liblua/lparser.c

   1 /*
   2 ** $Id: lparser.c,v 2.130 2013/02/06 13:37:39 roberto Exp $
   3 ** Lua Parser
   4 ** See Copyright Notice in lua.h
   5 */
   6
   7
   8 #include <string.h>
   9
  10 #define lparser_c
  11 #define LUA_CORE
  12
  13 #include "lua.h"
  14
  15 #include "lcode.h"
  16 #include "ldebug.h"
  17 #include "ldo.h"
  18 #include "lfunc.h"
  19 #include "llex.h"
  20 #include "lmem.h"
  21 #include "lobject.h"
  22 #include "lopcodes.h"
  23 #include "lparser.h"
  24 #include "lstate.h"
  25 #include "lstring.h"
  26 #include "ltable.h"
  27
  28
  29
  30 /* maximum number of local variables per function (must be smaller
  31    than 250, due to the bytecode format) */
  32 #define MAXVARS         200
  33
  34
  35 #define hasmultret(k)           ((k) == VCALL || (k) == VVARARG)
  36
  37
  38
  39 /*
  40 ** nodes for block list (list of active blocks)
  41 */
  42 typedef struct BlockCnt {
  43   struct BlockCnt *previous;  /* chain */
  44   short firstlabel;  /* index of first label in this block */
  45   short firstgoto;  /* index of first pending goto in this block */
  46   lu_byte nactvar;  /* # active locals outside the block */
  47   lu_byte upval;  /* true if some variable in the block is an upvalue */
  48   lu_byte isloop;  /* true if `block' is a loop */
  49 } BlockCnt;
  50
  51
  52
  53 /*
  54 ** prototypes for recursive non-terminal functions
  55 */
  56 static void statement (LexState *ls);
  57 static void expr (LexState *ls, expdesc *v);
  58
  59
  60 static void anchor_token (LexState *ls) {
  61   /* last token from outer function must be EOS */
  62   lua_assert(ls->fs != NULL || ls->t.token == TK_EOS);
  63   if (ls->t.token == TK_NAME || ls->t.token == TK_STRING) {
  64     TString *ts = ls->t.seminfo.ts;
  65     luaX_newstring(ls, getstr(ts), ts->tsv.len);
  66   }
  67 }
  68
  69
  70 /* semantic error */
  71 static l_noret semerror (LexState *ls, const char *msg) {
  72   ls->t.token = 0;  /* remove 'near to' from final message */
  73   luaX_syntaxerror(ls, msg);
  74 }
  75
  76
  77 static l_noret error_expected (LexState *ls, int token) {
  78   luaX_syntaxerror(ls,
  79       luaO_pushfstring(ls->L, "%s expected", luaX_token2str(ls, token)));
  80 }
  81
  82
  83 static l_noret errorlimit (FuncState *fs, int limit, const char *what) {
  84   lua_State *L = fs->ls->L;
  85   const char *msg;
  86   int line = fs->f->linedefined;
  87   const char *where = (line == 0)
  88                       ? "main function"
  89                       : luaO_pushfstring(L, "function at line %d", line);
  90   msg = luaO_pushfstring(L, "too many %s (limit is %d) in %s",
  91                              what, limit, where);
  92   luaX_syntaxerror(fs->ls, msg);
  93 }
  94
  95
  96 static void checklimit (FuncState *fs, int v, int l, const char *what) {
  97   if (v > l) errorlimit(fs, l, what);
  98 }
  99
 100
 101 static int testnext (LexState *ls, int c) {
 102   if (ls->t.token == c) {
 103     luaX_next(ls);
 104     return 1;
 105   }
 106   else return 0;
 107 }
 108
 109
 110 static void check (LexState *ls, int c) {
 111   if (ls->t.token != c)
 112     error_expected(ls, c);
 113 }
 114
 115
 116 static void checknext (LexState *ls, int c) {
 117   check(ls, c);
 118   luaX_next(ls);
 119 }
 120
 121
 122 #define check_condition(ls,c,msg)       { if (!(c)) luaX_syntaxerror(ls, msg); }
 123
 124
 125
 126 static void check_match (LexState *ls, int what, int who, int where) {
 127   if (!testnext(ls, what)) {
 128     if (where == ls->linenumber)
 129       error_expected(ls, what);
 130     else {
 131       luaX_syntaxerror(ls, luaO_pushfstring(ls->L,
 132              "%s expected (to close %s at line %d)",
 133               luaX_token2str(ls, what), luaX_token2str(ls, who), where));
 134     }
 135   }
 136 }
 137
 138
 139 static TString *str_checkname (LexState *ls) {
 140   TString *ts;
 141   check(ls, TK_NAME);
 142   ts = ls->t.seminfo.ts;
 143   luaX_next(ls);
 144   return ts;
 145 }
 146
 147
 148 static void init_exp (expdesc *e, expkind k, int i) {
 149   e->f = e->t = NO_JUMP;
 150   e->k = k;
 151   e->u.info = i;
 152 }
 153
 154
 155 static void codestring (LexState *ls, expdesc *e, TString *s) {
 156   init_exp(e, VK, luaK_stringK(ls->fs, s));
 157 }
 158
 159
 160 static void checkname (LexState *ls, expdesc *e) {
 161   codestring(ls, e, str_checkname(ls));
 162 }
 163
 164
 165 static int registerlocalvar (LexState *ls, TString *varname) {
 166   FuncState *fs = ls->fs;
 167   Proto *f = fs->f;
 168   int oldsize = f->sizelocvars;
 169   luaM_growvector(ls->L, f->locvars, fs->nlocvars, f->sizelocvars,
 170                   LocVar, SHRT_MAX, "local variables");
 171   while (oldsize < f->sizelocvars) f->locvars[oldsize++].varname = NULL;
 172   f->locvars[fs->nlocvars].varname = varname;
 173   luaC_objbarrier(ls->L, f, varname);
 174   return fs->nlocvars++;
 175 }
 176
 177
 178 static void new_localvar (LexState *ls, TString *name) {
 179   FuncState *fs = ls->fs;
 180   Dyndata *dyd = ls->dyd;
 181   int reg = registerlocalvar(ls, name);
 182   checklimit(fs, dyd->actvar.n + 1 - fs->firstlocal,
 183                   MAXVARS, "local variables");
 184   luaM_growvector(ls->L, dyd->actvar.arr, dyd->actvar.n + 1,
 185                   dyd->actvar.size, Vardesc, MAX_INT, "local variables");
 186   dyd->actvar.arr[dyd->actvar.n++].idx = cast(short, reg);
 187 }
 188
 189
 190 static void new_localvarliteral_ (LexState *ls, const char *name, size_t sz) {
 191   new_localvar(ls, luaX_newstring(ls, name, sz));
 192 }
 193
 194 #define new_localvarliteral(ls,v) \
 195         new_localvarliteral_(ls, "" v, (sizeof(v)/sizeof(char))-1)
 196
 197
 198 static LocVar *getlocvar (FuncState *fs, int i) {
 199   int idx = fs->ls->dyd->actvar.arr[fs->firstlocal + i].idx;
 200   lua_assert(idx < fs->nlocvars);
 201   return &fs->f->locvars[idx];
 202 }
 203
 204
 205 static void adjustlocalvars (LexState *ls, int nvars) {
 206   FuncState *fs = ls->fs;
 207   fs->nactvar = cast_byte(fs->nactvar + nvars);
 208   for (; nvars; nvars--) {
 209     getlocvar(fs, fs->nactvar - nvars)->startpc = fs->pc;
 210   }
 211 }
 212
 213
 214 static void removevars (FuncState *fs, int tolevel) {
 215   fs->ls->dyd->actvar.n -= (fs->nactvar - tolevel);
 216   while (fs->nactvar > tolevel)
 217     getlocvar(fs, --fs->nactvar)->endpc = fs->pc;
 218 }
 219
 220
 221 static int searchupvalue (FuncState *fs, TString *name) {
 222   int i;
 223   Upvaldesc *up = fs->f->upvalues;
 224   for (i = 0; i < fs->nups; i++) {
 225     if (luaS_eqstr(up[i].name, name)) return i;
 226   }
 227   return -1;  /* not found */
 228 }
 229
 230
 231 static int newupvalue (FuncState *fs, TString *name, expdesc *v) {
 232   Proto *f = fs->f;
 233   int oldsize = f->sizeupvalues;
 234   checklimit(fs, fs->nups + 1, MAXUPVAL, "upvalues");
 235   luaM_growvector(fs->ls->L, f->upvalues, fs->nups, f->sizeupvalues,
 236                   Upvaldesc, MAXUPVAL, "upvalues");
 237   while (oldsize < f->sizeupvalues) f->upvalues[oldsize++].name = NULL;
 238   f->upvalues[fs->nups].instack = (v->k == VLOCAL);
 239   f->upvalues[fs->nups].idx = cast_byte(v->u.info);
 240   f->upvalues[fs->nups].name = name;
 241   luaC_objbarrier(fs->ls->L, f, name);
 242   return fs->nups++;
 243 }
 244
 245
 246 static int searchvar (FuncState *fs, TString *n) {
 247   int i;
 248   for (i = cast_int(fs->nactvar) - 1; i >= 0; i--) {
 249     if (luaS_eqstr(n, getlocvar(fs, i)->varname))
 250       return i;
 251   }
 252   return -1;  /* not found */
 253 }
 254
 255
 256 /*
 257   Mark block where variable at given level was defined
 258   (to emit close instructions later).
 259 */
 260 static void markupval (FuncState *fs, int level) {
 261   BlockCnt *bl = fs->bl;
 262   while (bl->nactvar > level) bl = bl->previous;
 263   bl->upval = 1;
 264 }
 265
 266
 267 /*
 268   Find variable with given name 'n'. If it is an upvalue, add this
 269   upvalue into all intermediate functions.
 270 */
 271 static int singlevaraux (FuncState *fs, TString *n, expdesc *var, int base) {
 272   if (fs == NULL)  /* no more levels? */
 273     return VVOID;  /* default is global */
 274   else {
 275     int v = searchvar(fs, n);  /* look up locals at current level */
 276     if (v >= 0) {  /* found? */
 277       init_exp(var, VLOCAL, v);  /* variable is local */
 278       if (!base)
 279         markupval(fs, v);  /* local will be used as an upval */
 280       return VLOCAL;
 281     }
 282     else {  /* not found as local at current level; try upvalues */
 283       int idx = searchupvalue(fs, n);  /* try existing upvalues */
 284       if (idx < 0) {  /* not found? */
 285         if (singlevaraux(fs->prev, n, var, 0) == VVOID) /* try upper levels */
 286           return VVOID;  /* not found; is a global */
 287         /* else was LOCAL or UPVAL */
 288         idx  = newupvalue(fs, n, var);  /* will be a new upvalue */
 289       }
 290       init_exp(var, VUPVAL, idx);
 291       return VUPVAL;
 292     }
 293   }
 294 }
 295
 296
 297 static void singlevar (LexState *ls, expdesc *var) {
 298   TString *varname = str_checkname(ls);
 299   FuncState *fs = ls->fs;
 300   if (singlevaraux(fs, varname, var, 1) == VVOID) {  /* global name? */
 301     expdesc key;
 302     singlevaraux(fs, ls->envn, var, 1);  /* get environment variable */
 303     lua_assert(var->k == VLOCAL || var->k == VUPVAL);
 304     codestring(ls, &key, varname);  /* key is variable name */
 305     luaK_indexed(fs, var, &key);  /* env[varname] */
 306   }
 307 }
 308
 309
 310 static void adjust_assign (LexState *ls, int nvars, int nexps, expdesc *e) {
 311   FuncState *fs = ls->fs;
 312   int extra = nvars - nexps;
 313   if (hasmultret(e->k)) {
 314     extra++;  /* includes call itself */
 315     if (extra < 0) extra = 0;
 316     luaK_setreturns(fs, e, extra);  /* last exp. provides the difference */
 317     if (extra > 1) luaK_reserveregs(fs, extra-1);
 318   }
 319   else {
 320     if (e->k != VVOID) luaK_exp2nextreg(fs, e);  /* close last expression */
 321     if (extra > 0) {
 322       int reg = fs->freereg;
 323       luaK_reserveregs(fs, extra);
 324       luaK_nil(fs, reg, extra);
 325     }
 326   }
 327 }
 328
 329
 330 static void enterlevel (LexState *ls) {
 331   lua_State *L = ls->L;
 332   ++L->nCcalls;
 333   checklimit(ls->fs, L->nCcalls, LUAI_MAXCCALLS, "C levels");
 334 }
 335
 336
 337 #define leavelevel(ls)  ((ls)->L->nCcalls--)
 338
 339
 340 static void closegoto (LexState *ls, int g, Labeldesc *label) {
 341   int i;
 342   FuncState *fs = ls->fs;
 343   Labellist *gl = &ls->dyd->gt;
 344   Labeldesc *gt = &gl->arr[g];
 345   lua_assert(luaS_eqstr(gt->name, label->name));
 346   if (gt->nactvar < label->nactvar) {
 347     TString *vname = getlocvar(fs, gt->nactvar)->varname;
 348     const char *msg = luaO_pushfstring(ls->L,
 349       "<goto %s> at line %d jumps into the scope of local " LUA_QS,
 350       getstr(gt->name), gt->line, getstr(vname));
 351     semerror(ls, msg);
 352   }
 353   luaK_patchlist(fs, gt->pc, label->pc);
 354   /* remove goto from pending list */
 355   for (i = g; i < gl->n - 1; i++)
 356     gl->arr[i] = gl->arr[i + 1];
 357   gl->n--;
 358 }
 359
 360
 361 /*
 362 ** try to close a goto with existing labels; this solves backward jumps
 363 */
 364 static int findlabel (LexState *ls, int g) {
 365   int i;
 366   BlockCnt *bl = ls->fs->bl;
 367   Dyndata *dyd = ls->dyd;
 368   Labeldesc *gt = &dyd->gt.arr[g];
 369   /* check labels in current block for a match */
 370   for (i = bl->firstlabel; i < dyd->label.n; i++) {
 371     Labeldesc *lb = &dyd->label.arr[i];
 372     if (luaS_eqstr(lb->name, gt->name)) {  /* correct label? */
 373       if (gt->nactvar > lb->nactvar &&
 374           (bl->upval || dyd->label.n > bl->firstlabel))
 375         luaK_patchclose(ls->fs, gt->pc, lb->nactvar);
 376       closegoto(ls, g, lb);  /* close it */
 377       return 1;
 378     }
 379   }
 380   return 0;  /* label not found; cannot close goto */
 381 }
 382
 383
 384 static int newlabelentry (LexState *ls, Labellist *l, TString *name,
 385                           int line, int pc) {
 386   int n = l->n;
 387   luaM_growvector(ls->L, l->arr, n, l->size,
 388                   Labeldesc, SHRT_MAX, "labels/gotos");
 389   l->arr[n].name = name;
 390   l->arr[n].line = line;
 391   l->arr[n].nactvar = ls->fs->nactvar;
 392   l->arr[n].pc = pc;
 393   l->n++;
 394   return n;
 395 }
 396
 397
 398 /*
 399 ** check whether new label 'lb' matches any pending gotos in current
 400 ** block; solves forward jumps
 401 */
 402 static void findgotos (LexState *ls, Labeldesc *lb) {
 403   Labellist *gl = &ls->dyd->gt;
 404   int i = ls->fs->bl->firstgoto;
 405   while (i < gl->n) {
 406     if (luaS_eqstr(gl->arr[i].name, lb->name))
 407       closegoto(ls, i, lb);
 408     else
 409       i++;
 410   }
 411 }
 412
 413
 414 /*
 415 ** "export" pending gotos to outer level, to check them against
 416 ** outer labels; if the block being exited has upvalues, and
 417 ** the goto exits the scope of any variable (which can be the
 418 ** upvalue), close those variables being exited.
 419 */
 420 static void movegotosout (FuncState *fs, BlockCnt *bl) {
 421   int i = bl->firstgoto;
 422   Labellist *gl = &fs->ls->dyd->gt;
 423   /* correct pending gotos to current block and try to close it
 424      with visible labels */
 425   while (i < gl->n) {
 426     Labeldesc *gt = &gl->arr[i];
 427     if (gt->nactvar > bl->nactvar) {
 428       if (bl->upval)
 429         luaK_patchclose(fs, gt->pc, bl->nactvar);
 430       gt->nactvar = bl->nactvar;
 431     }
 432     if (!findlabel(fs->ls, i))
 433       i++;  /* move to next one */
 434   }
 435 }
 436
 437
 438 static void enterblock (FuncState *fs, BlockCnt *bl, lu_byte isloop) {
 439   bl->isloop = isloop;
 440   bl->nactvar = fs->nactvar;
 441   bl->firstlabel = fs->ls->dyd->label.n;
 442   bl->firstgoto = fs->ls->dyd->gt.n;
 443   bl->upval = 0;
 444   bl->previous = fs->bl;
 445   fs->bl = bl;
 446   lua_assert(fs->freereg == fs->nactvar);
 447 }
 448
 449
 450 /*
 451 ** create a label named "break" to resolve break statements
 452 */
 453 static void breaklabel (LexState *ls) {
 454   TString *n = luaS_new(ls->L, "break");
 455   int l = newlabelentry(ls, &ls->dyd->label, n, 0, ls->fs->pc);
 456   findgotos(ls, &ls->dyd->label.arr[l]);
 457 }
 458
 459 /*
 460 ** generates an error for an undefined 'goto'; choose appropriate
 461 ** message when label name is a reserved word (which can only be 'break')
 462 */
 463 static l_noret undefgoto (LexState *ls, Labeldesc *gt) {
 464   const char *msg = isreserved(gt->name)
 465                     ? "<%s> at line %d not inside a loop"
 466                     : "no visible label " LUA_QS " for <goto> at line %d";
 467   msg = luaO_pushfstring(ls->L, msg, getstr(gt->name), gt->line);
 468   semerror(ls, msg);
 469 }
 470
 471
 472 static void leaveblock (FuncState *fs) {
 473   BlockCnt *bl = fs->bl;
 474   LexState *ls = fs->ls;
 475   if (bl->previous && bl->upval) {
 476     /* create a 'jump to here' to close upvalues */
 477     int j = luaK_jump(fs);
 478     luaK_patchclose(fs, j, bl->nactvar);
 479     luaK_patchtohere(fs, j);
 480   }
 481   if (bl->isloop)
 482     breaklabel(ls);  /* close pending breaks */
 483   fs->bl = bl->previous;
 484   removevars(fs, bl->nactvar);
 485   lua_assert(bl->nactvar == fs->nactvar);
 486   fs->freereg = fs->nactvar;  /* free registers */
 487   ls->dyd->label.n = bl->firstlabel;  /* remove local labels */
 488   if (bl->previous)  /* inner block? */
 489     movegotosout(fs, bl);  /* update pending gotos to outer block */
 490   else if (bl->firstgoto < ls->dyd->gt.n)  /* pending gotos in outer block? */
 491     undefgoto(ls, &ls->dyd->gt.arr[bl->firstgoto]);  /* error */
 492 }
 493
 494
 495 /*
 496 ** adds a new prototype into list of prototypes
 497 */
 498 static Proto *addprototype (LexState *ls) {
 499   Proto *clp;
 500   lua_State *L = ls->L;
 501   FuncState *fs = ls->fs;
 502   Proto *f = fs->f;  /* prototype of current function */
 503   if (fs->np >= f->sizep) {
 504     int oldsize = f->sizep;
 505     luaM_growvector(L, f->p, fs->np, f->sizep, Proto *, MAXARG_Bx, "functions");
 506     while (oldsize < f->sizep) f->p[oldsize++] = NULL;
 507   }
 508   f->p[fs->np++] = clp = luaF_newproto(L);
 509   luaC_objbarrier(L, f, clp);
 510   return clp;
 511 }
 512
 513
 514 /*
 515 ** codes instruction to create new closure in parent function.
 516 ** The OP_CLOSURE instruction must use the last available register,
 517 ** so that, if it invokes the GC, the GC knows which registers
 518 ** are in use at that time.
 519 */
 520 static void codeclosure (LexState *ls, expdesc *v) {
 521   FuncState *fs = ls->fs->prev;
 522   init_exp(v, VRELOCABLE, luaK_codeABx(fs, OP_CLOSURE, 0, fs->np - 1));
 523   luaK_exp2nextreg(fs, v);  /* fix it at the last register */
 524 }
 525
 526
 527 static void open_func (LexState *ls, FuncState *fs, BlockCnt *bl) {
 528   lua_State *L = ls->L;
 529   Proto *f;
 530   fs->prev = ls->fs;  /* linked list of funcstates */
 531   fs->ls = ls;
 532   ls->fs = fs;
 533   fs->pc = 0;
 534   fs->lasttarget = 0;
 535   fs->jpc = NO_JUMP;
 536   fs->freereg = 0;
 537   fs->nk = 0;
 538   fs->np = 0;
 539   fs->nups = 0;
 540   fs->nlocvars = 0;
 541   fs->nactvar = 0;
 542   fs->firstlocal = ls->dyd->actvar.n;
 543   fs->bl = NULL;
 544   f = fs->f;
 545   f->source = ls->source;
 546   f->maxstacksize = 2;  /* registers 0/1 are always valid */
 547   fs->h = luaH_new(L);
 548   /* anchor table of constants (to avoid being collected) */
 549   sethvalue2s(L, L->top, fs->h);
 550   incr_top(L);
 551   enterblock(fs, bl, 0);
 552 }
 553
 554
 555 static void close_func (LexState *ls) {
 556   lua_State *L = ls->L;
 557   FuncState *fs = ls->fs;
 558   Proto *f = fs->f;
 559   luaK_ret(fs, 0, 0);  /* final return */
 560   leaveblock(fs);
 561   luaM_reallocvector(L, f->code, f->sizecode, fs->pc, Instruction);
 562   f->sizecode = fs->pc;
 563   luaM_reallocvector(L, f->lineinfo, f->sizelineinfo, fs->pc, int);
 564   f->sizelineinfo = fs->pc;
 565   luaM_reallocvector(L, f->k, f->sizek, fs->nk, TValue);
 566   f->sizek = fs->nk;
 567   luaM_reallocvector(L, f->p, f->sizep, fs->np, Proto *);
 568   f->sizep = fs->np;
 569   luaM_reallocvector(L, f->locvars, f->sizelocvars, fs->nlocvars, LocVar);
 570   f->sizelocvars = fs->nlocvars;
 571   luaM_reallocvector(L, f->upvalues, f->sizeupvalues, fs->nups, Upvaldesc);
 572   f->sizeupvalues = fs->nups;
 573   lua_assert(fs->bl == NULL);
 574   ls->fs = fs->prev;
 575   /* last token read was anchored in defunct function; must re-anchor it */
 576   anchor_token(ls);
 577   L->top--;  /* pop table of constants */
 578   luaC_checkGC(L);
 579 }
 580
 581
 582
 583 /*============================================================*/
 584 /* GRAMMAR RULES */
 585 /*============================================================*/
 586
 587
 588 /*
 589 ** check whether current token is in the follow set of a block.
 590 ** 'until' closes syntactical blocks, but do not close scope,
 591 ** so it handled in separate.
 592 */
 593 static int block_follow (LexState *ls, int withuntil) {
 594   switch (ls->t.token) {
 595     case TK_ELSE: case TK_ELSEIF:
 596     case TK_END: case TK_EOS:
 597       return 1;
 598     case TK_UNTIL: return withuntil;
 599     default: return 0;
 600   }
 601 }
 602
 603
 604 static void statlist (LexState *ls) {
 605   /* statlist -> { stat [`;'] } */
 606   while (!block_follow(ls, 1)) {
 607     if (ls->t.token == TK_RETURN) {
 608       statement(ls);
 609       return;  /* 'return' must be last statement */
 610     }
 611     statement(ls);
 612   }
 613 }
 614
 615
 616 static void fieldsel (LexState *ls, expdesc *v) {
 617   /* fieldsel -> ['.' | ':'] NAME */
 618   FuncState *fs = ls->fs;
 619   expdesc key;
 620   luaK_exp2anyregup(fs, v);
 621   luaX_next(ls);  /* skip the dot or colon */
 622   checkname(ls, &key);
 623   luaK_indexed(fs, v, &key);
 624 }
 625
 626
 627 static void yindex (LexState *ls, expdesc *v) {
 628   /* index -> '[' expr ']' */
 629   luaX_next(ls);  /* skip the '[' */
 630   expr(ls, v);
 631   luaK_exp2val(ls->fs, v);
 632   checknext(ls, ']');
 633 }
 634
 635
 636 /*
 637 ** {======================================================================
 638 ** Rules for Constructors
 639 ** =======================================================================
 640 */
 641
 642
 643 struct ConsControl {
 644   expdesc v;  /* last list item read */
 645   expdesc *t;  /* table descriptor */
 646   int nh;  /* total number of `record' elements */
 647   int na;  /* total number of array elements */
 648   int tostore;  /* number of array elements pending to be stored */
 649 };
 650
 651
 652 static void recfield (LexState *ls, struct ConsControl *cc) {
 653   /* recfield -> (NAME | `['exp1`]') = exp1 */
 654   FuncState *fs = ls->fs;
 655   int reg = ls->fs->freereg;
 656   expdesc key, val;
 657   int rkkey;
 658   if (ls->t.token == TK_NAME) {
 659     checklimit(fs, cc->nh, MAX_INT, "items in a constructor");
 660     checkname(ls, &key);
 661   }
 662   else  /* ls->t.token == '[' */
 663     yindex(ls, &key);
 664   cc->nh++;
 665   checknext(ls, '=');
 666   rkkey = luaK_exp2RK(fs, &key);
 667   expr(ls, &val);
 668   luaK_codeABC(fs, OP_SETTABLE, cc->t->u.info, rkkey, luaK_exp2RK(fs, &val));
 669   fs->freereg = reg;  /* free registers */
 670 }
 671
 672
 673 static void closelistfield (FuncState *fs, struct ConsControl *cc) {
 674   if (cc->v.k == VVOID) return;  /* there is no list item */
 675   luaK_exp2nextreg(fs, &cc->v);
 676   cc->v.k = VVOID;
 677   if (cc->tostore == LFIELDS_PER_FLUSH) {
 678     luaK_setlist(fs, cc->t->u.info, cc->na, cc->tostore);  /* flush */
 679     cc->tostore = 0;  /* no more items pending */
 680   }
 681 }
 682
 683
 684 static void lastlistfield (FuncState *fs, struct ConsControl *cc) {
 685   if (cc->tostore == 0) return;
 686   if (hasmultret(cc->v.k)) {
 687     luaK_setmultret(fs, &cc->v);
 688     luaK_setlist(fs, cc->t->u.info, cc->na, LUA_MULTRET);
 689     cc->na--;  /* do not count last expression (unknown number of elements) */
 690   }
 691   else {
 692     if (cc->v.k != VVOID)
 693       luaK_exp2nextreg(fs, &cc->v);
 694     luaK_setlist(fs, cc->t->u.info, cc->na, cc->tostore);
 695   }
 696 }
 697
 698
 699 static void listfield (LexState *ls, struct ConsControl *cc) {
 700   /* listfield -> exp */
 701   expr(ls, &cc->v);
 702   checklimit(ls->fs, cc->na, MAX_INT, "items in a constructor");
 703   cc->na++;
 704   cc->tostore++;
 705 }
 706
 707
 708 static void field (LexState *ls, struct ConsControl *cc) {
 709   /* field -> listfield | recfield */
 710   switch(ls->t.token) {
 711     case TK_NAME: {  /* may be 'listfield' or 'recfield' */
 712       if (luaX_lookahead(ls) != '=')  /* expression? */
 713         listfield(ls, cc);
 714       else
 715         recfield(ls, cc);
 716       break;
 717     }
 718     case '[': {
 719       recfield(ls, cc);
 720       break;
 721     }
 722     default: {
 723       listfield(ls, cc);
 724       break;
 725     }
 726   }
 727 }
 728
 729
 730 static void constructor (LexState *ls, expdesc *t) {
 731   /* constructor -> '{' [ field { sep field } [sep] ] '}'
 732      sep -> ',' | ';' */
 733   FuncState *fs = ls->fs;
 734   int line = ls->linenumber;
 735   int pc = luaK_codeABC(fs, OP_NEWTABLE, 0, 0, 0);
 736   struct ConsControl cc;
 737   cc.na = cc.nh = cc.tostore = 0;
 738   cc.t = t;
 739   init_exp(t, VRELOCABLE, pc);
 740   init_exp(&cc.v, VVOID, 0);  /* no value (yet) */
 741   luaK_exp2nextreg(ls->fs, t);  /* fix it at stack top */
 742   checknext(ls, '{');
 743   do {
 744     lua_assert(cc.v.k == VVOID || cc.tostore > 0);
 745     if (ls->t.token == '}') break;
 746     closelistfield(fs, &cc);
 747     field(ls, &cc);
 748   } while (testnext(ls, ',') || testnext(ls, ';'));
 749   check_match(ls, '}', '{', line);
 750   lastlistfield(fs, &cc);
 751   SETARG_B(fs->f->code[pc], luaO_int2fb(cc.na)); /* set initial array size */
 752   SETARG_C(fs->f->code[pc], luaO_int2fb(cc.nh));  /* set initial table size */
 753 }
 754
 755 /* }====================================================================== */
 756
 757
 758
 759 static void parlist (LexState *ls) {
 760   /* parlist -> [ param { `,' param } ] */
 761   FuncState *fs = ls->fs;
 762   Proto *f = fs->f;
 763   int nparams = 0;
 764   f->is_vararg = 0;
 765   if (ls->t.token != ')') {  /* is `parlist' not empty? */
 766     do {
 767       switch (ls->t.token) {
 768         case TK_NAME: {  /* param -> NAME */
 769           new_localvar(ls, str_checkname(ls));
 770           nparams++;
 771           break;
 772         }
 773         case TK_DOTS: {  /* param -> `...' */
 774           luaX_next(ls);
 775           f->is_vararg = 1;
 776           break;
 777         }
 778         default: luaX_syntaxerror(ls, "<name> or " LUA_QL("...") " expected");
 779       }
 780     } while (!f->is_vararg && testnext(ls, ','));
 781   }
 782   adjustlocalvars(ls, nparams);
 783   f->numparams = cast_byte(fs->nactvar);
 784   luaK_reserveregs(fs, fs->nactvar);  /* reserve register for parameters */
 785 }
 786
 787
 788 static void body (LexState *ls, expdesc *e, int ismethod, int line) {
 789   /* body ->  `(' parlist `)' block END */
 790   FuncState new_fs;
 791   BlockCnt bl;
 792   new_fs.f = addprototype(ls);
 793   new_fs.f->linedefined = line;
 794   open_func(ls, &new_fs, &bl);
 795   checknext(ls, '(');
 796   if (ismethod) {
 797     new_localvarliteral(ls, "self");  /* create 'self' parameter */
 798     adjustlocalvars(ls, 1);
 799   }
 800   parlist(ls);
 801   checknext(ls, ')');
 802   statlist(ls);
 803   new_fs.f->lastlinedefined = ls->linenumber;
 804   check_match(ls, TK_END, TK_FUNCTION, line);
 805   codeclosure(ls, e);
 806   close_func(ls);
 807 }
 808
 809
 810 static int explist (LexState *ls, expdesc *v) {
 811   /* explist -> expr { `,' expr } */
 812   int n = 1;  /* at least one expression */
 813   expr(ls, v);
 814   while (testnext(ls, ',')) {
 815     luaK_exp2nextreg(ls->fs, v);
 816     expr(ls, v);
 817     n++;
 818   }
 819   return n;
 820 }
 821
 822
 823 static void funcargs (LexState *ls, expdesc *f, int line) {
 824   FuncState *fs = ls->fs;
 825   expdesc args;
 826   int base, nparams;
 827   switch (ls->t.token) {
 828     case '(': {  /* funcargs -> `(' [ explist ] `)' */
 829       luaX_next(ls);
 830       if (ls->t.token == ')')  /* arg list is empty? */
 831         args.k = VVOID;
 832       else {
 833         explist(ls, &args);
 834         luaK_setmultret(fs, &args);
 835       }
 836       check_match(ls, ')', '(', line);
 837       break;
 838     }
 839     case '{': {  /* funcargs -> constructor */
 840       constructor(ls, &args);
 841       break;
 842     }
 843     case TK_STRING: {  /* funcargs -> STRING */
 844       codestring(ls, &args, ls->t.seminfo.ts);
 845       luaX_next(ls);  /* must use `seminfo' before `next' */
 846       break;
 847     }
 848     default: {
 849       luaX_syntaxerror(ls, "function arguments expected");
 850     }
 851   }
 852   lua_assert(f->k == VNONRELOC);
 853   base = f->u.info;  /* base register for call */
 854   if (hasmultret(args.k))
 855     nparams = LUA_MULTRET;  /* open call */
 856   else {
 857     if (args.k != VVOID)
 858       luaK_exp2nextreg(fs, &args);  /* close last argument */
 859     nparams = fs->freereg - (base+1);
 860   }
 861   init_exp(f, VCALL, luaK_codeABC(fs, OP_CALL, base, nparams+1, 2));
 862   luaK_fixline(fs, line);
 863   fs->freereg = base+1;  /* call remove function and arguments and leaves
 864                             (unless changed) one result */
 865 }
 866
 867
 868
 869
 870 /*
 871 ** {======================================================================
 872 ** Expression parsing
 873 ** =======================================================================
 874 */
 875
 876
 877 static void primaryexp (LexState *ls, expdesc *v) {
 878   /* primaryexp -> NAME | '(' expr ')' */
 879   switch (ls->t.token) {
 880     case '(': {
 881       int line = ls->linenumber;
 882       luaX_next(ls);
 883       expr(ls, v);
 884       check_match(ls, ')', '(', line);
 885       luaK_dischargevars(ls->fs, v);
 886       return;
 887     }
 888     case TK_NAME: {
 889       singlevar(ls, v);
 890       return;
 891     }
 892     default: {
 893       luaX_syntaxerror(ls, "unexpected symbol");
 894     }
 895   }
 896 }
 897
 898
 899 static void suffixedexp (LexState *ls, expdesc *v) {
 900   /* suffixedexp ->
 901        primaryexp { '.' NAME | '[' exp ']' | ':' NAME funcargs | funcargs } */
 902   FuncState *fs = ls->fs;
 903   int line = ls->linenumber;
 904   primaryexp(ls, v);
 905   for (;;) {
 906     switch (ls->t.token) {
 907       case '.': {  /* fieldsel */
 908         fieldsel(ls, v);
 909         break;
 910       }
 911       case '[': {  /* `[' exp1 `]' */
 912         expdesc key;
 913         luaK_exp2anyregup(fs, v);
 914         yindex(ls, &key);
 915         luaK_indexed(fs, v, &key);
 916         break;
 917       }
 918       case ':': {  /* `:' NAME funcargs */
 919         expdesc key;
 920         luaX_next(ls);
 921         checkname(ls, &key);
 922         luaK_self(fs, v, &key);
 923         funcargs(ls, v, line);
 924         break;
 925       }
 926       case '(': case TK_STRING: case '{': {  /* funcargs */
 927         luaK_exp2nextreg(fs, v);
 928         funcargs(ls, v, line);
 929         break;
 930       }
 931       default: return;
 932     }
 933   }
 934 }
 935
 936
 937 static void simpleexp (LexState *ls, expdesc *v) {
 938   /* simpleexp -> NUMBER | STRING | NIL | TRUE | FALSE | ... |
 939                   constructor | FUNCTION body | suffixedexp */
 940   switch (ls->t.token) {
 941     case TK_NUMBER: {
 942       init_exp(v, VKNUM, 0);
 943       v->u.nval = ls->t.seminfo.r;
 944       break;
 945     }
 946     case TK_STRING: {
 947       codestring(ls, v, ls->t.seminfo.ts);
 948       break;
 949     }
 950     case TK_NIL: {
 951       init_exp(v, VNIL, 0);
 952       break;
 953     }
 954     case TK_TRUE: {
 955       init_exp(v, VTRUE, 0);
 956       break;
 957     }
 958     case TK_FALSE: {
 959       init_exp(v, VFALSE, 0);
 960       break;
 961     }
 962     case TK_DOTS: {  /* vararg */
 963       FuncState *fs = ls->fs;
 964       check_condition(ls, fs->f->is_vararg,
 965                       "cannot use " LUA_QL("...") " outside a vararg function");
 966       init_exp(v, VVARARG, luaK_codeABC(fs, OP_VARARG, 0, 1, 0));
 967       break;
 968     }
 969     case '{': {  /* constructor */
 970       constructor(ls, v);
 971       return;
 972     }
 973     case TK_FUNCTION: {
 974       luaX_next(ls);
 975       body(ls, v, 0, ls->linenumber);
 976       return;
 977     }
 978     default: {
 979       suffixedexp(ls, v);
 980       return;
 981     }
 982   }
 983   luaX_next(ls);
 984 }
 985
 986
 987 static UnOpr getunopr (int op) {
 988   switch (op) {
 989     case TK_NOT: return OPR_NOT;
 990     case '-': return OPR_MINUS;
 991     case '#': return OPR_LEN;
 992     default: return OPR_NOUNOPR;
 993   }
 994 }
 995
 996
 997 static BinOpr getbinopr (int op) {
 998   switch (op) {
 999     case '+': return OPR_ADD;
1000     case '-': return OPR_SUB;
1001     case '*': return OPR_MUL;
1002     case '/': return OPR_DIV;
1003     case '%': return OPR_MOD;
1004     case '^': return OPR_POW;
1005     case TK_CONCAT: return OPR_CONCAT;
1006     case TK_NE: return OPR_NE;
1007     case TK_EQ: return OPR_EQ;
1008     case '<': return OPR_LT;
1009     case TK_LE: return OPR_LE;
1010     case '>': return OPR_GT;
1011     case TK_GE: return OPR_GE;
1012     case TK_AND: return OPR_AND;
1013     case TK_OR: return OPR_OR;
1014     default: return OPR_NOBINOPR;
1015   }
1016 }
1017
1018
1019 static const struct {
1020   lu_byte left;  /* left priority for each binary operator */
1021   lu_byte right; /* right priority */
1022 } priority[] = {  /* ORDER OPR */
1023    {6, 6}, {6, 6}, {7, 7}, {7, 7}, {7, 7},  /* `+' `-' `*' `/' `%' */
1024    {10, 9}, {5, 4},                 /* ^, .. (right associative) */
1025    {3, 3}, {3, 3}, {3, 3},          /* ==, <, <= */
1026    {3, 3}, {3, 3}, {3, 3},          /* ~=, >, >= */
1027    {2, 2}, {1, 1}                   /* and, or */
1028 };
1029
1030 #define UNARY_PRIORITY  8  /* priority for unary operators */
1031
1032
1033 /*
1034 ** subexpr -> (simpleexp | unop subexpr) { binop subexpr }
1035 ** where `binop' is any binary operator with a priority higher than `limit'
1036 */
1037 static BinOpr subexpr (LexState *ls, expdesc *v, int limit) {
1038   BinOpr op;
1039   UnOpr uop;
1040   enterlevel(ls);
1041   uop = getunopr(ls->t.token);
1042   if (uop != OPR_NOUNOPR) {
1043     int line = ls->linenumber;
1044     luaX_next(ls);
1045     subexpr(ls, v, UNARY_PRIORITY);
1046     luaK_prefix(ls->fs, uop, v, line);
1047   }
1048   else simpleexp(ls, v);
1049   /* expand while operators have priorities higher than `limit' */
1050   op = getbinopr(ls->t.token);
1051   while (op != OPR_NOBINOPR && priority[op].left > limit) {
1052     expdesc v2;
1053     BinOpr nextop;
1054     int line = ls->linenumber;
1055     luaX_next(ls);
1056     luaK_infix(ls->fs, op, v);
1057     /* read sub-expression with higher priority */
1058     nextop = subexpr(ls, &v2, priority[op].right);
1059     luaK_posfix(ls->fs, op, v, &v2, line);
1060     op = nextop;
1061   }
1062   leavelevel(ls);
1063   return op;  /* return first untreated operator */
1064 }
1065
1066
1067 static void expr (LexState *ls, expdesc *v) {
1068   subexpr(ls, v, 0);
1069 }
1070
1071 /* }==================================================================== */
1072
1073
1074
1075 /*
1076 ** {======================================================================
1077 ** Rules for Statements
1078 ** =======================================================================
1079 */
1080
1081
1082 static void block (LexState *ls) {
1083   /* block -> statlist */
1084   FuncState *fs = ls->fs;
1085   BlockCnt bl;
1086   enterblock(fs, &bl, 0);
1087   statlist(ls);
1088   leaveblock(fs);
1089 }
1090
1091
1092 /*
1093 ** structure to chain all variables in the left-hand side of an
1094 ** assignment
1095 */
1096 struct LHS_assign {
1097   struct LHS_assign *prev;
1098   expdesc v;  /* variable (global, local, upvalue, or indexed) */
1099 };
1100
1101
1102 /*
1103 ** check whether, in an assignment to an upvalue/local variable, the
1104 ** upvalue/local variable is begin used in a previous assignment to a
1105 ** table. If so, save original upvalue/local value in a safe place and
1106 ** use this safe copy in the previous assignment.
1107 */
1108 static void check_conflict (LexState *ls, struct LHS_assign *lh, expdesc *v) {
1109   FuncState *fs = ls->fs;
1110   int extra = fs->freereg;  /* eventual position to save local variable */
1111   int conflict = 0;
1112   for (; lh; lh = lh->prev) {  /* check all previous assignments */
1113     if (lh->v.k == VINDEXED) {  /* assigning to a table? */
1114       /* table is the upvalue/local being assigned now? */
1115       if (lh->v.u.ind.vt == v->k && lh->v.u.ind.t == v->u.info) {
1116         conflict = 1;
1117         lh->v.u.ind.vt = VLOCAL;
1118         lh->v.u.ind.t = extra;  /* previous assignment will use safe copy */
1119       }
1120       /* index is the local being assigned? (index cannot be upvalue) */
1121       if (v->k == VLOCAL && lh->v.u.ind.idx == v->u.info) {
1122         conflict = 1;
1123         lh->v.u.ind.idx = extra;  /* previous assignment will use safe copy */
1124       }
1125     }
1126   }
1127   if (conflict) {
1128     /* copy upvalue/local value to a temporary (in position 'extra') */
1129     OpCode op = (v->k == VLOCAL) ? OP_MOVE : OP_GETUPVAL;
1130     luaK_codeABC(fs, op, extra, v->u.info, 0);
1131     luaK_reserveregs(fs, 1);
1132   }
1133 }
1134
1135
1136 static void assignment (LexState *ls, struct LHS_assign *lh, int nvars) {
1137   expdesc e;
1138   check_condition(ls, vkisvar(lh->v.k), "syntax error");
1139   if (testnext(ls, ',')) {  /* assignment -> ',' suffixedexp assignment */
1140     struct LHS_assign nv;
1141     nv.prev = lh;
1142     suffixedexp(ls, &nv.v);
1143     if (nv.v.k != VINDEXED)
1144       check_conflict(ls, lh, &nv.v);
1145     checklimit(ls->fs, nvars + ls->L->nCcalls, LUAI_MAXCCALLS,
1146                     "C levels");
1147     assignment(ls, &nv, nvars+1);
1148   }
1149   else {  /* assignment -> `=' explist */
1150     int nexps;
1151     checknext(ls, '=');
1152     nexps = explist(ls, &e);
1153     if (nexps != nvars) {
1154       adjust_assign(ls, nvars, nexps, &e);
1155       if (nexps > nvars)
1156         ls->fs->freereg -= nexps - nvars;  /* remove extra values */
1157     }
1158     else {
1159       luaK_setoneret(ls->fs, &e);  /* close last expression */
1160       luaK_storevar(ls->fs, &lh->v, &e);
1161       return;  /* avoid default */
1162     }
1163   }
1164   init_exp(&e, VNONRELOC, ls->fs->freereg-1);  /* default assignment */
1165   luaK_storevar(ls->fs, &lh->v, &e);
1166 }
1167
1168
1169 static int cond (LexState *ls) {
1170   /* cond -> exp */
1171   expdesc v;
1172   expr(ls, &v);  /* read condition */
1173   if (v.k == VNIL) v.k = VFALSE;  /* `falses' are all equal here */
1174   luaK_goiftrue(ls->fs, &v);
1175   return v.f;
1176 }
1177
1178
1179 static void gotostat (LexState *ls, int pc) {
1180   int line = ls->linenumber;
1181   TString *label;
1182   int g;
1183   if (testnext(ls, TK_GOTO))
1184     label = str_checkname(ls);
1185   else {
1186     luaX_next(ls);  /* skip break */
1187     label = luaS_new(ls->L, "break");
1188   }
1189   g = newlabelentry(ls, &ls->dyd->gt, label, line, pc);
1190   findlabel(ls, g);  /* close it if label already defined */
1191 }
1192
1193
1194 /* check for repeated labels on the same block */
1195 static void checkrepeated (FuncState *fs, Labellist *ll, TString *label) {
1196   int i;
1197   for (i = fs->bl->firstlabel; i < ll->n; i++) {
1198     if (luaS_eqstr(label, ll->arr[i].name)) {
1199       const char *msg = luaO_pushfstring(fs->ls->L,
1200                           "label " LUA_QS " already defined on line %d",
1201                           getstr(label), ll->arr[i].line);
1202       semerror(fs->ls, msg);
1203     }
1204   }
1205 }
1206
1207
1208 /* skip no-op statements */
1209 static void skipnoopstat (LexState *ls) {
1210   while (ls->t.token == ';' || ls->t.token == TK_DBCOLON)
1211     statement(ls);
1212 }
1213
1214
1215 static void labelstat (LexState *ls, TString *label, int line) {
1216   /* label -> '::' NAME '::' */
1217   FuncState *fs = ls->fs;
1218   Labellist *ll = &ls->dyd->label;
1219   int l;  /* index of new label being created */
1220   checkrepeated(fs, ll, label);  /* check for repeated labels */
1221   checknext(ls, TK_DBCOLON);  /* skip double colon */
1222   /* create new entry for this label */
1223   l = newlabelentry(ls, ll, label, line, fs->pc);
1224   skipnoopstat(ls);  /* skip other no-op statements */
1225   if (block_follow(ls, 0)) {  /* label is last no-op statement in the block? */
1226     /* assume that locals are already out of scope */
1227     ll->arr[l].nactvar = fs->bl->nactvar;
1228   }
1229   findgotos(ls, &ll->arr[l]);
1230 }
1231
1232
1233 static void whilestat (LexState *ls, int line) {
1234   /* whilestat -> WHILE cond DO block END */
1235   FuncState *fs = ls->fs;
1236   int whileinit;
1237   int condexit;
1238   BlockCnt bl;
1239   luaX_next(ls);  /* skip WHILE */
1240   whileinit = luaK_getlabel(fs);
1241   condexit = cond(ls);
1242   enterblock(fs, &bl, 1);
1243   checknext(ls, TK_DO);
1244   block(ls);
1245   luaK_jumpto(fs, whileinit);
1246   check_match(ls, TK_END, TK_WHILE, line);
1247   leaveblock(fs);
1248   luaK_patchtohere(fs, condexit);  /* false conditions finish the loop */
1249 }
1250
1251
1252 static void repeatstat (LexState *ls, int line) {
1253   /* repeatstat -> REPEAT block UNTIL cond */
1254   int condexit;
1255   FuncState *fs = ls->fs;
1256   int repeat_init = luaK_getlabel(fs);
1257   BlockCnt bl1, bl2;
1258   enterblock(fs, &bl1, 1);  /* loop block */
1259   enterblock(fs, &bl2, 0);  /* scope block */
1260   luaX_next(ls);  /* skip REPEAT */
1261   statlist(ls);
1262   check_match(ls, TK_UNTIL, TK_REPEAT, line);
1263   condexit = cond(ls);  /* read condition (inside scope block) */
1264   if (bl2.upval)  /* upvalues? */
1265     luaK_patchclose(fs, condexit, bl2.nactvar);
1266   leaveblock(fs);  /* finish scope */
1267   luaK_patchlist(fs, condexit, repeat_init);  /* close the loop */
1268   leaveblock(fs);  /* finish loop */
1269 }
1270
1271
1272 static int exp1 (LexState *ls) {
1273   expdesc e;
1274   int reg;
1275   expr(ls, &e);
1276   luaK_exp2nextreg(ls->fs, &e);
1277   lua_assert(e.k == VNONRELOC);
1278   reg = e.u.info;
1279   return reg;
1280 }
1281
1282
1283 static void forbody (LexState *ls, int base, int line, int nvars, int isnum) {
1284   /* forbody -> DO block */
1285   BlockCnt bl;
1286   FuncState *fs = ls->fs;
1287   int prep, endfor;
1288   adjustlocalvars(ls, 3);  /* control variables */
1289   checknext(ls, TK_DO);
1290   prep = isnum ? luaK_codeAsBx(fs, OP_FORPREP, base, NO_JUMP) : luaK_jump(fs);
1291   enterblock(fs, &bl, 0);  /* scope for declared variables */
1292   adjustlocalvars(ls, nvars);
1293   luaK_reserveregs(fs, nvars);
1294   block(ls);
1295   leaveblock(fs);  /* end of scope for declared variables */
1296   luaK_patchtohere(fs, prep);
1297   if (isnum)  /* numeric for? */
1298     endfor = luaK_codeAsBx(fs, OP_FORLOOP, base, NO_JUMP);
1299   else {  /* generic for */
1300     luaK_codeABC(fs, OP_TFORCALL, base, 0, nvars);
1301     luaK_fixline(fs, line);
1302     endfor = luaK_codeAsBx(fs, OP_TFORLOOP, base + 2, NO_JUMP);
1303   }
1304   luaK_patchlist(fs, endfor, prep + 1);
1305   luaK_fixline(fs, line);
1306 }
1307
1308
1309 static void fornum (LexState *ls, TString *varname, int line) {
1310   /* fornum -> NAME = exp1,exp1[,exp1] forbody */
1311   FuncState *fs = ls->fs;
1312   int base = fs->freereg;
1313   new_localvarliteral(ls, "(for index)");
1314   new_localvarliteral(ls, "(for limit)");
1315   new_localvarliteral(ls, "(for step)");
1316   new_localvar(ls, varname);
1317   checknext(ls, '=');
1318   exp1(ls);  /* initial value */
1319   checknext(ls, ',');
1320   exp1(ls);  /* limit */
1321   if (testnext(ls, ','))
1322     exp1(ls);  /* optional step */
1323   else {  /* default step = 1 */
1324     luaK_codek(fs, fs->freereg, luaK_numberK(fs, 1));
1325     luaK_reserveregs(fs, 1);
1326   }
1327   forbody(ls, base, line, 1, 1);
1328 }
1329
1330
1331 static void forlist (LexState *ls, TString *indexname) {
1332   /* forlist -> NAME {,NAME} IN explist forbody */
1333   FuncState *fs = ls->fs;
1334   expdesc e;
1335   int nvars = 4;  /* gen, state, control, plus at least one declared var */
1336   int line;
1337   int base = fs->freereg;
1338   /* create control variables */
1339   new_localvarliteral(ls, "(for generator)");
1340   new_localvarliteral(ls, "(for state)");
1341   new_localvarliteral(ls, "(for control)");
1342   /* create declared variables */
1343   new_localvar(ls, indexname);
1344   while (testnext(ls, ',')) {
1345     new_localvar(ls, str_checkname(ls));
1346     nvars++;
1347   }
1348   checknext(ls, TK_IN);
1349   line = ls->linenumber;
1350   adjust_assign(ls, 3, explist(ls, &e), &e);
1351   luaK_checkstack(fs, 3);  /* extra space to call generator */
1352   forbody(ls, base, line, nvars - 3, 0);
1353 }
1354
1355
1356 static void forstat (LexState *ls, int line) {
1357   /* forstat -> FOR (fornum | forlist) END */
1358   FuncState *fs = ls->fs;
1359   TString *varname;
1360   BlockCnt bl;
1361   enterblock(fs, &bl, 1);  /* scope for loop and control variables */
1362   luaX_next(ls);  /* skip `for' */
1363   varname = str_checkname(ls);  /* first variable name */
1364   switch (ls->t.token) {
1365     case '=': fornum(ls, varname, line); break;
1366     case ',': case TK_IN: forlist(ls, varname); break;
1367     default: luaX_syntaxerror(ls, LUA_QL("=") " or " LUA_QL("in") " expected");
1368   }
1369   check_match(ls, TK_END, TK_FOR, line);
1370   leaveblock(fs);  /* loop scope (`break' jumps to this point) */
1371 }
1372
1373
1374 static void test_then_block (LexState *ls, int *escapelist) {
1375   /* test_then_block -> [IF | ELSEIF] cond THEN block */
1376   BlockCnt bl;
1377   FuncState *fs = ls->fs;
1378   expdesc v;
1379   int jf;  /* instruction to skip 'then' code (if condition is false) */
1380   luaX_next(ls);  /* skip IF or ELSEIF */
1381   expr(ls, &v);  /* read condition */
1382   checknext(ls, TK_THEN);
1383   if (ls->t.token == TK_GOTO || ls->t.token == TK_BREAK) {
1384     luaK_goiffalse(ls->fs, &v);  /* will jump to label if condition is true */
1385     enterblock(fs, &bl, 0);  /* must enter block before 'goto' */
1386     gotostat(ls, v.t);  /* handle goto/break */
1387     skipnoopstat(ls);  /* skip other no-op statements */
1388     if (block_follow(ls, 0)) {  /* 'goto' is the entire block? */
1389       leaveblock(fs);
1390       return;  /* and that is it */
1391     }
1392     else  /* must skip over 'then' part if condition is false */
1393       jf = luaK_jump(fs);
1394   }
1395   else {  /* regular case (not goto/break) */
1396     luaK_goiftrue(ls->fs, &v);  /* skip over block if condition is false */
1397     enterblock(fs, &bl, 0);
1398     jf = v.f;
1399   }
1400   statlist(ls);  /* `then' part */
1401   leaveblock(fs);
1402   if (ls->t.token == TK_ELSE ||
1403       ls->t.token == TK_ELSEIF)  /* followed by 'else'/'elseif'? */
1404     luaK_concat(fs, escapelist, luaK_jump(fs));  /* must jump over it */
1405   luaK_patchtohere(fs, jf);
1406 }
1407
1408
1409 static void ifstat (LexState *ls, int line) {
1410   /* ifstat -> IF cond THEN block {ELSEIF cond THEN block} [ELSE block] END */
1411   FuncState *fs = ls->fs;
1412   int escapelist = NO_JUMP;  /* exit list for finished parts */
1413   test_then_block(ls, &escapelist);  /* IF cond THEN block */
1414   while (ls->t.token == TK_ELSEIF)
1415     test_then_block(ls, &escapelist);  /* ELSEIF cond THEN block */
1416   if (testnext(ls, TK_ELSE))
1417     block(ls);  /* `else' part */
1418   check_match(ls, TK_END, TK_IF, line);
1419   luaK_patchtohere(fs, escapelist);  /* patch escape list to 'if' end */
1420 }
1421
1422
1423 static void localfunc (LexState *ls) {
1424   expdesc b;
1425   FuncState *fs = ls->fs;
1426   new_localvar(ls, str_checkname(ls));  /* new local variable */
1427   adjustlocalvars(ls, 1);  /* enter its scope */
1428   body(ls, &b, 0, ls->linenumber);  /* function created in next register */
1429   /* debug information will only see the variable after this point! */
1430   getlocvar(fs, b.u.info)->startpc = fs->pc;
1431 }
1432
1433
1434 static void localstat (LexState *ls) {
1435   /* stat -> LOCAL NAME {`,' NAME} [`=' explist] */
1436   int nvars = 0;
1437   int nexps;
1438   expdesc e;
1439   do {
1440     new_localvar(ls, str_checkname(ls));
1441     nvars++;
1442   } while (testnext(ls, ','));
1443   if (testnext(ls, '='))
1444     nexps = explist(ls, &e);
1445   else {
1446     e.k = VVOID;
1447     nexps = 0;
1448   }
1449   adjust_assign(ls, nvars, nexps, &e);
1450   adjustlocalvars(ls, nvars);
1451 }
1452
1453
1454 static int funcname (LexState *ls, expdesc *v) {
1455   /* funcname -> NAME {fieldsel} [`:' NAME] */
1456   int ismethod = 0;
1457   singlevar(ls, v);
1458   while (ls->t.token == '.')
1459     fieldsel(ls, v);
1460   if (ls->t.token == ':') {
1461     ismethod = 1;
1462     fieldsel(ls, v);
1463   }
1464   return ismethod;
1465 }
1466
1467
1468 static void funcstat (LexState *ls, int line) {
1469   /* funcstat -> FUNCTION funcname body */
1470   int ismethod;
1471   expdesc v, b;
1472   luaX_next(ls);  /* skip FUNCTION */
1473   ismethod = funcname(ls, &v);
1474   body(ls, &b, ismethod, line);
1475   luaK_storevar(ls->fs, &v, &b);
1476   luaK_fixline(ls->fs, line);  /* definition `happens' in the first line */
1477 }
1478
1479
1480 static void exprstat (LexState *ls) {
1481   /* stat -> func | assignment */
1482   FuncState *fs = ls->fs;
1483   struct LHS_assign v;
1484   suffixedexp(ls, &v.v);
1485   if (ls->t.token == '=' || ls->t.token == ',') { /* stat -> assignment ? */
1486     v.prev = NULL;
1487     assignment(ls, &v, 1);
1488   }
1489   else {  /* stat -> func */
1490     check_condition(ls, v.v.k == VCALL, "syntax error");
1491     SETARG_C(getcode(fs, &v.v), 1);  /* call statement uses no results */
1492   }
1493 }
1494
1495
1496 static void retstat (LexState *ls) {
1497   /* stat -> RETURN [explist] [';'] */
1498   FuncState *fs = ls->fs;
1499   expdesc e;
1500   int first, nret;  /* registers with returned values */
1501   if (block_follow(ls, 1) || ls->t.token == ';')
1502     first = nret = 0;  /* return no values */
1503   else {
1504     nret = explist(ls, &e);  /* optional return values */
1505     if (hasmultret(e.k)) {
1506       luaK_setmultret(fs, &e);
1507       if (e.k == VCALL && nret == 1) {  /* tail call? */
1508         SET_OPCODE(getcode(fs,&e), OP_TAILCALL);
1509         lua_assert(GETARG_A(getcode(fs,&e)) == fs->nactvar);
1510       }
1511       first = fs->nactvar;
1512       nret = LUA_MULTRET;  /* return all values */
1513     }
1514     else {
1515       if (nret == 1)  /* only one single value? */
1516         first = luaK_exp2anyreg(fs, &e);
1517       else {
1518         luaK_exp2nextreg(fs, &e);  /* values must go to the `stack' */
1519         first = fs->nactvar;  /* return all `active' values */
1520         lua_assert(nret == fs->freereg - first);
1521       }
1522     }
1523   }
1524   luaK_ret(fs, first, nret);
1525   testnext(ls, ';');  /* skip optional semicolon */
1526 }
1527
1528
1529 static void statement (LexState *ls) {
1530   int line = ls->linenumber;  /* may be needed for error messages */
1531   enterlevel(ls);
1532   switch (ls->t.token) {
1533     case ';': {  /* stat -> ';' (empty statement) */
1534       luaX_next(ls);  /* skip ';' */
1535       break;
1536     }
1537     case TK_IF: {  /* stat -> ifstat */
1538       ifstat(ls, line);
1539       break;
1540     }
1541     case TK_WHILE: {  /* stat -> whilestat */
1542       whilestat(ls, line);
1543       break;
1544     }
1545     case TK_DO: {  /* stat -> DO block END */
1546       luaX_next(ls);  /* skip DO */
1547       block(ls);
1548       check_match(ls, TK_END, TK_DO, line);
1549       break;
1550     }
1551     case TK_FOR: {  /* stat -> forstat */
1552       forstat(ls, line);
1553       break;
1554     }
1555     case TK_REPEAT: {  /* stat -> repeatstat */
1556       repeatstat(ls, line);
1557       break;
1558     }
1559     case TK_FUNCTION: {  /* stat -> funcstat */
1560       funcstat(ls, line);
1561       break;
1562     }
1563     case TK_LOCAL: {  /* stat -> localstat */
1564       luaX_next(ls);  /* skip LOCAL */
1565       if (testnext(ls, TK_FUNCTION))  /* local function? */
1566         localfunc(ls);
1567       else
1568         localstat(ls);
1569       break;
1570     }
1571     case TK_DBCOLON: {  /* stat -> label */
1572       luaX_next(ls);  /* skip double colon */
1573       labelstat(ls, str_checkname(ls), line);
1574       break;
1575     }
1576     case TK_RETURN: {  /* stat -> retstat */
1577       luaX_next(ls);  /* skip RETURN */
1578       retstat(ls);
1579       break;
1580     }
1581     case TK_BREAK:   /* stat -> breakstat */
1582     case TK_GOTO: {  /* stat -> 'goto' NAME */
1583       gotostat(ls, luaK_jump(ls->fs));
1584       break;
1585     }
1586     default: {  /* stat -> func | assignment */
1587       exprstat(ls);
1588       break;
1589     }
1590   }
1591   lua_assert(ls->fs->f->maxstacksize >= ls->fs->freereg &&
1592              ls->fs->freereg >= ls->fs->nactvar);
1593   ls->fs->freereg = ls->fs->nactvar;  /* free registers */
1594   leavelevel(ls);
1595 }
1596
1597 /* }====================================================================== */
1598
1599
1600 /*
1601 ** compiles the main function, which is a regular vararg function with an
1602 ** upvalue named LUA_ENV
1603 */
1604 static void mainfunc (LexState *ls, FuncState *fs) {
1605   BlockCnt bl;
1606   expdesc v;
1607   open_func(ls, fs, &bl);
1608   fs->f->is_vararg = 1;  /* main function is always vararg */
1609   init_exp(&v, VLOCAL, 0);  /* create and... */
1610   newupvalue(fs, ls->envn, &v);  /* ...set environment upvalue */
1611   luaX_next(ls);  /* read first token */
1612   statlist(ls);  /* parse main body */
1613   check(ls, TK_EOS);
1614   close_func(ls);
1615 }
1616
1617
1618 Closure *luaY_parser (lua_State *L, ZIO *z, Mbuffer *buff,
1619                       Dyndata *dyd, const char *name, int firstchar) {
1620   LexState lexstate;
1621   FuncState funcstate;
1622   Closure *cl = luaF_newLclosure(L, 1);  /* create main closure */
1623   /* anchor closure (to avoid being collected) */
1624   setclLvalue(L, L->top, cl);
1625   incr_top(L);
1626   funcstate.f = cl->l.p = luaF_newproto(L);
1627   funcstate.f->source = luaS_new(L, name);  /* create and anchor TString */
1628   lexstate.buff = buff;
1629   lexstate.dyd = dyd;
1630   dyd->actvar.n = dyd->gt.n = dyd->label.n = 0;
1631   luaX_setinput(L, &lexstate, z, funcstate.f->source, firstchar);
1632   mainfunc(&lexstate, &funcstate);
1633   lua_assert(!funcstate.prev && funcstate.nups == 1 && !lexstate.fs);
1634   /* all scopes should be correctly finished */
1635   lua_assert(dyd->actvar.n == 0 && dyd->gt.n == 0 && dyd->label.n == 0);
1636   return cl;  /* it's on the stack too */
1637 }
1638