src/lparser.c

   1 /*
   2 ** $Id: lparser.c,v 1.116 2000/10/27 11:39:52 roberto Exp $
   3 ** LL(1) Parser and code generator for Lua
   4 ** See Copyright Notice in lua.h
   5 */
   6
   7
   8 #include <stdio.h>
   9 #include <string.h>
  10
  11 #include "lua.h"
  12
  13 #include "lcode.h"
  14 #include "lfunc.h"
  15 #include "llex.h"
  16 #include "lmem.h"
  17 #include "lobject.h"
  18 #include "lopcodes.h"
  19 #include "lparser.h"
  20 #include "lstate.h"
  21 #include "lstring.h"
  22
  23
  24 /*
  25 ** Constructors descriptor:
  26 ** `n' indicates number of elements, and `k' signals whether
  27 ** it is a list constructor (k = 0) or a record constructor (k = 1)
  28 ** or empty (k = ';' or '}')
  29 */
  30 typedef struct Constdesc {
  31   int n;
  32   int k;
  33 } Constdesc;
  34
  35
  36 typedef struct Breaklabel {
  37   struct Breaklabel *previous;  /* chain */
  38   int breaklist;
  39   int stacklevel;
  40 } Breaklabel;
  41
  42
  43
  44
  45 /*
  46 ** prototypes for recursive non-terminal functions
  47 */
  48 static void body (LexState *ls, int needself, int line);
  49 static void chunk (LexState *ls);
  50 static void constructor (LexState *ls);
  51 static void expr (LexState *ls, expdesc *v);
  52 static void exp1 (LexState *ls);
  53
  54
  55
  56 static void next (LexState *ls) {
  57   ls->lastline = ls->linenumber;
  58   if (ls->lookahead.token != TK_EOS) {  /* is there a look-ahead token? */
  59     ls->t = ls->lookahead;  /* use this one */
  60     ls->lookahead.token = TK_EOS;  /* and discharge it */
  61   }
  62   else
  63     ls->t.token = luaX_lex(ls, &ls->t.seminfo);  /* read next token */
  64 }
  65
  66
  67 static void lookahead (LexState *ls) {
  68   LUA_ASSERT(ls->lookahead.token == TK_EOS, "two look-aheads");
  69   ls->lookahead.token = luaX_lex(ls, &ls->lookahead.seminfo);
  70 }
  71
  72
  73 static void error_expected (LexState *ls, int token) {
  74   char buff[100], t[TOKEN_LEN];
  75   luaX_token2str(token, t);
  76   sprintf(buff, "`%.20s' expected", t);
  77   luaK_error(ls, buff);
  78 }
  79
  80
  81 static void check (LexState *ls, int c) {
  82   if (ls->t.token != c)
  83     error_expected(ls, c);
  84   next(ls);
  85 }
  86
  87
  88 static void check_condition (LexState *ls, int c, const char *msg) {
  89   if (!c) luaK_error(ls, msg);
  90 }
  91
  92
  93 static int optional (LexState *ls, int c) {
  94   if (ls->t.token == c) {
  95     next(ls);
  96     return 1;
  97   }
  98   else return 0;
  99 }
 100
 101
 102 static void check_match (LexState *ls, int what, int who, int where) {
 103   if (ls->t.token != what) {
 104     if (where == ls->linenumber)
 105       error_expected(ls, what);
 106     else {
 107       char buff[100];
 108       char t_what[TOKEN_LEN], t_who[TOKEN_LEN];
 109       luaX_token2str(what, t_what);
 110       luaX_token2str(who, t_who);
 111       sprintf(buff, "`%.20s' expected (to close `%.20s' at line %d)",
 112               t_what, t_who, where);
 113       luaK_error(ls, buff);
 114     }
 115   }
 116   next(ls);
 117 }
 118
 119
 120 static int string_constant (FuncState *fs, TString *s) {
 121   Proto *f = fs->f;
 122   int c = s->u.s.constindex;
 123   if (c >= f->nkstr || f->kstr[c] != s) {
 124     luaM_growvector(fs->L, f->kstr, f->nkstr, 1, TString *,
 125                     "constant table overflow", MAXARG_U);
 126     c = f->nkstr++;
 127     f->kstr[c] = s;
 128     s->u.s.constindex = c;  /* hint for next time */
 129   }
 130   return c;
 131 }
 132
 133
 134 static void code_string (LexState *ls, TString *s) {
 135   luaK_kstr(ls, string_constant(ls->fs, s));
 136 }
 137
 138
 139 static TString *str_checkname (LexState *ls) {
 140   TString *ts;
 141   check_condition(ls, (ls->t.token == TK_NAME), "<name> expected");
 142   ts = ls->t.seminfo.ts;
 143   next(ls);
 144   return ts;
 145 }
 146
 147
 148 static int checkname (LexState *ls) {
 149   return string_constant(ls->fs, str_checkname(ls));
 150 }
 151
 152
 153 static int luaI_registerlocalvar (LexState *ls, TString *varname) {
 154   Proto *f = ls->fs->f;
 155   luaM_growvector(ls->L, f->locvars, f->nlocvars, 1, LocVar, "", MAX_INT);
 156   f->locvars[f->nlocvars].varname = varname;
 157   return f->nlocvars++;
 158 }
 159
 160
 161 static void new_localvar (LexState *ls, TString *name, int n) {
 162   FuncState *fs = ls->fs;
 163   luaX_checklimit(ls, fs->nactloc+n+1, MAXLOCALS, "local variables");
 164   fs->actloc[fs->nactloc+n] = luaI_registerlocalvar(ls, name);
 165 }
 166
 167
 168 static void adjustlocalvars (LexState *ls, int nvars) {
 169   FuncState *fs = ls->fs;
 170   while (nvars--)
 171     fs->f->locvars[fs->actloc[fs->nactloc++]].startpc = fs->pc;
 172 }
 173
 174
 175 static void removelocalvars (LexState *ls, int nvars) {
 176   FuncState *fs = ls->fs;
 177   while (nvars--)
 178     fs->f->locvars[fs->actloc[--fs->nactloc]].endpc = fs->pc;
 179 }
 180
 181
 182 static void new_localvarstr (LexState *ls, const char *name, int n) {
 183   new_localvar(ls, luaS_newfixed(ls->L, name), n);
 184 }
 185
 186
 187 static int search_local (LexState *ls, TString *n, expdesc *var) {
 188   FuncState *fs;
 189   int level = 0;
 190   for (fs=ls->fs; fs; fs=fs->prev) {
 191     int i;
 192     for (i=fs->nactloc-1; i >= 0; i--) {
 193       if (n == fs->f->locvars[fs->actloc[i]].varname) {
 194         var->k = VLOCAL;
 195         var->u.index = i;
 196         return level;
 197       }
 198     }
 199     level++;  /* `var' not found; check outer level */
 200   }
 201   var->k = VGLOBAL;  /* not found in any level; must be global */
 202   return -1;
 203 }
 204
 205
 206 static void singlevar (LexState *ls, TString *n, expdesc *var) {
 207   int level = search_local(ls, n, var);
 208   if (level >= 1)  /* neither local (0) nor global (-1)? */
 209     luaX_syntaxerror(ls, "cannot access a variable in outer scope", n->str);
 210   else if (level == -1)  /* global? */
 211     var->u.index = string_constant(ls->fs, n);
 212 }
 213
 214
 215 static int indexupvalue (LexState *ls, expdesc *v) {
 216   FuncState *fs = ls->fs;
 217   int i;
 218   for (i=0; i<fs->nupvalues; i++) {
 219     if (fs->upvalues[i].k == v->k && fs->upvalues[i].u.index == v->u.index)
 220       return i;
 221   }
 222   /* new one */
 223   luaX_checklimit(ls, fs->nupvalues+1, MAXUPVALUES, "upvalues");
 224   fs->upvalues[fs->nupvalues] = *v;
 225   return fs->nupvalues++;
 226 }
 227
 228
 229 static void pushupvalue (LexState *ls, TString *n) {
 230   FuncState *fs = ls->fs;
 231   expdesc v;
 232   int level = search_local(ls, n, &v);
 233   if (level == -1) {  /* global? */
 234     if (fs->prev == NULL)
 235       luaX_syntaxerror(ls, "cannot access upvalue in main", n->str);
 236     v.u.index = string_constant(fs->prev, n);
 237   }
 238   else if (level != 1)
 239     luaX_syntaxerror(ls,
 240          "upvalue must be global or local to immediately outer scope", n->str);
 241   luaK_code1(fs, OP_PUSHUPVALUE, indexupvalue(ls, &v));
 242 }
 243
 244
 245 static void adjust_mult_assign (LexState *ls, int nvars, int nexps) {
 246   FuncState *fs = ls->fs;
 247   int diff = nexps - nvars;
 248   if (nexps > 0 && luaK_lastisopen(fs)) { /* list ends in a function call */
 249     diff--;  /* do not count function call itself */
 250     if (diff <= 0) {  /* more variables than values? */
 251       luaK_setcallreturns(fs, -diff);  /* function call provide extra values */
 252       diff = 0;  /* no more difference */
 253     }
 254     else  /* more values than variables */
 255       luaK_setcallreturns(fs, 0);  /* call should provide no value */
 256   }
 257   /* push or pop eventual difference between list lengths */
 258   luaK_adjuststack(fs, diff);
 259 }
 260
 261
 262 static void code_params (LexState *ls, int nparams, int dots) {
 263   FuncState *fs = ls->fs;
 264   adjustlocalvars(ls, nparams);
 265   luaX_checklimit(ls, fs->nactloc, MAXPARAMS, "parameters");
 266   fs->f->numparams = fs->nactloc;  /* `self' could be there already */
 267   fs->f->is_vararg = dots;
 268   if (dots) {
 269     new_localvarstr(ls, "arg", 0);
 270     adjustlocalvars(ls, 1);
 271   }
 272   luaK_deltastack(fs, fs->nactloc);  /* count parameters in the stack */
 273 }
 274
 275
 276 static void enterbreak (FuncState *fs, Breaklabel *bl) {
 277   bl->stacklevel = fs->stacklevel;
 278   bl->breaklist = NO_JUMP;
 279   bl->previous = fs->bl;
 280   fs->bl = bl;
 281 }
 282
 283
 284 static void leavebreak (FuncState *fs, Breaklabel *bl) {
 285   fs->bl = bl->previous;
 286   LUA_ASSERT(bl->stacklevel == fs->stacklevel, "wrong levels");
 287   luaK_patchlist(fs, bl->breaklist, luaK_getlabel(fs));
 288 }
 289
 290
 291 static void pushclosure (LexState *ls, FuncState *func) {
 292   FuncState *fs = ls->fs;
 293   Proto *f = fs->f;
 294   int i;
 295   for (i=0; i<func->nupvalues; i++)
 296     luaK_tostack(ls, &func->upvalues[i], 1);
 297   luaM_growvector(ls->L, f->kproto, f->nkproto, 1, Proto *,
 298                   "constant table overflow", MAXARG_A);
 299   f->kproto[f->nkproto++] = func->f;
 300   luaK_code2(fs, OP_CLOSURE, f->nkproto-1, func->nupvalues);
 301 }
 302
 303
 304 static void open_func (LexState *ls, FuncState *fs) {
 305   Proto *f = luaF_newproto(ls->L);
 306   fs->prev = ls->fs;  /* linked list of funcstates */
 307   fs->ls = ls;
 308   fs->L = ls->L;
 309   ls->fs = fs;
 310   fs->stacklevel = 0;
 311   fs->nactloc = 0;
 312   fs->nupvalues = 0;
 313   fs->bl = NULL;
 314   fs->f = f;
 315   f->source = ls->source;
 316   fs->pc = 0;
 317   fs->lasttarget = 0;
 318   fs->lastline = 0;
 319   fs->jlt = NO_JUMP;
 320   f->code = NULL;
 321   f->maxstacksize = 0;
 322   f->numparams = 0;  /* default for main chunk */
 323   f->is_vararg = 0;  /* default for main chunk */
 324 }
 325
 326
 327 static void close_func (LexState *ls) {
 328   lua_State *L = ls->L;
 329   FuncState *fs = ls->fs;
 330   Proto *f = fs->f;
 331   luaK_code0(fs, OP_END);
 332   luaK_getlabel(fs);  /* close eventual list of pending jumps */
 333   luaM_reallocvector(L, f->code, fs->pc, Instruction);
 334   luaM_reallocvector(L, f->kstr, f->nkstr, TString *);
 335   luaM_reallocvector(L, f->knum, f->nknum, Number);
 336   luaM_reallocvector(L, f->kproto, f->nkproto, Proto *);
 337   removelocalvars(ls, fs->nactloc);
 338   luaM_reallocvector(L, f->locvars, f->nlocvars, LocVar);
 339   luaM_reallocvector(L, f->lineinfo, f->nlineinfo+1, int);
 340   f->lineinfo[f->nlineinfo++] = MAX_INT;  /* end flag */
 341   luaF_protook(L, f, fs->pc);  /* proto is ok now */
 342   ls->fs = fs->prev;
 343   LUA_ASSERT(fs->bl == NULL, "wrong list end");
 344 }
 345
 346
 347 Proto *luaY_parser (lua_State *L, ZIO *z) {
 348   struct LexState lexstate;
 349   struct FuncState funcstate;
 350   luaX_setinput(L, &lexstate, z, luaS_new(L, zname(z)));
 351   open_func(&lexstate, &funcstate);
 352   next(&lexstate);  /* read first token */
 353   chunk(&lexstate);
 354   check_condition(&lexstate, (lexstate.t.token == TK_EOS), "<eof> expected");
 355   close_func(&lexstate);
 356   LUA_ASSERT(funcstate.prev == NULL, "wrong list end");
 357   LUA_ASSERT(funcstate.nupvalues == 0, "no upvalues in main");
 358   return funcstate.f;
 359 }
 360
 361
 362
 363 /*============================================================*/
 364 /* GRAMMAR RULES */
 365 /*============================================================*/
 366
 367
 368 static int explist1 (LexState *ls) {
 369   /* explist1 -> expr { ',' expr } */
 370   int n = 1;  /* at least one expression */
 371   expdesc v;
 372   expr(ls, &v);
 373   while (ls->t.token == ',') {
 374     luaK_tostack(ls, &v, 1);  /* gets only 1 value from previous expression */
 375     next(ls);  /* skip comma */
 376     expr(ls, &v);
 377     n++;
 378   }
 379   luaK_tostack(ls, &v, 0);  /* keep open number of values of last expression */
 380   return n;
 381 }
 382
 383
 384 static void funcargs (LexState *ls, int slf) {
 385   FuncState *fs = ls->fs;
 386   int slevel = fs->stacklevel - slf - 1;  /* where is func in the stack */
 387   switch (ls->t.token) {
 388     case '(': {  /* funcargs -> '(' [ explist1 ] ')' */
 389       int line = ls->linenumber;
 390       int nargs = 0;
 391       next(ls);
 392       if (ls->t.token != ')')  /* arg list not empty? */
 393         nargs = explist1(ls);
 394       check_match(ls, ')', '(', line);
 395 #ifdef LUA_COMPAT_ARGRET
 396       if (nargs > 0)  /* arg list is not empty? */
 397         luaK_setcallreturns(fs, 1);  /* last call returns only 1 value */
 398 #else
 399       UNUSED(nargs);  /* to avoid warnings */
 400 #endif
 401       break;
 402     }
 403     case '{': {  /* funcargs -> constructor */
 404       constructor(ls);
 405       break;
 406     }
 407     case TK_STRING: {  /* funcargs -> STRING */
 408       code_string(ls, ls->t.seminfo.ts);  /* must use `seminfo' before `next' */
 409       next(ls);
 410       break;
 411     }
 412     default: {
 413       luaK_error(ls, "function arguments expected");
 414       break;
 415     }
 416   }
 417   fs->stacklevel = slevel;  /* call will remove function and arguments */
 418   luaK_code2(fs, OP_CALL, slevel, MULT_RET);
 419 }
 420
 421
 422 static void var_or_func_tail (LexState *ls, expdesc *v) {
 423   for (;;) {
 424     switch (ls->t.token) {
 425       case '.': {  /* var_or_func_tail -> '.' NAME */
 426         next(ls);
 427         luaK_tostack(ls, v, 1);  /* `v' must be on stack */
 428         luaK_kstr(ls, checkname(ls));
 429         v->k = VINDEXED;
 430         break;
 431       }
 432       case '[': {  /* var_or_func_tail -> '[' exp1 ']' */
 433         next(ls);
 434         luaK_tostack(ls, v, 1);  /* `v' must be on stack */
 435         v->k = VINDEXED;
 436         exp1(ls);
 437         check(ls, ']');
 438         break;
 439       }
 440       case ':': {  /* var_or_func_tail -> ':' NAME funcargs */
 441         int name;
 442         next(ls);
 443         name = checkname(ls);
 444         luaK_tostack(ls, v, 1);  /* `v' must be on stack */
 445         luaK_code1(ls->fs, OP_PUSHSELF, name);
 446         funcargs(ls, 1);
 447         v->k = VEXP;
 448         v->u.l.t = v->u.l.f = NO_JUMP;
 449         break;
 450       }
 451       case '(': case TK_STRING: case '{': {  /* var_or_func_tail -> funcargs */
 452         luaK_tostack(ls, v, 1);  /* `v' must be on stack */
 453         funcargs(ls, 0);
 454         v->k = VEXP;
 455         v->u.l.t = v->u.l.f = NO_JUMP;
 456         break;
 457       }
 458       default: return;  /* should be follow... */
 459     }
 460   }
 461 }
 462
 463
 464 static void var_or_func (LexState *ls, expdesc *v) {
 465   /* var_or_func -> ['%'] NAME var_or_func_tail */
 466   if (optional(ls, '%')) {  /* upvalue? */
 467     pushupvalue(ls, str_checkname(ls));
 468     v->k = VEXP;
 469     v->u.l.t = v->u.l.f = NO_JUMP;
 470   }
 471   else  /* variable name */
 472     singlevar(ls, str_checkname(ls), v);
 473   var_or_func_tail(ls, v);
 474 }
 475
 476
 477
 478 /*
 479 ** {======================================================================
 480 ** Rules for Constructors
 481 ** =======================================================================
 482 */
 483
 484
 485 static void recfield (LexState *ls) {
 486   /* recfield -> (NAME | '['exp1']') = exp1 */
 487   switch (ls->t.token) {
 488     case TK_NAME: {
 489       luaK_kstr(ls, checkname(ls));
 490       break;
 491     }
 492     case '[': {
 493       next(ls);
 494       exp1(ls);
 495       check(ls, ']');
 496       break;
 497     }
 498     default: luaK_error(ls, "<name> or `[' expected");
 499   }
 500   check(ls, '=');
 501   exp1(ls);
 502 }
 503
 504
 505 static int recfields (LexState *ls) {
 506   /* recfields -> recfield { ',' recfield } [','] */
 507   FuncState *fs = ls->fs;
 508   int n = 1;  /* at least one element */
 509   recfield(ls);
 510   while (ls->t.token == ',') {
 511     next(ls);
 512     if (ls->t.token == ';' || ls->t.token == '}')
 513       break;
 514     recfield(ls);
 515     n++;
 516     if (n%RFIELDS_PER_FLUSH == 0)
 517       luaK_code1(fs, OP_SETMAP, RFIELDS_PER_FLUSH);
 518   }
 519   luaK_code1(fs, OP_SETMAP, n%RFIELDS_PER_FLUSH);
 520   return n;
 521 }
 522
 523
 524 static int listfields (LexState *ls) {
 525   /* listfields -> exp1 { ',' exp1 } [','] */
 526   FuncState *fs = ls->fs;
 527   int n = 1;  /* at least one element */
 528   exp1(ls);
 529   while (ls->t.token == ',') {
 530     next(ls);
 531     if (ls->t.token == ';' || ls->t.token == '}')
 532       break;
 533     exp1(ls);
 534     n++;
 535     luaX_checklimit(ls, n/LFIELDS_PER_FLUSH, MAXARG_A,
 536                "`item groups' in a list initializer");
 537     if (n%LFIELDS_PER_FLUSH == 0)
 538       luaK_code2(fs, OP_SETLIST, n/LFIELDS_PER_FLUSH - 1, LFIELDS_PER_FLUSH);
 539   }
 540   luaK_code2(fs, OP_SETLIST, n/LFIELDS_PER_FLUSH, n%LFIELDS_PER_FLUSH);
 541   return n;
 542 }
 543
 544
 545
 546 static void constructor_part (LexState *ls, Constdesc *cd) {
 547   switch (ls->t.token) {
 548     case ';': case '}': {  /* constructor_part -> empty */
 549       cd->n = 0;
 550       cd->k = ls->t.token;
 551       break;
 552     }
 553     case TK_NAME: {  /* may be listfields or recfields */
 554       lookahead(ls);
 555       if (ls->lookahead.token != '=')  /* expression? */
 556         goto case_default;
 557       /* else go through to recfields */
 558     }
 559     case '[': {  /* constructor_part -> recfields */
 560       cd->n = recfields(ls);
 561       cd->k = 1;  /* record */
 562       break;
 563     }
 564     default: {  /* constructor_part -> listfields */
 565     case_default:
 566       cd->n = listfields(ls);
 567       cd->k = 0;  /* list */
 568       break;
 569     }
 570   }
 571 }
 572
 573
 574 static void constructor (LexState *ls) {
 575   /* constructor -> '{' constructor_part [';' constructor_part] '}' */
 576   FuncState *fs = ls->fs;
 577   int line = ls->linenumber;
 578   int pc = luaK_code1(fs, OP_CREATETABLE, 0);
 579   int nelems;
 580   Constdesc cd;
 581   check(ls, '{');
 582   constructor_part(ls, &cd);
 583   nelems = cd.n;
 584   if (optional(ls, ';')) {
 585     Constdesc other_cd;
 586     constructor_part(ls, &other_cd);
 587     check_condition(ls, (cd.k != other_cd.k), "invalid constructor syntax");
 588     nelems += other_cd.n;
 589   }
 590   check_match(ls, '}', '{', line);
 591   luaX_checklimit(ls, nelems, MAXARG_U, "elements in a table constructor");
 592   SETARG_U(fs->f->code[pc], nelems);  /* set initial table size */
 593 }
 594
 595 /* }====================================================================== */
 596
 597
 598
 599
 600 /*
 601 ** {======================================================================
 602 ** Expression parsing
 603 ** =======================================================================
 604 */
 605
 606
 607 static void simpleexp (LexState *ls, expdesc *v) {
 608   FuncState *fs = ls->fs;
 609   switch (ls->t.token) {
 610     case TK_NUMBER: {  /* simpleexp -> NUMBER */
 611       Number r = ls->t.seminfo.r;
 612       next(ls);
 613       luaK_number(fs, r);
 614       break;
 615     }
 616     case TK_STRING: {  /* simpleexp -> STRING */
 617       code_string(ls, ls->t.seminfo.ts);  /* must use `seminfo' before `next' */
 618       next(ls);
 619       break;
 620     }
 621     case TK_NIL: {  /* simpleexp -> NIL */
 622       luaK_adjuststack(fs, -1);
 623       next(ls);
 624       break;
 625     }
 626     case '{': {  /* simpleexp -> constructor */
 627       constructor(ls);
 628       break;
 629     }
 630     case TK_FUNCTION: {  /* simpleexp -> FUNCTION body */
 631       next(ls);
 632       body(ls, 0, ls->linenumber);
 633       break;
 634     }
 635     case '(': {  /* simpleexp -> '(' expr ')' */
 636       next(ls);
 637       expr(ls, v);
 638       check(ls, ')');
 639       return;
 640     }
 641     case TK_NAME: case '%': {
 642       var_or_func(ls, v);
 643       return;
 644     }
 645     default: {
 646       luaK_error(ls, "<expression> expected");
 647       return;
 648     }
 649   }
 650   v->k = VEXP;
 651   v->u.l.t = v->u.l.f = NO_JUMP;
 652 }
 653
 654
 655 static void exp1 (LexState *ls) {
 656   expdesc v;
 657   expr(ls, &v);
 658   luaK_tostack(ls, &v, 1);
 659 }
 660
 661
 662 static UnOpr getunopr (int op) {
 663   switch (op) {
 664     case TK_NOT: return OPR_NOT;
 665     case '-': return OPR_MINUS;
 666     default: return OPR_NOUNOPR;
 667   }
 668 }
 669
 670
 671 static BinOpr getbinopr (int op) {
 672   switch (op) {
 673     case '+': return OPR_ADD;
 674     case '-': return OPR_SUB;
 675     case '*': return OPR_MULT;
 676     case '/': return OPR_DIV;
 677     case '^': return OPR_POW;
 678     case TK_CONCAT: return OPR_CONCAT;
 679     case TK_NE: return OPR_NE;
 680     case TK_EQ: return OPR_EQ;
 681     case '<': return OPR_LT;
 682     case TK_LE: return OPR_LE;
 683     case '>': return OPR_GT;
 684     case TK_GE: return OPR_GE;
 685     case TK_AND: return OPR_AND;
 686     case TK_OR: return OPR_OR;
 687     default: return OPR_NOBINOPR;
 688   }
 689 }
 690
 691
 692 static const struct {
 693   char left;  /* left priority for each binary operator */
 694   char right; /* right priority */
 695 } priority[] = {  /* ORDER OPR */
 696    {5, 5}, {5, 5}, {6, 6}, {6, 6},  /* arithmetic */
 697    {9, 8}, {4, 3},                  /* power and concat (right associative) */
 698    {2, 2}, {2, 2},                  /* equality */
 699    {2, 2}, {2, 2}, {2, 2}, {2, 2},  /* order */
 700    {1, 1}, {1, 1}                   /* logical */
 701 };
 702
 703 #define UNARY_PRIORITY  7  /* priority for unary operators */
 704
 705
 706 /*
 707 ** subexpr -> (simplexep | unop subexpr) { binop subexpr }
 708 ** where `binop' is any binary operator with a priority higher than `limit'
 709 */
 710 static BinOpr subexpr (LexState *ls, expdesc *v, int limit) {
 711   BinOpr op;
 712   UnOpr uop = getunopr(ls->t.token);
 713   if (uop != OPR_NOUNOPR) {
 714     next(ls);
 715     subexpr(ls, v, UNARY_PRIORITY);
 716     luaK_prefix(ls, uop, v);
 717   }
 718   else simpleexp(ls, v);
 719   /* expand while operators have priorities higher than `limit' */
 720   op = getbinopr(ls->t.token);
 721   while (op != OPR_NOBINOPR && priority[op].left > limit) {
 722     expdesc v2;
 723     BinOpr nextop;
 724     next(ls);
 725     luaK_infix(ls, op, v);
 726     /* read sub-expression with higher priority */
 727     nextop = subexpr(ls, &v2, priority[op].right);
 728     luaK_posfix(ls, op, v, &v2);
 729     op = nextop;
 730   }
 731   return op;  /* return first untreated operator */
 732 }
 733
 734
 735 static void expr (LexState *ls, expdesc *v) {
 736   subexpr(ls, v, -1);
 737 }
 738
 739 /* }==================================================================== */
 740
 741
 742 /*
 743 ** {======================================================================
 744 ** Rules for Statements
 745 ** =======================================================================
 746 */
 747
 748
 749 static int block_follow (int token) {
 750   switch (token) {
 751     case TK_ELSE: case TK_ELSEIF: case TK_END:
 752     case TK_UNTIL: case TK_EOS:
 753       return 1;
 754     default: return 0;
 755   }
 756 }
 757
 758
 759 static void block (LexState *ls) {
 760   /* block -> chunk */
 761   FuncState *fs = ls->fs;
 762   int nactloc = fs->nactloc;
 763   chunk(ls);
 764   luaK_adjuststack(fs, fs->nactloc - nactloc);  /* remove local variables */
 765   removelocalvars(ls, fs->nactloc - nactloc);
 766 }
 767
 768
 769 static int assignment (LexState *ls, expdesc *v, int nvars) {
 770   int left = 0;  /* number of values left in the stack after assignment */
 771   luaX_checklimit(ls, nvars, MAXVARSLH, "variables in a multiple assignment");
 772   if (ls->t.token == ',') {  /* assignment -> ',' NAME assignment */
 773     expdesc nv;
 774     next(ls);
 775     var_or_func(ls, &nv);
 776     check_condition(ls, (nv.k != VEXP), "syntax error");
 777     left = assignment(ls, &nv, nvars+1);
 778   }
 779   else {  /* assignment -> '=' explist1 */
 780     int nexps;
 781     check(ls, '=');
 782     nexps = explist1(ls);
 783     adjust_mult_assign(ls, nvars, nexps);
 784   }
 785   if (v->k != VINDEXED)
 786     luaK_storevar(ls, v);
 787   else {  /* there may be garbage between table-index and value */
 788     luaK_code2(ls->fs, OP_SETTABLE, left+nvars+2, 1);
 789     left += 2;
 790   }
 791   return left;
 792 }
 793
 794
 795 static void cond (LexState *ls, expdesc *v) {
 796   /* cond -> exp */
 797   expr(ls, v);  /* read condition */
 798   luaK_goiftrue(ls->fs, v, 0);
 799 }
 800
 801
 802 static void whilestat (LexState *ls, int line) {
 803   /* whilestat -> WHILE cond DO block END */
 804   FuncState *fs = ls->fs;
 805   int while_init = luaK_getlabel(fs);
 806   expdesc v;
 807   Breaklabel bl;
 808   enterbreak(fs, &bl);
 809   next(ls);
 810   cond(ls, &v);
 811   check(ls, TK_DO);
 812   block(ls);
 813   luaK_patchlist(fs, luaK_jump(fs), while_init);
 814   luaK_patchlist(fs, v.u.l.f, luaK_getlabel(fs));
 815   check_match(ls, TK_END, TK_WHILE, line);
 816   leavebreak(fs, &bl);
 817 }
 818
 819
 820 static void repeatstat (LexState *ls, int line) {
 821   /* repeatstat -> REPEAT block UNTIL cond */
 822   FuncState *fs = ls->fs;
 823   int repeat_init = luaK_getlabel(fs);
 824   expdesc v;
 825   Breaklabel bl;
 826   enterbreak(fs, &bl);
 827   next(ls);
 828   block(ls);
 829   check_match(ls, TK_UNTIL, TK_REPEAT, line);
 830   cond(ls, &v);
 831   luaK_patchlist(fs, v.u.l.f, repeat_init);
 832   leavebreak(fs, &bl);
 833 }
 834
 835
 836 static void forbody (LexState *ls, int nvar, OpCode prepfor, OpCode loopfor) {
 837   /* forbody -> DO block END */
 838   FuncState *fs = ls->fs;
 839   int prep = luaK_code1(fs, prepfor, NO_JUMP);
 840   int blockinit = luaK_getlabel(fs);
 841   check(ls, TK_DO);
 842   adjustlocalvars(ls, nvar);  /* scope for control variables */
 843   block(ls);
 844   luaK_patchlist(fs, luaK_code1(fs, loopfor, NO_JUMP), blockinit);
 845   luaK_patchlist(fs, prep, luaK_getlabel(fs));
 846   removelocalvars(ls, nvar);
 847 }
 848
 849
 850 static void fornum (LexState *ls, TString *varname) {
 851   /* fornum -> NAME = exp1,exp1[,exp1] forbody */
 852   FuncState *fs = ls->fs;
 853   check(ls, '=');
 854   exp1(ls);  /* initial value */
 855   check(ls, ',');
 856   exp1(ls);  /* limit */
 857   if (optional(ls, ','))
 858     exp1(ls);  /* optional step */
 859   else
 860     luaK_code1(fs, OP_PUSHINT, 1);  /* default step */
 861   new_localvar(ls, varname, 0);
 862   new_localvarstr(ls, "(limit)", 1);
 863   new_localvarstr(ls, "(step)", 2);
 864   forbody(ls, 3, OP_FORPREP, OP_FORLOOP);
 865 }
 866
 867
 868 static void forlist (LexState *ls, TString *indexname) {
 869   /* forlist -> NAME,NAME IN exp1 forbody */
 870   TString *valname;
 871   check(ls, ',');
 872   valname = str_checkname(ls);
 873   /* next test is dirty, but avoids `in' being a reserved word */
 874   check_condition(ls,
 875        (ls->t.token == TK_NAME && ls->t.seminfo.ts == luaS_new(ls->L, "in")),
 876        "`in' expected");
 877   next(ls);  /* skip `in' */
 878   exp1(ls);  /* table */
 879   new_localvarstr(ls, "(table)", 0);
 880   new_localvar(ls, indexname, 1);
 881   new_localvar(ls, valname, 2);
 882   forbody(ls, 3, OP_LFORPREP, OP_LFORLOOP);
 883 }
 884
 885
 886 static void forstat (LexState *ls, int line) {
 887   /* forstat -> fornum | forlist */
 888   FuncState *fs = ls->fs;
 889   TString *varname;
 890   Breaklabel bl;
 891   enterbreak(fs, &bl);
 892   next(ls);  /* skip `for' */
 893   varname = str_checkname(ls);  /* first variable name */
 894   switch (ls->t.token) {
 895     case '=': fornum(ls, varname); break;
 896     case ',': forlist(ls, varname); break;
 897     default: luaK_error(ls, "`=' or `,' expected");
 898   }
 899   check_match(ls, TK_END, TK_FOR, line);
 900   leavebreak(fs, &bl);
 901 }
 902
 903
 904 static void test_then_block (LexState *ls, expdesc *v) {
 905   /* test_then_block -> [IF | ELSEIF] cond THEN block */
 906   next(ls);  /* skip IF or ELSEIF */
 907   cond(ls, v);
 908   check(ls, TK_THEN);
 909   block(ls);  /* `then' part */
 910 }
 911
 912
 913 static void ifstat (LexState *ls, int line) {
 914   /* ifstat -> IF cond THEN block {ELSEIF cond THEN block} [ELSE block] END */
 915   FuncState *fs = ls->fs;
 916   expdesc v;
 917   int escapelist = NO_JUMP;
 918   test_then_block(ls, &v);  /* IF cond THEN block */
 919   while (ls->t.token == TK_ELSEIF) {
 920     luaK_concat(fs, &escapelist, luaK_jump(fs));
 921     luaK_patchlist(fs, v.u.l.f, luaK_getlabel(fs));
 922     test_then_block(ls, &v);  /* ELSEIF cond THEN block */
 923   }
 924   if (ls->t.token == TK_ELSE) {
 925     luaK_concat(fs, &escapelist, luaK_jump(fs));
 926     luaK_patchlist(fs, v.u.l.f, luaK_getlabel(fs));
 927     next(ls);  /* skip ELSE */
 928     block(ls);  /* `else' part */
 929   }
 930   else
 931     luaK_concat(fs, &escapelist, v.u.l.f);
 932   luaK_patchlist(fs, escapelist, luaK_getlabel(fs));
 933   check_match(ls, TK_END, TK_IF, line);
 934 }
 935
 936
 937 static void localstat (LexState *ls) {
 938   /* stat -> LOCAL NAME {',' NAME} ['=' explist1] */
 939   int nvars = 0;
 940   int nexps;
 941   do {
 942     next(ls);  /* skip LOCAL or ',' */
 943     new_localvar(ls, str_checkname(ls), nvars++);
 944   } while (ls->t.token == ',');
 945   if (optional(ls, '='))
 946     nexps = explist1(ls);
 947   else
 948     nexps = 0;
 949   adjust_mult_assign(ls, nvars, nexps);
 950   adjustlocalvars(ls, nvars);
 951 }
 952
 953
 954 static int funcname (LexState *ls, expdesc *v) {
 955   /* funcname -> NAME [':' NAME | '.' NAME] */
 956   int needself = 0;
 957   singlevar(ls, str_checkname(ls), v);
 958   if (ls->t.token == ':' || ls->t.token == '.') {
 959     needself = (ls->t.token == ':');
 960     next(ls);
 961     luaK_tostack(ls, v, 1);
 962     luaK_kstr(ls, checkname(ls));
 963     v->k = VINDEXED;
 964   }
 965   return needself;
 966 }
 967
 968
 969 static void funcstat (LexState *ls, int line) {
 970   /* funcstat -> FUNCTION funcname body */
 971   int needself;
 972   expdesc v;
 973   next(ls);  /* skip FUNCTION */
 974   needself = funcname(ls, &v);
 975   body(ls, needself, line);
 976   luaK_storevar(ls, &v);
 977 }
 978
 979
 980 static void namestat (LexState *ls) {
 981   /* stat -> func | ['%'] NAME assignment */
 982   FuncState *fs = ls->fs;
 983   expdesc v;
 984   var_or_func(ls, &v);
 985   if (v.k == VEXP) {  /* stat -> func */
 986     check_condition(ls, luaK_lastisopen(fs), "syntax error");  /* an upvalue? */
 987     luaK_setcallreturns(fs, 0);  /* call statement uses no results */
 988   }
 989   else {  /* stat -> ['%'] NAME assignment */
 990     int left = assignment(ls, &v, 1);
 991     luaK_adjuststack(fs, left);  /* remove eventual garbage left on stack */
 992   }
 993 }
 994
 995
 996 static void retstat (LexState *ls) {
 997   /* stat -> RETURN explist */
 998   FuncState *fs = ls->fs;
 999   next(ls);  /* skip RETURN */
1000   if (!block_follow(ls->t.token))
1001     explist1(ls);  /* optional return values */
1002   luaK_code1(fs, OP_RETURN, ls->fs->nactloc);
1003   fs->stacklevel = fs->nactloc;  /* removes all temp values */
1004 }
1005
1006
1007 static void breakstat (LexState *ls) {
1008   /* stat -> BREAK [NAME] */
1009   FuncState *fs = ls->fs;
1010   int currentlevel = fs->stacklevel;
1011   Breaklabel *bl = fs->bl;
1012   if (!bl)
1013     luaK_error(ls, "no loop to break");
1014   next(ls);  /* skip BREAK */
1015   luaK_adjuststack(fs, currentlevel - bl->stacklevel);
1016   luaK_concat(fs, &bl->breaklist, luaK_jump(fs));
1017   /* correct stack for compiler and symbolic execution */
1018   luaK_adjuststack(fs, bl->stacklevel - currentlevel);
1019 }
1020
1021
1022 static int stat (LexState *ls) {
1023   int line = ls->linenumber;  /* may be needed for error messages */
1024   switch (ls->t.token) {
1025     case TK_IF: {  /* stat -> ifstat */
1026       ifstat(ls, line);
1027       return 0;
1028     }
1029     case TK_WHILE: {  /* stat -> whilestat */
1030       whilestat(ls, line);
1031       return 0;
1032     }
1033     case TK_DO: {  /* stat -> DO block END */
1034       next(ls);  /* skip DO */
1035       block(ls);
1036       check_match(ls, TK_END, TK_DO, line);
1037       return 0;
1038     }
1039     case TK_FOR: {  /* stat -> forstat */
1040       forstat(ls, line);
1041       return 0;
1042     }
1043     case TK_REPEAT: {  /* stat -> repeatstat */
1044       repeatstat(ls, line);
1045       return 0;
1046     }
1047     case TK_FUNCTION: {  /* stat -> funcstat */
1048       funcstat(ls, line);
1049       return 0;
1050     }
1051     case TK_LOCAL: {  /* stat -> localstat */
1052       localstat(ls);
1053       return 0;
1054     }
1055     case TK_NAME: case '%': {  /* stat -> namestat */
1056       namestat(ls);
1057       return 0;
1058     }
1059     case TK_RETURN: {  /* stat -> retstat */
1060       retstat(ls);
1061       return 1;  /* must be last statement */
1062     }
1063     case TK_BREAK: {  /* stat -> breakstat */
1064       breakstat(ls);
1065       return 1;  /* must be last statement */
1066     }
1067     default: {
1068       luaK_error(ls, "<statement> expected");
1069       return 0;  /* to avoid warnings */
1070     }
1071   }
1072 }
1073
1074
1075 static void parlist (LexState *ls) {
1076   /* parlist -> [ param { ',' param } ] */
1077   int nparams = 0;
1078   int dots = 0;
1079   if (ls->t.token != ')') {  /* is `parlist' not empty? */
1080     do {
1081       switch (ls->t.token) {
1082         case TK_DOTS: next(ls); dots = 1; break;
1083         case TK_NAME: new_localvar(ls, str_checkname(ls), nparams++); break;
1084         default: luaK_error(ls, "<name> or `...' expected");
1085       }
1086     } while (!dots && optional(ls, ','));
1087   }
1088   code_params(ls, nparams, dots);
1089 }
1090
1091
1092 static void body (LexState *ls, int needself, int line) {
1093   /* body ->  '(' parlist ')' chunk END */
1094   FuncState new_fs;
1095   open_func(ls, &new_fs);
1096   new_fs.f->lineDefined = line;
1097   check(ls, '(');
1098   if (needself) {
1099     new_localvarstr(ls, "self", 0);
1100     adjustlocalvars(ls, 1);
1101   }
1102   parlist(ls);
1103   check(ls, ')');
1104   chunk(ls);
1105   check_match(ls, TK_END, TK_FUNCTION, line);
1106   close_func(ls);
1107   pushclosure(ls, &new_fs);
1108 }
1109
1110
1111 /* }====================================================================== */
1112
1113
1114 static void chunk (LexState *ls) {
1115   /* chunk -> { stat [';'] } */
1116   int islast = 0;
1117   while (!islast && !block_follow(ls->t.token)) {
1118     islast = stat(ls);
1119     optional(ls, ';');
1120     LUA_ASSERT(ls->fs->stacklevel == ls->fs->nactloc,
1121                "stack size != # local vars");
1122   }
1123 }
1124