ls, int c) {
90   if (ls->t.token != c)
91     error_expected(ls, c);
92 }
93
94 static void checknext (LexState *ls, int c) {
95   check(ls, c);
96   luaX_next(ls);
97 }
98
99
100 #define check_condition(ls,c,msg)       { if (!(c)) luaX_syntaxerror(ls, msg); }
101
102
103
104 static void check_match (LexState *ls, int what, int who, int where) {
105   if (!testnext(ls, what)) {
106     if (where == ls->linenumber)
107       error_expected(ls, what);
108     else {
109       luaX_syntaxerror(ls, luaO_pushfstring(ls->L,
110              LUA_QS " expected (to close " LUA_QS " at line %d)",
111               luaX_token2str(ls, what), luaX_token2str(ls, who), where));
112     }
113   }
114 }
115
116
117 static TString *str_checkname (LexState *ls) {
118   TString *ts;
119   check(ls, TK_NAME);
120   ts = ls->t.seminfo.ts;
121   luaX_next(ls);
122   return ts;
123 }
124
125
126 static void init_exp (expdesc *e, expkind k, int i) {
127   e->f = e->t = NO_JUMP;
128   e->k = k;
129   e->u.s.info = i;
130 }
131
132
133 static void codestring (LexState *ls, expdesc *e, TString *s) {
134   init_exp(e, VK, luaK_stringK(ls->fs, s));
135 }
136
137
138 static void checkname(LexState *ls, expdesc *e) {
139   codestring(ls, e, str_checkname(ls));
140 }
141
142
143 static int registerlocalvar (LexState *ls, TString *varname) {
144   FuncState *fs = ls->fs;
145   Proto *f = fs->f;
146   int oldsize = f->sizelocvars;
147   luaM_growvector(ls->L, f->locvars, fs->nlocvars, f->sizelocvars,
148                   LocVar, SHRT_MAX, "too many local variables");
149   while (oldsize < f->sizelocvars) f->locvars[oldsize++].varname = NULL;
150   f->locvars[fs->nlocvars].varname = varname;
151   luaC_objbarrier(ls->L, f, varname);
152   return fs->nlocvars++;
153 }
154
155
156 #define new_localvarliteral(ls,v,n) \
157   new_localvar(ls, luaX_newstring(ls, "" v, (sizeof(v)/sizeof(char))-1), n)
158
159
160 static void new_localvar (LexState *ls, TString *name, int n) {
161   FuncState *fs = ls->fs;
162   luaY_checklimit(fs, fs->nactvar+n+1, LUAI_MAXVARS, "local variables");
163   fs->actvar[fs->nactvar+n] = cast(unsigned short, registerlocalvar(ls, name));
164 }
165
166
167 static void adjustlocalvars (LexState *ls, int nvars) {
168   FuncState *fs = ls->fs;
169   fs->nactvar = cast_byte(fs->nactvar + nvars);
170   for (; nvars; nvars--) {
171     getlocvar(fs, fs->nactvar - nvars).startpc = fs->pc;
172   }
173 }
174
175
176 static void removevars (LexState *ls, int tolevel) {
177   FuncState *fs = ls->fs;
178   while (fs->nactvar > tolevel)
179     getlocvar(fs, --fs->nactvar).endpc = fs->pc;
180 }
181
182
183 static int indexupvalue (FuncState *fs, TString *name, expdesc *v) {
184   int i;
185   Proto *f = fs->f;
186   int oldsize = f->sizeupvalues;
187   for (i=0; i<f->nups; i++) {
188     if (fs->upvalues[i].k == v->k && fs->upvalues[i].info == v->u.s.info) {
189       lua_assert(f->upvalues[i] == name);
190       return i;
191     }
192   }
193   /* new one */
194   luaY_checklimit(fs, f->nups + 1, LUAI_MAXUPVALUES, "upvalues");
195   luaM_growvector(fs->L, f->upvalues, f->nups, f->sizeupvalues,
196                   TString *, MAX_INT, "");
197   while (oldsize < f->sizeupvalues) f->upvalues[oldsize++] = NULL;
198   f->upvalues[f->nups] = name;
199   luaC_objbarrier(fs->L, f, name);
200   lua_assert(v->k == VLOCAL || v->k == VUPVAL);
201   fs->upvalues[f->nups].k = cast_byte(v->k);
202   fs->upvalues[f->nups].info = cast_byte(v->u.s.info);
203   return f->nups++;
204 }
205
206
207 static int searchvar (FuncState *fs, TString *n) {
208   int i;
209   for (i=fs->nactvar-1; i >= 0; i--) {
210     if (n == getlocvar(fs, i).varname)
211       return i;
212   }
213   return -1;  /* not found */
214 }
215
216
217 static void markupval (FuncState *fs, int level) {
218   BlockCnt *bl = fs->bl;
219   while (bl && bl->nactvar > level) bl = bl->previous;
220   if (bl) bl->upval = 1;
221 }
222
223
224 static int singlevaraux (FuncState *fs, TString *n, expdesc *var, int base) {
225   if (fs == NULL) {  /* no more levels? */
226     init_exp(var, VGLOBAL, NO_REG);  /* default is global variable */
227     return VGLOBAL;
228   }
229   else {
230     int v = searchvar(fs, n);  /* look up at current level */
231     if (v >= 0) {
232       init_exp(var, VLOCAL, v);
233       if (!base)
234         markupval(fs, v);  /* local will be used as an upval */
235       return VLOCAL;
236     }
237     else {  /* not found at current level; try upper one */
238       if (singlevaraux(fs->prev, n, var, 0) == VGLOBAL)
239         return VGLOBAL;
240       var->u.s.info = indexupvalue(fs, n, var);  /* else was LOCAL or UPVAL */
241       var->k = VUPVAL;  /* upvalue in this level */
242       return VUPVAL;
243     }
244   }
245 }
246
247
248 static void singlevar (LexState *ls, expdesc *var) {
249   TString *varname = str_checkname(ls);
250   FuncState *fs = ls->fs;
251   if (singlevaraux(fs, varname, var, 1) == VGLOBAL)
252     var->u.s.info = luaK_stringK(fs, varname);  /* info points to global name */
253 }
254
255
256 static void adjust_assign (LexState *ls, int nvars, int nexps, expdesc *e) {
257   FuncState *fs = ls->fs;
258   int extra = nvars - nexps;
259   if (hasmultret(e->k)) {
260     extra++;  /* includes call itself */
261     if (extra < 0) extra = 0;
262     luaK_setreturns(fs, e, extra);  /* last exp. provides the difference */
263     if (extra > 1) luaK_reserveregs(fs, extra-1);
264   }
265   else {
266     if (e->k != VVOID) luaK_exp2nextreg(fs, e);  /* close last expression */
267     if (extra > 0) {
268       int reg = fs->freereg;
269       luaK_reserveregs(fs, extra);
270       luaK_nil(fs, reg, extra);
271     }
272   }
273 }
274
275
276 static void enterlevel (LexState *ls) {
277   if (++ls->L->nCcalls > LUAI_MAXCCALLS)
278         luaX_lexerror(ls, "chunk has too many syntax levels", 0);
279 }
280
281
282 #define leavelevel(ls)  ((ls)->L->nCcalls--)
283
284
285 static void enterblock (FuncState *fs, BlockCnt *bl, lu_byte isbreakable) {
286   bl->breaklist = NO_JUMP;
287   bl->isbreakable = isbreakable;
288   bl->nactvar = fs->nactvar;
289   bl->upval = 0;
290   bl->previous = fs->bl;
291   fs->bl = bl;
292   lua_assert(fs->freereg == fs->nactvar);
293 }
294
295
296 static void leaveblock (FuncState *fs) {
297   BlockCnt *bl = fs->bl;
298   fs->bl = bl->previous;
299   removevars(fs->ls, bl->nactvar);
300   if (bl->upval)
301     luaK_codeABC(fs, OP_CLOSE, bl->nactvar, 0, 0);
302   /* a block either controls scope or breaks (never both) */
303   lua_assert(!bl->isbreakable || !bl->upval);
304   lua_assert(bl->nactvar == fs->nactvar);
305   fs->freereg = fs->nactvar;  /* free registers */
306   luaK_patchtohere(fs, bl->breaklist);
307 }
308
309
310 static void pushclosure (LexState *ls, FuncState *func, expdesc *v) {
311   FuncState *fs = ls->fs;
312   Proto *f = fs->f;
313   int oldsize = f->sizep;
314   int i;
315   luaM_growvector(ls->L, f->p, fs->np, f->sizep, Proto *,
316                   MAXARG_Bx, "constant table overflow");
317   while (oldsize < f->sizep) f->p[oldsize++] = NULL;
318   f->p[fs->np++] = func->f;
319   luaC_objbarrier(ls->L, f, func->f);
320   init_exp(v, VRELOCABLE, luaK_codeABx(fs, OP_CLOSURE, 0, fs->np-1));
321   for (i=0; i<func->f->nups; i++) {
322     OpCode o = (func->upvalues[i].k == VLOCAL) ? OP_MOVE : OP_GETUPVAL;
323     luaK_codeABC(fs, o, 0, func->upvalues[i].info, 0);
324   }
325 }
326
327
328 static void open_func (LexState *ls, FuncState *fs) {
329   lua_State *L = ls->L;
330   Proto *f = luaF_newproto(L);
331   fs->f = f;
332   fs->prev = ls->fs;  /* linked list of funcstates */
333   fs->ls = ls;
334   fs->L = L;
335   ls->fs = fs;
336   fs->pc = 0;
337   fs->lasttarget = -1;
338   fs->jpc = NO_JUMP;
339   fs->freereg = 0;
340   fs->nk = 0;
341   fs->np = 0;
342   fs->nlocvars = 0;
343   fs->nactvar = 0;
344   fs->bl = NULL;
345   f->source = ls->source;
346   f->maxstacksize = 2;  /* registers 0/1 are always valid */
347   fs->h = luaH_new(L, 0, 0);
348   /* anchor table of constants and prototype (to avoid being collected) */
349   sethvalue2s(L, L->top, fs->h);
350   incr_top(L);
351   setptvalue2s(L, L->top, f);
352   incr_top(L);
353 }
354
355
356 static void close_func (LexState *ls) {
357   lua_State *L = ls->L;
358   FuncState *fs = ls->fs;
359   Proto *f = fs->f;
360   removevars(ls, 0);
361   luaK_ret(fs, 0, 0);  /* final return */
362   luaM_reallocvector(L, f->code, f->sizecode, fs->pc, Instruction);
363   f->sizecode = fs->pc;
364   luaM_reallocvector(L, f->lineinfo, f->sizelineinfo, fs->pc, int);
365   f->sizelineinfo = fs->pc;
366   luaM_reallocvector(L, f->k, f->sizek, fs->nk, TValue);
367   f->sizek = fs->nk;
368   luaM_reallocvector(L, f->p, f->sizep, fs->np, Proto *);
369   f->sizep = fs->np;
370   luaM_reallocvector(L, f->locvars, f->sizelocvars, fs->nlocvars, LocVar);
371   f->sizelocvars = fs->nlocvars;
372   luaM_reallocvector(L, f->upvalues, f->sizeupvalues, f->nups, TString *);
373   f->sizeupvalues = f->nups;
374   lua_assert(luaG_checkcode(f));
375   lua_assert(fs->bl == NULL);
376   ls->fs = fs->prev;
377   L->top -= 2;  /* remove table and prototype from the stack */
378   /* last token read was anchored in defunct function; must reanchor it */
379   if (fs) anchor_token(ls);
380 }
381
382
383 Proto *luaY_parser (lua_State *L, ZIO *z, Mbuffer *buff, const char *name) {
384   struct LexState lexstate;
385   struct FuncState funcstate;
386   lexstate.buff = buff;
387   luaX_setinput(L, &lexstate, z, luaS_new(L, name));
388   open_func(&lexstate, &funcstate);
389   funcstate.f->is_vararg = VARARG_ISVARARG;  /* main func. is always vararg */
390   luaX_next(&lexstate);  /* read first token */
391   chunk(&lexstate);
392   check(&lexstate, TK_EOS);
393   close_func(&lexstate);
394   lua_assert(funcstate.prev == NULL);
395   lua_assert(funcstate.f->nups == 0);
396   lua_assert(lexstate.fs == NULL);
397   return funcstate.f;
398 }
399
400
401
402 /*============================================================*/
403 /* GRAMMAR RULES */
404 /*============================================================*/
405
406
407 static void field (LexState *ls, expdesc *v) {
408   /* field -> ['.' | ':'] NAME */
409   FuncState *fs = ls->fs;
410   expdesc key;
411   luaK_exp2anyreg(fs, v);
412   luaX_next(ls);  /* skip the dot or colon */
413   checkname(ls, &key);
414   luaK_indexed(fs, v, &key);
415 }
416
417
418 static void yindex (LexState *ls, expdesc *v) {
419   /* index -> '[' expr ']' */
420   luaX_next(ls);  /* skip the '[' */
421   expr(ls, v);
422   luaK_exp2val(ls->fs, v);
423   checknext(ls, ']');
424 }
425
426
427 /*
428 ** {======================================================================
429 ** Rules for Constructors
430 ** =======================================================================
431 */
432
433
434 struct ConsControl {
435   expdesc v;  /* last list item read */
436   expdesc *t;  /* table descriptor */
437   int nh;  /* total number of `record' elements */
438   int na;  /* total number of array elements */
439   int tostore;  /* number of array elements pending to be stored */
440 };
441
442
443 static void recfield (LexState *ls, struct ConsControl *cc) {
444   /* recfield -> (NAME | `['exp1`]') = exp1 */
445   FuncState *fs = ls->fs;
446   int reg = ls->fs->freereg;
447   expdesc key, val;
448   int rkkey;
449   if (ls->t.token == TK_NAME) {
450     luaY_checklimit(fs, cc->nh, MAX_INT, "items in a constructor");
451     checkname(ls, &key);
452   }
453   else  /* ls->t.token == '[' */
454     yindex(ls, &key);
455   cc->nh++;
456   checknext(ls, '=');
457   rkkey = luaK_exp2RK(fs, &key);
458   expr(ls, &val);
459   luaK_codeABC(fs, OP_SETTABLE, cc->t->u.s.info, rkkey, luaK_exp2RK(fs, &val));
460   fs->freereg = reg;  /* free registers */
461 }
462
463
464 static void closelistfield (FuncState *fs, struct ConsControl *cc) {
465   if (cc->v.k == VVOID) return;  /* there is no list item */
466   luaK_exp2nextreg(fs, &cc->v);
467   cc->v.k = VVOID;
468   if (cc->tostore == LFIELDS_PER_FLUSH) {
469     luaK_setlist(fs, cc->t->u.s.info, cc->na, cc->tostore);  /* flush */
470     cc->tostore = 0;  /* no more items pending */
471   }
472 }
473
474
475 static void lastlistfield (FuncState *fs, struct ConsControl *cc) {
476   if (cc->tostore == 0) return;
477   if (hasmultret(cc->v.k)) {
478     luaK_setmultret(fs, &cc->v);
479     luaK_setlist(fs, cc->t->u.s.info, cc->na, LUA_MULTRET);
480     cc->na--;  /* do not count last expression (unknown number of elements) */
481   }
482   else {
483     if (cc->v.k != VVOID)
484       luaK_exp2nextreg(fs, &cc->v);
485     luaK_setlist(fs, cc->t->u.s.info, cc->na, cc->tostore);
486   }
487 }
488
489
490 static void listfield (LexState *ls, struct ConsControl *cc) {
491   expr(ls, &cc->v);
492   luaY_checklimit(ls->fs, cc->na, MAX_INT, "items in a constructor");
493   cc->na++;
494   cc->tostore++;
495 }
496
497
498 static void constructor (LexState *ls, expdesc *t) {
499   /* constructor -> ?? */
500   FuncState *fs = ls->fs;
501   int line = ls->linenumber;
502   int pc = luaK_codeABC(fs, OP_NEWTABLE, 0, 0, 0);
503   struct ConsControl cc;
504   cc.na = cc.nh = cc.tostore = 0;
505   cc.t = t;
506   init_exp(t, VRELOCABLE, pc);
507   init_exp(&cc.v, VVOID, 0);  /* no value (yet) */
508   luaK_exp2nextreg(ls->fs, t);  /* fix it at stack top (for gc) */
509   checknext(ls, '{');
510   do {
511     lua_assert(cc.v.k == VVOID || cc.tostore > 0);
512     if (ls->t.token == '}') break;
513     closelistfield(fs, &cc);
514     switch(ls->t.token) {
515       case TK_NAME: {  /* may be listfields or recfields */
516         luaX_lookahead(ls);
517         if (ls->lookahead.token != '=')  /* expression? */
518           listfield(ls, &cc);
519         else
520           recfield(ls, &cc);
521         break;
522       }
523       case '[': {  /* constructor_item -> recfield */
524         recfield(ls, &cc);
525         break;
526       }
527       default: {  /* constructor_part -> listfield */
528         listfield(ls, &cc);
529         break;
530       }
531     }
532   } while (testnext(ls, ',') || testnext(ls, ';'));
533   check_match(ls, '}', '{', line);
534   lastlistfield(fs, &cc);
535   SETARG_B(fs->f->code[pc], luaO_int2fb(cc.na)); /* set initial array size */
536   SETARG_C(fs->f->code[pc], luaO_int2fb(cc.nh));  /* set initial table size */
537 }
538
539 /* }====================================================================== */
540
541
542
543 static void parlist (LexState *ls) {
544   /* parlist -> [ param { `,' param } ] */
545   FuncState *fs = ls->fs;
546   Proto *f = fs->f;
547   int nparams = 0;
548   f->is_vararg = 0;
549   if (ls->t.token != ')') {  /* is `parlist' not empty? */
550     do {
551       switch (ls->t.token) {
552         case TK_NAME: {  /* param -> NAME */
553           new_localvar(ls, str_checkname(ls), nparams++);
554           break;
555         }
556         case TK_DOTS: {  /* param -> `...' */
557           luaX_next(ls);
558 #if defined(LUA_COMPAT_VARARG)
559           /* use `arg' as default name */
560           new_localvarliteral(ls, "arg", nparams++);
561           f->is_vararg = VARARG_HASARG | VARARG_NEEDSARG;
562 #endif
563           f->is_vararg |= VARARG_ISVARARG;
564           break;
565         }
566         default: luaX_syntaxerror(ls, "<name> or " LUA_QL("...") " expected");
567       }
568     } while (!f->is_vararg && testnext(ls, ','));
569   }
570   adjustlocalvars(ls, nparams);
571   f->numparams = cast_byte(fs->nactvar - (f->is_vararg & VARARG_HASARG));
572   luaK_reserveregs(fs, fs->nactvar);  /* reserve register for parameters */
573 }
574
575
576 static void body (LexState *ls, expdesc *e, int needself, int line) {
577   /* body ->  `(' parlist `)' chunk END */
578   FuncState new_fs;
579   open_func(ls, &new_fs);
580   new_fs.f->linedefined = line;
581   checknext(ls, '(');
582   if (needself) {
583     new_localvarliteral(ls, "self", 0);
584     adjustlocalvars(ls, 1);
585   }
586   parlist(ls);
587   checknext(ls, ')');
588   chunk(ls);
589   new_fs.f->lastlinedefined = ls->linenumber;
590   check_match(ls, TK_END, TK_FUNCTION, line);
591   close_func(ls);
592   pushclosure(ls, &new_fs, e);
593 }
594
595
596 static int explist1 (LexState *ls, expdesc *v) {
597   /* explist1 -> expr { `,' expr } */
598   int n = 1;  /* at least one expression */
599   expr(ls, v);
600   while (testnext(ls, ',')) {
601     luaK_exp2nextreg(ls->fs, v);
602     expr(ls, v);
603     n++;
604   }
605   return n;
606 }
607
608
609 static void funcargs (LexState *ls, expdesc *f) {
610   FuncState *fs = ls->fs;
611   expdesc args;
612   int base, nparams;
613   int line = ls->linenumber;
614   switch (ls->t.token) {
615     case '(': {  /* funcargs -> `(' [ explist1 ] `)' */
616       if (line != ls->lastline)
617         luaX_syntaxerror(ls,"ambiguous syntax (function call x new statement)");
618       luaX_next(ls);
619       if (ls->t.token == ')')  /* arg list is empty? */
620         args.k = VVOID;
621       else {
622         explist1(ls, &args);
623         luaK_setmultret(fs, &args);
624       }
625       check_match(ls, ')', '(', line);
626       break;
627     }
628     case '{': {  /* funcargs -> constructor */
629       constructor(ls, &args);
630       break;
631     }
632     case TK_STRING: {  /* funcargs -> STRING */
633       codestring(ls, &args, ls->t.seminfo.ts);
634       luaX_next(ls);  /* must use `seminfo' before `next' */
635       break;
636     }
637     default: {
638       luaX_syntaxerror(ls, "function arguments expected");
639       return;
640     }
641   }
642   lua_assert(f->k == VNONRELOC);
643   base = f->u.s.info;  /* base register for call */
644   if (hasmultret(args.k))
645     nparams = LUA_MULTRET;  /* open call */
646   else {
647     if (args.k != VVOID)
648       luaK_exp2nextreg(fs, &args);  /* close last argument */
649     nparams = fs->freereg - (base+1);
650   }
651   init_exp(f, VCALL, luaK_codeABC(fs, OP_CALL, base, nparams+1, 2));
652   luaK_fixline(fs, line);
653   fs->freereg = base+1;  /* call remove function and arguments and leaves
654                             (unless changed) one result */
655 }
656
657
658
659
660 /*
661 ** {======================================================================
662 ** Expression parsing
663 ** =======================================================================
664 */
665
666
667 static void prefixexp (LexState *ls, expdesc *v) {
668   /* prefixexp -> NAME | '(' expr ')' */
669   switch (ls->t.token) {
670     case '(': {
671       int line = ls->linenumber;
672       luaX_next(ls);
673       expr(ls, v);
674       check_match(ls, ')', '(', line);
675       luaK_dischargevars(ls->fs, v);
676       return;
677     }
678     case TK_NAME: {
679       singlevar(ls, v);
680       return;
681     }
682     default: {
683       luaX_syntaxerror(ls, "unexpected symbol");
684       return;
685     }
686   }
687 }
688
689
690 static void primaryexp (LexState *ls, expdesc *v) {
691   /* primaryexp ->
692         prefixexp { `.' NAME | `[' exp `]' | `:' NAME funcargs | funcargs } */
693   FuncState *fs = ls->fs;
694   prefixexp(ls, v);
695   for (;;) {
696     switch (ls->t.token) {
697       case '.': {  /* field */
698         field(ls, v);
699         break;
700       }
701       case '[': {  /* `[' exp1 `]' */
702         expdesc key;
703         luaK_exp2anyreg(fs, v);
704         yindex(ls, &key);
705         luaK_indexed(fs, v, &key);
706         break;
707       }
708       case ':': {  /* `:' NAME funcargs */
709         expdesc key;
710         luaX_next(ls);
711         checkname(ls, &key);
712         luaK_self(fs, v, &key);
713         funcargs(ls, v);
714         break;
715       }
716       case '(': case TK_STRING: case '{': {  /* funcargs */
717         luaK_exp2nextreg(fs, v);
718         funcargs(ls, v);
719         break;
720       }
721       default: return;
722     }
723   }
724 }
725
726
727 static void simpleexp (LexState *ls, expdesc *v) {
728   /* simpleexp -> NUMBER | STRING | NIL | true | false | ... |
729                   constructor | FUNCTION body | primaryexp */
730   switch (ls->t.token) {
731     case TK_NUMBER: {
732       init_exp(v, VKNUM, 0);
733       v->u.nval = ls->t.seminfo.r;
734       break;
735     }
736     case TK_STRING: {
737       codestring(ls, v, ls->t.seminfo.ts);
738       break;
739     }
740     case TK_NIL: {
741       init_exp(v, VNIL, 0);
742       break;
743     }
744     case TK_TRUE: {
745       init_exp(v, VTRUE, 0);
746       break;
747     }
748     case TK_FALSE: {
749       init_exp(v, VFALSE, 0);
750       break;
751     }
752     case TK_DOTS: {  /* vararg */
753       FuncState *fs = ls->fs;
754       check_condition(ls, fs->f->is_vararg,
755                       "cannot use " LUA_QL("...") " outside a vararg function");
756       fs->f->is_vararg &= ~VARARG_NEEDSARG;  /* don't need 'arg' */
757       init_exp(v, VVARARG, luaK_codeABC(fs, OP_VARARG, 0, 1, 0));
758       break;
759     }
760     case '{': {  /* constructor */
761       constructor(ls, v);
762       return;
763     }
764     case TK_FUNCTION: {
765       luaX_next(ls);
766       body(ls, v, 0, ls->linenumber);
767       return;
768     }
769     default: {
770       primaryexp(ls, v);
771       return;
772     }
773   }
774   luaX_next(ls);
775 }
776
777
778 static UnOpr getunopr (int op) {
779   switch (op) {
780     case TK_NOT: return OPR_NOT;
781     case '-': return OPR_MINUS;
782     case '#': return OPR_LEN;
783     default: return OPR_NOUNOPR;
784   }
785 }
786
787
788 static BinOpr getbinopr (int op) {
789   switch (op) {
790     case '+': return OPR_ADD;
791     case '-': return OPR_SUB;
792     case '*': return OPR_MUL;
793     case '/': return OPR_DIV;
794     case '%': return OPR_MOD;
795     case '^': return OPR_POW;
796     case TK_CONCAT: return OPR_CONCAT;
797     case TK_NE: return OPR_NE;
798     case TK_EQ: return OPR_EQ;
799     case '<': return OPR_LT;
800     case TK_LE: return OPR_LE;
801     case '>': return OPR_GT;
802     case TK_GE: return OPR_GE;
803     case TK_AND: return OPR_AND;
804     case TK_OR: return OPR_OR;
805     default: return OPR_NOBINOPR;
806   }
807 }
808
809
810 static const struct {
811   lu_byte left;  /* left priority for each binary operator */
812   lu_byte right; /* right priority */
813 } priority[] = {  /* ORDER OPR */
814    {6, 6}, {6, 6}, {7, 7}, {7, 7}, {7, 7},  /* `+' `-' `/' `%' */
815    {10, 9}, {5, 4},                 /* power and concat (right associative) */
816    {3, 3}, {3, 3},                  /* equality and inequality */
817    {3, 3}, {3, 3}, {3, 3}, {3, 3},  /* order */
818    {2, 2}, {1, 1}                   /* logical (and/or) */
819 };
820
821 #define UNARY_PRIORITY  8  /* priority for unary operators */
822
823
824 /*
825 ** subexpr -> (simpleexp | unop subexpr) { binop subexpr }
826 ** where `binop' is any binary operator with a priority higher than `limit'
827 */
828 static BinOpr subexpr (LexState *ls, expdesc *v, unsigned int limit) {
829   BinOpr op;
830   UnOpr uop;
831   enterlevel(ls);
832   uop = getunopr(ls->t.token);
833   if (uop != OPR_NOUNOPR) {
834     luaX_next(ls);
835     subexpr(ls, v, UNARY_PRIORITY);
836     luaK_prefix(ls->fs, uop, v);
837   }
838   else simpleexp(ls, v);
839   /* expand while operators have priorities higher than `limit' */
840   op = getbinopr(ls->t.token);
841   while (op != OPR_NOBINOPR && priority[op].left > limit) {
842     expdesc v2;
843     BinOpr nextop;
844     luaX_next(ls);
845     luaK_infix(ls->fs, op, v);
846     /* read sub-expression with higher priority */
847     nextop = subexpr(ls, &v2, priority[op].right);
848     luaK_posfix(ls->fs, op, v, &v2);
849     op = nextop;
850   }
851   leavelevel(ls);
852   return op;  /* return first untreated operator */
853 }
854
855
856 static void expr (LexState *ls, expdesc *v) {
857   subexpr(ls, v, 0);
858 }
859
860 /* }==================================================================== */
861
862
863
864 /*
865 ** {======================================================================
866 ** Rules for Statements
867 ** =======================================================================
868 */
869
870
871 static int block_follow (int token) {
872   switch (token) {
873     case TK_ELSE: case TK_ELSEIF: case TK_END:
874     case TK_UNTIL: case TK_EOS:
875       return 1;
876     default: return 0;
877   }
878 }
879
880
881 static void block (LexState *ls) {
882   /* block -> chunk */
883   FuncState *fs = ls->fs;
884   BlockCnt bl;
885   enterblock(fs, &bl, 0);
886   chunk(ls);
887   lua_assert(bl.breaklist == NO_JUMP);
888   leaveblock(fs);
889 }
890
891
892 /*
893 ** structure to chain all variables in the left-hand side of an
894 ** assignment
895 */
896 struct LHS_assign {
897   struct LHS_assign *prev;
898   expdesc v;  /* variable (global, local, upvalue, or indexed) */
899 };
900
901
902 /*
903 ** check whether, in an assignment to a local variable, the local variable
904 ** is needed in a previous assignment (to a table). If so, save original
905 ** local value in a safe place and use this safe copy in the previous
906 ** assignment.
907 */
908 static void check_conflict (LexState *ls, struct LHS_assign *lh, expdesc *v) {
909   FuncState *fs = ls->fs;
910   int extra = fs->freereg;  /* eventual position to save local variable */
911   int conflict = 0;
912   for (; lh; lh = lh->prev) {
913     if (lh->v.k == VINDEXED) {
914       if (lh->v.u.s.info == v->u.s.info) {  /* conflict? */
915         conflict = 1;
916         lh->v.u.s.info = extra;  /* previous assignment will use safe copy */
917       }
918       if (lh->v.u.s.aux == v->u.s.info) {  /* conflict? */
919         conflict = 1;
920         lh->v.u.s.aux = extra;  /* previous assignment will use safe copy */
921       }
922     }
923   }
924   if (conflict) {
925     luaK_codeABC(fs, OP_MOVE, fs->freereg, v->u.s.info, 0);  /* make copy */
926     luaK_reserveregs(fs, 1);
927   }
928 }
929
930
931 static void assignment (LexState *ls, struct LHS_assign *lh, int nvars) {
932   expdesc e;
933   check_condition(ls, VLOCAL <= lh->v.k && lh->v.k <= VINDEXED,
934                       "syntax error");
935   if (testnext(ls, ',')) {  /* assignment -> `,' primaryexp assignment */
936     struct LHS_assign nv;
937     nv.prev = lh;
938     primaryexp(ls, &nv.v);
939     if (nv.v.k == VLOCAL)
940       check_conflict(ls, lh, &nv.v);
941     luaY_checklimit(ls->fs, nvars, LUAI_MAXCCALLS - ls->L->nCcalls,
942                     "variables in assignment");
943     assignment(ls, &nv, nvars+1);
944   }
945   else {  /* assignment -> `=' explist1 */
946     int nexps;
947     checknext(ls, '=');
948     nexps = explist1(ls, &e);
949     if (nexps != nvars) {
950       adjust_assign(ls, nvars, nexps, &e);
951       if (nexps > nvars)
952         ls->fs->freereg -= nexps - nvars;  /* remove extra values */
953     }
954     else {
955       luaK_setoneret(ls->fs, &e);  /* close last expression */
956       luaK_storevar(ls->fs, &lh->v, &e);
957       return;  /* avoid default */
958     }
959   }
960   init_exp(&e, VNONRELOC, ls->fs->freereg-1);  /* default assignment */
961   luaK_storevar(ls->fs, &lh->v, &e);
962 }
963
964
965 static int cond (LexState *ls) {
966   /* cond -> exp */
967   expdesc v;
968   expr(ls, &v);  /* read condition */
969   if (v.k == VNIL) v.k = VFALSE;  /* `falses' are all equal here */
970   luaK_goiftrue(ls->fs, &v);
971   return v.f;
972 }
973
974
975 static void breakstat (LexState *ls) {
976   FuncState *fs = ls->fs;
977   BlockCnt *bl = fs->bl;
978   int upval = 0;
979   while (bl && !bl->isbreakable) {
980     upval |= bl->upval;
981     bl = bl->previous;
982   }
983   if (!bl)
984     luaX_syntaxerror(ls, "no loop to break");
985   if (upval)
986     luaK_codeABC(fs, OP_CLOSE, bl->nactvar, 0, 0);
987   luaK_concat(fs, &bl->breaklist, luaK_jump(fs));
988 }
989
990
991 static void whilestat (LexState *ls, int line) {
992   /* whilestat -> WHILE cond DO block END */
993   FuncState *fs = ls->fs;
994   int whileinit;
995   int condexit;
996   BlockCnt bl;
997   luaX_next(ls);  /* skip WHILE */
998   whileinit = luaK_getlabel(fs);
999   condexit = cond(ls);
1000   enterblock(fs, &bl, 1);
1001   checknext(ls, TK_DO);
1002   block(ls);
1003   luaK_patchlist(fs, luaK_jump(fs), whileinit);
1004   check_match(ls, TK_END, TK_WHILE, line);
1005   leaveblock(fs);
1006   luaK_patchtohere(fs, condexit);  /* false conditions finish the loop */
1007 }
1008
1009
1010 static void repeatstat (LexState *ls, int line) {
1011   /* repeatstat -> REPEAT block UNTIL cond */
1012   int condexit;
1013   FuncState *fs = ls->fs;
1014   int repeat_init = luaK_getlabel(fs);
1015   BlockCnt bl1, bl2;
1016   enterblock(fs, &bl1, 1);  /* loop block */
1017   enterblock(fs, &bl2, 0);  /* scope block */
1018   luaX_next(ls);  /* skip REPEAT */
1019   chunk(ls);
1020   check_match(ls, TK_UNTIL, TK_REPEAT, line);
1021   condexit = cond(ls);  /* read condition (inside scope block) */
1022   if (!bl2.upval) {  /* no upvalues? */
1023     leaveblock(fs);  /* finish scope */
1024     luaK_patchlist(ls->fs, condexit, repeat_init);  /* close the loop */
1025   }
1026   else {  /* complete semantics when there are upvalues */
1027     breakstat(ls);  /* if condition then break */
1028     luaK_patchtohere(ls->fs, condexit);  /* else... */
1029     leaveblock(fs);  /* finish scope... */
1030     luaK_patchlist(ls->fs, luaK_jump(fs), repeat_init);  /* and repeat */
1031   }
1032   leaveblock(fs);  /* finish loop */
1033 }
1034
1035
1036 static int exp1 (LexState *ls) {
1037   expdesc e;
1038   int k;
1039   expr(ls, &e);
1040   k = e.k;
1041   luaK_exp2nextreg(ls->fs, &e);
1042   return k;
1043 }
1044
1045
1046 static void forbody (LexState *ls, int base, int line, int nvars, int isnum) {
1047   /* forbody -> DO block */
1048   BlockCnt bl;
1049   FuncState *fs = ls->fs;
1050   int prep, endfor;
1051   adjustlocalvars(ls, 3);  /* control variables */
1052   checknext(ls, TK_DO);
1053   prep = isnum ? luaK_codeAsBx(fs, OP_FORPREP, base, NO_JUMP) : luaK_jump(fs);
1054   enterblock(fs, &bl, 0);  /* scope for declared variables */
1055   adjustlocalvars(ls, nvars);
1056   luaK_reserveregs(fs, nvars);
1057   block(ls);
1058   leaveblock(fs);  /* end of scope for declared variables */
1059   luaK_patchtohere(fs, prep);
1060   endfor = (isnum) ? luaK_codeAsBx(fs, OP_FORLOOP, base, NO_JUMP) :
1061                      luaK_codeABC(fs, OP_TFORLOOP, base, 0, nvars);
1062   luaK_fixline(fs, line);  /* pretend that `OP_FOR' starts the loop */
1063   luaK_patchlist(fs, (isnum ? endfor : luaK_jump(fs)), prep + 1);
1064 }
1065
1066
1067 static void fornum (LexState *ls, TString *varname, int line) {
1068   /* fornum -> NAME = exp1,exp1[,exp1] forbody */
1069   FuncState *fs = ls->fs;
1070   int base = fs->freereg;
1071   new_localvarliteral(ls, "(for index)", 0);
1072   new_localvarliteral(ls, "(for limit)", 1);
1073   new_localvarliteral(ls, "(for step)", 2);
1074   new_localvar(ls, varname, 3);
1075   checknext(ls, '=');
1076   exp1(ls);  /* initial value */
1077   checknext(ls, ',');
1078   exp1(ls);  /* limit */
1079   if (testnext(ls, ','))
1080     exp1(ls);  /* optional step */
1081   else {  /* default step = 1 */
1082     luaK_codeABx(fs, OP_LOADK, fs->freereg, luaK_numberK(fs, 1));
1083     luaK_reserveregs(fs, 1);
1084   }
1085   forbody(ls, base, line, 1, 1);
1086 }
1087
1088
1089 static void forlist (LexState *ls, TString *indexname) {
1090   /* forlist -> NAME {,NAME} IN explist1 forbody */
1091   FuncState *fs = ls->fs;
1092   expdesc e;
1093   int nvars = 0;
1094   int line;
1095   int base = fs->freereg;
1096   /* create control variables */
1097   new_localvarliteral(ls, "(for generator)", nvars++);
1098   new_localvarliteral(ls, "(for state)", nvars++);
1099   new_localvarliteral(ls, "(for control)", nvars++);
1100   /* create declared variables */
1101   new_localvar(ls, indexname, nvars++);
1102   while (testnext(ls, ','))
1103     new_localvar(ls, str_checkname(ls), nvars++);
1104   checknext(ls, TK_IN);
1105   line = ls->linenumber;
1106   adjust_assign(ls, 3, explist1(ls, &e), &e);
1107   luaK_checkstack(fs, 3);  /* extra space to call generator */
1108   forbody(ls, base, line, nvars - 3, 0);
1109 }
1110
1111
1112 static void forstat (LexState *ls, int line) {
1113   /* forstat -> FOR (fornum | forlist) END */
1114   FuncState *fs = ls->fs;
1115   TString *varname;
1116   BlockCnt bl;
1117   enterblock(fs, &bl, 1);  /* scope for loop and control variables */
1118   luaX_next(ls);  /* skip `for' */
1119   varname = str_checkname(ls);  /* first variable name */
1120   switch (ls->t.token) {
1121     case '=': fornum(ls, varname, line); break;
1122     case ',': case TK_IN: forlist(ls, varname); break;
1123     default: luaX_syntaxerror(ls, LUA_QL("=") " or " LUA_QL("in") " expected");
1124   }
1125   check_match(ls, TK_END, TK_FOR, line);
1126   leaveblock(fs);  /* loop scope (`break' jumps to this point) */
1127 }
1128
1129
1130 static int test_then_block (LexState *ls) {
1131   /* test_then_block -> [IF | ELSEIF] cond THEN block */
1132   int condexit;
1133   luaX_next(ls);  /* skip IF or ELSEIF */
1134   condexit = cond(ls);
1135   checknext(ls, TK_THEN);
1136   block(ls);  /* `then' part */
1137   return condexit;
1138 }
1139
1140
1141 static void ifstat (LexState *ls, int line) {
1142   /* ifstat -> IF cond THEN block {ELSEIF cond THEN block} [ELSE block] END */
1143   FuncState *fs = ls->fs;
1144   int flist;
1145   int escapelist = NO_JUMP;
1146   flist = test_then_block(ls);  /* IF cond THEN block */
1147   while (ls->t.token == TK_ELSEIF) {
1148     luaK_concat(fs, &escapelist, luaK_jump(fs));
1149     luaK_patchtohere(fs, flist);
1150     flist = test_then_block(ls);  /* ELSEIF cond THEN block */
1151   }
1152   if (ls->t.token == TK_ELSE) {
1153     luaK_concat(fs, &escapelist, luaK_jump(fs));
1154     luaK_patchtohere(fs, flist);
1155     luaX_next(ls);  /* skip ELSE (after patch, for correct line info) */
1156     block(ls);  /* `else' part */
1157   }
1158   else
1159     luaK_concat(fs, &escapelist, flist);
1160   luaK_patchtohere(fs, escapelist);
1161   check_match(ls, TK_END, TK_IF, line);
1162 }
1163
1164
1165 static void localfunc (LexState *ls) {
1166   expdesc v, b;
1167   FuncState *fs = ls->fs;
1168   new_localvar(ls, str_checkname(ls), 0);
1169   init_exp(&v, VLOCAL, fs->freereg);
1170   luaK_reserveregs(fs, 1);
1171   adjustlocalvars(ls, 1);
1172   body(ls, &b, 0, ls->linenumber);
1173   luaK_storevar(fs, &v, &b);
1174   /* debug information will only see the variable after this point! */
1175   getlocvar(fs, fs->nactvar - 1).startpc = fs->pc;
1176 }
1177
1178
1179 static void localstat (LexState *ls) {
1180   /* stat -> LOCAL NAME {`,' NAME} [`=' explist1] */
1181   int nvars = 0;
1182   int nexps;
1183   expdesc e;
1184   do {
1185     new_localvar(ls, str_checkname(ls), nvars++);
1186   } while (testnext(ls, ','));
1187   if (testnext(ls, '='))
1188     nexps = explist1(ls, &e);
1189   else {
1190     e.k = VVOID;
1191     nexps = 0;
1192   }
1193   adjust_assign(ls, nvars, nexps, &e);
1194   adjustlocalvars(ls, nvars);
1195 }
1196
1197
1198 static int funcname (LexState *ls, expdesc *v) {
1199   /* funcname -> NAME {field} [`:' NAME] */
1200   int needself = 0;
1201   singlevar(ls, v);
1202   while (ls->t.token == '.')
1203     field(ls, v);
1204   if (ls->t.token == ':') {
1205     needself = 1;
1206     field(ls, v);
1207   }
1208   return needself;
1209 }
1210
1211
1212 static void funcstat (LexState *ls, int line) {
1213   /* funcstat -> FUNCTION funcname body */
1214   int needself;
1215   expdesc v, b;
1216   luaX_next(ls);  /* skip FUNCTION */
1217   needself = funcname(ls, &v);
1218   body(ls, &b, needself, line);
1219   luaK_storevar(ls->fs, &v, &b);
1220   luaK_fixline(ls->fs, line);  /* definition `happens' in the first line */
1221 }
1222
1223
1224 static void exprstat (LexState *ls) {
1225   /* stat -> func | assignment */
1226   FuncState *fs = ls->fs;
1227   struct LHS_assign v;
1228   primaryexp(ls, &v.v);
1229   if (v.v.k == VCALL)  /* stat -> func */
1230     SETARG_C(getcode(fs, &v.v), 1);  /* call statement uses no results */
1231   else {  /* stat -> assignment */
1232     v.prev = NULL;
1233     assignment(ls, &v, 1);
1234   }
1235 }
1236
1237
1238 static void retstat (LexState *ls) {
1239   /* stat -> RETURN explist */
1240   FuncState *fs = ls->fs;
1241   expdesc e;
1242   int first, nret;  /* registers with returned values */
1243   luaX_next(ls);  /* skip RETURN */
1244   if (block_follow(ls->t.token) || ls->t.token == ';')
1245     first = nret = 0;  /* return no values */
1246   else {
1247     nret = explist1(ls, &e);  /* optional return values */
1248     if (hasmultret(e.k)) {
1249       luaK_setmultret(fs, &e);
1250       if (e.k == VCALL && nret == 1) {  /* tail call? */
1251         SET_OPCODE(getcode(fs,&e), OP_TAILCALL);
1252         lua_assert(GETARG_A(getcode(fs,&e)) == fs->nactvar);
1253       }
1254       first = fs->nactvar;
1255       nret = LUA_MULTRET;  /* return all values */
1256     }
1257     else {
1258       if (nret == 1)  /* only one single value? */
1259         first = luaK_exp2anyreg(fs, &e);
1260       else {
1261         luaK_exp2nextreg(fs, &e);  /* values must go to the `stack' */
1262         first = fs->nactvar;  /* return all `active' values */
1263         lua_assert(nret == fs->freereg - first);
1264       }
1265     }
1266   }
1267   luaK_ret(fs, first, nret);
1268 }
1269
1270
1271 static int statement (LexState *ls) {
1272   int line = ls->linenumber;  /* may be needed for error messages */
1273   switch (ls->t.token) {
1274     case TK_IF: {  /* stat -> ifstat */
1275       ifstat(ls, line);
1276       return 0;
1277     }
1278     case TK_WHILE: {  /* stat -> whilestat */
1279       whilestat(ls, line);
1280       return 0;
1281     }
1282     case TK_DO: {  /* stat -> DO block END */
1283       luaX_next(ls);  /* skip DO */
1284       block(ls);
1285       check_match(ls, TK_END, TK_DO, line);
1286       return 0;
1287     }
1288     case TK_FOR: {  /* stat -> forstat */
1289       forstat(ls, line);
1290       return 0;
1291     }
1292     case TK_REPEAT: {  /* stat -> repeatstat */
1293       repeatstat(ls, line);
1294       return 0;
1295     }
1296     case TK_FUNCTION: {
1297       funcstat(ls, line);  /* stat -> funcstat */
1298       return 0;
1299     }
1300     case TK_LOCAL: {  /* stat -> localstat */
1301       luaX_next(ls);  /* skip LOCAL */
1302       if (testnext(ls, TK_FUNCTION))  /* local function? */
1303         localfunc(ls);
1304       else
1305         localstat(ls);
1306       return 0;
1307     }
1308     case TK_RETURN: {  /* stat -> retstat */
1309       retstat(ls);
1310       return 1;  /* must be last statement */
1311     }
1312     case TK_BREAK: {  /* stat -> breakstat */
1313       luaX_next(ls);  /* skip BREAK */
1314       breakstat(ls);
1315       return 1;  /* must be last statement */
1316     }
1317     default: {
1318       exprstat(ls);
1319       return 0;  /* to avoid warnings */
1320     }
1321   }
1322 }
1323
1324
1325 static void chunk (LexState *ls) {
1326   /* chunk -> { stat [`;'] } */
1327   int islast = 0;
1328   enterlevel(ls);
1329   while (!islast && !block_follow(ls->t.token)) {
1330     islast = statement(ls);
1331     testnext(ls, ';');
1332     lua_assert(ls->fs->f->maxstacksize >= ls->fs->freereg &&
1333                ls->fs->freereg >= ls->fs->nactvar);
1334     ls->fs->freereg = ls->fs->nactvar;  /* free registers */
1335   }
1336   leavelevel(ls);
1337 }
1338
1339 /* }====================================================================== */
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