ceph/src/lua/src/lparser.c

   1 /*
   2 ** $Id: lparser.c,v 2.149 2015/11/02 16:09:30 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 "lprefix.h"
  11
  12
  13 #include <string.h>
  14
  15 #include "lua.h"
  16
  17 #include "lcode.h"
  18 #include "ldebug.h"
  19 #include "ldo.h"
  20 #include "lfunc.h"
  21 #include "llex.h"
  22 #include "lmem.h"
  23 #include "lobject.h"
  24 #include "lopcodes.h"
  25 #include "lparser.h"
  26 #include "lstate.h"
  27 #include "lstring.h"
  28 #include "ltable.h"
  29
  30
  31
  32 /* maximum number of local variables per function (must be smaller
  33    than 250, due to the bytecode format) */
  34 #define MAXVARS         200
  35
  36
  37 #define hasmultret(k)           ((k) == VCALL || (k) == VVARARG)
  38
  39
  40 /* because all strings are unified by the scanner, the parser
  41    can use pointer equality for string equality */
  42 #define eqstr(a,b)      ((a) == (b))
  43
  44
  45 /*
  46 ** nodes for block list (list of active blocks)
  47 */
  48 typedef struct BlockCnt {
  49   struct BlockCnt *previous;  /* chain */
  50   int firstlabel;  /* index of first label in this block */
  51   int firstgoto;  /* index of first pending goto in this block */
  52   lu_byte nactvar;  /* # active locals outside the block */
  53   lu_byte upval;  /* true if some variable in the block is an upvalue */
  54   lu_byte isloop;  /* true if 'block' is a loop */
  55 } BlockCnt;
  56
  57
  58
  59 /*
  60 ** prototypes for recursive non-terminal functions
  61 */
  62 static void statement (LexState *ls);
  63 static void expr (LexState *ls, expdesc *v);
  64
  65
  66 /* semantic error */
  67 static l_noret semerror (LexState *ls, const char *msg) {
  68   ls->t.token = 0;  /* remove "near <token>" from final message */
  69   luaX_syntaxerror(ls, msg);
  70 }
  71
  72
  73 static l_noret error_expected (LexState *ls, int token) {
  74   luaX_syntaxerror(ls,
  75       luaO_pushfstring(ls->L, "%s expected", luaX_token2str(ls, token)));
  76 }
  77
  78
  79 static l_noret errorlimit (FuncState *fs, int limit, const char *what) {
  80   lua_State *L = fs->ls->L;
  81   const char *msg;
  82   int line = fs->f->linedefined;
  83   const char *where = (line == 0)
  84                       ? "main function"
  85                       : luaO_pushfstring(L, "function at line %d", line);
  86   msg = luaO_pushfstring(L, "too many %s (limit is %d) in %s",
  87                              what, limit, where);
  88   luaX_syntaxerror(fs->ls, msg);
  89 }
  90
  91
  92 static void checklimit (FuncState *fs, int v, int l, const char *what) {
  93   if (v > l) errorlimit(fs, l, what);
  94 }
  95
  96
  97 static int testnext (LexState *ls, int c) {
  98   if (ls->t.token == c) {
  99     luaX_next(ls);
 100     return 1;
 101   }
 102   else return 0;
 103 }
 104
 105
 106 static void check (LexState *ls, int c) {
 107   if (ls->t.token != c)
 108     error_expected(ls, c);
 109 }
 110
 111
 112 static void checknext (LexState *ls, int c) {
 113   check(ls, c);
 114   luaX_next(ls);
 115 }
 116
 117
 118 #define check_condition(ls,c,msg)       { if (!(c)) luaX_syntaxerror(ls, msg); }
 119
 120
 121
 122 static void check_match (LexState *ls, int what, int who, int where) {
 123   if (!testnext(ls, what)) {
 124     if (where == ls->linenumber)
 125       error_expected(ls, what);
 126     else {
 127       luaX_syntaxerror(ls, luaO_pushfstring(ls->L,
 128              "%s expected (to close %s at line %d)",
 129               luaX_token2str(ls, what), luaX_token2str(ls, who), where));
 130     }
 131   }
 132 }
 133
 134
 135 static TString *str_checkname (LexState *ls) {
 136   TString *ts;
 137   check(ls, TK_NAME);
 138   ts = ls->t.seminfo.ts;
 139   luaX_next(ls);
 140   return ts;
 141 }
 142
 143
 144 static void init_exp (expdesc *e, expkind k, int i) {
 145   e->f = e->t = NO_JUMP;
 146   e->k = k;
 147   e->u.info = i;
 148 }
 149
 150
 151 static void codestring (LexState *ls, expdesc *e, TString *s) {
 152   init_exp(e, VK, luaK_stringK(ls->fs, s));
 153 }
 154
 155
 156 static void checkname (LexState *ls, expdesc *e) {
 157   codestring(ls, e, str_checkname(ls));
 158 }
 159
 160
 161 static int registerlocalvar (LexState *ls, TString *varname) {
 162   FuncState *fs = ls->fs;
 163   Proto *f = fs->f;
 164   int oldsize = f->sizelocvars;
 165   luaM_growvector(ls->L, f->locvars, fs->nlocvars, f->sizelocvars,
 166                   LocVar, SHRT_MAX, "local variables");
 167   while (oldsize < f->sizelocvars) f->locvars[oldsize++].varname = NULL;
 168   f->locvars[fs->nlocvars].varname = varname;
 169   luaC_objbarrier(ls->L, f, varname);
 170   return fs->nlocvars++;
 171 }
 172
 173
 174 static void new_localvar (LexState *ls, TString *name) {
 175   FuncState *fs = ls->fs;
 176   Dyndata *dyd = ls->dyd;
 177   int reg = registerlocalvar(ls, name);
 178   checklimit(fs, dyd->actvar.n + 1 - fs->firstlocal,
 179                   MAXVARS, "local variables");
 180   luaM_growvector(ls->L, dyd->actvar.arr, dyd->actvar.n + 1,
 181                   dyd->actvar.size, Vardesc, MAX_INT, "local variables");
 182   dyd->actvar.arr[dyd->actvar.n++].idx = cast(short, reg);
 183 }
 184
 185
 186 static void new_localvarliteral_ (LexState *ls, const char *name, size_t sz) {
 187   new_localvar(ls, luaX_newstring(ls, name, sz));
 188 }
 189
 190 #define new_localvarliteral(ls,v) \
 191         new_localvarliteral_(ls, "" v, (sizeof(v)/sizeof(char))-1)
 192
 193
 194 static LocVar *getlocvar (FuncState *fs, int i) {
 195   int idx = fs->ls->dyd->actvar.arr[fs->firstlocal + i].idx;
 196   lua_assert(idx < fs->nlocvars);
 197   return &fs->f->locvars[idx];
 198 }
 199
 200
 201 static void adjustlocalvars (LexState *ls, int nvars) {
 202   FuncState *fs = ls->fs;
 203   fs->nactvar = cast_byte(fs->nactvar + nvars);
 204   for (; nvars; nvars--) {
 205     getlocvar(fs, fs->nactvar - nvars)->startpc = fs->pc;
 206   }
 207 }
 208
 209
 210 static void removevars (FuncState *fs, int tolevel) {
 211   fs->ls->dyd->actvar.n -= (fs->nactvar - tolevel);
 212   while (fs->nactvar > tolevel)
 213     getlocvar(fs, --fs->nactvar)->endpc = fs->pc;
 214 }
 215
 216
 217 static int searchupvalue (FuncState *fs, TString *name) {
 218   int i;
 219   Upvaldesc *up = fs->f->upvalues;
 220   for (i = 0; i < fs->nups; i++) {
 221     if (eqstr(up[i].name, name)) return i;
 222   }
 223   return -1;  /* not found */
 224 }
 225
 226
 227 static int newupvalue (FuncState *fs, TString *name, expdesc *v) {
 228   Proto *f = fs->f;
 229   int oldsize = f->sizeupvalues;
 230   checklimit(fs, fs->nups + 1, MAXUPVAL, "upvalues");
 231   luaM_growvector(fs->ls->L, f->upvalues, fs->nups, f->sizeupvalues,
 232                   Upvaldesc, MAXUPVAL, "upvalues");
 233   while (oldsize < f->sizeupvalues) f->upvalues[oldsize++].name = NULL;
 234   f->upvalues[fs->nups].instack = (v->k == VLOCAL);
 235   f->upvalues[fs->nups].idx = cast_byte(v->u.info);
 236   f->upvalues[fs->nups].name = name;
 237   luaC_objbarrier(fs->ls->L, f, name);
 238   return fs->nups++;
 239 }
 240
 241
 242 static int searchvar (FuncState *fs, TString *n) {
 243   int i;
 244   for (i = cast_int(fs->nactvar) - 1; i >= 0; i--) {
 245     if (eqstr(n, getlocvar(fs, i)->varname))
 246       return i;
 247   }
 248   return -1;  /* not found */
 249 }
 250
 251
 252 /*
 253   Mark block where variable at given level was defined
 254   (to emit close instructions later).
 255 */
 256 static void markupval (FuncState *fs, int level) {
 257   BlockCnt *bl = fs->bl;
 258   while (bl->nactvar > level) bl = bl->previous;
 259   bl->upval = 1;
 260 }
 261
 262
 263 /*
 264   Find variable with given name 'n'. If it is an upvalue, add this
 265   upvalue into all intermediate functions.
 266 */
 267 static int singlevaraux (FuncState *fs, TString *n, expdesc *var, int base) {
 268   if (fs == NULL)  /* no more levels? */
 269     return VVOID;  /* default is global */
 270   else {
 271     int v = searchvar(fs, n);  /* look up locals at current level */
 272     if (v >= 0) {  /* found? */
 273       init_exp(var, VLOCAL, v);  /* variable is local */
 274       if (!base)
 275         markupval(fs, v);  /* local will be used as an upval */
 276       return VLOCAL;
 277     }
 278     else {  /* not found as local at current level; try upvalues */
 279       int idx = searchupvalue(fs, n);  /* try existing upvalues */
 280       if (idx < 0) {  /* not found? */
 281         if (singlevaraux(fs->prev, n, var, 0) == VVOID) /* try upper levels */
 282           return VVOID;  /* not found; is a global */
 283         /* else was LOCAL or UPVAL */
 284         idx  = newupvalue(fs, n, var);  /* will be a new upvalue */
 285       }
 286       init_exp(var, VUPVAL, idx);
 287       return VUPVAL;
 288     }
 289   }
 290 }
 291
 292
 293 static void singlevar (LexState *ls, expdesc *var) {
 294   TString *varname = str_checkname(ls);
 295   FuncState *fs = ls->fs;
 296   if (singlevaraux(fs, varname, var, 1) == VVOID) {  /* global name? */
 297     expdesc key;
 298     singlevaraux(fs, ls->envn, var, 1);  /* get environment variable */
 299     lua_assert(var->k == VLOCAL || var->k == VUPVAL);
 300     codestring(ls, &key, varname);  /* key is variable name */
 301     luaK_indexed(fs, var, &key);  /* env[varname] */
 302   }
 303 }
 304
 305
 306 static void adjust_assign (LexState *ls, int nvars, int nexps, expdesc *e) {
 307   FuncState *fs = ls->fs;
 308   int extra = nvars - nexps;
 309   if (hasmultret(e->k)) {
 310     extra++;  /* includes call itself */
 311     if (extra < 0) extra = 0;
 312     luaK_setreturns(fs, e, extra);  /* last exp. provides the difference */
 313     if (extra > 1) luaK_reserveregs(fs, extra-1);
 314   }
 315   else {
 316     if (e->k != VVOID) luaK_exp2nextreg(fs, e);  /* close last expression */
 317     if (extra > 0) {
 318       int reg = fs->freereg;
 319       luaK_reserveregs(fs, extra);
 320       luaK_nil(fs, reg, extra);
 321     }
 322   }
 323 }
 324
 325
 326 static void enterlevel (LexState *ls) {
 327   lua_State *L = ls->L;
 328   ++L->nCcalls;
 329   checklimit(ls->fs, L->nCcalls, LUAI_MAXCCALLS, "C levels");
 330 }
 331
 332
 333 #define leavelevel(ls)  ((ls)->L->nCcalls--)
 334
 335
 336 static void closegoto (LexState *ls, int g, Labeldesc *label) {
 337   int i;
 338   FuncState *fs = ls->fs;
 339   Labellist *gl = &ls->dyd->gt;
 340   Labeldesc *gt = &gl->arr[g];
 341   lua_assert(eqstr(gt->name, label->name));
 342   if (gt->nactvar < label->nactvar) {
 343     TString *vname = getlocvar(fs, gt->nactvar)->varname;
 344     const char *msg = luaO_pushfstring(ls->L,
 345       "<goto %s> at line %d jumps into the scope of local '%s'",
 346       getstr(gt->name), gt->line, getstr(vname));
 347     semerror(ls, msg);
 348   }
 349   luaK_patchlist(fs, gt->pc, label->pc);
 350   /* remove goto from pending list */
 351   for (i = g; i < gl->n - 1; i++)
 352     gl->arr[i] = gl->arr[i + 1];
 353   gl->n--;
 354 }
 355
 356
 357 /*
 358 ** try to close a goto with existing labels; this solves backward jumps
 359 */
 360 static int findlabel (LexState *ls, int g) {
 361   int i;
 362   BlockCnt *bl = ls->fs->bl;
 363   Dyndata *dyd = ls->dyd;
 364   Labeldesc *gt = &dyd->gt.arr[g];
 365   /* check labels in current block for a match */
 366   for (i = bl->firstlabel; i < dyd->label.n; i++) {
 367     Labeldesc *lb = &dyd->label.arr[i];
 368     if (eqstr(lb->name, gt->name)) {  /* correct label? */
 369       if (gt->nactvar > lb->nactvar &&
 370           (bl->upval || dyd->label.n > bl->firstlabel))
 371         luaK_patchclose(ls->fs, gt->pc, lb->nactvar);
 372       closegoto(ls, g, lb);  /* close it */
 373       return 1;
 374     }
 375   }
 376   return 0;  /* label not found; cannot close goto */
 377 }
 378
 379
 380 static int newlabelentry (LexState *ls, Labellist *l, TString *name,
 381                           int line, int pc) {
 382   int n = l->n;
 383   luaM_growvector(ls->L, l->arr, n, l->size,
 384                   Labeldesc, SHRT_MAX, "labels/gotos");
 385   l->arr[n].name = name;
 386   l->arr[n].line = line;
 387   l->arr[n].nactvar = ls->fs->nactvar;
 388   l->arr[n].pc = pc;
 389   l->n = n + 1;
 390   return n;
 391 }
 392
 393
 394 /*
 395 ** check whether new label 'lb' matches any pending gotos in current
 396 ** block; solves forward jumps
 397 */
 398 static void findgotos (LexState *ls, Labeldesc *lb) {
 399   Labellist *gl = &ls->dyd->gt;
 400   int i = ls->fs->bl->firstgoto;
 401   while (i < gl->n) {
 402     if (eqstr(gl->arr[i].name, lb->name))
 403       closegoto(ls, i, lb);
 404     else
 405       i++;
 406   }
 407 }
 408
 409
 410 /*
 411 ** export pending gotos to outer level, to check them against
 412 ** outer labels; if the block being exited has upvalues, and
 413 ** the goto exits the scope of any variable (which can be the
 414 ** upvalue), close those variables being exited.
 415 */
 416 static void movegotosout (FuncState *fs, BlockCnt *bl) {
 417   int i = bl->firstgoto;
 418   Labellist *gl = &fs->ls->dyd->gt;
 419   /* correct pending gotos to current block and try to close it
 420      with visible labels */
 421   while (i < gl->n) {
 422     Labeldesc *gt = &gl->arr[i];
 423     if (gt->nactvar > bl->nactvar) {
 424       if (bl->upval)
 425         luaK_patchclose(fs, gt->pc, bl->nactvar);
 426       gt->nactvar = bl->nactvar;
 427     }
 428     if (!findlabel(fs->ls, i))
 429       i++;  /* move to next one */
 430   }
 431 }
 432
 433
 434 static void enterblock (FuncState *fs, BlockCnt *bl, lu_byte isloop) {
 435   bl->isloop = isloop;
 436   bl->nactvar = fs->nactvar;
 437   bl->firstlabel = fs->ls->dyd->label.n;
 438   bl->firstgoto = fs->ls->dyd->gt.n;
 439   bl->upval = 0;
 440   bl->previous = fs->bl;
 441   fs->bl = bl;
 442   lua_assert(fs->freereg == fs->nactvar);
 443 }
 444
 445
 446 /*
 447 ** create a label named 'break' to resolve break statements
 448 */
 449 static void breaklabel (LexState *ls) {
 450   TString *n = luaS_new(ls->L, "break");
 451   int l = newlabelentry(ls, &ls->dyd->label, n, 0, ls->fs->pc);
 452   findgotos(ls, &ls->dyd->label.arr[l]);
 453 }
 454
 455 /*
 456 ** generates an error for an undefined 'goto'; choose appropriate
 457 ** message when label name is a reserved word (which can only be 'break')
 458 */
 459 static l_noret undefgoto (LexState *ls, Labeldesc *gt) {
 460   const char *msg = isreserved(gt->name)
 461                     ? "<%s> at line %d not inside a loop"
 462                     : "no visible label '%s' for <goto> at line %d";
 463   msg = luaO_pushfstring(ls->L, msg, getstr(gt->name), gt->line);
 464   semerror(ls, msg);
 465 }
 466
 467
 468 static void leaveblock (FuncState *fs) {
 469   BlockCnt *bl = fs->bl;
 470   LexState *ls = fs->ls;
 471   if (bl->previous && bl->upval) {
 472     /* create a 'jump to here' to close upvalues */
 473     int j = luaK_jump(fs);
 474     luaK_patchclose(fs, j, bl->nactvar);
 475     luaK_patchtohere(fs, j);
 476   }
 477   if (bl->isloop)
 478     breaklabel(ls);  /* close pending breaks */
 479   fs->bl = bl->previous;
 480   removevars(fs, bl->nactvar);
 481   lua_assert(bl->nactvar == fs->nactvar);
 482   fs->freereg = fs->nactvar;  /* free registers */
 483   ls->dyd->label.n = bl->firstlabel;  /* remove local labels */
 484   if (bl->previous)  /* inner block? */
 485     movegotosout(fs, bl);  /* update pending gotos to outer block */
 486   else if (bl->firstgoto < ls->dyd->gt.n)  /* pending gotos in outer block? */
 487     undefgoto(ls, &ls->dyd->gt.arr[bl->firstgoto]);  /* error */
 488 }
 489
 490
 491 /*
 492 ** adds a new prototype into list of prototypes
 493 */
 494 static Proto *addprototype (LexState *ls) {
 495   Proto *clp;
 496   lua_State *L = ls->L;
 497   FuncState *fs = ls->fs;
 498   Proto *f = fs->f;  /* prototype of current function */
 499   if (fs->np >= f->sizep) {
 500     int oldsize = f->sizep;
 501     luaM_growvector(L, f->p, fs->np, f->sizep, Proto *, MAXARG_Bx, "functions");
 502     while (oldsize < f->sizep) f->p[oldsize++] = NULL;
 503   }
 504   f->p[fs->np++] = clp = luaF_newproto(L);
 505   luaC_objbarrier(L, f, clp);
 506   return clp;
 507 }
 508
 509
 510 /*
 511 ** codes instruction to create new closure in parent function.
 512 ** The OP_CLOSURE instruction must use the last available register,
 513 ** so that, if it invokes the GC, the GC knows which registers
 514 ** are in use at that time.
 515 */
 516 static void codeclosure (LexState *ls, expdesc *v) {
 517   FuncState *fs = ls->fs->prev;
 518   init_exp(v, VRELOCABLE, luaK_codeABx(fs, OP_CLOSURE, 0, fs->np - 1));
 519   luaK_exp2nextreg(fs, v);  /* fix it at the last register */
 520 }
 521
 522
 523 static void open_func (LexState *ls, FuncState *fs, BlockCnt *bl) {
 524   Proto *f;
 525   fs->prev = ls->fs;  /* linked list of funcstates */
 526   fs->ls = ls;
 527   ls->fs = fs;
 528   fs->pc = 0;
 529   fs->lasttarget = 0;
 530   fs->jpc = NO_JUMP;
 531   fs->freereg = 0;
 532   fs->nk = 0;
 533   fs->np = 0;
 534   fs->nups = 0;
 535   fs->nlocvars = 0;
 536   fs->nactvar = 0;
 537   fs->firstlocal = ls->dyd->actvar.n;
 538   fs->bl = NULL;
 539   f = fs->f;
 540   f->source = ls->source;
 541   f->maxstacksize = 2;  /* registers 0/1 are always valid */
 542   enterblock(fs, bl, 0);
 543 }
 544
 545
 546 static void close_func (LexState *ls) {
 547   lua_State *L = ls->L;
 548   FuncState *fs = ls->fs;
 549   Proto *f = fs->f;
 550   luaK_ret(fs, 0, 0);  /* final return */
 551   leaveblock(fs);
 552   luaM_reallocvector(L, f->code, f->sizecode, fs->pc, Instruction);
 553   f->sizecode = fs->pc;
 554   luaM_reallocvector(L, f->lineinfo, f->sizelineinfo, fs->pc, int);
 555   f->sizelineinfo = fs->pc;
 556   luaM_reallocvector(L, f->k, f->sizek, fs->nk, TValue);
 557   f->sizek = fs->nk;
 558   luaM_reallocvector(L, f->p, f->sizep, fs->np, Proto *);
 559   f->sizep = fs->np;
 560   luaM_reallocvector(L, f->locvars, f->sizelocvars, fs->nlocvars, LocVar);
 561   f->sizelocvars = fs->nlocvars;
 562   luaM_reallocvector(L, f->upvalues, f->sizeupvalues, fs->nups, Upvaldesc);
 563   f->sizeupvalues = fs->nups;
 564   lua_assert(fs->bl == NULL);
 565   ls->fs = fs->prev;
 566   luaC_checkGC(L);
 567 }
 568
 569
 570
 571 /*============================================================*/
 572 /* GRAMMAR RULES */
 573 /*============================================================*/
 574
 575
 576 /*
 577 ** check whether current token is in the follow set of a block.
 578 ** 'until' closes syntactical blocks, but do not close scope,
 579 ** so it is handled in separate.
 580 */
 581 static int block_follow (LexState *ls, int withuntil) {
 582   switch (ls->t.token) {
 583     case TK_ELSE: case TK_ELSEIF:
 584     case TK_END: case TK_EOS:
 585       return 1;
 586     case TK_UNTIL: return withuntil;
 587     default: return 0;
 588   }
 589 }
 590
 591
 592 static void statlist (LexState *ls) {
 593   /* statlist -> { stat [';'] } */
 594   while (!block_follow(ls, 1)) {
 595     if (ls->t.token == TK_RETURN) {
 596       statement(ls);
 597       return;  /* 'return' must be last statement */
 598     }
 599     statement(ls);
 600   }
 601 }
 602
 603
 604 static void fieldsel (LexState *ls, expdesc *v) {
 605   /* fieldsel -> ['.' | ':'] NAME */
 606   FuncState *fs = ls->fs;
 607   expdesc key;
 608   luaK_exp2anyregup(fs, v);
 609   luaX_next(ls);  /* skip the dot or colon */
 610   checkname(ls, &key);
 611   luaK_indexed(fs, v, &key);
 612 }
 613
 614
 615 static void yindex (LexState *ls, expdesc *v) {
 616   /* index -> '[' expr ']' */
 617   luaX_next(ls);  /* skip the '[' */
 618   expr(ls, v);
 619   luaK_exp2val(ls->fs, v);
 620   checknext(ls, ']');
 621 }
 622
 623
 624 /*
 625 ** {======================================================================
 626 ** Rules for Constructors
 627 ** =======================================================================
 628 */
 629
 630
 631 struct ConsControl {
 632   expdesc v;  /* last list item read */
 633   expdesc *t;  /* table descriptor */
 634   int nh;  /* total number of 'record' elements */
 635   int na;  /* total number of array elements */
 636   int tostore;  /* number of array elements pending to be stored */
 637 };
 638
 639
 640 static void recfield (LexState *ls, struct ConsControl *cc) {
 641   /* recfield -> (NAME | '['exp1']') = exp1 */
 642   FuncState *fs = ls->fs;
 643   int reg = ls->fs->freereg;
 644   expdesc key, val;
 645   int rkkey;
 646   if (ls->t.token == TK_NAME) {
 647     checklimit(fs, cc->nh, MAX_INT, "items in a constructor");
 648     checkname(ls, &key);
 649   }
 650   else  /* ls->t.token == '[' */
 651     yindex(ls, &key);
 652   cc->nh++;
 653   checknext(ls, '=');
 654   rkkey = luaK_exp2RK(fs, &key);
 655   expr(ls, &val);
 656   luaK_codeABC(fs, OP_SETTABLE, cc->t->u.info, rkkey, luaK_exp2RK(fs, &val));
 657   fs->freereg = reg;  /* free registers */
 658 }
 659
 660
 661 static void closelistfield (FuncState *fs, struct ConsControl *cc) {
 662   if (cc->v.k == VVOID) return;  /* there is no list item */
 663   luaK_exp2nextreg(fs, &cc->v);
 664   cc->v.k = VVOID;
 665   if (cc->tostore == LFIELDS_PER_FLUSH) {
 666     luaK_setlist(fs, cc->t->u.info, cc->na, cc->tostore);  /* flush */
 667     cc->tostore = 0;  /* no more items pending */
 668   }
 669 }
 670
 671
 672 static void lastlistfield (FuncState *fs, struct ConsControl *cc) {
 673   if (cc->tostore == 0) return;
 674   if (hasmultret(cc->v.k)) {
 675     luaK_setmultret(fs, &cc->v);
 676     luaK_setlist(fs, cc->t->u.info, cc->na, LUA_MULTRET);
 677     cc->na--;  /* do not count last expression (unknown number of elements) */
 678   }
 679   else {
 680     if (cc->v.k != VVOID)
 681       luaK_exp2nextreg(fs, &cc->v);
 682     luaK_setlist(fs, cc->t->u.info, cc->na, cc->tostore);
 683   }
 684 }
 685
 686
 687 static void listfield (LexState *ls, struct ConsControl *cc) {
 688   /* listfield -> exp */
 689   expr(ls, &cc->v);
 690   checklimit(ls->fs, cc->na, MAX_INT, "items in a constructor");
 691   cc->na++;
 692   cc->tostore++;
 693 }
 694
 695
 696 static void field (LexState *ls, struct ConsControl *cc) {
 697   /* field -> listfield | recfield */
 698   switch(ls->t.token) {
 699     case TK_NAME: {  /* may be 'listfield' or 'recfield' */
 700       if (luaX_lookahead(ls) != '=')  /* expression? */
 701         listfield(ls, cc);
 702       else
 703         recfield(ls, cc);
 704       break;
 705     }
 706     case '[': {
 707       recfield(ls, cc);
 708       break;
 709     }
 710     default: {
 711       listfield(ls, cc);
 712       break;
 713     }
 714   }
 715 }
 716
 717
 718 static void constructor (LexState *ls, expdesc *t) {
 719   /* constructor -> '{' [ field { sep field } [sep] ] '}'
 720      sep -> ',' | ';' */
 721   FuncState *fs = ls->fs;
 722   int line = ls->linenumber;
 723   int pc = luaK_codeABC(fs, OP_NEWTABLE, 0, 0, 0);
 724   struct ConsControl cc;
 725   cc.na = cc.nh = cc.tostore = 0;
 726   cc.t = t;
 727   init_exp(t, VRELOCABLE, pc);
 728   init_exp(&cc.v, VVOID, 0);  /* no value (yet) */
 729   luaK_exp2nextreg(ls->fs, t);  /* fix it at stack top */
 730   checknext(ls, '{');
 731   do {
 732     lua_assert(cc.v.k == VVOID || cc.tostore > 0);
 733     if (ls->t.token == '}') break;
 734     closelistfield(fs, &cc);
 735     field(ls, &cc);
 736   } while (testnext(ls, ',') || testnext(ls, ';'));
 737   check_match(ls, '}', '{', line);
 738   lastlistfield(fs, &cc);
 739   SETARG_B(fs->f->code[pc], luaO_int2fb(cc.na)); /* set initial array size */
 740   SETARG_C(fs->f->code[pc], luaO_int2fb(cc.nh));  /* set initial table size */
 741 }
 742
 743 /* }====================================================================== */
 744
 745
 746
 747 static void parlist (LexState *ls) {
 748   /* parlist -> [ param { ',' param } ] */
 749   FuncState *fs = ls->fs;
 750   Proto *f = fs->f;
 751   int nparams = 0;
 752   f->is_vararg = 0;
 753   if (ls->t.token != ')') {  /* is 'parlist' not empty? */
 754     do {
 755       switch (ls->t.token) {
 756         case TK_NAME: {  /* param -> NAME */
 757           new_localvar(ls, str_checkname(ls));
 758           nparams++;
 759           break;
 760         }
 761         case TK_DOTS: {  /* param -> '...' */
 762           luaX_next(ls);
 763           f->is_vararg = 2;  /* declared vararg */
 764           break;
 765         }
 766         default: luaX_syntaxerror(ls, "<name> or '...' expected");
 767       }
 768     } while (!f->is_vararg && testnext(ls, ','));
 769   }
 770   adjustlocalvars(ls, nparams);
 771   f->numparams = cast_byte(fs->nactvar);
 772   luaK_reserveregs(fs, fs->nactvar);  /* reserve register for parameters */
 773 }
 774
 775
 776 static void body (LexState *ls, expdesc *e, int ismethod, int line) {
 777   /* body ->  '(' parlist ')' block END */
 778   FuncState new_fs;
 779   BlockCnt bl;
 780   new_fs.f = addprototype(ls);
 781   new_fs.f->linedefined = line;
 782   open_func(ls, &new_fs, &bl);
 783   checknext(ls, '(');
 784   if (ismethod) {
 785     new_localvarliteral(ls, "self");  /* create 'self' parameter */
 786     adjustlocalvars(ls, 1);
 787   }
 788   parlist(ls);
 789   checknext(ls, ')');
 790   statlist(ls);
 791   new_fs.f->lastlinedefined = ls->linenumber;
 792   check_match(ls, TK_END, TK_FUNCTION, line);
 793   codeclosure(ls, e);
 794   close_func(ls);
 795 }
 796
 797
 798 static int explist (LexState *ls, expdesc *v) {
 799   /* explist -> expr { ',' expr } */
 800   int n = 1;  /* at least one expression */
 801   expr(ls, v);
 802   while (testnext(ls, ',')) {
 803     luaK_exp2nextreg(ls->fs, v);
 804     expr(ls, v);
 805     n++;
 806   }
 807   return n;
 808 }
 809
 810
 811 static void funcargs (LexState *ls, expdesc *f, int line) {
 812   FuncState *fs = ls->fs;
 813   expdesc args;
 814   int base, nparams;
 815   switch (ls->t.token) {
 816     case '(': {  /* funcargs -> '(' [ explist ] ')' */
 817       luaX_next(ls);
 818       if (ls->t.token == ')')  /* arg list is empty? */
 819         args.k = VVOID;
 820       else {
 821         explist(ls, &args);
 822         luaK_setmultret(fs, &args);
 823       }
 824       check_match(ls, ')', '(', line);
 825       break;
 826     }
 827     case '{': {  /* funcargs -> constructor */
 828       constructor(ls, &args);
 829       break;
 830     }
 831     case TK_STRING: {  /* funcargs -> STRING */
 832       codestring(ls, &args, ls->t.seminfo.ts);
 833       luaX_next(ls);  /* must use 'seminfo' before 'next' */
 834       break;
 835     }
 836     default: {
 837       luaX_syntaxerror(ls, "function arguments expected");
 838     }
 839   }
 840   lua_assert(f->k == VNONRELOC);
 841   base = f->u.info;  /* base register for call */
 842   if (hasmultret(args.k))
 843     nparams = LUA_MULTRET;  /* open call */
 844   else {
 845     if (args.k != VVOID)
 846       luaK_exp2nextreg(fs, &args);  /* close last argument */
 847     nparams = fs->freereg - (base+1);
 848   }
 849   init_exp(f, VCALL, luaK_codeABC(fs, OP_CALL, base, nparams+1, 2));
 850   luaK_fixline(fs, line);
 851   fs->freereg = base+1;  /* call remove function and arguments and leaves
 852                             (unless changed) one result */
 853 }
 854
 855
 856
 857
 858 /*
 859 ** {======================================================================
 860 ** Expression parsing
 861 ** =======================================================================
 862 */
 863
 864
 865 static void primaryexp (LexState *ls, expdesc *v) {
 866   /* primaryexp -> NAME | '(' expr ')' */
 867   switch (ls->t.token) {
 868     case '(': {
 869       int line = ls->linenumber;
 870       luaX_next(ls);
 871       expr(ls, v);
 872       check_match(ls, ')', '(', line);
 873       luaK_dischargevars(ls->fs, v);
 874       return;
 875     }
 876     case TK_NAME: {
 877       singlevar(ls, v);
 878       return;
 879     }
 880     default: {
 881       luaX_syntaxerror(ls, "unexpected symbol");
 882     }
 883   }
 884 }
 885
 886
 887 static void suffixedexp (LexState *ls, expdesc *v) {
 888   /* suffixedexp ->
 889        primaryexp { '.' NAME | '[' exp ']' | ':' NAME funcargs | funcargs } */
 890   FuncState *fs = ls->fs;
 891   int line = ls->linenumber;
 892   primaryexp(ls, v);
 893   for (;;) {
 894     switch (ls->t.token) {
 895       case '.': {  /* fieldsel */
 896         fieldsel(ls, v);
 897         break;
 898       }
 899       case '[': {  /* '[' exp1 ']' */
 900         expdesc key;
 901         luaK_exp2anyregup(fs, v);
 902         yindex(ls, &key);
 903         luaK_indexed(fs, v, &key);
 904         break;
 905       }
 906       case ':': {  /* ':' NAME funcargs */
 907         expdesc key;
 908         luaX_next(ls);
 909         checkname(ls, &key);
 910         luaK_self(fs, v, &key);
 911         funcargs(ls, v, line);
 912         break;
 913       }
 914       case '(': case TK_STRING: case '{': {  /* funcargs */
 915         luaK_exp2nextreg(fs, v);
 916         funcargs(ls, v, line);
 917         break;
 918       }
 919       default: return;
 920     }
 921   }
 922 }
 923
 924
 925 static void simpleexp (LexState *ls, expdesc *v) {
 926   /* simpleexp -> FLT | INT | STRING | NIL | TRUE | FALSE | ... |
 927                   constructor | FUNCTION body | suffixedexp */
 928   switch (ls->t.token) {
 929     case TK_FLT: {
 930       init_exp(v, VKFLT, 0);
 931       v->u.nval = ls->t.seminfo.r;
 932       break;
 933     }
 934     case TK_INT: {
 935       init_exp(v, VKINT, 0);
 936       v->u.ival = ls->t.seminfo.i;
 937       break;
 938     }
 939     case TK_STRING: {
 940       codestring(ls, v, ls->t.seminfo.ts);
 941       break;
 942     }
 943     case TK_NIL: {
 944       init_exp(v, VNIL, 0);
 945       break;
 946     }
 947     case TK_TRUE: {
 948       init_exp(v, VTRUE, 0);
 949       break;
 950     }
 951     case TK_FALSE: {
 952       init_exp(v, VFALSE, 0);
 953       break;
 954     }
 955     case TK_DOTS: {  /* vararg */
 956       FuncState *fs = ls->fs;
 957       check_condition(ls, fs->f->is_vararg,
 958                       "cannot use '...' outside a vararg function");
 959       fs->f->is_vararg = 1;  /* function actually uses vararg */
 960       init_exp(v, VVARARG, luaK_codeABC(fs, OP_VARARG, 0, 1, 0));
 961       break;
 962     }
 963     case '{': {  /* constructor */
 964       constructor(ls, v);
 965       return;
 966     }
 967     case TK_FUNCTION: {
 968       luaX_next(ls);
 969       body(ls, v, 0, ls->linenumber);
 970       return;
 971     }
 972     default: {
 973       suffixedexp(ls, v);
 974       return;
 975     }
 976   }
 977   luaX_next(ls);
 978 }
 979
 980
 981 static UnOpr getunopr (int op) {
 982   switch (op) {
 983     case TK_NOT: return OPR_NOT;
 984     case '-': return OPR_MINUS;
 985     case '~': return OPR_BNOT;
 986     case '#': return OPR_LEN;
 987     default: return OPR_NOUNOPR;
 988   }
 989 }
 990
 991
 992 static BinOpr getbinopr (int op) {
 993   switch (op) {
 994     case '+': return OPR_ADD;
 995     case '-': return OPR_SUB;
 996     case '*': return OPR_MUL;
 997     case '%': return OPR_MOD;
 998     case '^': return OPR_POW;
 999     case '/': return OPR_DIV;
1000     case TK_IDIV: return OPR_IDIV;
1001     case '&': return OPR_BAND;
1002     case '|': return OPR_BOR;
1003     case '~': return OPR_BXOR;
1004     case TK_SHL: return OPR_SHL;
1005     case TK_SHR: return OPR_SHR;
1006     case TK_CONCAT: return OPR_CONCAT;
1007     case TK_NE: return OPR_NE;
1008     case TK_EQ: return OPR_EQ;
1009     case '<': return OPR_LT;
1010     case TK_LE: return OPR_LE;
1011     case '>': return OPR_GT;
1012     case TK_GE: return OPR_GE;
1013     case TK_AND: return OPR_AND;
1014     case TK_OR: return OPR_OR;
1015     default: return OPR_NOBINOPR;
1016   }
1017 }
1018
1019
1020 static const struct {
1021   lu_byte left;  /* left priority for each binary operator */
1022   lu_byte right; /* right priority */
1023 } priority[] = {  /* ORDER OPR */
1024    {10, 10}, {10, 10},           /* '+' '-' */
1025    {11, 11}, {11, 11},           /* '*' '%' */
1026    {14, 13},                  /* '^' (right associative) */
1027    {11, 11}, {11, 11},           /* '/' '//' */
1028    {6, 6}, {4, 4}, {5, 5},   /* '&' '|' '~' */
1029    {7, 7}, {7, 7},           /* '<<' '>>' */
1030    {9, 8},                   /* '..' (right associative) */
1031    {3, 3}, {3, 3}, {3, 3},   /* ==, <, <= */
1032    {3, 3}, {3, 3}, {3, 3},   /* ~=, >, >= */
1033    {2, 2}, {1, 1}            /* and, or */
1034 };
1035
1036 #define UNARY_PRIORITY  12  /* priority for unary operators */
1037
1038
1039 /*
1040 ** subexpr -> (simpleexp | unop subexpr) { binop subexpr }
1041 ** where 'binop' is any binary operator with a priority higher than 'limit'
1042 */
1043 static BinOpr subexpr (LexState *ls, expdesc *v, int limit) {
1044   BinOpr op;
1045   UnOpr uop;
1046   enterlevel(ls);
1047   uop = getunopr(ls->t.token);
1048   if (uop != OPR_NOUNOPR) {
1049     int line = ls->linenumber;
1050     luaX_next(ls);
1051     subexpr(ls, v, UNARY_PRIORITY);
1052     luaK_prefix(ls->fs, uop, v, line);
1053   }
1054   else simpleexp(ls, v);
1055   /* expand while operators have priorities higher than 'limit' */
1056   op = getbinopr(ls->t.token);
1057   while (op != OPR_NOBINOPR && priority[op].left > limit) {
1058     expdesc v2;
1059     BinOpr nextop;
1060     int line = ls->linenumber;
1061     luaX_next(ls);
1062     luaK_infix(ls->fs, op, v);
1063     /* read sub-expression with higher priority */
1064     nextop = subexpr(ls, &v2, priority[op].right);
1065     luaK_posfix(ls->fs, op, v, &v2, line);
1066     op = nextop;
1067   }
1068   leavelevel(ls);
1069   return op;  /* return first untreated operator */
1070 }
1071
1072
1073 static void expr (LexState *ls, expdesc *v) {
1074   subexpr(ls, v, 0);
1075 }
1076
1077 /* }==================================================================== */
1078
1079
1080
1081 /*
1082 ** {======================================================================
1083 ** Rules for Statements
1084 ** =======================================================================
1085 */
1086
1087
1088 static void block (LexState *ls) {
1089   /* block -> statlist */
1090   FuncState *fs = ls->fs;
1091   BlockCnt bl;
1092   enterblock(fs, &bl, 0);
1093   statlist(ls);
1094   leaveblock(fs);
1095 }
1096
1097
1098 /*
1099 ** structure to chain all variables in the left-hand side of an
1100 ** assignment
1101 */
1102 struct LHS_assign {
1103   struct LHS_assign *prev;
1104   expdesc v;  /* variable (global, local, upvalue, or indexed) */
1105 };
1106
1107
1108 /*
1109 ** check whether, in an assignment to an upvalue/local variable, the
1110 ** upvalue/local variable is begin used in a previous assignment to a
1111 ** table. If so, save original upvalue/local value in a safe place and
1112 ** use this safe copy in the previous assignment.
1113 */
1114 static void check_conflict (LexState *ls, struct LHS_assign *lh, expdesc *v) {
1115   FuncState *fs = ls->fs;
1116   int extra = fs->freereg;  /* eventual position to save local variable */
1117   int conflict = 0;
1118   for (; lh; lh = lh->prev) {  /* check all previous assignments */
1119     if (lh->v.k == VINDEXED) {  /* assigning to a table? */
1120       /* table is the upvalue/local being assigned now? */
1121       if (lh->v.u.ind.vt == v->k && lh->v.u.ind.t == v->u.info) {
1122         conflict = 1;
1123         lh->v.u.ind.vt = VLOCAL;
1124         lh->v.u.ind.t = extra;  /* previous assignment will use safe copy */
1125       }
1126       /* index is the local being assigned? (index cannot be upvalue) */
1127       if (v->k == VLOCAL && lh->v.u.ind.idx == v->u.info) {
1128         conflict = 1;
1129         lh->v.u.ind.idx = extra;  /* previous assignment will use safe copy */
1130       }
1131     }
1132   }
1133   if (conflict) {
1134     /* copy upvalue/local value to a temporary (in position 'extra') */
1135     OpCode op = (v->k == VLOCAL) ? OP_MOVE : OP_GETUPVAL;
1136     luaK_codeABC(fs, op, extra, v->u.info, 0);
1137     luaK_reserveregs(fs, 1);
1138   }
1139 }
1140
1141
1142 static void assignment (LexState *ls, struct LHS_assign *lh, int nvars) {
1143   expdesc e;
1144   check_condition(ls, vkisvar(lh->v.k), "syntax error");
1145   if (testnext(ls, ',')) {  /* assignment -> ',' suffixedexp assignment */
1146     struct LHS_assign nv;
1147     nv.prev = lh;
1148     suffixedexp(ls, &nv.v);
1149     if (nv.v.k != VINDEXED)
1150       check_conflict(ls, lh, &nv.v);
1151     checklimit(ls->fs, nvars + ls->L->nCcalls, LUAI_MAXCCALLS,
1152                     "C levels");
1153     assignment(ls, &nv, nvars+1);
1154   }
1155   else {  /* assignment -> '=' explist */
1156     int nexps;
1157     checknext(ls, '=');
1158     nexps = explist(ls, &e);
1159     if (nexps != nvars) {
1160       adjust_assign(ls, nvars, nexps, &e);
1161       if (nexps > nvars)
1162         ls->fs->freereg -= nexps - nvars;  /* remove extra values */
1163     }
1164     else {
1165       luaK_setoneret(ls->fs, &e);  /* close last expression */
1166       luaK_storevar(ls->fs, &lh->v, &e);
1167       return;  /* avoid default */
1168     }
1169   }
1170   init_exp(&e, VNONRELOC, ls->fs->freereg-1);  /* default assignment */
1171   luaK_storevar(ls->fs, &lh->v, &e);
1172 }
1173
1174
1175 static int cond (LexState *ls) {
1176   /* cond -> exp */
1177   expdesc v;
1178   expr(ls, &v);  /* read condition */
1179   if (v.k == VNIL) v.k = VFALSE;  /* 'falses' are all equal here */
1180   luaK_goiftrue(ls->fs, &v);
1181   return v.f;
1182 }
1183
1184
1185 static void gotostat (LexState *ls, int pc) {
1186   int line = ls->linenumber;
1187   TString *label;
1188   int g;
1189   if (testnext(ls, TK_GOTO))
1190     label = str_checkname(ls);
1191   else {
1192     luaX_next(ls);  /* skip break */
1193     label = luaS_new(ls->L, "break");
1194   }
1195   g = newlabelentry(ls, &ls->dyd->gt, label, line, pc);
1196   findlabel(ls, g);  /* close it if label already defined */
1197 }
1198
1199
1200 /* check for repeated labels on the same block */
1201 static void checkrepeated (FuncState *fs, Labellist *ll, TString *label) {
1202   int i;
1203   for (i = fs->bl->firstlabel; i < ll->n; i++) {
1204     if (eqstr(label, ll->arr[i].name)) {
1205       const char *msg = luaO_pushfstring(fs->ls->L,
1206                           "label '%s' already defined on line %d",
1207                           getstr(label), ll->arr[i].line);
1208       semerror(fs->ls, msg);
1209     }
1210   }
1211 }
1212
1213
1214 /* skip no-op statements */
1215 static void skipnoopstat (LexState *ls) {
1216   while (ls->t.token == ';' || ls->t.token == TK_DBCOLON)
1217     statement(ls);
1218 }
1219
1220
1221 static void labelstat (LexState *ls, TString *label, int line) {
1222   /* label -> '::' NAME '::' */
1223   FuncState *fs = ls->fs;
1224   Labellist *ll = &ls->dyd->label;
1225   int l;  /* index of new label being created */
1226   checkrepeated(fs, ll, label);  /* check for repeated labels */
1227   checknext(ls, TK_DBCOLON);  /* skip double colon */
1228   /* create new entry for this label */
1229   l = newlabelentry(ls, ll, label, line, fs->pc);
1230   skipnoopstat(ls);  /* skip other no-op statements */
1231   if (block_follow(ls, 0)) {  /* label is last no-op statement in the block? */
1232     /* assume that locals are already out of scope */
1233     ll->arr[l].nactvar = fs->bl->nactvar;
1234   }
1235   findgotos(ls, &ll->arr[l]);
1236 }
1237
1238
1239 static void whilestat (LexState *ls, int line) {
1240   /* whilestat -> WHILE cond DO block END */
1241   FuncState *fs = ls->fs;
1242   int whileinit;
1243   int condexit;
1244   BlockCnt bl;
1245   luaX_next(ls);  /* skip WHILE */
1246   whileinit = luaK_getlabel(fs);
1247   condexit = cond(ls);
1248   enterblock(fs, &bl, 1);
1249   checknext(ls, TK_DO);
1250   block(ls);
1251   luaK_jumpto(fs, whileinit);
1252   check_match(ls, TK_END, TK_WHILE, line);
1253   leaveblock(fs);
1254   luaK_patchtohere(fs, condexit);  /* false conditions finish the loop */
1255 }
1256
1257
1258 static void repeatstat (LexState *ls, int line) {
1259   /* repeatstat -> REPEAT block UNTIL cond */
1260   int condexit;
1261   FuncState *fs = ls->fs;
1262   int repeat_init = luaK_getlabel(fs);
1263   BlockCnt bl1, bl2;
1264   enterblock(fs, &bl1, 1);  /* loop block */
1265   enterblock(fs, &bl2, 0);  /* scope block */
1266   luaX_next(ls);  /* skip REPEAT */
1267   statlist(ls);
1268   check_match(ls, TK_UNTIL, TK_REPEAT, line);
1269   condexit = cond(ls);  /* read condition (inside scope block) */
1270   if (bl2.upval)  /* upvalues? */
1271     luaK_patchclose(fs, condexit, bl2.nactvar);
1272   leaveblock(fs);  /* finish scope */
1273   luaK_patchlist(fs, condexit, repeat_init);  /* close the loop */
1274   leaveblock(fs);  /* finish loop */
1275 }
1276
1277
1278 static int exp1 (LexState *ls) {
1279   expdesc e;
1280   int reg;
1281   expr(ls, &e);
1282   luaK_exp2nextreg(ls->fs, &e);
1283   lua_assert(e.k == VNONRELOC);
1284   reg = e.u.info;
1285   return reg;
1286 }
1287
1288
1289 static void forbody (LexState *ls, int base, int line, int nvars, int isnum) {
1290   /* forbody -> DO block */
1291   BlockCnt bl;
1292   FuncState *fs = ls->fs;
1293   int prep, endfor;
1294   adjustlocalvars(ls, 3);  /* control variables */
1295   checknext(ls, TK_DO);
1296   prep = isnum ? luaK_codeAsBx(fs, OP_FORPREP, base, NO_JUMP) : luaK_jump(fs);
1297   enterblock(fs, &bl, 0);  /* scope for declared variables */
1298   adjustlocalvars(ls, nvars);
1299   luaK_reserveregs(fs, nvars);
1300   block(ls);
1301   leaveblock(fs);  /* end of scope for declared variables */
1302   luaK_patchtohere(fs, prep);
1303   if (isnum)  /* numeric for? */
1304     endfor = luaK_codeAsBx(fs, OP_FORLOOP, base, NO_JUMP);
1305   else {  /* generic for */
1306     luaK_codeABC(fs, OP_TFORCALL, base, 0, nvars);
1307     luaK_fixline(fs, line);
1308     endfor = luaK_codeAsBx(fs, OP_TFORLOOP, base + 2, NO_JUMP);
1309   }
1310   luaK_patchlist(fs, endfor, prep + 1);
1311   luaK_fixline(fs, line);
1312 }
1313
1314
1315 static void fornum (LexState *ls, TString *varname, int line) {
1316   /* fornum -> NAME = exp1,exp1[,exp1] forbody */
1317   FuncState *fs = ls->fs;
1318   int base = fs->freereg;
1319   new_localvarliteral(ls, "(for index)");
1320   new_localvarliteral(ls, "(for limit)");
1321   new_localvarliteral(ls, "(for step)");
1322   new_localvar(ls, varname);
1323   checknext(ls, '=');
1324   exp1(ls);  /* initial value */
1325   checknext(ls, ',');
1326   exp1(ls);  /* limit */
1327   if (testnext(ls, ','))
1328     exp1(ls);  /* optional step */
1329   else {  /* default step = 1 */
1330     luaK_codek(fs, fs->freereg, luaK_intK(fs, 1));
1331     luaK_reserveregs(fs, 1);
1332   }
1333   forbody(ls, base, line, 1, 1);
1334 }
1335
1336
1337 static void forlist (LexState *ls, TString *indexname) {
1338   /* forlist -> NAME {,NAME} IN explist forbody */
1339   FuncState *fs = ls->fs;
1340   expdesc e;
1341   int nvars = 4;  /* gen, state, control, plus at least one declared var */
1342   int line;
1343   int base = fs->freereg;
1344   /* create control variables */
1345   new_localvarliteral(ls, "(for generator)");
1346   new_localvarliteral(ls, "(for state)");
1347   new_localvarliteral(ls, "(for control)");
1348   /* create declared variables */
1349   new_localvar(ls, indexname);
1350   while (testnext(ls, ',')) {
1351     new_localvar(ls, str_checkname(ls));
1352     nvars++;
1353   }
1354   checknext(ls, TK_IN);
1355   line = ls->linenumber;
1356   adjust_assign(ls, 3, explist(ls, &e), &e);
1357   luaK_checkstack(fs, 3);  /* extra space to call generator */
1358   forbody(ls, base, line, nvars - 3, 0);
1359 }
1360
1361
1362 static void forstat (LexState *ls, int line) {
1363   /* forstat -> FOR (fornum | forlist) END */
1364   FuncState *fs = ls->fs;
1365   TString *varname;
1366   BlockCnt bl;
1367   enterblock(fs, &bl, 1);  /* scope for loop and control variables */
1368   luaX_next(ls);  /* skip 'for' */
1369   varname = str_checkname(ls);  /* first variable name */
1370   switch (ls->t.token) {
1371     case '=': fornum(ls, varname, line); break;
1372     case ',': case TK_IN: forlist(ls, varname); break;
1373     default: luaX_syntaxerror(ls, "'=' or 'in' expected");
1374   }
1375   check_match(ls, TK_END, TK_FOR, line);
1376   leaveblock(fs);  /* loop scope ('break' jumps to this point) */
1377 }
1378
1379
1380 static void test_then_block (LexState *ls, int *escapelist) {
1381   /* test_then_block -> [IF | ELSEIF] cond THEN block */
1382   BlockCnt bl;
1383   FuncState *fs = ls->fs;
1384   expdesc v;
1385   int jf;  /* instruction to skip 'then' code (if condition is false) */
1386   luaX_next(ls);  /* skip IF or ELSEIF */
1387   expr(ls, &v);  /* read condition */
1388   checknext(ls, TK_THEN);
1389   if (ls->t.token == TK_GOTO || ls->t.token == TK_BREAK) {
1390     luaK_goiffalse(ls->fs, &v);  /* will jump to label if condition is true */
1391     enterblock(fs, &bl, 0);  /* must enter block before 'goto' */
1392     gotostat(ls, v.t);  /* handle goto/break */
1393     skipnoopstat(ls);  /* skip other no-op statements */
1394     if (block_follow(ls, 0)) {  /* 'goto' is the entire block? */
1395       leaveblock(fs);
1396       return;  /* and that is it */
1397     }
1398     else  /* must skip over 'then' part if condition is false */
1399       jf = luaK_jump(fs);
1400   }
1401   else {  /* regular case (not goto/break) */
1402     luaK_goiftrue(ls->fs, &v);  /* skip over block if condition is false */
1403     enterblock(fs, &bl, 0);
1404     jf = v.f;
1405   }
1406   statlist(ls);  /* 'then' part */
1407   leaveblock(fs);
1408   if (ls->t.token == TK_ELSE ||
1409       ls->t.token == TK_ELSEIF)  /* followed by 'else'/'elseif'? */
1410     luaK_concat(fs, escapelist, luaK_jump(fs));  /* must jump over it */
1411   luaK_patchtohere(fs, jf);
1412 }
1413
1414
1415 static void ifstat (LexState *ls, int line) {
1416   /* ifstat -> IF cond THEN block {ELSEIF cond THEN block} [ELSE block] END */
1417   FuncState *fs = ls->fs;
1418   int escapelist = NO_JUMP;  /* exit list for finished parts */
1419   test_then_block(ls, &escapelist);  /* IF cond THEN block */
1420   while (ls->t.token == TK_ELSEIF)
1421     test_then_block(ls, &escapelist);  /* ELSEIF cond THEN block */
1422   if (testnext(ls, TK_ELSE))
1423     block(ls);  /* 'else' part */
1424   check_match(ls, TK_END, TK_IF, line);
1425   luaK_patchtohere(fs, escapelist);  /* patch escape list to 'if' end */
1426 }
1427
1428
1429 static void localfunc (LexState *ls) {
1430   expdesc b;
1431   FuncState *fs = ls->fs;
1432   new_localvar(ls, str_checkname(ls));  /* new local variable */
1433   adjustlocalvars(ls, 1);  /* enter its scope */
1434   body(ls, &b, 0, ls->linenumber);  /* function created in next register */
1435   /* debug information will only see the variable after this point! */
1436   getlocvar(fs, b.u.info)->startpc = fs->pc;
1437 }
1438
1439
1440 static void localstat (LexState *ls) {
1441   /* stat -> LOCAL NAME {',' NAME} ['=' explist] */
1442   int nvars = 0;
1443   int nexps;
1444   expdesc e;
1445   do {
1446     new_localvar(ls, str_checkname(ls));
1447     nvars++;
1448   } while (testnext(ls, ','));
1449   if (testnext(ls, '='))
1450     nexps = explist(ls, &e);
1451   else {
1452     e.k = VVOID;
1453     nexps = 0;
1454   }
1455   adjust_assign(ls, nvars, nexps, &e);
1456   adjustlocalvars(ls, nvars);
1457 }
1458
1459
1460 static int funcname (LexState *ls, expdesc *v) {
1461   /* funcname -> NAME {fieldsel} [':' NAME] */
1462   int ismethod = 0;
1463   singlevar(ls, v);
1464   while (ls->t.token == '.')
1465     fieldsel(ls, v);
1466   if (ls->t.token == ':') {
1467     ismethod = 1;
1468     fieldsel(ls, v);
1469   }
1470   return ismethod;
1471 }
1472
1473
1474 static void funcstat (LexState *ls, int line) {
1475   /* funcstat -> FUNCTION funcname body */
1476   int ismethod;
1477   expdesc v, b;
1478   luaX_next(ls);  /* skip FUNCTION */
1479   ismethod = funcname(ls, &v);
1480   body(ls, &b, ismethod, line);
1481   luaK_storevar(ls->fs, &v, &b);
1482   luaK_fixline(ls->fs, line);  /* definition "happens" in the first line */
1483 }
1484
1485
1486 static void exprstat (LexState *ls) {
1487   /* stat -> func | assignment */
1488   FuncState *fs = ls->fs;
1489   struct LHS_assign v;
1490   suffixedexp(ls, &v.v);
1491   if (ls->t.token == '=' || ls->t.token == ',') { /* stat -> assignment ? */
1492     v.prev = NULL;
1493     assignment(ls, &v, 1);
1494   }
1495   else {  /* stat -> func */
1496     check_condition(ls, v.v.k == VCALL, "syntax error");
1497     SETARG_C(getcode(fs, &v.v), 1);  /* call statement uses no results */
1498   }
1499 }
1500
1501
1502 static void retstat (LexState *ls) {
1503   /* stat -> RETURN [explist] [';'] */
1504   FuncState *fs = ls->fs;
1505   expdesc e;
1506   int first, nret;  /* registers with returned values */
1507   if (block_follow(ls, 1) || ls->t.token == ';')
1508     first = nret = 0;  /* return no values */
1509   else {
1510     nret = explist(ls, &e);  /* optional return values */
1511     if (hasmultret(e.k)) {
1512       luaK_setmultret(fs, &e);
1513       if (e.k == VCALL && nret == 1) {  /* tail call? */
1514         SET_OPCODE(getcode(fs,&e), OP_TAILCALL);
1515         lua_assert(GETARG_A(getcode(fs,&e)) == fs->nactvar);
1516       }
1517       first = fs->nactvar;
1518       nret = LUA_MULTRET;  /* return all values */
1519     }
1520     else {
1521       if (nret == 1)  /* only one single value? */
1522         first = luaK_exp2anyreg(fs, &e);
1523       else {
1524         luaK_exp2nextreg(fs, &e);  /* values must go to the stack */
1525         first = fs->nactvar;  /* return all active values */
1526         lua_assert(nret == fs->freereg - first);
1527       }
1528     }
1529   }
1530   luaK_ret(fs, first, nret);
1531   testnext(ls, ';');  /* skip optional semicolon */
1532 }
1533
1534
1535 static void statement (LexState *ls) {
1536   int line = ls->linenumber;  /* may be needed for error messages */
1537   enterlevel(ls);
1538   switch (ls->t.token) {
1539     case ';': {  /* stat -> ';' (empty statement) */
1540       luaX_next(ls);  /* skip ';' */
1541       break;
1542     }
1543     case TK_IF: {  /* stat -> ifstat */
1544       ifstat(ls, line);
1545       break;
1546     }
1547     case TK_WHILE: {  /* stat -> whilestat */
1548       whilestat(ls, line);
1549       break;
1550     }
1551     case TK_DO: {  /* stat -> DO block END */
1552       luaX_next(ls);  /* skip DO */
1553       block(ls);
1554       check_match(ls, TK_END, TK_DO, line);
1555       break;
1556     }
1557     case TK_FOR: {  /* stat -> forstat */
1558       forstat(ls, line);
1559       break;
1560     }
1561     case TK_REPEAT: {  /* stat -> repeatstat */
1562       repeatstat(ls, line);
1563       break;
1564     }
1565     case TK_FUNCTION: {  /* stat -> funcstat */
1566       funcstat(ls, line);
1567       break;
1568     }
1569     case TK_LOCAL: {  /* stat -> localstat */
1570       luaX_next(ls);  /* skip LOCAL */
1571       if (testnext(ls, TK_FUNCTION))  /* local function? */
1572         localfunc(ls);
1573       else
1574         localstat(ls);
1575       break;
1576     }
1577     case TK_DBCOLON: {  /* stat -> label */
1578       luaX_next(ls);  /* skip double colon */
1579       labelstat(ls, str_checkname(ls), line);
1580       break;
1581     }
1582     case TK_RETURN: {  /* stat -> retstat */
1583       luaX_next(ls);  /* skip RETURN */
1584       retstat(ls);
1585       break;
1586     }
1587     case TK_BREAK:   /* stat -> breakstat */
1588     case TK_GOTO: {  /* stat -> 'goto' NAME */
1589       gotostat(ls, luaK_jump(ls->fs));
1590       break;
1591     }
1592     default: {  /* stat -> func | assignment */
1593       exprstat(ls);
1594       break;
1595     }
1596   }
1597   lua_assert(ls->fs->f->maxstacksize >= ls->fs->freereg &&
1598              ls->fs->freereg >= ls->fs->nactvar);
1599   ls->fs->freereg = ls->fs->nactvar;  /* free registers */
1600   leavelevel(ls);
1601 }
1602
1603 /* }====================================================================== */
1604
1605
1606 /*
1607 ** compiles the main function, which is a regular vararg function with an
1608 ** upvalue named LUA_ENV
1609 */
1610 static void mainfunc (LexState *ls, FuncState *fs) {
1611   BlockCnt bl;
1612   expdesc v;
1613   open_func(ls, fs, &bl);
1614   fs->f->is_vararg = 2;  /* main function is always declared vararg */
1615   init_exp(&v, VLOCAL, 0);  /* create and... */
1616   newupvalue(fs, ls->envn, &v);  /* ...set environment upvalue */
1617   luaX_next(ls);  /* read first token */
1618   statlist(ls);  /* parse main body */
1619   check(ls, TK_EOS);
1620   close_func(ls);
1621 }
1622
1623
1624 LClosure *luaY_parser (lua_State *L, ZIO *z, Mbuffer *buff,
1625                        Dyndata *dyd, const char *name, int firstchar) {
1626   LexState lexstate;
1627   FuncState funcstate;
1628   LClosure *cl = luaF_newLclosure(L, 1);  /* create main closure */
1629   setclLvalue(L, L->top, cl);  /* anchor it (to avoid being collected) */
1630   luaD_inctop(L);
1631   lexstate.h = luaH_new(L);  /* create table for scanner */
1632   sethvalue(L, L->top, lexstate.h);  /* anchor it */
1633   luaD_inctop(L);
1634   funcstate.f = cl->p = luaF_newproto(L);
1635   funcstate.f->source = luaS_new(L, name);  /* create and anchor TString */
1636   lua_assert(iswhite(funcstate.f));  /* do not need barrier here */
1637   lexstate.buff = buff;
1638   lexstate.dyd = dyd;
1639   dyd->actvar.n = dyd->gt.n = dyd->label.n = 0;
1640   luaX_setinput(L, &lexstate, z, funcstate.f->source, firstchar);
1641   mainfunc(&lexstate, &funcstate);
1642   lua_assert(!funcstate.prev && funcstate.nups == 1 && !lexstate.fs);
1643   /* all scopes should be correctly finished */
1644   lua_assert(dyd->actvar.n == 0 && dyd->gt.n == 0 && dyd->label.n == 0);
1645   L->top--;  /* remove scanner's table */
1646   return cl;  /* closure is on the stack, too */
1647 }
1648