deps/lua/src/lparser.c

   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 /* }====================================================================== */