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 #if 0
   8 #include <string.h>
   9 #endif
  10
  11 #define lparser_c
  12 #define LUA_CORE
  13
  14 #include "lua.h"
  15
  16 #include "lcode.h"
  17 #include "ldebug.h"
  18 #include "ldo.h"
  19 #include "lfunc.h"
  20 #include "llex.h"
  21 #include "lmem.h"
  22 #include "lobject.h"
  23 #include "lopcodes.h"
  24 #include "lparser.h"
  25 #include "lstate.h"
  26 #include "lstring.h"
  27 #include "ltable.h"
  28
  29
  30
  31 #define hasmultret(k)           ((k) == VCALL || (k) == VVARARG)
  32
  33 #define getlocvar(fs, i)        ((fs)->f->locvars[(fs)->actvar[i]])
  34
  35 #define luaY_checklimit(fs,v,l,m)       if ((v)>(l)) errorlimit(fs,l,m)
  36
  37
  38 /*
  39 ** nodes for block list (list of active blocks)
  40 */
  41 typedef struct BlockCnt {
  42   struct BlockCnt *previous;  /* chain */
  43   int breaklist;  /* list of jumps out of this loop */
  44   lu_byte nactvar;  /* # active locals outside the breakable structure */
  45   lu_byte upval;  /* true if some variable in the block is an upvalue */
  46   lu_byte isbreakable;  /* true if `block' is a loop */
  47 } BlockCnt;
  48
  49
  50
  51 /*
  52 ** prototypes for recursive non-terminal functions
  53 */
  54 static void chunk (LexState *ls);
  55 static void expr (LexState *ls, expdesc *v);
  56
  57
  58 static void anchor_token (LexState *ls) {
  59   if (ls->t.token == TK_NAME || ls->t.token == TK_STRING) {
  60     TString *ts = ls->t.seminfo.ts;
  61     luaX_newstring(ls, getstr(ts), ts->tsv.len);
  62   }
  63 }
  64
  65
  66 static void error_expected (LexState *ls, int token) {
  67   luaX_syntaxerror(ls,
  68       luaO_pushfstring(ls->L, LUA_QS " expected", luaX_token2str(ls, token)));
  69 }
  70
  71
  72 static void errorlimit (FuncState *fs, int limit, const char *what) {
  73   const char *msg = (fs->f->linedefined == 0) ?
  74     luaO_pushfstring(fs->L, "main function has more than %d %s", limit, what) :
  75     luaO_pushfstring(fs->L, "function at line %d has more than %d %s",
  76                             fs->f->linedefined, limit, what);
  77   luaX_lexerror(fs->ls, msg, 0);
  78 }
  79
  80
  81 static int testnext (LexState *ls, int c) {
  82   if (ls->t.token == c) {
  83     luaX_next(ls);
  84     return 1;
  85   }
  86   else return 0;
  87 }
  88
  89
  90 static void check (LexState *ls, int c) {
  91   if (ls->t.token != c)
  92     error_expected(ls, c);
  93 }
  94
  95 static void checknext (LexState *ls, int c) {
  96   check(ls, c);
  97   luaX_next(ls);
  98 }
  99
 100
 101 #define check_condition(ls,c,msg)       { if (!(c)) luaX_syntaxerror(ls, msg); }
 102
 103
 104
 105 static void check_match (LexState *ls, int what, int who, int where) {
 106   if (!testnext(ls, what)) {
 107     if (where == ls->linenumber)
 108       error_expected(ls, what);
 109     else {
 110       luaX_syntaxerror(ls, luaO_pushfstring(ls->L,
 111              LUA_QS " expected (to close " LUA_QS " at line %d)",
 112               luaX_token2str(ls, what), luaX_token2str(ls, who), where));
 113     }
 114   }
 115 }
 116
 117
 118 static TString *str_checkname (LexState *ls) {
 119   TString *ts;
 120   check(ls, TK_NAME);
 121   ts = ls->t.seminfo.ts;
 122   luaX_next(ls);
 123   return ts;
 124 }
 125
 126
 127 static void init_exp (expdesc *e, expkind k, int i) {
 128   e->f = e->t = NO_JUMP;
 129   e->k = k;
 130   e->u.s.info = i;
 131 }
 132
 133
 134 static void codestring (LexState *ls, expdesc *e, TString *s) {
 135   init_exp(e, VK, luaK_stringK(ls->fs, s));
 136 }
 137
 138
 139 static void checkname(LexState *ls, expdesc *e) {
 140   codestring(ls, e, str_checkname(ls));
 141 }
 142
 143
 144 static int registerlocalvar (LexState *ls, TString *varname) {
 145   FuncState *fs = ls->fs;
 146   Proto *f = fs->f;
 147   int oldsize = f->sizelocvars;
 148   luaM_growvector(ls->L, f->locvars, fs->nlocvars, f->sizelocvars,
 149                   LocVar, SHRT_MAX, "too many local variables");
 150   while (oldsize < f->sizelocvars) f->locvars[oldsize++].varname = NULL;
 151   f->locvars[fs->nlocvars].varname = varname;
 152   luaC_objbarrier(ls->L, f, varname);
 153   return fs->nlocvars++;
 154 }
 155
 156
 157 #define new_localvarliteral(ls,v,n) \
 158   new_localvar(ls, luaX_newstring(ls, "" v, (sizeof(v)/sizeof(char))-1), n)
 159
 160
 161 static void new_localvar (LexState *ls, TString *name, int n) {
 162   FuncState *fs = ls->fs;
 163   luaY_checklimit(fs, fs->nactvar+n+1, LUAI_MAXVARS, "local variables");
 164   fs->actvar[fs->nactvar+n] = cast(unsigned short, registerlocalvar(ls, name));
 165 }
 166
 167
 168 static void adjustlocalvars (LexState *ls, int nvars) {
 169   FuncState *fs = ls->fs;
 170   fs->nactvar = cast_byte(fs->nactvar + nvars);
 171   for (; nvars; nvars--) {
 172     getlocvar(fs, fs->nactvar - nvars).startpc = fs->pc;
 173   }
 174 }
 175
 176
 177 static void removevars (LexState *ls, int tolevel) {
 178   FuncState *fs = ls->fs;
 179   while (fs->nactvar > tolevel)
 180     getlocvar(fs, --fs->nactvar).endpc = fs->pc;
 181 }
 182
 183
 184 static int indexupvalue (FuncState *fs, TString *name, expdesc *v) {
 185   int i;
 186   Proto *f = fs->f;
 187   int oldsize = f->sizeupvalues;
 188   for (i=0; i<f->nups; i++) {
 189     if (fs->upvalues[i].k == v->k && fs->upvalues[i].info == v->u.s.info) {
 190       lua_assert(f->upvalues[i] == name);
 191       return i;
 192     }
 193   }
 194   /* new one */
 195   luaY_checklimit(fs, f->nups + 1, LUAI_MAXUPVALUES, "upvalues");
 196   luaM_growvector(fs->L, f->upvalues, f->nups, f->sizeupvalues,
 197                   TString *, MAX_INT, "");
 198   while (oldsize < f->sizeupvalues) f->upvalues[oldsize++] = NULL;
 199   f->upvalues[f->nups] = name;
 200   luaC_objbarrier(fs->L, f, name);
 201   lua_assert(v->k == VLOCAL || v->k == VUPVAL);
 202   fs->upvalues[f->nups].k = cast_byte(v->k);
 203   fs->upvalues[f->nups].info = cast_byte(v->u.s.info);
 204   return f->nups++;
 205 }
 206
 207
 208 static int searchvar (FuncState *fs, TString *n) {
 209   int i;
 210   for (i=fs->nactvar-1; i >= 0; i--) {
 211     if (n == getlocvar(fs, i).varname)
 212       return i;
 213   }
 214   return -1;  /* not found */
 215 }
 216
 217
 218 static void markupval (FuncState *fs, int level) {
 219   BlockCnt *bl = fs->bl;
 220   while (bl && bl->nactvar > level) bl = bl->previous;
 221   if (bl) bl->upval = 1;
 222 }
 223
 224
 225 static int singlevaraux (FuncState *fs, TString *n, expdesc *var, int base) {
 226   if (fs == NULL) {  /* no more levels? */
 227     init_exp(var, VGLOBAL, NO_REG);  /* default is global variable */
 228     return VGLOBAL;
 229   }
 230   else {
 231     int v = searchvar(fs, n);  /* look up at current level */
 232     if (v >= 0) {
 233       init_exp(var, VLOCAL, v);
 234       if (!base)
 235         markupval(fs, v);  /* local will be used as an upval */
 236       return VLOCAL;
 237     }
 238     else {  /* not found at current level; try upper one */
 239       if (singlevaraux(fs->prev, n, var, 0) == VGLOBAL)
 240         return VGLOBAL;
 241       var->u.s.info = indexupvalue(fs, n, var);  /* else was LOCAL or UPVAL */
 242       var->k = VUPVAL;  /* upvalue in this level */
 243       return VUPVAL;
 244     }
 245   }
 246 }
 247
 248
 249 static void singlevar (LexState *ls, expdesc *var) {
 250   TString *varname = str_checkname(ls);
 251   FuncState *fs = ls->fs;
 252   if (singlevaraux(fs, varname, var, 1) == VGLOBAL)
 253     var->u.s.info = luaK_stringK(fs, varname);  /* info points to global name */
 254 }
 255
 256
 257 static void adjust_assign (LexState *ls, int nvars, int nexps, expdesc *e) {
 258   FuncState *fs = ls->fs;
 259   int extra = nvars - nexps;
 260   if (hasmultret(e->k)) {
 261     extra++;  /* includes call itself */
 262     if (extra < 0) extra = 0;
 263     luaK_setreturns(fs, e, extra);  /* last exp. provides the difference */
 264     if (extra > 1) luaK_reserveregs(fs, extra-1);
 265   }
 266   else {
 267     if (e->k != VVOID) luaK_exp2nextreg(fs, e);  /* close last expression */
 268     if (extra > 0) {
 269       int reg = fs->freereg;
 270       luaK_reserveregs(fs, extra);
 271       luaK_nil(fs, reg, extra);
 272     }
 273   }
 274 }
 275
 276
 277 static void enterlevel (LexState *ls) {
 278   if (++ls->L->nCcalls > LUAI_MAXCCALLS)
 279         luaX_lexerror(ls, "chunk has too many syntax levels", 0);
 280 }
 281
 282
 283 #define leavelevel(ls)  ((ls)->L->nCcalls--)
 284
 285
 286 static void enterblock (FuncState *fs, BlockCnt *bl, lu_byte isbreakable) {
 287   bl->breaklist = NO_JUMP;
 288   bl->isbreakable = isbreakable;
 289   bl->nactvar = fs->nactvar;
 290   bl->upval = 0;
 291   bl->previous = fs->bl;
 292   fs->bl = bl;
 293   lua_assert(fs->freereg == fs->nactvar);
 294 }
 295
 296
 297 static void leaveblock (FuncState *fs) {
 298   BlockCnt *bl = fs->bl;
 299   fs->bl = bl->previous;
 300   removevars(fs->ls, bl->nactvar);
 301   if (bl->upval)
 302     luaK_codeABC(fs, OP_CLOSE, bl->nactvar, 0, 0);
 303   /* a block either controls scope or breaks (never both) */
 304   lua_assert(!bl->isbreakable || !bl->upval);
 305   lua_assert(bl->nactvar == fs->nactvar);
 306   fs->freereg = fs->nactvar;  /* free registers */
 307   luaK_patchtohere(fs, bl->breaklist);
 308 }
 309
 310
 311 static void pushclosure (LexState *ls, FuncState *func, expdesc *v) {
 312   FuncState *fs = ls->fs;
 313   Proto *f = fs->f;
 314   int oldsize = f->sizep;
 315   int i;
 316   luaM_growvector(ls->L, f->p, fs->np, f->sizep, Proto *,
 317                   MAXARG_Bx, "constant table overflow");
 318   while (oldsize < f->sizep) f->p[oldsize++] = NULL;
 319   f->p[fs->np++] = func->f;
 320   luaC_objbarrier(ls->L, f, func->f);
 321   init_exp(v, VRELOCABLE, luaK_codeABx(fs, OP_CLOSURE, 0, fs->np-1));
 322   for (i=0; i<func->f->nups; i++) {
 323     OpCode o = (func->upvalues[i].k == VLOCAL) ? OP_MOVE : OP_GETUPVAL;
 324     luaK_codeABC(fs, o, 0, func->upvalues[i].info, 0);
 325   }
 326 }
 327
 328
 329 static void open_func (LexState *ls, FuncState *fs) {
 330   lua_State *L = ls->L;
 331   Proto *f = luaF_newproto(L);
 332   fs->f = f;
 333   fs->prev = ls->fs;  /* linked list of funcstates */
 334   fs->ls = ls;
 335   fs->L = L;
 336   ls->fs = fs;
 337   fs->pc = 0;
 338   fs->lasttarget = -1;
 339   fs->jpc = NO_JUMP;
 340   fs->freereg = 0;
 341   fs->nk = 0;
 342   fs->np = 0;
 343   fs->nlocvars = 0;
 344   fs->nactvar = 0;
 345   fs->bl = NULL;
 346   f->source = ls->source;
 347   f->maxstacksize = 2;  /* registers 0/1 are always valid */
 348   fs->h = luaH_new(L, 0, 0);
 349   /* anchor table of constants and prototype (to avoid being collected) */
 350   sethvalue2s(L, L->top, fs->h);
 351   incr_top(L);
 352   setptvalue2s(L, L->top, f);
 353   incr_top(L);
 354 }
 355
 356
 357 static void close_func (LexState *ls) {
 358   lua_State *L = ls->L;
 359   FuncState *fs = ls->fs;
 360   Proto *f = fs->f;
 361   removevars(ls, 0);
 362   luaK_ret(fs, 0, 0);  /* final return */
 363   luaM_reallocvector(L, f->code, f->sizecode, fs->pc, Instruction);
 364   f->sizecode = fs->pc;
 365   luaM_reallocvector(L, f->lineinfo, f->sizelineinfo, fs->pc, int);
 366   f->sizelineinfo = fs->pc;
 367   luaM_reallocvector(L, f->k, f->sizek, fs->nk, TValue);
 368   f->sizek = fs->nk;
 369   luaM_reallocvector(L, f->p, f->sizep, fs->np, Proto *);
 370   f->sizep = fs->np;
 371   luaM_reallocvector(L, f->locvars, f->sizelocvars, fs->nlocvars, LocVar);
 372   f->sizelocvars = fs->nlocvars;
 373   luaM_reallocvector(L, f->upvalues, f->sizeupvalues, f->nups, TString *);
 374   f->sizeupvalues = f->nups;
 375   lua_assert(luaG_checkcode(f));
 376   lua_assert(fs->bl == NULL);
 377   ls->fs = fs->prev;
 378   L->top -= 2;  /* remove table and prototype from the stack */
 379   /* last token read was anchored in defunct function; must reanchor it */
 380   if (fs) anchor_token(ls);
 381 }
 382
 383
 384 Proto *luaY_parser (lua_State *L, ZIO *z, Mbuffer *buff, const char *name) {
 385   struct LexState lexstate;
 386   struct FuncState funcstate;
 387   lexstate.buff = buff;
 388   luaX_setinput(L, &lexstate, z, luaS_new(L, name));
 389   open_func(&lexstate, &funcstate);
 390   funcstate.f->is_vararg = VARARG_ISVARARG;  /* main func. is always vararg */
 391   luaX_next(&lexstate);  /* read first token */
 392   chunk(&lexstate);
 393   check(&lexstate, TK_EOS);
 394   close_func(&lexstate);
 395   lua_assert(funcstate.prev == NULL);
 396   lua_assert(funcstate.f->nups == 0);
 397   lua_assert(lexstate.fs == NULL);
 398   return funcstate.f;
 399 }
 400
 401
 402
 403 /*============================================================*/
 404 /* GRAMMAR RULES */
 405 /*============================================================*/
 406
 407
 408 static void field (LexState *ls, expdesc *v) {
 409   /* field -> ['.' | ':'] NAME */
 410   FuncState *fs = ls->fs;
 411   expdesc key;
 412   luaK_exp2anyreg(fs, v);
 413   luaX_next(ls);  /* skip the dot or colon */
 414   checkname(ls, &key);
 415   luaK_indexed(fs, v, &key);
 416 }
 417
 418
 419 static void yindex (LexState *ls, expdesc *v) {
 420   /* index -> '[' expr ']' */
 421   luaX_next(ls);  /* skip the '[' */
 422   expr(ls, v);
 423   luaK_exp2val(ls->fs, v);
 424   checknext(ls, ']');
 425 }
 426
 427
 428 /*
 429 ** {======================================================================
 430 ** Rules for Constructors
 431 ** =======================================================================
 432 */
 433
 434
 435 struct ConsControl {
 436   expdesc v;  /* last list item read */
 437   expdesc *t;  /* table descriptor */
 438   int nh;  /* total number of `record' elements */
 439   int na;  /* total number of array elements */
 440   int tostore;  /* number of array elements pending to be stored */
 441 };
 442
 443
 444 static void recfield (LexState *ls, struct ConsControl *cc) {
 445   /* recfield -> (NAME | `['exp1`]') = exp1 */
 446   FuncState *fs = ls->fs;
 447   int reg = ls->fs->freereg;
 448   expdesc key, val;
 449   int rkkey;
 450   if (ls->t.token == TK_NAME) {
 451     luaY_checklimit(fs, cc->nh, MAX_INT, "items in a constructor");
 452     checkname(ls, &key);
 453   }
 454   else  /* ls->t.token == '[' */
 455     yindex(ls, &key);
 456   cc->nh++;
 457   checknext(ls, '=');
 458   rkkey = luaK_exp2RK(fs, &key);
 459   expr(ls, &val);
 460   luaK_codeABC(fs, OP_SETTABLE, cc->t->u.s.info, rkkey, luaK_exp2RK(fs, &val));
 461   fs->freereg = reg;  /* free registers */
 462 }
 463
 464
 465 static void closelistfield (FuncState *fs, struct ConsControl *cc) {
 466   if (cc->v.k == VVOID) return;  /* there is no list item */
 467   luaK_exp2nextreg(fs, &cc->v);
 468   cc->v.k = VVOID;
 469   if (cc->tostore == LFIELDS_PER_FLUSH) {
 470     luaK_setlist(fs, cc->t->u.s.info, cc->na, cc->tostore);  /* flush */
 471     cc->tostore = 0;  /* no more items pending */
 472   }
 473 }
 474
 475
 476 static void lastlistfield (FuncState *fs, struct ConsControl *cc) {
 477   if (cc->tostore == 0) return;
 478   if (hasmultret(cc->v.k)) {
 479     luaK_setmultret(fs, &cc->v);
 480     luaK_setlist(fs, cc->t->u.s.info, cc->na, LUA_MULTRET);
 481     cc->na--;  /* do not count last expression (unknown number of elements) */
 482   }
 483   else {
 484     if (cc->v.k != VVOID)
 485       luaK_exp2nextreg(fs, &cc->v);
 486     luaK_setlist(fs, cc->t->u.s.info, cc->na, cc->tostore);
 487   }
 488 }
 489
 490
 491 static void listfield (LexState *ls, struct ConsControl *cc) {
 492   expr(ls, &cc->v);
 493   luaY_checklimit(ls->fs, cc->na, MAX_INT, "items in a constructor");
 494   cc->na++;
 495   cc->tostore++;
 496 }
 497
 498
 499 static void constructor (LexState *ls, expdesc *t) {
 500   /* constructor -> ?? */
 501   FuncState *fs = ls->fs;
 502   int line = ls->linenumber;
 503   int pc = luaK_codeABC(fs, OP_NEWTABLE, 0, 0, 0);
 504   struct ConsControl cc;
 505   cc.na = cc.nh = cc.tostore = 0;
 506   cc.t = t;
 507   init_exp(t, VRELOCABLE, pc);
 508   init_exp(&cc.v, VVOID, 0);  /* no value (yet) */
 509   luaK_exp2nextreg(ls->fs, t);  /* fix it at stack top (for gc) */
 510   checknext(ls, '{');
 511   do {
 512     lua_assert(cc.v.k == VVOID || cc.tostore > 0);
 513     if (ls->t.token == '}') break;
 514     closelistfield(fs, &cc);
 515     switch(ls->t.token) {
 516       case TK_NAME: {  /* may be listfields or recfields */
 517         luaX_lookahead(ls);
 518         if (ls->lookahead.token != '=')  /* expression? */
 519           listfield(ls, &cc);
 520         else
 521           recfield(ls, &cc);
 522         break;
 523       }
 524       case '[': {  /* constructor_item -> recfield */
 525         recfield(ls, &cc);
 526         break;
 527       }
 528       default: {  /* constructor_part -> listfield */
 529         listfield(ls, &cc);
 530         break;
 531       }
 532     }
 533   } while (testnext(ls, ',') || testnext(ls, ';'));
 534   check_match(ls, '}', '{', line);
 535   lastlistfield(fs, &cc);
 536   SETARG_B(fs->f->code[pc], luaO_int2fb(cc.na)); /* set initial array size */
 537   SETARG_C(fs->f->code[pc], luaO_int2fb(cc.nh));  /* set initial table size */
 538 }
 539
 540 /* }====================================================================== */
 541
 542
 543
 544 static void parlist (LexState *ls) {
 545   /* parlist -> [ param { `,' param } ] */
 546   FuncState *fs = ls->fs;
 547   Proto *f = fs->f;
 548   int nparams = 0;
 549   f->is_vararg = 0;
 550   if (ls->t.token != ')') {  /* is `parlist' not empty? */
 551     do {
 552       switch (ls->t.token) {
 553         case TK_NAME: {  /* param -> NAME */
 554           new_localvar(ls, str_checkname(ls), nparams++);
 555           break;
 556         }
 557         case TK_DOTS: {  /* param -> `...' */
 558           luaX_next(ls);
 559 #if defined(LUA_COMPAT_VARARG)
 560           /* use `arg' as default name */
 561           new_localvarliteral(ls, "arg", nparams++);
 562           f->is_vararg = VARARG_HASARG | VARARG_NEEDSARG;
 563 #endif
 564           f->is_vararg |= VARARG_ISVARARG;
 565           break;
 566         }
 567         default: luaX_syntaxerror(ls, "<name> or " LUA_QL("...") " expected");
 568       }
 569     } while (!f->is_vararg && testnext(ls, ','));
 570   }
 571   adjustlocalvars(ls, nparams);
 572   f->numparams = cast_byte(fs->nactvar - (f->is_vararg & VARARG_HASARG));
 573   luaK_reserveregs(fs, fs->nactvar);  /* reserve register for parameters */
 574 }
 575
 576
 577 static void body (LexState *ls, expdesc *e, int needself, int line) {
 578   /* body ->  `(' parlist `)' chunk END */
 579   FuncState new_fs;
 580   open_func(ls, &new_fs);
 581   new_fs.f->linedefined = line;
 582   checknext(ls, '(');
 583   if (needself) {
 584     new_localvarliteral(ls, "self", 0);
 585     adjustlocalvars(ls, 1);
 586   }
 587   parlist(ls);
 588   checknext(ls, ')');
 589   chunk(ls);
 590   new_fs.f->lastlinedefined = ls->linenumber;
 591   check_match(ls, TK_END, TK_FUNCTION, line);
 592   close_func(ls);
 593   pushclosure(ls, &new_fs, e);
 594 }
 595
 596
 597 static int explist1 (LexState *ls, expdesc *v) {
 598   /* explist1 -> expr { `,' expr } */
 599   int n = 1;  /* at least one expression */
 600   expr(ls, v);
 601   while (testnext(ls, ',')) {
 602     luaK_exp2nextreg(ls->fs, v);
 603     expr(ls, v);
 604     n++;
 605   }
 606   return n;
 607 }
 608
 609
 610 static void funcargs (LexState *ls, expdesc *f) {
 611   FuncState *fs = ls->fs;
 612   expdesc args;
 613   int base, nparams;
 614   int line = ls->linenumber;
 615   switch (ls->t.token) {
 616     case '(': {  /* funcargs -> `(' [ explist1 ] `)' */
 617       if (line != ls->lastline)
 618         luaX_syntaxerror(ls,"ambiguous syntax (function call x new statement)");
 619       luaX_next(ls);
 620       if (ls->t.token == ')')  /* arg list is empty? */
 621         args.k = VVOID;
 622       else {
 623         explist1(ls, &args);
 624         luaK_setmultret(fs, &args);
 625       }
 626       check_match(ls, ')', '(', line);
 627       break;
 628     }
 629     case '{': {  /* funcargs -> constructor */
 630       constructor(ls, &args);
 631       break;
 632     }
 633     case TK_STRING: {  /* funcargs -> STRING */
 634       codestring(ls, &args, ls->t.seminfo.ts);
 635       luaX_next(ls);  /* must use `seminfo' before `next' */
 636       break;
 637     }
 638     default: {
 639       luaX_syntaxerror(ls, "function arguments expected");
 640       return;
 641     }
 642   }
 643   lua_assert(f->k == VNONRELOC);
 644   base = f->u.s.info;  /* base register for call */
 645   if (hasmultret(args.k))
 646     nparams = LUA_MULTRET;  /* open call */
 647   else {
 648     if (args.k != VVOID)
 649       luaK_exp2nextreg(fs, &args);  /* close last argument */
 650     nparams = fs->freereg - (base+1);
 651   }
 652   init_exp(f, VCALL, luaK_codeABC(fs, OP_CALL, base, nparams+1, 2));
 653   luaK_fixline(fs, line);
 654   fs->freereg = base+1;  /* call remove function and arguments and leaves
 655                             (unless changed) one result */
 656 }
 657
 658
 659
 660
 661 /*
 662 ** {======================================================================
 663 ** Expression parsing
 664 ** =======================================================================
 665 */
 666
 667
 668 static void prefixexp (LexState *ls, expdesc *v) {
 669   /* prefixexp -> NAME | '(' expr ')' */
 670   switch (ls->t.token) {
 671     case '(': {
 672       int line = ls->linenumber;
 673       luaX_next(ls);
 674       expr(ls, v);
 675       check_match(ls, ')', '(', line);
 676       luaK_dischargevars(ls->fs, v);
 677       return;
 678     }
 679     case TK_NAME: {
 680       singlevar(ls, v);
 681       return;
 682     }
 683     default: {
 684       luaX_syntaxerror(ls, "unexpected symbol");
 685       return;
 686     }
 687   }
 688 }
 689
 690
 691 static void primaryexp (LexState *ls, expdesc *v) {
 692   /* primaryexp ->
 693         prefixexp { `.' NAME | `[' exp `]' | `:' NAME funcargs | funcargs } */
 694   FuncState *fs = ls->fs;
 695   prefixexp(ls, v);
 696   for (;;) {
 697     switch (ls->t.token) {
 698       case '.': {  /* field */
 699         field(ls, v);
 700         break;
 701       }
 702       case '[': {  /* `[' exp1 `]' */
 703         expdesc key;
 704         luaK_exp2anyreg(fs, v);
 705         yindex(ls, &key);
 706         luaK_indexed(fs, v, &key);
 707         break;
 708       }
 709       case ':': {  /* `:' NAME funcargs */
 710         expdesc key;
 711         luaX_next(ls);
 712         checkname(ls, &key);
 713         luaK_self(fs, v, &key);
 714         funcargs(ls, v);
 715         break;
 716       }
 717       case '(': case TK_STRING: case '{': {  /* funcargs */
 718         luaK_exp2nextreg(fs, v);
 719         funcargs(ls, v);
 720         break;
 721       }
 722       default: return;
 723     }
 724   }
 725 }
 726
 727
 728 static void simpleexp (LexState *ls, expdesc *v) {
 729   /* simpleexp -> NUMBER | STRING | NIL | true | false | ... |
 730                   constructor | FUNCTION body | primaryexp */
 731   switch (ls->t.token) {
 732     case TK_NUMBER: {
 733       init_exp(v, VKNUM, 0);
 734       v->u.nval = ls->t.seminfo.r;
 735       break;
 736     }
 737     case TK_STRING: {
 738       codestring(ls, v, ls->t.seminfo.ts);
 739       break;
 740     }
 741     case TK_NIL: {
 742       init_exp(v, VNIL, 0);
 743       break;
 744     }
 745     case TK_TRUE: {
 746       init_exp(v, VTRUE, 0);
 747       break;
 748     }
 749     case TK_FALSE: {
 750       init_exp(v, VFALSE, 0);
 751       break;
 752     }
 753     case TK_DOTS: {  /* vararg */
 754       FuncState *fs = ls->fs;
 755       check_condition(ls, fs->f->is_vararg,
 756                       "cannot use " LUA_QL("...") " outside a vararg function");
 757       fs->f->is_vararg &= ~VARARG_NEEDSARG;  /* don't need 'arg' */
 758       init_exp(v, VVARARG, luaK_codeABC(fs, OP_VARARG, 0, 1, 0));
 759       break;
 760     }
 761     case '{': {  /* constructor */
 762       constructor(ls, v);
 763       return;
 764     }
 765     case TK_FUNCTION: {
 766       luaX_next(ls);
 767       body(ls, v, 0, ls->linenumber);
 768       return;
 769     }
 770     default: {
 771       primaryexp(ls, v);
 772       return;
 773     }
 774   }
 775   luaX_next(ls);
 776 }
 777
 778
 779 static UnOpr getunopr (int op) {
 780   switch (op) {
 781     case TK_NOT: return OPR_NOT;
 782     case '-': return OPR_MINUS;
 783     case '#': return OPR_LEN;
 784     default: return OPR_NOUNOPR;
 785   }
 786 }
 787
 788
 789 static BinOpr getbinopr (int op) {
 790   switch (op) {
 791     case '+': return OPR_ADD;
 792     case '-': return OPR_SUB;
 793     case '*': return OPR_MUL;
 794     case '/': return OPR_DIV;
 795     case '%': return OPR_MOD;
 796     case '^': return OPR_POW;
 797     case TK_CONCAT: return OPR_CONCAT;
 798     case TK_NE: return OPR_NE;
 799     case TK_EQ: return OPR_EQ;
 800     case '<': return OPR_LT;
 801     case TK_LE: return OPR_LE;
 802     case '>': return OPR_GT;
 803     case TK_GE: return OPR_GE;
 804     case TK_AND: return OPR_AND;
 805     case TK_OR: return OPR_OR;
 806     default: return OPR_NOBINOPR;
 807   }
 808 }
 809
 810
 811 static const struct {
 812   lu_byte left;  /* left priority for each binary operator */
 813   lu_byte right; /* right priority */
 814 } priority[] = {  /* ORDER OPR */
 815    {6, 6}, {6, 6}, {7, 7}, {7, 7}, {7, 7},  /* `+' `-' `/' `%' */
 816    {10, 9}, {5, 4},                 /* power and concat (right associative) */
 817    {3, 3}, {3, 3},                  /* equality and inequality */
 818    {3, 3}, {3, 3}, {3, 3}, {3, 3},  /* order */
 819    {2, 2}, {1, 1}                   /* logical (and/or) */
 820 };
 821
 822 #define UNARY_PRIORITY  8  /* priority for unary operators */
 823
 824
 825 /*
 826 ** subexpr -> (simpleexp | unop subexpr) { binop subexpr }
 827 ** where `binop' is any binary operator with a priority higher than `limit'
 828 */
 829 static BinOpr subexpr (LexState *ls, expdesc *v, unsigned int limit) {
 830   BinOpr op;
 831   UnOpr uop;
 832   enterlevel(ls);
 833   uop = getunopr(ls->t.token);
 834   if (uop != OPR_NOUNOPR) {
 835     luaX_next(ls);
 836     subexpr(ls, v, UNARY_PRIORITY);
 837     luaK_prefix(ls->fs, uop, v);
 838   }
 839   else simpleexp(ls, v);
 840   /* expand while operators have priorities higher than `limit' */
 841   op = getbinopr(ls->t.token);
 842   while (op != OPR_NOBINOPR && priority[op].left > limit) {
 843     expdesc v2;
 844     BinOpr nextop;
 845     luaX_next(ls);
 846     luaK_infix(ls->fs, op, v);
 847     /* read sub-expression with higher priority */
 848     nextop = subexpr(ls, &v2, priority[op].right);
 849     luaK_posfix(ls->fs, op, v, &v2);
 850     op = nextop;
 851   }
 852   leavelevel(ls);
 853   return op;  /* return first untreated operator */
 854 }
 855
 856
 857 static void expr (LexState *ls, expdesc *v) {
 858   subexpr(ls, v, 0);
 859 }
 860
 861 /* }==================================================================== */
 862
 863
 864
 865 /*
 866 ** {======================================================================
 867 ** Rules for Statements
 868 ** =======================================================================
 869 */
 870
 871
 872 static int block_follow (int token) {
 873   switch (token) {
 874     case TK_ELSE: case TK_ELSEIF: case TK_END:
 875     case TK_UNTIL: case TK_EOS:
 876       return 1;
 877     default: return 0;
 878   }
 879 }
 880
 881
 882 static void block (LexState *ls) {
 883   /* block -> chunk */
 884   FuncState *fs = ls->fs;
 885   BlockCnt bl;
 886   enterblock(fs, &bl, 0);
 887   chunk(ls);
 888   lua_assert(bl.breaklist == NO_JUMP);
 889   leaveblock(fs);
 890 }
 891
 892
 893 /*
 894 ** structure to chain all variables in the left-hand side of an
 895 ** assignment
 896 */
 897 struct LHS_assign {
 898   struct LHS_assign *prev;
 899   expdesc v;  /* variable (global, local, upvalue, or indexed) */
 900 };
 901
 902
 903 /*
 904 ** check whether, in an assignment to a local variable, the local variable
 905 ** is needed in a previous assignment (to a table). If so, save original
 906 ** local value in a safe place and use this safe copy in the previous
 907 ** assignment.
 908 */
 909 static void check_conflict (LexState *ls, struct LHS_assign *lh, expdesc *v) {
 910   FuncState *fs = ls->fs;
 911   int extra = fs->freereg;  /* eventual position to save local variable */
 912   int conflict = 0;
 913   for (; lh; lh = lh->prev) {
 914     if (lh->v.k == VINDEXED) {
 915       if (lh->v.u.s.info == v->u.s.info) {  /* conflict? */
 916         conflict = 1;
 917         lh->v.u.s.info = extra;  /* previous assignment will use safe copy */
 918       }
 919       if (lh->v.u.s.aux == v->u.s.info) {  /* conflict? */
 920         conflict = 1;
 921         lh->v.u.s.aux = extra;  /* previous assignment will use safe copy */
 922       }
 923     }
 924   }
 925   if (conflict) {
 926     luaK_codeABC(fs, OP_MOVE, fs->freereg, v->u.s.info, 0);  /* make copy */
 927     luaK_reserveregs(fs, 1);
 928   }
 929 }
 930
 931
 932 static void assignment (LexState *ls, struct LHS_assign *lh, int nvars) {
 933   expdesc e;
 934   check_condition(ls, VLOCAL <= lh->v.k && lh->v.k <= VINDEXED,
 935                       "syntax error");
 936   if (testnext(ls, ',')) {  /* assignment -> `,' primaryexp assignment */
 937     struct LHS_assign nv;
 938     nv.prev = lh;
 939     primaryexp(ls, &nv.v);
 940     if (nv.v.k == VLOCAL)
 941       check_conflict(ls, lh, &nv.v);
 942     luaY_checklimit(ls->fs, nvars, LUAI_MAXCCALLS - ls->L->nCcalls,
 943                     "variables in assignment");
 944     assignment(ls, &nv, nvars+1);
 945   }
 946   else {  /* assignment -> `=' explist1 */
 947     int nexps;
 948     checknext(ls, '=');
 949     nexps = explist1(ls, &e);
 950     if (nexps != nvars) {
 951       adjust_assign(ls, nvars, nexps, &e);
 952       if (nexps > nvars)
 953         ls->fs->freereg -= nexps - nvars;  /* remove extra values */
 954     }
 955     else {
 956       luaK_setoneret(ls->fs, &e);  /* close last expression */
 957       luaK_storevar(ls->fs, &lh->v, &e);
 958       return;  /* avoid default */
 959     }
 960   }
 961   init_exp(&e, VNONRELOC, ls->fs->freereg-1);  /* default assignment */
 962   luaK_storevar(ls->fs, &lh->v, &e);
 963 }
 964
 965
 966 static int cond (LexState *ls) {
 967   /* cond -> exp */
 968   expdesc v;
 969   expr(ls, &v);  /* read condition */
 970   if (v.k == VNIL) v.k = VFALSE;  /* `falses' are all equal here */
 971   luaK_goiftrue(ls->fs, &v);
 972   return v.f;
 973 }
 974
 975
 976 static void breakstat (LexState *ls) {
 977   FuncState *fs = ls->fs;
 978   BlockCnt *bl = fs->bl;
 979   int upval = 0;
 980   while (bl && !bl->isbreakable) {
 981     upval |= bl->upval;
 982     bl = bl->previous;
 983   }
 984   if (!bl)
 985     luaX_syntaxerror(ls, "no loop to break");
 986   if (upval)
 987     luaK_codeABC(fs, OP_CLOSE, bl->nactvar, 0, 0);
 988   luaK_concat(fs, &bl->breaklist, luaK_jump(fs));
 989 }
 990
 991
 992 static void whilestat (LexState *ls, int line) {
 993   /* whilestat -> WHILE cond DO block END */
 994   FuncState *fs = ls->fs;
 995   int whileinit;
 996   int condexit;
 997   BlockCnt bl;
 998   luaX_next(ls);  /* skip WHILE */
 999   whileinit = luaK_getlabel(fs);
1000   condexit = cond(ls);
1001   enterblock(fs, &bl, 1);
1002   checknext(ls, TK_DO);
1003   block(ls);
1004   luaK_patchlist(fs, luaK_jump(fs), whileinit);
1005   check_match(ls, TK_END, TK_WHILE, line);
1006   leaveblock(fs);
1007   luaK_patchtohere(fs, condexit);  /* false conditions finish the loop */
1008 }
1009
1010
1011 static void repeatstat (LexState *ls, int line) {
1012   /* repeatstat -> REPEAT block UNTIL cond */
1013   int condexit;
1014   FuncState *fs = ls->fs;
1015   int repeat_init = luaK_getlabel(fs);
1016   BlockCnt bl1, bl2;
1017   enterblock(fs, &bl1, 1);  /* loop block */
1018   enterblock(fs, &bl2, 0);  /* scope block */
1019   luaX_next(ls);  /* skip REPEAT */
1020   chunk(ls);
1021   check_match(ls, TK_UNTIL, TK_REPEAT, line);
1022   condexit = cond(ls);  /* read condition (inside scope block) */
1023   if (!bl2.upval) {  /* no upvalues? */
1024     leaveblock(fs);  /* finish scope */
1025     luaK_patchlist(ls->fs, condexit, repeat_init);  /* close the loop */
1026   }
1027   else {  /* complete semantics when there are upvalues */
1028     breakstat(ls);  /* if condition then break */
1029     luaK_patchtohere(ls->fs, condexit);  /* else... */
1030     leaveblock(fs);  /* finish scope... */
1031     luaK_patchlist(ls->fs, luaK_jump(fs), repeat_init);  /* and repeat */
1032   }
1033   leaveblock(fs);  /* finish loop */
1034 }
1035
1036
1037 static int exp1 (LexState *ls) {
1038   expdesc e;
1039   int k;
1040   expr(ls, &e);
1041   k = e.k;
1042   luaK_exp2nextreg(ls->fs, &e);
1043   return k;
1044 }
1045
1046
1047 static void forbody (LexState *ls, int base, int line, int nvars, int isnum) {
1048   /* forbody -> DO block */
1049   BlockCnt bl;
1050   FuncState *fs = ls->fs;
1051   int prep, endfor;
1052   adjustlocalvars(ls, 3);  /* control variables */
1053   checknext(ls, TK_DO);
1054   prep = isnum ? luaK_codeAsBx(fs, OP_FORPREP, base, NO_JUMP) : luaK_jump(fs);
1055   enterblock(fs, &bl, 0);  /* scope for declared variables */
1056   adjustlocalvars(ls, nvars);
1057   luaK_reserveregs(fs, nvars);
1058   block(ls);
1059   leaveblock(fs);  /* end of scope for declared variables */
1060   luaK_patchtohere(fs, prep);
1061   endfor = (isnum) ? luaK_codeAsBx(fs, OP_FORLOOP, base, NO_JUMP) :
1062                      luaK_codeABC(fs, OP_TFORLOOP, base, 0, nvars);
1063   luaK_fixline(fs, line);  /* pretend that `OP_FOR' starts the loop */
1064   luaK_patchlist(fs, (isnum ? endfor : luaK_jump(fs)), prep + 1);
1065 }
1066
1067
1068 static void fornum (LexState *ls, TString *varname, int line) {
1069   /* fornum -> NAME = exp1,exp1[,exp1] forbody */
1070   FuncState *fs = ls->fs;
1071   int base = fs->freereg;
1072   new_localvarliteral(ls, "(for index)", 0);
1073   new_localvarliteral(ls, "(for limit)", 1);
1074   new_localvarliteral(ls, "(for step)", 2);
1075   new_localvar(ls, varname, 3);
1076   checknext(ls, '=');
1077   exp1(ls);  /* initial value */
1078   checknext(ls, ',');
1079   exp1(ls);  /* limit */
1080   if (testnext(ls, ','))
1081     exp1(ls);  /* optional step */
1082   else {  /* default step = 1 */
1083     luaK_codeABx(fs, OP_LOADK, fs->freereg, luaK_numberK(fs, 1));
1084     luaK_reserveregs(fs, 1);
1085   }
1086   forbody(ls, base, line, 1, 1);
1087 }
1088
1089
1090 static void forlist (LexState *ls, TString *indexname) {
1091   /* forlist -> NAME {,NAME} IN explist1 forbody */
1092   FuncState *fs = ls->fs;
1093   expdesc e;
1094   int nvars = 0;
1095   int line;
1096   int base = fs->freereg;
1097   /* create control variables */
1098   new_localvarliteral(ls, "(for generator)", nvars++);
1099   new_localvarliteral(ls, "(for state)", nvars++);
1100   new_localvarliteral(ls, "(for control)", nvars++);
1101   /* create declared variables */
1102   new_localvar(ls, indexname, nvars++);
1103   while (testnext(ls, ','))
1104     new_localvar(ls, str_checkname(ls), nvars++);
1105   checknext(ls, TK_IN);
1106   line = ls->linenumber;
1107   adjust_assign(ls, 3, explist1(ls, &e), &e);
1108   luaK_checkstack(fs, 3);  /* extra space to call generator */
1109   forbody(ls, base, line, nvars - 3, 0);
1110 }
1111
1112
1113 static void forstat (LexState *ls, int line) {
1114   /* forstat -> FOR (fornum | forlist) END */
1115   FuncState *fs = ls->fs;
1116   TString *varname;
1117   BlockCnt bl;
1118   enterblock(fs, &bl, 1);  /* scope for loop and control variables */
1119   luaX_next(ls);  /* skip `for' */
1120   varname = str_checkname(ls);  /* first variable name */
1121   switch (ls->t.token) {
1122     case '=': fornum(ls, varname, line); break;
1123     case ',': case TK_IN: forlist(ls, varname); break;
1124     default: luaX_syntaxerror(ls, LUA_QL("=") " or " LUA_QL("in") " expected");
1125   }
1126   check_match(ls, TK_END, TK_FOR, line);
1127   leaveblock(fs);  /* loop scope (`break' jumps to this point) */
1128 }
1129
1130
1131 static int test_then_block (LexState *ls) {
1132   /* test_then_block -> [IF | ELSEIF] cond THEN block */
1133   int condexit;
1134   luaX_next(ls);  /* skip IF or ELSEIF */
1135   condexit = cond(ls);
1136   checknext(ls, TK_THEN);
1137   block(ls);  /* `then' part */
1138   return condexit;
1139 }
1140
1141
1142 static void ifstat (LexState *ls, int line) {
1143   /* ifstat -> IF cond THEN block {ELSEIF cond THEN block} [ELSE block] END */
1144   FuncState *fs = ls->fs;
1145   int flist;
1146   int escapelist = NO_JUMP;
1147   flist = test_then_block(ls);  /* IF cond THEN block */
1148   while (ls->t.token == TK_ELSEIF) {
1149     luaK_concat(fs, &escapelist, luaK_jump(fs));
1150     luaK_patchtohere(fs, flist);
1151     flist = test_then_block(ls);  /* ELSEIF cond THEN block */
1152   }
1153   if (ls->t.token == TK_ELSE) {
1154     luaK_concat(fs, &escapelist, luaK_jump(fs));
1155     luaK_patchtohere(fs, flist);
1156     luaX_next(ls);  /* skip ELSE (after patch, for correct line info) */
1157     block(ls);  /* `else' part */
1158   }
1159   else
1160     luaK_concat(fs, &escapelist, flist);
1161   luaK_patchtohere(fs, escapelist);
1162   check_match(ls, TK_END, TK_IF, line);
1163 }
1164
1165
1166 static void localfunc (LexState *ls) {
1167   expdesc v, b;
1168   FuncState *fs = ls->fs;
1169   new_localvar(ls, str_checkname(ls), 0);
1170   init_exp(&v, VLOCAL, fs->freereg);
1171   luaK_reserveregs(fs, 1);
1172   adjustlocalvars(ls, 1);
1173   body(ls, &b, 0, ls->linenumber);
1174   luaK_storevar(fs, &v, &b);
1175   /* debug information will only see the variable after this point! */
1176   getlocvar(fs, fs->nactvar - 1).startpc = fs->pc;
1177 }
1178
1179
1180 static void localstat (LexState *ls) {
1181   /* stat -> LOCAL NAME {`,' NAME} [`=' explist1] */
1182   int nvars = 0;
1183   int nexps;
1184   expdesc e;
1185   do {
1186     new_localvar(ls, str_checkname(ls), nvars++);
1187   } while (testnext(ls, ','));
1188   if (testnext(ls, '='))
1189     nexps = explist1(ls, &e);
1190   else {
1191     e.k = VVOID;
1192     nexps = 0;
1193   }
1194   adjust_assign(ls, nvars, nexps, &e);
1195   adjustlocalvars(ls, nvars);
1196 }
1197
1198
1199 static int funcname (LexState *ls, expdesc *v) {
1200   /* funcname -> NAME {field} [`:' NAME] */
1201   int needself = 0;
1202   singlevar(ls, v);
1203   while (ls->t.token == '.')
1204     field(ls, v);
1205   if (ls->t.token == ':') {
1206     needself = 1;
1207     field(ls, v);
1208   }
1209   return needself;
1210 }
1211
1212
1213 static void funcstat (LexState *ls, int line) {
1214   /* funcstat -> FUNCTION funcname body */
1215   int needself;
1216   expdesc v, b;
1217   luaX_next(ls);  /* skip FUNCTION */
1218   needself = funcname(ls, &v);
1219   body(ls, &b, needself, line);
1220   luaK_storevar(ls->fs, &v, &b);
1221   luaK_fixline(ls->fs, line);  /* definition `happens' in the first line */
1222 }
1223
1224
1225 static void exprstat (LexState *ls) {
1226   /* stat -> func | assignment */
1227   FuncState *fs = ls->fs;
1228   struct LHS_assign v;
1229   primaryexp(ls, &v.v);
1230   if (v.v.k == VCALL)  /* stat -> func */
1231     SETARG_C(getcode(fs, &v.v), 1);  /* call statement uses no results */
1232   else {  /* stat -> assignment */
1233     v.prev = NULL;
1234     assignment(ls, &v, 1);
1235   }
1236 }
1237
1238
1239 static void retstat (LexState *ls) {
1240   /* stat -> RETURN explist */
1241   FuncState *fs = ls->fs;
1242   expdesc e;
1243   int first, nret;  /* registers with returned values */
1244   luaX_next(ls);  /* skip RETURN */
1245   if (block_follow(ls->t.token) || ls->t.token == ';')
1246     first = nret = 0;  /* return no values */
1247   else {
1248     nret = explist1(ls, &e);  /* optional return values */
1249     if (hasmultret(e.k)) {
1250       luaK_setmultret(fs, &e);
1251       if (e.k == VCALL && nret == 1) {  /* tail call? */
1252         SET_OPCODE(getcode(fs,&e), OP_TAILCALL);
1253         lua_assert(GETARG_A(getcode(fs,&e)) == fs->nactvar);
1254       }
1255       first = fs->nactvar;
1256       nret = LUA_MULTRET;  /* return all values */
1257     }
1258     else {
1259       if (nret == 1)  /* only one single value? */
1260         first = luaK_exp2anyreg(fs, &e);
1261       else {
1262         luaK_exp2nextreg(fs, &e);  /* values must go to the `stack' */
1263         first = fs->nactvar;  /* return all `active' values */
1264         lua_assert(nret == fs->freereg - first);
1265       }
1266     }
1267   }
1268   luaK_ret(fs, first, nret);
1269 }
1270
1271
1272 static int statement (LexState *ls) {
1273   int line = ls->linenumber;  /* may be needed for error messages */
1274   switch (ls->t.token) {
1275     case TK_IF: {  /* stat -> ifstat */
1276       ifstat(ls, line);
1277       return 0;
1278     }
1279     case TK_WHILE: {  /* stat -> whilestat */
1280       whilestat(ls, line);
1281       return 0;
1282     }
1283     case TK_DO: {  /* stat -> DO block END */
1284       luaX_next(ls);  /* skip DO */
1285       block(ls);
1286       check_match(ls, TK_END, TK_DO, line);
1287       return 0;
1288     }
1289     case TK_FOR: {  /* stat -> forstat */
1290       forstat(ls, line);
1291       return 0;
1292     }
1293     case TK_REPEAT: {  /* stat -> repeatstat */
1294       repeatstat(ls, line);
1295       return 0;
1296     }
1297     case TK_FUNCTION: {
1298       funcstat(ls, line);  /* stat -> funcstat */
1299       return 0;
1300     }
1301     case TK_LOCAL: {  /* stat -> localstat */
1302       luaX_next(ls);  /* skip LOCAL */
1303       if (testnext(ls, TK_FUNCTION))  /* local function? */
1304         localfunc(ls);
1305       else
1306         localstat(ls);
1307       return 0;
1308     }
1309     case TK_RETURN: {  /* stat -> retstat */
1310       retstat(ls);
1311       return 1;  /* must be last statement */
1312     }
1313     case TK_BREAK: {  /* stat -> breakstat */
1314       luaX_next(ls);  /* skip BREAK */
1315       breakstat(ls);
1316       return 1;  /* must be last statement */
1317     }
1318     default: {
1319       exprstat(ls);
1320       return 0;  /* to avoid warnings */
1321     }
1322   }
1323 }
1324
1325
1326 static void chunk (LexState *ls) {
1327   /* chunk -> { stat [`;'] } */
1328   int islast = 0;
1329   enterlevel(ls);
1330   while (!islast && !block_follow(ls->t.token)) {
1331     islast = statement(ls);
1332     testnext(ls, ';');
1333     lua_assert(ls->fs->f->maxstacksize >= ls->fs->freereg &&
1334                ls->fs->freereg >= ls->fs->nactvar);
1335     ls->fs->freereg = ls->fs->nactvar;  /* free registers */
1336   }
1337   leavelevel(ls);
1338 }
1339
1340 /* }====================================================================== */