module/lua/lparser.c

   1 /*
   2 ** $Id: lparser.c,v 2.130.1.1 2013/04/12 18:48:47 roberto Exp $
   3 ** Lua Parser
   4 ** See Copyright Notice in lua.h
   5 */
   6
   7 #define lparser_c
   8 #define LUA_CORE
   9
  10 #include <sys/lua/lua.h>
  11
  12 #include "lcode.h"
  13 #include "ldebug.h"
  14 #include "ldo.h"
  15 #include "lfunc.h"
  16 #include "llex.h"
  17 #include "lmem.h"
  18 #include "lobject.h"
  19 #include "lopcodes.h"
  20 #include "lparser.h"
  21 #include "lstate.h"
  22 #include "lstring.h"
  23 #include "ltable.h"
  24
  25
  26
  27 /* maximum number of local variables per function (must be smaller
  28    than 250, due to the bytecode format) */
  29 #define MAXVARS         200
  30
  31
  32 #define hasmultret(k)           ((k) == VCALL || (k) == VVARARG)
  33
  34
  35
  36 /*
  37 ** nodes for block list (list of active blocks)
  38 */
  39 typedef struct BlockCnt {
  40   struct BlockCnt *previous;  /* chain */
  41   short firstlabel;  /* index of first label in this block */
  42   short firstgoto;  /* index of first pending goto in this block */
  43   lu_byte nactvar;  /* # active locals outside the block */
  44   lu_byte upval;  /* true if some variable in the block is an upvalue */
  45   lu_byte isloop;  /* true if `block' is a loop */
  46 } BlockCnt;
  47
  48
  49
  50 /*
  51 ** prototypes for recursive non-terminal functions
  52 */
  53 static void statement (LexState *ls);
  54 static void expr (LexState *ls, expdesc *v);
  55
  56
  57 static void anchor_token (LexState *ls) {
  58   /* last token from outer function must be EOS */
  59   lua_assert(ls->fs != NULL || ls->t.token == TK_EOS);
  60   if (ls->t.token == TK_NAME || ls->t.token == TK_STRING) {
  61     TString *ts = ls->t.seminfo.ts;
  62     luaX_newstring(ls, getstr(ts), ts->tsv.len);
  63   }
  64 }
  65
  66
  67 /* semantic error */
  68 static l_noret semerror (LexState *ls, const char *msg) {
  69   ls->t.token = 0;  /* remove 'near to' from final message */
  70   luaX_syntaxerror(ls, msg);
  71 }
  72
  73
  74 static l_noret error_expected (LexState *ls, int token) {
  75   luaX_syntaxerror(ls,
  76       luaO_pushfstring(ls->L, "%s expected", luaX_token2str(ls, token)));
  77 }
  78
  79
  80 static l_noret errorlimit (FuncState *fs, int limit, const char *what) {
  81   lua_State *L = fs->ls->L;
  82   const char *msg;
  83   int line = fs->f->linedefined;
  84   const char *where = (line == 0)
  85                       ? "main function"
  86                       : luaO_pushfstring(L, "function at line %d", line);
  87   msg = luaO_pushfstring(L, "too many %s (limit is %d) in %s",
  88                              what, limit, where);
  89   luaX_syntaxerror(fs->ls, msg);
  90 }
  91
  92
  93 static void checklimit (FuncState *fs, int v, int l, const char *what) {
  94   if (v > l) errorlimit(fs, l, what);
  95 }
  96
  97
  98 static int testnext (LexState *ls, int c) {
  99   if (ls->t.token == c) {
 100     luaX_next(ls);
 101     return 1;
 102   }
 103   else return 0;
 104 }
 105
 106
 107 static void check (LexState *ls, int c) {
 108   if (ls->t.token != c)
 109     error_expected(ls, c);
 110 }
 111
 112
 113 static void checknext (LexState *ls, int c) {
 114   check(ls, c);
 115   luaX_next(ls);
 116 }
 117
 118
 119 #define check_condition(ls,c,msg)       { if (!(c)) luaX_syntaxerror(ls, msg); }
 120
 121
 122
 123 static void check_match (LexState *ls, int what, int who, int where) {
 124   if (!testnext(ls, what)) {
 125     if (where == ls->linenumber)
 126       error_expected(ls, what);
 127     else {
 128       luaX_syntaxerror(ls, luaO_pushfstring(ls->L,
 129              "%s expected (to close %s at line %d)",
 130               luaX_token2str(ls, what), luaX_token2str(ls, who), where));
 131     }
 132   }
 133 }
 134
 135
 136 static TString *str_checkname (LexState *ls) {
 137   TString *ts;
 138   check(ls, TK_NAME);
 139   ts = ls->t.seminfo.ts;
 140   luaX_next(ls);
 141   return ts;
 142 }
 143
 144
 145 static void init_exp (expdesc *e, expkind k, int i) {
 146   e->f = e->t = NO_JUMP;
 147   e->k = k;
 148   e->u.info = i;
 149 }
 150
 151
 152 static void codestring (LexState *ls, expdesc *e, TString *s) {
 153   init_exp(e, VK, luaK_stringK(ls->fs, s));
 154 }
 155
 156
 157 static void checkname (LexState *ls, expdesc *e) {
 158   codestring(ls, e, str_checkname(ls));
 159 }
 160
 161
 162 static int registerlocalvar (LexState *ls, TString *varname) {
 163   FuncState *fs = ls->fs;
 164   Proto *f = fs->f;
 165   int oldsize = f->sizelocvars;
 166   luaM_growvector(ls->L, f->locvars, fs->nlocvars, f->sizelocvars,
 167                   LocVar, SHRT_MAX, "local variables");
 168   while (oldsize < f->sizelocvars) f->locvars[oldsize++].varname = NULL;
 169   f->locvars[fs->nlocvars].varname = varname;
 170   luaC_objbarrier(ls->L, f, varname);
 171   return fs->nlocvars++;
 172 }
 173
 174
 175 static void new_localvar (LexState *ls, TString *name) {
 176   FuncState *fs = ls->fs;
 177   Dyndata *dyd = ls->dyd;
 178   int reg = registerlocalvar(ls, name);
 179   checklimit(fs, dyd->actvar.n + 1 - fs->firstlocal,
 180                   MAXVARS, "local variables");
 181   luaM_growvector(ls->L, dyd->actvar.arr, dyd->actvar.n + 1,
 182                   dyd->actvar.size, Vardesc, MAX_INT, "local variables");
 183   dyd->actvar.arr[dyd->actvar.n++].idx = cast(short, reg);
 184 }
 185
 186
 187 static void new_localvarliteral_ (LexState *ls, const char *name, size_t sz) {
 188   new_localvar(ls, luaX_newstring(ls, name, sz));
 189 }
 190
 191 #define new_localvarliteral(ls,v) \
 192         new_localvarliteral_(ls, "" v, (sizeof(v)/sizeof(char))-1)
 193
 194
 195 static LocVar *getlocvar (FuncState *fs, int i) {
 196   int idx = fs->ls->dyd->actvar.arr[fs->firstlocal + i].idx;
 197   lua_assert(idx < fs->nlocvars);
 198   return &fs->f->locvars[idx];
 199 }
 200
 201
 202 static void adjustlocalvars (LexState *ls, int nvars) {
 203   FuncState *fs = ls->fs;
 204   fs->nactvar = cast_byte(fs->nactvar + nvars);
 205   for (; nvars; nvars--) {
 206     getlocvar(fs, fs->nactvar - nvars)->startpc = fs->pc;
 207   }
 208 }
 209
 210
 211 static void removevars (FuncState *fs, int tolevel) {
 212   fs->ls->dyd->actvar.n -= (fs->nactvar - tolevel);
 213   while (fs->nactvar > tolevel)
 214     getlocvar(fs, --fs->nactvar)->endpc = fs->pc;
 215 }
 216
 217
 218 static int searchupvalue (FuncState *fs, TString *name) {
 219   int i;
 220   Upvaldesc *up = fs->f->upvalues;
 221   for (i = 0; i < fs->nups; i++) {
 222     if (luaS_eqstr(up[i].name, name)) return i;
 223   }
 224   return -1;  /* not found */
 225 }
 226
 227
 228 static int newupvalue (FuncState *fs, TString *name, expdesc *v) {
 229   Proto *f = fs->f;
 230   int oldsize = f->sizeupvalues;
 231   checklimit(fs, fs->nups + 1, MAXUPVAL, "upvalues");
 232   luaM_growvector(fs->ls->L, f->upvalues, fs->nups, f->sizeupvalues,
 233                   Upvaldesc, MAXUPVAL, "upvalues");
 234   while (oldsize < f->sizeupvalues) f->upvalues[oldsize++].name = NULL;
 235   f->upvalues[fs->nups].instack = (v->k == VLOCAL);
 236   f->upvalues[fs->nups].idx = cast_byte(v->u.info);
 237   f->upvalues[fs->nups].name = name;
 238   luaC_objbarrier(fs->ls->L, f, name);
 239   return fs->nups++;
 240 }
 241
 242
 243 static int searchvar (FuncState *fs, TString *n) {
 244   int i;
 245   for (i = cast_int(fs->nactvar) - 1; i >= 0; i--) {
 246     if (luaS_eqstr(n, getlocvar(fs, i)->varname))
 247       return i;
 248   }
 249   return -1;  /* not found */
 250 }
 251
 252
 253 /*
 254   Mark block where variable at given level was defined
 255   (to emit close instructions later).
 256 */
 257 static void markupval (FuncState *fs, int level) {
 258   BlockCnt *bl = fs->bl;
 259   while (bl->nactvar > level) bl = bl->previous;
 260   bl->upval = 1;
 261 }
 262
 263
 264 /*
 265   Find variable with given name 'n'. If it is an upvalue, add this
 266   upvalue into all intermediate functions.
 267 */
 268 static int singlevaraux (FuncState *fs, TString *n, expdesc *var, int base) {
 269   if (fs == NULL)  /* no more levels? */
 270     return VVOID;  /* default is global */
 271   else {
 272     int v = searchvar(fs, n);  /* look up locals at current level */
 273     if (v >= 0) {  /* found? */
 274       init_exp(var, VLOCAL, v);  /* variable is local */
 275       if (!base)
 276         markupval(fs, v);  /* local will be used as an upval */
 277       return VLOCAL;
 278     }
 279     else {  /* not found as local at current level; try upvalues */
 280       int idx = searchupvalue(fs, n);  /* try existing upvalues */
 281       if (idx < 0) {  /* not found? */
 282         if (singlevaraux(fs->prev, n, var, 0) == VVOID) /* try upper levels */
 283           return VVOID;  /* not found; is a global */
 284         /* else was LOCAL or UPVAL */
 285         idx  = newupvalue(fs, n, var);  /* will be a new upvalue */
 286       }
 287       init_exp(var, VUPVAL, idx);
 288       return VUPVAL;
 289     }
 290   }
 291 }
 292
 293
 294 static void singlevar (LexState *ls, expdesc *var) {
 295   TString *varname = str_checkname(ls);
 296   FuncState *fs = ls->fs;
 297   if (singlevaraux(fs, varname, var, 1) == VVOID) {  /* global name? */
 298     expdesc key;
 299     singlevaraux(fs, ls->envn, var, 1);  /* get environment variable */
 300     lua_assert(var->k == VLOCAL || var->k == VUPVAL);
 301     codestring(ls, &key, varname);  /* key is variable name */
 302     luaK_indexed(fs, var, &key);  /* env[varname] */
 303   }
 304 }
 305
 306
 307 static void adjust_assign (LexState *ls, int nvars, int nexps, expdesc *e) {
 308   FuncState *fs = ls->fs;
 309   int extra = nvars - nexps;
 310   if (hasmultret(e->k)) {
 311     extra++;  /* includes call itself */
 312     if (extra < 0) extra = 0;
 313     luaK_setreturns(fs, e, extra);  /* last exp. provides the difference */
 314     if (extra > 1) luaK_reserveregs(fs, extra-1);
 315   }
 316   else {
 317     if (e->k != VVOID) luaK_exp2nextreg(fs, e);  /* close last expression */
 318     if (extra > 0) {
 319       int reg = fs->freereg;
 320       luaK_reserveregs(fs, extra);
 321       luaK_nil(fs, reg, extra);
 322     }
 323   }
 324 }
 325
 326
 327 static void enterlevel (LexState *ls) {
 328   lua_State *L = ls->L;
 329   ++L->nCcalls;
 330   checklimit(ls->fs, L->nCcalls, LUAI_MAXCCALLS, "C levels");
 331 }
 332
 333
 334 #define leavelevel(ls)  ((ls)->L->nCcalls--)
 335
 336
 337 static void closegoto (LexState *ls, int g, Labeldesc *label) {
 338   int i;
 339   FuncState *fs = ls->fs;
 340   Labellist *gl = &ls->dyd->gt;
 341   Labeldesc *gt = &gl->arr[g];
 342   lua_assert(luaS_eqstr(gt->name, label->name));
 343   if (gt->nactvar < label->nactvar) {
 344     TString *vname = getlocvar(fs, gt->nactvar)->varname;
 345     const char *msg = luaO_pushfstring(ls->L,
 346       "<goto %s> at line %d jumps into the scope of local " LUA_QS,
 347       getstr(gt->name), gt->line, getstr(vname));
 348     semerror(ls, msg);
 349   }
 350   luaK_patchlist(fs, gt->pc, label->pc);
 351   /* remove goto from pending list */
 352   for (i = g; i < gl->n - 1; i++)
 353     gl->arr[i] = gl->arr[i + 1];
 354   gl->n--;
 355 }
 356
 357
 358 /*
 359 ** try to close a goto with existing labels; this solves backward jumps
 360 */
 361 static int findlabel (LexState *ls, int g) {
 362   int i;
 363   BlockCnt *bl = ls->fs->bl;
 364   Dyndata *dyd = ls->dyd;
 365   Labeldesc *gt = &dyd->gt.arr[g];
 366   /* check labels in current block for a match */
 367   for (i = bl->firstlabel; i < dyd->label.n; i++) {
 368     Labeldesc *lb = &dyd->label.arr[i];
 369     if (luaS_eqstr(lb->name, gt->name)) {  /* correct label? */
 370       if (gt->nactvar > lb->nactvar &&
 371           (bl->upval || dyd->label.n > bl->firstlabel))
 372         luaK_patchclose(ls->fs, gt->pc, lb->nactvar);
 373       closegoto(ls, g, lb);  /* close it */
 374       return 1;
 375     }
 376   }
 377   return 0;  /* label not found; cannot close goto */
 378 }
 379
 380
 381 static int newlabelentry (LexState *ls, Labellist *l, TString *name,
 382                           int line, int pc) {
 383   int n = l->n;
 384   luaM_growvector(ls->L, l->arr, n, l->size,
 385                   Labeldesc, SHRT_MAX, "labels/gotos");
 386   l->arr[n].name = name;
 387   l->arr[n].line = line;
 388   l->arr[n].nactvar = ls->fs->nactvar;
 389   l->arr[n].pc = pc;
 390   l->n++;
 391   return n;
 392 }
 393
 394
 395 /*
 396 ** check whether new label 'lb' matches any pending gotos in current
 397 ** block; solves forward jumps
 398 */
 399 static void findgotos (LexState *ls, Labeldesc *lb) {
 400   Labellist *gl = &ls->dyd->gt;
 401   int i = ls->fs->bl->firstgoto;
 402   while (i < gl->n) {
 403     if (luaS_eqstr(gl->arr[i].name, lb->name))
 404       closegoto(ls, i, lb);
 405     else
 406       i++;
 407   }
 408 }
 409
 410
 411 /*
 412 ** "export" pending gotos to outer level, to check them against
 413 ** outer labels; if the block being exited has upvalues, and
 414 ** the goto exits the scope of any variable (which can be the
 415 ** upvalue), close those variables being exited.
 416 */
 417 static void movegotosout (FuncState *fs, BlockCnt *bl) {
 418   int i = bl->firstgoto;
 419   Labellist *gl = &fs->ls->dyd->gt;
 420   /* correct pending gotos to current block and try to close it
 421      with visible labels */
 422   while (i < gl->n) {
 423     Labeldesc *gt = &gl->arr[i];
 424     if (gt->nactvar > bl->nactvar) {
 425       if (bl->upval)
 426         luaK_patchclose(fs, gt->pc, bl->nactvar);
 427       gt->nactvar = bl->nactvar;
 428     }
 429     if (!findlabel(fs->ls, i))
 430       i++;  /* move to next one */
 431   }
 432 }
 433
 434
 435 static void enterblock (FuncState *fs, BlockCnt *bl, lu_byte isloop) {
 436   bl->isloop = isloop;
 437   bl->nactvar = fs->nactvar;
 438   bl->firstlabel = fs->ls->dyd->label.n;
 439   bl->firstgoto = fs->ls->dyd->gt.n;
 440   bl->upval = 0;
 441   bl->previous = fs->bl;
 442   fs->bl = bl;
 443   lua_assert(fs->freereg == fs->nactvar);
 444 }
 445
 446
 447 /*
 448 ** create a label named "break" to resolve break statements
 449 */
 450 static void breaklabel (LexState *ls) {
 451   TString *n = luaS_new(ls->L, "break");
 452   int l = newlabelentry(ls, &ls->dyd->label, n, 0, ls->fs->pc);
 453   findgotos(ls, &ls->dyd->label.arr[l]);
 454 }
 455
 456 /*
 457 ** generates an error for an undefined 'goto'; choose appropriate
 458 ** message when label name is a reserved word (which can only be 'break')
 459 */
 460 static l_noret undefgoto (LexState *ls, Labeldesc *gt) {
 461   const char *msg = isreserved(gt->name)
 462                     ? "<%s> at line %d not inside a loop"
 463                     : "no visible label " LUA_QS " for <goto> at line %d";
 464   msg = luaO_pushfstring(ls->L, msg, getstr(gt->name), gt->line);
 465   semerror(ls, msg);
 466 }
 467
 468
 469 static void leaveblock (FuncState *fs) {
 470   BlockCnt *bl = fs->bl;
 471   LexState *ls = fs->ls;
 472   if (bl->previous && bl->upval) {
 473     /* create a 'jump to here' to close upvalues */
 474     int j = luaK_jump(fs);
 475     luaK_patchclose(fs, j, bl->nactvar);
 476     luaK_patchtohere(fs, j);
 477   }
 478   if (bl->isloop)
 479     breaklabel(ls);  /* close pending breaks */
 480   fs->bl = bl->previous;
 481   removevars(fs, bl->nactvar);
 482   lua_assert(bl->nactvar == fs->nactvar);
 483   fs->freereg = fs->nactvar;  /* free registers */
 484   ls->dyd->label.n = bl->firstlabel;  /* remove local labels */
 485   if (bl->previous)  /* inner block? */
 486     movegotosout(fs, bl);  /* update pending gotos to outer block */
 487   else if (bl->firstgoto < ls->dyd->gt.n)  /* pending gotos in outer block? */
 488     undefgoto(ls, &ls->dyd->gt.arr[bl->firstgoto]);  /* error */
 489 }
 490
 491
 492 /*
 493 ** adds a new prototype into list of prototypes
 494 */
 495 static Proto *addprototype (LexState *ls) {
 496   Proto *clp;
 497   lua_State *L = ls->L;
 498   FuncState *fs = ls->fs;
 499   Proto *f = fs->f;  /* prototype of current function */
 500   if (fs->np >= f->sizep) {
 501     int oldsize = f->sizep;
 502     luaM_growvector(L, f->p, fs->np, f->sizep, Proto *, MAXARG_Bx, "functions");
 503     while (oldsize < f->sizep) f->p[oldsize++] = NULL;
 504   }
 505   f->p[fs->np++] = clp = luaF_newproto(L);
 506   luaC_objbarrier(L, f, clp);
 507   return clp;
 508 }
 509
 510
 511 /*
 512 ** codes instruction to create new closure in parent function.
 513 ** The OP_CLOSURE instruction must use the last available register,
 514 ** so that, if it invokes the GC, the GC knows which registers
 515 ** are in use at that time.
 516 */
 517 static void codeclosure (LexState *ls, expdesc *v) {
 518   FuncState *fs = ls->fs->prev;
 519   init_exp(v, VRELOCABLE, luaK_codeABx(fs, OP_CLOSURE, 0, fs->np - 1));
 520   luaK_exp2nextreg(fs, v);  /* fix it at the last register */
 521 }
 522
 523
 524 static void open_func (LexState *ls, FuncState *fs, BlockCnt *bl) {
 525   lua_State *L = ls->L;
 526   Proto *f;
 527   fs->prev = ls->fs;  /* linked list of funcstates */
 528   fs->ls = ls;
 529   ls->fs = fs;
 530   fs->pc = 0;
 531   fs->lasttarget = 0;
 532   fs->jpc = NO_JUMP;
 533   fs->freereg = 0;
 534   fs->nk = 0;
 535   fs->np = 0;
 536   fs->nups = 0;
 537   fs->nlocvars = 0;
 538   fs->nactvar = 0;
 539   fs->firstlocal = ls->dyd->actvar.n;
 540   fs->bl = NULL;
 541   f = fs->f;
 542   f->source = ls->source;
 543   f->maxstacksize = 2;  /* registers 0/1 are always valid */
 544   fs->h = luaH_new(L);
 545   /* anchor table of constants (to avoid being collected) */
 546   sethvalue2s(L, L->top, fs->h);
 547   incr_top(L);
 548   enterblock(fs, bl, 0);
 549 }
 550
 551
 552 static void close_func (LexState *ls) {
 553   lua_State *L = ls->L;
 554   FuncState *fs = ls->fs;
 555   Proto *f = fs->f;
 556   luaK_ret(fs, 0, 0);  /* final return */
 557   leaveblock(fs);
 558   luaM_reallocvector(L, f->code, f->sizecode, fs->pc, Instruction);
 559   f->sizecode = fs->pc;
 560   luaM_reallocvector(L, f->lineinfo, f->sizelineinfo, fs->pc, int);
 561   f->sizelineinfo = fs->pc;
 562   luaM_reallocvector(L, f->k, f->sizek, fs->nk, TValue);
 563   f->sizek = fs->nk;
 564   luaM_reallocvector(L, f->p, f->sizep, fs->np, Proto *);
 565   f->sizep = fs->np;
 566   luaM_reallocvector(L, f->locvars, f->sizelocvars, fs->nlocvars, LocVar);
 567   f->sizelocvars = fs->nlocvars;
 568   luaM_reallocvector(L, f->upvalues, f->sizeupvalues, fs->nups, Upvaldesc);
 569   f->sizeupvalues = fs->nups;
 570   lua_assert(fs->bl == NULL);
 571   ls->fs = fs->prev;
 572   /* last token read was anchored in defunct function; must re-anchor it */
 573   anchor_token(ls);
 574   L->top--;  /* pop table of constants */
 575   luaC_checkGC(L);
 576 }
 577
 578
 579
 580 /*============================================================*/
 581 /* GRAMMAR RULES */
 582 /*============================================================*/
 583
 584
 585 /*
 586 ** check whether current token is in the follow set of a block.
 587 ** 'until' closes syntactical blocks, but do not close scope,
 588 ** so it handled in separate.
 589 */
 590 static int block_follow (LexState *ls, int withuntil) {
 591   switch (ls->t.token) {
 592     case TK_ELSE: case TK_ELSEIF:
 593     case TK_END: case TK_EOS:
 594       return 1;
 595     case TK_UNTIL: return withuntil;
 596     default: return 0;
 597   }
 598 }
 599
 600
 601 /*
 602  * by inlining statlist() and test_then_block() we cut back the
 603  * native stack usage per nested C call from 272 bytes to 152
 604  * which allows us to stay within budget for 8K kernel stacks
 605  */
 606 __attribute__((always_inline)) inline
 607 static void statlist (LexState *ls) {
 608   /* statlist -> { stat [`;'] } */
 609   while (!block_follow(ls, 1)) {
 610     if (ls->t.token == TK_RETURN) {
 611       statement(ls);
 612       return;  /* 'return' must be last statement */
 613     }
 614     statement(ls);
 615   }
 616 }
 617
 618
 619 static void fieldsel (LexState *ls, expdesc *v) {
 620   /* fieldsel -> ['.' | ':'] NAME */
 621   FuncState *fs = ls->fs;
 622   expdesc key;
 623   luaK_exp2anyregup(fs, v);
 624   luaX_next(ls);  /* skip the dot or colon */
 625   checkname(ls, &key);
 626   luaK_indexed(fs, v, &key);
 627 }
 628
 629
 630 static void yindex (LexState *ls, expdesc *v) {
 631   /* index -> '[' expr ']' */
 632   luaX_next(ls);  /* skip the '[' */
 633   expr(ls, v);
 634   luaK_exp2val(ls->fs, v);
 635   checknext(ls, ']');
 636 }
 637
 638
 639 /*
 640 ** {======================================================================
 641 ** Rules for Constructors
 642 ** =======================================================================
 643 */
 644
 645
 646 struct ConsControl {
 647   expdesc v;  /* last list item read */
 648   expdesc *t;  /* table descriptor */
 649   int nh;  /* total number of `record' elements */
 650   int na;  /* total number of array elements */
 651   int tostore;  /* number of array elements pending to be stored */
 652 };
 653
 654
 655 static void recfield (LexState *ls, struct ConsControl *cc) {
 656   /* recfield -> (NAME | `['exp1`]') = exp1 */
 657   FuncState *fs = ls->fs;
 658   int reg = ls->fs->freereg;
 659   expdesc key, val;
 660   int rkkey;
 661   if (ls->t.token == TK_NAME) {
 662     checklimit(fs, cc->nh, MAX_INT, "items in a constructor");
 663     checkname(ls, &key);
 664   }
 665   else  /* ls->t.token == '[' */
 666     yindex(ls, &key);
 667   cc->nh++;
 668   checknext(ls, '=');
 669   rkkey = luaK_exp2RK(fs, &key);
 670   expr(ls, &val);
 671   luaK_codeABC(fs, OP_SETTABLE, cc->t->u.info, rkkey, luaK_exp2RK(fs, &val));
 672   fs->freereg = reg;  /* free registers */
 673 }
 674
 675
 676 static void closelistfield (FuncState *fs, struct ConsControl *cc) {
 677   if (cc->v.k == VVOID) return;  /* there is no list item */
 678   luaK_exp2nextreg(fs, &cc->v);
 679   cc->v.k = VVOID;
 680   if (cc->tostore == LFIELDS_PER_FLUSH) {
 681     luaK_setlist(fs, cc->t->u.info, cc->na, cc->tostore);  /* flush */
 682     cc->tostore = 0;  /* no more items pending */
 683   }
 684 }
 685
 686
 687 static void lastlistfield (FuncState *fs, struct ConsControl *cc) {
 688   if (cc->tostore == 0) return;
 689   if (hasmultret(cc->v.k)) {
 690     luaK_setmultret(fs, &cc->v);
 691     luaK_setlist(fs, cc->t->u.info, cc->na, LUA_MULTRET);
 692     cc->na--;  /* do not count last expression (unknown number of elements) */
 693   }
 694   else {
 695     if (cc->v.k != VVOID)
 696       luaK_exp2nextreg(fs, &cc->v);
 697     luaK_setlist(fs, cc->t->u.info, cc->na, cc->tostore);
 698   }
 699 }
 700
 701
 702 static void listfield (LexState *ls, struct ConsControl *cc) {
 703   /* listfield -> exp */
 704   expr(ls, &cc->v);
 705   checklimit(ls->fs, cc->na, MAX_INT, "items in a constructor");
 706   cc->na++;
 707   cc->tostore++;
 708 }
 709
 710
 711 static void field (LexState *ls, struct ConsControl *cc) {
 712   /* field -> listfield | recfield */
 713   switch(ls->t.token) {
 714     case TK_NAME: {  /* may be 'listfield' or 'recfield' */
 715       if (luaX_lookahead(ls) != '=')  /* expression? */
 716         listfield(ls, cc);
 717       else
 718         recfield(ls, cc);
 719       break;
 720     }
 721     case '[': {
 722       recfield(ls, cc);
 723       break;
 724     }
 725     default: {
 726       listfield(ls, cc);
 727       break;
 728     }
 729   }
 730 }
 731
 732
 733 static void constructor (LexState *ls, expdesc *t) {
 734   /* constructor -> '{' [ field { sep field } [sep] ] '}'
 735      sep -> ',' | ';' */
 736   FuncState *fs = ls->fs;
 737   int line = ls->linenumber;
 738   int pc = luaK_codeABC(fs, OP_NEWTABLE, 0, 0, 0);
 739   struct ConsControl cc;
 740   cc.na = cc.nh = cc.tostore = 0;
 741   cc.t = t;
 742   init_exp(t, VRELOCABLE, pc);
 743   init_exp(&cc.v, VVOID, 0);  /* no value (yet) */
 744   luaK_exp2nextreg(ls->fs, t);  /* fix it at stack top */
 745   checknext(ls, '{');
 746   do {
 747     lua_assert(cc.v.k == VVOID || cc.tostore > 0);
 748     if (ls->t.token == '}') break;
 749     closelistfield(fs, &cc);
 750     field(ls, &cc);
 751   } while (testnext(ls, ',') || testnext(ls, ';'));
 752   check_match(ls, '}', '{', line);
 753   lastlistfield(fs, &cc);
 754   SETARG_B(fs->f->code[pc], luaO_int2fb(cc.na)); /* set initial array size */
 755   SETARG_C(fs->f->code[pc], luaO_int2fb(cc.nh));  /* set initial table size */
 756 }
 757
 758 /* }====================================================================== */
 759
 760
 761
 762 static void parlist (LexState *ls) {
 763   /* parlist -> [ param { `,' param } ] */
 764   FuncState *fs = ls->fs;
 765   Proto *f = fs->f;
 766   int nparams = 0;
 767   f->is_vararg = 0;
 768   if (ls->t.token != ')') {  /* is `parlist' not empty? */
 769     do {
 770       switch (ls->t.token) {
 771         case TK_NAME: {  /* param -> NAME */
 772           new_localvar(ls, str_checkname(ls));
 773           nparams++;
 774           break;
 775         }
 776         case TK_DOTS: {  /* param -> `...' */
 777           luaX_next(ls);
 778           f->is_vararg = 1;
 779           break;
 780         }
 781         default: luaX_syntaxerror(ls, "<name> or " LUA_QL("...") " expected");
 782       }
 783     } while (!f->is_vararg && testnext(ls, ','));
 784   }
 785   adjustlocalvars(ls, nparams);
 786   f->numparams = cast_byte(fs->nactvar);
 787   luaK_reserveregs(fs, fs->nactvar);  /* reserve register for parameters */
 788 }
 789
 790
 791 static void body (LexState *ls, expdesc *e, int ismethod, int line) {
 792   /* body ->  `(' parlist `)' block END */
 793   FuncState new_fs;
 794   BlockCnt bl;
 795   new_fs.f = addprototype(ls);
 796   new_fs.f->linedefined = line;
 797   open_func(ls, &new_fs, &bl);
 798   checknext(ls, '(');
 799   if (ismethod) {
 800     new_localvarliteral(ls, "self");  /* create 'self' parameter */
 801     adjustlocalvars(ls, 1);
 802   }
 803   parlist(ls);
 804   checknext(ls, ')');
 805   statlist(ls);
 806   new_fs.f->lastlinedefined = ls->linenumber;
 807   check_match(ls, TK_END, TK_FUNCTION, line);
 808   codeclosure(ls, e);
 809   close_func(ls);
 810 }
 811
 812
 813 static int explist (LexState *ls, expdesc *v) {
 814   /* explist -> expr { `,' expr } */
 815   int n = 1;  /* at least one expression */
 816   expr(ls, v);
 817   while (testnext(ls, ',')) {
 818     luaK_exp2nextreg(ls->fs, v);
 819     expr(ls, v);
 820     n++;
 821   }
 822   return n;
 823 }
 824
 825
 826 static void funcargs (LexState *ls, expdesc *f, int line) {
 827   FuncState *fs = ls->fs;
 828   expdesc args;
 829   int base, nparams;
 830   switch (ls->t.token) {
 831     case '(': {  /* funcargs -> `(' [ explist ] `)' */
 832       luaX_next(ls);
 833       if (ls->t.token == ')')  /* arg list is empty? */
 834         args.k = VVOID;
 835       else {
 836         explist(ls, &args);
 837         luaK_setmultret(fs, &args);
 838       }
 839       check_match(ls, ')', '(', line);
 840       break;
 841     }
 842     case '{': {  /* funcargs -> constructor */
 843       constructor(ls, &args);
 844       break;
 845     }
 846     case TK_STRING: {  /* funcargs -> STRING */
 847       codestring(ls, &args, ls->t.seminfo.ts);
 848       luaX_next(ls);  /* must use `seminfo' before `next' */
 849       break;
 850     }
 851     default: {
 852       luaX_syntaxerror(ls, "function arguments expected");
 853     }
 854   }
 855   lua_assert(f->k == VNONRELOC);
 856   base = f->u.info;  /* base register for call */
 857   if (hasmultret(args.k))
 858     nparams = LUA_MULTRET;  /* open call */
 859   else {
 860     if (args.k != VVOID)
 861       luaK_exp2nextreg(fs, &args);  /* close last argument */
 862     nparams = fs->freereg - (base+1);
 863   }
 864   init_exp(f, VCALL, luaK_codeABC(fs, OP_CALL, base, nparams+1, 2));
 865   luaK_fixline(fs, line);
 866   fs->freereg = base+1;  /* call remove function and arguments and leaves
 867                             (unless changed) one result */
 868 }
 869
 870
 871
 872
 873 /*
 874 ** {======================================================================
 875 ** Expression parsing
 876 ** =======================================================================
 877 */
 878
 879
 880 static void primaryexp (LexState *ls, expdesc *v) {
 881   /* primaryexp -> NAME | '(' expr ')' */
 882   switch (ls->t.token) {
 883     case '(': {
 884       int line = ls->linenumber;
 885       luaX_next(ls);
 886       expr(ls, v);
 887       check_match(ls, ')', '(', line);
 888       luaK_dischargevars(ls->fs, v);
 889       return;
 890     }
 891     case TK_NAME: {
 892       singlevar(ls, v);
 893       return;
 894     }
 895     default: {
 896       luaX_syntaxerror(ls, "unexpected symbol");
 897     }
 898   }
 899 }
 900
 901
 902 static void suffixedexp (LexState *ls, expdesc *v) {
 903   /* suffixedexp ->
 904        primaryexp { '.' NAME | '[' exp ']' | ':' NAME funcargs | funcargs } */
 905   FuncState *fs = ls->fs;
 906   int line = ls->linenumber;
 907   primaryexp(ls, v);
 908   for (;;) {
 909     switch (ls->t.token) {
 910       case '.': {  /* fieldsel */
 911         fieldsel(ls, v);
 912         break;
 913       }
 914       case '[': {  /* `[' exp1 `]' */
 915         expdesc key;
 916         luaK_exp2anyregup(fs, v);
 917         yindex(ls, &key);
 918         luaK_indexed(fs, v, &key);
 919         break;
 920       }
 921       case ':': {  /* `:' NAME funcargs */
 922         expdesc key;
 923         luaX_next(ls);
 924         checkname(ls, &key);
 925         luaK_self(fs, v, &key);
 926         funcargs(ls, v, line);
 927         break;
 928       }
 929       case '(': case TK_STRING: case '{': {  /* funcargs */
 930         luaK_exp2nextreg(fs, v);
 931         funcargs(ls, v, line);
 932         break;
 933       }
 934       default: return;
 935     }
 936   }
 937 }
 938
 939
 940 static void simpleexp (LexState *ls, expdesc *v) {
 941   /* simpleexp -> NUMBER | STRING | NIL | TRUE | FALSE | ... |
 942                   constructor | FUNCTION body | suffixedexp */
 943   switch (ls->t.token) {
 944     case TK_NUMBER: {
 945       init_exp(v, VKNUM, 0);
 946       v->u.nval = ls->t.seminfo.r;
 947       break;
 948     }
 949     case TK_STRING: {
 950       codestring(ls, v, ls->t.seminfo.ts);
 951       break;
 952     }
 953     case TK_NIL: {
 954       init_exp(v, VNIL, 0);
 955       break;
 956     }
 957     case TK_TRUE: {
 958       init_exp(v, VTRUE, 0);
 959       break;
 960     }
 961     case TK_FALSE: {
 962       init_exp(v, VFALSE, 0);
 963       break;
 964     }
 965     case TK_DOTS: {  /* vararg */
 966       FuncState *fs = ls->fs;
 967       check_condition(ls, fs->f->is_vararg,
 968                       "cannot use " LUA_QL("...") " outside a vararg function");
 969       init_exp(v, VVARARG, luaK_codeABC(fs, OP_VARARG, 0, 1, 0));
 970       break;
 971     }
 972     case '{': {  /* constructor */
 973       constructor(ls, v);
 974       return;
 975     }
 976     case TK_FUNCTION: {
 977       luaX_next(ls);
 978       body(ls, v, 0, ls->linenumber);
 979       return;
 980     }
 981     default: {
 982       suffixedexp(ls, v);
 983       return;
 984     }
 985   }
 986   luaX_next(ls);
 987 }
 988
 989
 990 static UnOpr getunopr (int op) {
 991   switch (op) {
 992     case TK_NOT: return OPR_NOT;
 993     case '-': return OPR_MINUS;
 994     case '#': return OPR_LEN;
 995     default: return OPR_NOUNOPR;
 996   }
 997 }
 998
 999
1000 static BinOpr getbinopr (int op) {
1001   switch (op) {
1002     case '+': return OPR_ADD;
1003     case '-': return OPR_SUB;
1004     case '*': return OPR_MUL;
1005     case '/': return OPR_DIV;
1006     case '%': return OPR_MOD;
1007     case '^': return OPR_POW;
1008     case TK_CONCAT: return OPR_CONCAT;
1009     case TK_NE: return OPR_NE;
1010     case TK_EQ: return OPR_EQ;
1011     case '<': return OPR_LT;
1012     case TK_LE: return OPR_LE;
1013     case '>': return OPR_GT;
1014     case TK_GE: return OPR_GE;
1015     case TK_AND: return OPR_AND;
1016     case TK_OR: return OPR_OR;
1017     default: return OPR_NOBINOPR;
1018   }
1019 }
1020
1021
1022 static const struct {
1023   lu_byte left;  /* left priority for each binary operator */
1024   lu_byte right; /* right priority */
1025 } priority[] = {  /* ORDER OPR */
1026    {6, 6}, {6, 6}, {7, 7}, {7, 7}, {7, 7},  /* `+' `-' `*' `/' `%' */
1027    {10, 9}, {5, 4},                 /* ^, .. (right associative) */
1028    {3, 3}, {3, 3}, {3, 3},          /* ==, <, <= */
1029    {3, 3}, {3, 3}, {3, 3},          /* ~=, >, >= */
1030    {2, 2}, {1, 1}                   /* and, or */
1031 };
1032
1033 #define UNARY_PRIORITY  8  /* priority for unary operators */
1034
1035
1036 /*
1037 ** subexpr -> (simpleexp | unop subexpr) { binop subexpr }
1038 ** where `binop' is any binary operator with a priority higher than `limit'
1039 */
1040 static BinOpr subexpr (LexState *ls, expdesc *v, int limit) {
1041   BinOpr op;
1042   UnOpr uop;
1043   enterlevel(ls);
1044   uop = getunopr(ls->t.token);
1045   if (uop != OPR_NOUNOPR) {
1046     int line = ls->linenumber;
1047     luaX_next(ls);
1048     subexpr(ls, v, UNARY_PRIORITY);
1049     luaK_prefix(ls->fs, uop, v, line);
1050   }
1051   else simpleexp(ls, v);
1052   /* expand while operators have priorities higher than `limit' */
1053   op = getbinopr(ls->t.token);
1054   while (op != OPR_NOBINOPR && priority[op].left > limit) {
1055     expdesc v2;
1056     BinOpr nextop;
1057     int line = ls->linenumber;
1058     luaX_next(ls);
1059     luaK_infix(ls->fs, op, v);
1060     /* read sub-expression with higher priority */
1061     nextop = subexpr(ls, &v2, priority[op].right);
1062     luaK_posfix(ls->fs, op, v, &v2, line);
1063     op = nextop;
1064   }
1065   leavelevel(ls);
1066   return op;  /* return first untreated operator */
1067 }
1068
1069
1070 static void expr (LexState *ls, expdesc *v) {
1071   subexpr(ls, v, 0);
1072 }
1073
1074 /* }==================================================================== */
1075
1076
1077
1078 /*
1079 ** {======================================================================
1080 ** Rules for Statements
1081 ** =======================================================================
1082 */
1083
1084
1085 static void block (LexState *ls) {
1086   /* block -> statlist */
1087   FuncState *fs = ls->fs;
1088   BlockCnt bl;
1089   enterblock(fs, &bl, 0);
1090   statlist(ls);
1091   leaveblock(fs);
1092 }
1093
1094
1095 /*
1096 ** structure to chain all variables in the left-hand side of an
1097 ** assignment
1098 */
1099 struct LHS_assign {
1100   struct LHS_assign *prev;
1101   expdesc v;  /* variable (global, local, upvalue, or indexed) */
1102 };
1103
1104
1105 /*
1106 ** check whether, in an assignment to an upvalue/local variable, the
1107 ** upvalue/local variable is begin used in a previous assignment to a
1108 ** table. If so, save original upvalue/local value in a safe place and
1109 ** use this safe copy in the previous assignment.
1110 */
1111 static void check_conflict (LexState *ls, struct LHS_assign *lh, expdesc *v) {
1112   FuncState *fs = ls->fs;
1113   int extra = fs->freereg;  /* eventual position to save local variable */
1114   int conflict = 0;
1115   for (; lh; lh = lh->prev) {  /* check all previous assignments */
1116     if (lh->v.k == VINDEXED) {  /* assigning to a table? */
1117       /* table is the upvalue/local being assigned now? */
1118       if (lh->v.u.ind.vt == v->k && lh->v.u.ind.t == v->u.info) {
1119         conflict = 1;
1120         lh->v.u.ind.vt = VLOCAL;
1121         lh->v.u.ind.t = extra;  /* previous assignment will use safe copy */
1122       }
1123       /* index is the local being assigned? (index cannot be upvalue) */
1124       if (v->k == VLOCAL && lh->v.u.ind.idx == v->u.info) {
1125         conflict = 1;
1126         lh->v.u.ind.idx = extra;  /* previous assignment will use safe copy */
1127       }
1128     }
1129   }
1130   if (conflict) {
1131     /* copy upvalue/local value to a temporary (in position 'extra') */
1132     OpCode op = (v->k == VLOCAL) ? OP_MOVE : OP_GETUPVAL;
1133     luaK_codeABC(fs, op, extra, v->u.info, 0);
1134     luaK_reserveregs(fs, 1);
1135   }
1136 }
1137
1138
1139 static void assignment (LexState *ls, struct LHS_assign *lh, int nvars) {
1140   expdesc e;
1141   check_condition(ls, vkisvar(lh->v.k), "syntax error");
1142   if (testnext(ls, ',')) {  /* assignment -> ',' suffixedexp assignment */
1143     struct LHS_assign nv;
1144     nv.prev = lh;
1145     suffixedexp(ls, &nv.v);
1146     if (nv.v.k != VINDEXED)
1147       check_conflict(ls, lh, &nv.v);
1148     checklimit(ls->fs, nvars + ls->L->nCcalls, LUAI_MAXCCALLS,
1149                     "C levels");
1150     assignment(ls, &nv, nvars+1);
1151   }
1152   else {  /* assignment -> `=' explist */
1153     int nexps;
1154     checknext(ls, '=');
1155     nexps = explist(ls, &e);
1156     if (nexps != nvars) {
1157       adjust_assign(ls, nvars, nexps, &e);
1158       if (nexps > nvars)
1159         ls->fs->freereg -= nexps - nvars;  /* remove extra values */
1160     }
1161     else {
1162       luaK_setoneret(ls->fs, &e);  /* close last expression */
1163       luaK_storevar(ls->fs, &lh->v, &e);
1164       return;  /* avoid default */
1165     }
1166   }
1167   init_exp(&e, VNONRELOC, ls->fs->freereg-1);  /* default assignment */
1168   luaK_storevar(ls->fs, &lh->v, &e);
1169 }
1170
1171
1172 static int cond (LexState *ls) {
1173   /* cond -> exp */
1174   expdesc v;
1175   expr(ls, &v);  /* read condition */
1176   if (v.k == VNIL) v.k = VFALSE;  /* `falses' are all equal here */
1177   luaK_goiftrue(ls->fs, &v);
1178   return v.f;
1179 }
1180
1181
1182 static void gotostat (LexState *ls, int pc) {
1183   int line = ls->linenumber;
1184   TString *label;
1185   int g;
1186   if (testnext(ls, TK_GOTO))
1187     label = str_checkname(ls);
1188   else {
1189     luaX_next(ls);  /* skip break */
1190     label = luaS_new(ls->L, "break");
1191   }
1192   g = newlabelentry(ls, &ls->dyd->gt, label, line, pc);
1193   findlabel(ls, g);  /* close it if label already defined */
1194 }
1195
1196
1197 /* check for repeated labels on the same block */
1198 static void checkrepeated (FuncState *fs, Labellist *ll, TString *label) {
1199   int i;
1200   for (i = fs->bl->firstlabel; i < ll->n; i++) {
1201     if (luaS_eqstr(label, ll->arr[i].name)) {
1202       const char *msg = luaO_pushfstring(fs->ls->L,
1203                           "label " LUA_QS " already defined on line %d",
1204                           getstr(label), ll->arr[i].line);
1205       semerror(fs->ls, msg);
1206     }
1207   }
1208 }
1209
1210
1211 /* skip no-op statements */
1212 static void skipnoopstat (LexState *ls) {
1213   while (ls->t.token == ';' || ls->t.token == TK_DBCOLON)
1214     statement(ls);
1215 }
1216
1217
1218 static void labelstat (LexState *ls, TString *label, int line) {
1219   /* label -> '::' NAME '::' */
1220   FuncState *fs = ls->fs;
1221   Labellist *ll = &ls->dyd->label;
1222   int l;  /* index of new label being created */
1223   checkrepeated(fs, ll, label);  /* check for repeated labels */
1224   checknext(ls, TK_DBCOLON);  /* skip double colon */
1225   /* create new entry for this label */
1226   l = newlabelentry(ls, ll, label, line, fs->pc);
1227   skipnoopstat(ls);  /* skip other no-op statements */
1228   if (block_follow(ls, 0)) {  /* label is last no-op statement in the block? */
1229     /* assume that locals are already out of scope */
1230     ll->arr[l].nactvar = fs->bl->nactvar;
1231   }
1232   findgotos(ls, &ll->arr[l]);
1233 }
1234
1235
1236 static void whilestat (LexState *ls, int line) {
1237   /* whilestat -> WHILE cond DO block END */
1238   FuncState *fs = ls->fs;
1239   int whileinit;
1240   int condexit;
1241   BlockCnt bl;
1242   luaX_next(ls);  /* skip WHILE */
1243   whileinit = luaK_getlabel(fs);
1244   condexit = cond(ls);
1245   enterblock(fs, &bl, 1);
1246   checknext(ls, TK_DO);
1247   block(ls);
1248   luaK_jumpto(fs, whileinit);
1249   check_match(ls, TK_END, TK_WHILE, line);
1250   leaveblock(fs);
1251   luaK_patchtohere(fs, condexit);  /* false conditions finish the loop */
1252 }
1253
1254
1255 static void repeatstat (LexState *ls, int line) {
1256   /* repeatstat -> REPEAT block UNTIL cond */
1257   int condexit;
1258   FuncState *fs = ls->fs;
1259   int repeat_init = luaK_getlabel(fs);
1260   BlockCnt bl1, bl2;
1261   enterblock(fs, &bl1, 1);  /* loop block */
1262   enterblock(fs, &bl2, 0);  /* scope block */
1263   luaX_next(ls);  /* skip REPEAT */
1264   statlist(ls);
1265   check_match(ls, TK_UNTIL, TK_REPEAT, line);
1266   condexit = cond(ls);  /* read condition (inside scope block) */
1267   if (bl2.upval)  /* upvalues? */
1268     luaK_patchclose(fs, condexit, bl2.nactvar);
1269   leaveblock(fs);  /* finish scope */
1270   luaK_patchlist(fs, condexit, repeat_init);  /* close the loop */
1271   leaveblock(fs);  /* finish loop */
1272 }
1273
1274
1275 static int exp1 (LexState *ls) {
1276   expdesc e;
1277   int reg;
1278   expr(ls, &e);
1279   luaK_exp2nextreg(ls->fs, &e);
1280   lua_assert(e.k == VNONRELOC);
1281   reg = e.u.info;
1282   return reg;
1283 }
1284
1285
1286 static void forbody (LexState *ls, int base, int line, int nvars, int isnum) {
1287   /* forbody -> DO block */
1288   BlockCnt bl;
1289   FuncState *fs = ls->fs;
1290   int prep, endfor;
1291   adjustlocalvars(ls, 3);  /* control variables */
1292   checknext(ls, TK_DO);
1293   prep = isnum ? luaK_codeAsBx(fs, OP_FORPREP, base, NO_JUMP) : luaK_jump(fs);
1294   enterblock(fs, &bl, 0);  /* scope for declared variables */
1295   adjustlocalvars(ls, nvars);
1296   luaK_reserveregs(fs, nvars);
1297   block(ls);
1298   leaveblock(fs);  /* end of scope for declared variables */
1299   luaK_patchtohere(fs, prep);
1300   if (isnum)  /* numeric for? */
1301     endfor = luaK_codeAsBx(fs, OP_FORLOOP, base, NO_JUMP);
1302   else {  /* generic for */
1303     luaK_codeABC(fs, OP_TFORCALL, base, 0, nvars);
1304     luaK_fixline(fs, line);
1305     endfor = luaK_codeAsBx(fs, OP_TFORLOOP, base + 2, NO_JUMP);
1306   }
1307   luaK_patchlist(fs, endfor, prep + 1);
1308   luaK_fixline(fs, line);
1309 }
1310
1311
1312 static void fornum (LexState *ls, TString *varname, int line) {
1313   /* fornum -> NAME = exp1,exp1[,exp1] forbody */
1314   FuncState *fs = ls->fs;
1315   int base = fs->freereg;
1316   new_localvarliteral(ls, "(for index)");
1317   new_localvarliteral(ls, "(for limit)");
1318   new_localvarliteral(ls, "(for step)");
1319   new_localvar(ls, varname);
1320   checknext(ls, '=');
1321   exp1(ls);  /* initial value */
1322   checknext(ls, ',');
1323   exp1(ls);  /* limit */
1324   if (testnext(ls, ','))
1325     exp1(ls);  /* optional step */
1326   else {  /* default step = 1 */
1327     luaK_codek(fs, fs->freereg, luaK_numberK(fs, 1));
1328     luaK_reserveregs(fs, 1);
1329   }
1330   forbody(ls, base, line, 1, 1);
1331 }
1332
1333
1334 static void forlist (LexState *ls, TString *indexname) {
1335   /* forlist -> NAME {,NAME} IN explist forbody */
1336   FuncState *fs = ls->fs;
1337   expdesc e;
1338   int nvars = 4;  /* gen, state, control, plus at least one declared var */
1339   int line;
1340   int base = fs->freereg;
1341   /* create control variables */
1342   new_localvarliteral(ls, "(for generator)");
1343   new_localvarliteral(ls, "(for state)");
1344   new_localvarliteral(ls, "(for control)");
1345   /* create declared variables */
1346   new_localvar(ls, indexname);
1347   while (testnext(ls, ',')) {
1348     new_localvar(ls, str_checkname(ls));
1349     nvars++;
1350   }
1351   checknext(ls, TK_IN);
1352   line = ls->linenumber;
1353   adjust_assign(ls, 3, explist(ls, &e), &e);
1354   luaK_checkstack(fs, 3);  /* extra space to call generator */
1355   forbody(ls, base, line, nvars - 3, 0);
1356 }
1357
1358
1359 static void forstat (LexState *ls, int line) {
1360   /* forstat -> FOR (fornum | forlist) END */
1361   FuncState *fs = ls->fs;
1362   TString *varname;
1363   BlockCnt bl;
1364   enterblock(fs, &bl, 1);  /* scope for loop and control variables */
1365   luaX_next(ls);  /* skip `for' */
1366   varname = str_checkname(ls);  /* first variable name */
1367   switch (ls->t.token) {
1368     case '=': fornum(ls, varname, line); break;
1369     case ',': case TK_IN: forlist(ls, varname); break;
1370     default: luaX_syntaxerror(ls, LUA_QL("=") " or " LUA_QL("in") " expected");
1371   }
1372   check_match(ls, TK_END, TK_FOR, line);
1373   leaveblock(fs);  /* loop scope (`break' jumps to this point) */
1374 }
1375
1376
1377 __attribute__((always_inline)) inline
1378 static void test_then_block (LexState *ls, int *escapelist) {
1379   /* test_then_block -> [IF | ELSEIF] cond THEN block */
1380   BlockCnt bl;
1381   FuncState *fs = ls->fs;
1382   expdesc v;
1383   int jf;  /* instruction to skip 'then' code (if condition is false) */
1384   luaX_next(ls);  /* skip IF or ELSEIF */
1385   expr(ls, &v);  /* read condition */
1386   checknext(ls, TK_THEN);
1387   if (ls->t.token == TK_GOTO || ls->t.token == TK_BREAK) {
1388     luaK_goiffalse(ls->fs, &v);  /* will jump to label if condition is true */
1389     enterblock(fs, &bl, 0);  /* must enter block before 'goto' */
1390     gotostat(ls, v.t);  /* handle goto/break */
1391     skipnoopstat(ls);  /* skip other no-op statements */
1392     if (block_follow(ls, 0)) {  /* 'goto' is the entire block? */
1393       leaveblock(fs);
1394       return;  /* and that is it */
1395     }
1396     else  /* must skip over 'then' part if condition is false */
1397       jf = luaK_jump(fs);
1398   }
1399   else {  /* regular case (not goto/break) */
1400     luaK_goiftrue(ls->fs, &v);  /* skip over block if condition is false */
1401     enterblock(fs, &bl, 0);
1402     jf = v.f;
1403   }
1404   statlist(ls);  /* `then' part */
1405   leaveblock(fs);
1406   if (ls->t.token == TK_ELSE ||
1407       ls->t.token == TK_ELSEIF)  /* followed by 'else'/'elseif'? */
1408     luaK_concat(fs, escapelist, luaK_jump(fs));  /* must jump over it */
1409   luaK_patchtohere(fs, jf);
1410 }
1411
1412
1413 static void ifstat (LexState *ls, int line) {
1414   /* ifstat -> IF cond THEN block {ELSEIF cond THEN block} [ELSE block] END */
1415   FuncState *fs = ls->fs;
1416   int escapelist = NO_JUMP;  /* exit list for finished parts */
1417   test_then_block(ls, &escapelist);  /* IF cond THEN block */
1418   while (ls->t.token == TK_ELSEIF)
1419     test_then_block(ls, &escapelist);  /* ELSEIF cond THEN block */
1420   if (testnext(ls, TK_ELSE))
1421     block(ls);  /* `else' part */
1422   check_match(ls, TK_END, TK_IF, line);
1423   luaK_patchtohere(fs, escapelist);  /* patch escape list to 'if' end */
1424 }
1425
1426
1427 static void localfunc (LexState *ls) {
1428   expdesc b;
1429   FuncState *fs = ls->fs;
1430   new_localvar(ls, str_checkname(ls));  /* new local variable */
1431   adjustlocalvars(ls, 1);  /* enter its scope */
1432   body(ls, &b, 0, ls->linenumber);  /* function created in next register */
1433   /* debug information will only see the variable after this point! */
1434   getlocvar(fs, b.u.info)->startpc = fs->pc;
1435 }
1436
1437
1438 static void localstat (LexState *ls) {
1439   /* stat -> LOCAL NAME {`,' NAME} [`=' explist] */
1440   int nvars = 0;
1441   int nexps;
1442   expdesc e;
1443   do {
1444     new_localvar(ls, str_checkname(ls));
1445     nvars++;
1446   } while (testnext(ls, ','));
1447   if (testnext(ls, '='))
1448     nexps = explist(ls, &e);
1449   else {
1450     e.k = VVOID;
1451     nexps = 0;
1452   }
1453   adjust_assign(ls, nvars, nexps, &e);
1454   adjustlocalvars(ls, nvars);
1455 }
1456
1457
1458 static int funcname (LexState *ls, expdesc *v) {
1459   /* funcname -> NAME {fieldsel} [`:' NAME] */
1460   int ismethod = 0;
1461   singlevar(ls, v);
1462   while (ls->t.token == '.')
1463     fieldsel(ls, v);
1464   if (ls->t.token == ':') {
1465     ismethod = 1;
1466     fieldsel(ls, v);
1467   }
1468   return ismethod;
1469 }
1470
1471
1472 static void funcstat (LexState *ls, int line) {
1473   /* funcstat -> FUNCTION funcname body */
1474   int ismethod;
1475   expdesc v, b;
1476   luaX_next(ls);  /* skip FUNCTION */
1477   ismethod = funcname(ls, &v);
1478   body(ls, &b, ismethod, line);
1479   luaK_storevar(ls->fs, &v, &b);
1480   luaK_fixline(ls->fs, line);  /* definition `happens' in the first line */
1481 }
1482
1483
1484 static void exprstat (LexState *ls) {
1485   /* stat -> func | assignment */
1486   FuncState *fs = ls->fs;
1487   struct LHS_assign v;
1488   suffixedexp(ls, &v.v);
1489   if (ls->t.token == '=' || ls->t.token == ',') { /* stat -> assignment ? */
1490     v.prev = NULL;
1491     assignment(ls, &v, 1);
1492   }
1493   else {  /* stat -> func */
1494     check_condition(ls, v.v.k == VCALL, "syntax error");
1495     SETARG_C(getcode(fs, &v.v), 1);  /* call statement uses no results */
1496   }
1497 }
1498
1499
1500 static void retstat (LexState *ls) {
1501   /* stat -> RETURN [explist] [';'] */
1502   FuncState *fs = ls->fs;
1503   expdesc e;
1504   int first, nret;  /* registers with returned values */
1505   if (block_follow(ls, 1) || ls->t.token == ';')
1506     first = nret = 0;  /* return no values */
1507   else {
1508     nret = explist(ls, &e);  /* optional return values */
1509     if (hasmultret(e.k)) {
1510       luaK_setmultret(fs, &e);
1511       if (e.k == VCALL && nret == 1) {  /* tail call? */
1512         SET_OPCODE(getcode(fs,&e), OP_TAILCALL);
1513         lua_assert(GETARG_A(getcode(fs,&e)) == fs->nactvar);
1514       }
1515       first = fs->nactvar;
1516       nret = LUA_MULTRET;  /* return all values */
1517     }
1518     else {
1519       if (nret == 1)  /* only one single value? */
1520         first = luaK_exp2anyreg(fs, &e);
1521       else {
1522         luaK_exp2nextreg(fs, &e);  /* values must go to the `stack' */
1523         first = fs->nactvar;  /* return all `active' values */
1524         lua_assert(nret == fs->freereg - first);
1525       }
1526     }
1527   }
1528   luaK_ret(fs, first, nret);
1529   (void) testnext(ls, ';');  /* skip optional semicolon */
1530 }
1531
1532
1533 static void statement (LexState *ls) {
1534   int line = ls->linenumber;  /* may be needed for error messages */
1535   enterlevel(ls);
1536   switch (ls->t.token) {
1537     case ';': {  /* stat -> ';' (empty statement) */
1538       luaX_next(ls);  /* skip ';' */
1539       break;
1540     }
1541     case TK_IF: {  /* stat -> ifstat */
1542       ifstat(ls, line);
1543       break;
1544     }
1545     case TK_WHILE: {  /* stat -> whilestat */
1546       whilestat(ls, line);
1547       break;
1548     }
1549     case TK_DO: {  /* stat -> DO block END */
1550       luaX_next(ls);  /* skip DO */
1551       block(ls);
1552       check_match(ls, TK_END, TK_DO, line);
1553       break;
1554     }
1555     case TK_FOR: {  /* stat -> forstat */
1556       forstat(ls, line);
1557       break;
1558     }
1559     case TK_REPEAT: {  /* stat -> repeatstat */
1560       repeatstat(ls, line);
1561       break;
1562     }
1563     case TK_FUNCTION: {  /* stat -> funcstat */
1564       funcstat(ls, line);
1565       break;
1566     }
1567     case TK_LOCAL: {  /* stat -> localstat */
1568       luaX_next(ls);  /* skip LOCAL */
1569       if (testnext(ls, TK_FUNCTION))  /* local function? */
1570         localfunc(ls);
1571       else
1572         localstat(ls);
1573       break;
1574     }
1575     case TK_DBCOLON: {  /* stat -> label */
1576       luaX_next(ls);  /* skip double colon */
1577       labelstat(ls, str_checkname(ls), line);
1578       break;
1579     }
1580     case TK_RETURN: {  /* stat -> retstat */
1581       luaX_next(ls);  /* skip RETURN */
1582       retstat(ls);
1583       break;
1584     }
1585     case TK_BREAK:   /* stat -> breakstat */
1586     case TK_GOTO: {  /* stat -> 'goto' NAME */
1587       gotostat(ls, luaK_jump(ls->fs));
1588       break;
1589     }
1590     default: {  /* stat -> func | assignment */
1591       exprstat(ls);
1592       break;
1593     }
1594   }
1595   lua_assert(ls->fs->f->maxstacksize >= ls->fs->freereg &&
1596              ls->fs->freereg >= ls->fs->nactvar);
1597   ls->fs->freereg = ls->fs->nactvar;  /* free registers */
1598   leavelevel(ls);
1599 }
1600
1601 /* }====================================================================== */
1602
1603
1604 /*
1605 ** compiles the main function, which is a regular vararg function with an
1606 ** upvalue named LUA_ENV
1607 */
1608 static void mainfunc (LexState *ls, FuncState *fs) {
1609   BlockCnt bl;
1610   expdesc v;
1611   open_func(ls, fs, &bl);
1612   fs->f->is_vararg = 1;  /* main function is always vararg */
1613   init_exp(&v, VLOCAL, 0);  /* create and... */
1614   newupvalue(fs, ls->envn, &v);  /* ...set environment upvalue */
1615   luaX_next(ls);  /* read first token */
1616   statlist(ls);  /* parse main body */
1617   check(ls, TK_EOS);
1618   close_func(ls);
1619 }
1620
1621
1622 Closure *luaY_parser (lua_State *L, ZIO *z, Mbuffer *buff,
1623                       Dyndata *dyd, const char *name, int firstchar) {
1624   LexState lexstate;
1625   FuncState funcstate;
1626   Closure *cl = luaF_newLclosure(L, 1);  /* create main closure */
1627   /* anchor closure (to avoid being collected) */
1628   setclLvalue(L, L->top, cl);
1629   incr_top(L);
1630   funcstate.f = cl->l.p = luaF_newproto(L);
1631   funcstate.f->source = luaS_new(L, name);  /* create and anchor TString */
1632   lexstate.buff = buff;
1633   lexstate.dyd = dyd;
1634   dyd->actvar.n = dyd->gt.n = dyd->label.n = 0;
1635   luaX_setinput(L, &lexstate, z, funcstate.f->source, firstchar);
1636   mainfunc(&lexstate, &funcstate);
1637   lua_assert(!funcstate.prev && funcstate.nups == 1 && !lexstate.fs);
1638   /* all scopes should be correctly finished */
1639   lua_assert(dyd->actvar.n == 0 && dyd->gt.n == 0 && dyd->label.n == 0);
1640   return cl;  /* it's on the stack too */
1641 }