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      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 
   1639