/*

 ** $Id: lparser.c,v 2.42.1.3 2007/12/28 15:32:23 roberto Exp $

 ** Lua Parser

 ** See Copyright Notice in lua.h

 */

 

 

 #include <string.h>

 

 #define lparser_c

 #define LUA_CORE

 

 #include "lua.h"

 

 #include "lcode.h"

 #include "ldebug.h"

 #include "ldo.h"

 #include "lfunc.h"

 #include "llex.h"

 #include "lmem.h"

 #include "lobject.h"

 #include "lopcodes.h"

 #include "lparser.h"

 #include "lstate.h"

 #include "lstring.h"

 #include "ltable.h"

 

 

 

 #define hasmultret(k)		((k) == VCALL || (k) == VVARARG)

 

 #define getlocvar(fs, i)	((fs)->f->locvars[(fs)->actvar[i]])

 

 #define luaY_checklimit(fs,v,l,m)	if ((v)>(l)) errorlimit(fs,l,m)

 

 

 /*

 ** nodes for block list (list of active blocks)

 */

 typedef struct BlockCnt {

   struct BlockCnt *previous;  /* chain */

   int breaklist;  /* list of jumps out of this loop */

   lu_byte nactvar;  /* # active locals outside the breakable structure */

   lu_byte upval;  /* true if some variable in the block is an upvalue */

   lu_byte isbreakable;  /* true if `block' is a loop */

 } BlockCnt;

 

 

 

 /*

 ** prototypes for recursive non-terminal functions

 */

 static void chunk (LexState *ls);

 static void expr (LexState *ls, expdesc *v);

 

 

 static void anchor_token (LexState *ls) {

   if (ls->t.token == TK_NAME || ls->t.token == TK_STRING) {

     TString *ts = ls->t.seminfo.ts;

     luaX_newstring(ls, getstr(ts), ts->tsv.len);

   }

 }

 

 

 static void error_expected (LexState *ls, int token) {

   luaX_syntaxerror(ls,

       luaO_pushfstring(ls->L, LUA_QS " expected", luaX_token2str(ls, token)));

 }

 

 

 static void errorlimit (FuncState *fs, int limit, const char *what) {

   const char *msg = (fs->f->linedefined == 0) ?

     luaO_pushfstring(fs->L, "main function has more than %d %s", limit, what) :

     luaO_pushfstring(fs->L, "function at line %d has more than %d %s",

                             fs->f->linedefined, limit, what);

   luaX_lexerror(fs->ls, msg, 0);

 }

 

 

 static int testnext (LexState *ls, int c) {

   if (ls->t.token == c) {

     luaX_next(ls);

     return 1;

   }

   else return 0;

 }

 

 

 static void check (LexState *ls, int c) {

   if (ls->t.token != c)

     error_expected(ls, c);

 }

 

 static void checknext (LexState *ls, int c) {

   check(ls, c);

   luaX_next(ls);

 }

 

 

 #define check_condition(ls,c,msg)	{ if (!(c)) luaX_syntaxerror(ls, msg); }

 

 

 

 static void check_match (LexState *ls, int what, int who, int where) {

   if (!testnext(ls, what)) {

     if (where == ls->linenumber)

       error_expected(ls, what);

     else {

       luaX_syntaxerror(ls, luaO_pushfstring(ls->L,

              LUA_QS " expected (to close " LUA_QS " at line %d)",

               luaX_token2str(ls, what), luaX_token2str(ls, who), where));

     }

   }

 }

 

 

 static TString *str_checkname (LexState *ls) {

   TString *ts;

   check(ls, TK_NAME);

   ts = ls->t.seminfo.ts;

   luaX_next(ls);

   return ts;

 }

 

 

 static void init_exp (expdesc *e, expkind k, int i) {

   e->f = e->t = NO_JUMP;

   e->k = k;

   e->u.s.info = i;

 }

 

 

 static void codestring (LexState *ls, expdesc *e, TString *s) {

   init_exp(e, VK, luaK_stringK(ls->fs, s));

 }

 

 

 static void checkname(LexState *ls, expdesc *e) {

   codestring(ls, e, str_checkname(ls));

 }

 

 

 static int registerlocalvar (LexState *ls, TString *varname) {

   FuncState *fs = ls->fs;

   Proto *f = fs->f;

   int oldsize = f->sizelocvars;

   luaM_growvector(ls->L, f->locvars, fs->nlocvars, f->sizelocvars,

                   LocVar, SHRT_MAX, "too many local variables");

   while (oldsize < f->sizelocvars) f->locvars[oldsize++].varname = NULL;

   f->locvars[fs->nlocvars].varname = varname;

   luaC_objbarrier(ls->L, f, varname);

   return fs->nlocvars++;

 }

 

 

 #define new_localvarliteral(ls,v,n) \

   new_localvar(ls, luaX_newstring(ls, "" v, (sizeof(v)/sizeof(char))-1), n)

 

 

 static void new_localvar (LexState *ls, TString *name, int n) {

   FuncState *fs = ls->fs;

   luaY_checklimit(fs, fs->nactvar+n+1, LUAI_MAXVARS, "local variables");

   fs->actvar[fs->nactvar+n] = cast(unsigned short, registerlocalvar(ls, name));

 }

 

 

 static void adjustlocalvars (LexState *ls, int nvars) {

   FuncState *fs = ls->fs;

   fs->nactvar = cast_byte(fs->nactvar + nvars);

   for (; nvars; nvars--) {

     getlocvar(fs, fs->nactvar - nvars).startpc = fs->pc;

   }

 }

 

 

 static void removevars (LexState *ls, int tolevel) {

   FuncState *fs = ls->fs;

   while (fs->nactvar > tolevel)

     getlocvar(fs, --fs->nactvar).endpc = fs->pc;

 }

 

 

 static int indexupvalue (FuncState *fs, TString *name, expdesc *v) {

   int i;

   Proto *f = fs->f;

   int oldsize = f->sizeupvalues;

   for (i=0; i<f->nups; i++) {

     if (fs->upvalues[i].k == v->k && fs->upvalues[i].info == v->u.s.info) {

       lua_assert(f->upvalues[i] == name);

       return i;

     }

   }

   /* new one */

   luaY_checklimit(fs, f->nups + 1, LUAI_MAXUPVALUES, "upvalues");

   luaM_growvector(fs->L, f->upvalues, f->nups, f->sizeupvalues,

                   TString *, MAX_INT, "");

   while (oldsize < f->sizeupvalues) f->upvalues[oldsize++] = NULL;

   f->upvalues[f->nups] = name;

   luaC_objbarrier(fs->L, f, name);

   lua_assert(v->k == VLOCAL || v->k == VUPVAL);

   fs->upvalues[f->nups].k = cast_byte(v->k);

   fs->upvalues[f->nups].info = cast_byte(v->u.s.info);

   return f->nups++;

 }

 

 

 static int searchvar (FuncState *fs, TString *n) {

   int i;

   for (i=fs->nactvar-1; i >= 0; i--) {

     if (n == getlocvar(fs, i).varname)

       return i;

   }

   return -1;  /* not found */

 }

 

 

 static void markupval (FuncState *fs, int level) {

   BlockCnt *bl = fs->bl;

   while (bl && bl->nactvar > level) bl = bl->previous;

   if (bl) bl->upval = 1;

 }

 

 

 static int singlevaraux (FuncState *fs, TString *n, expdesc *var, int base) {

   if (fs == NULL) {  /* no more levels? */

     init_exp(var, VGLOBAL, NO_REG);  /* default is global variable */

     return VGLOBAL;

   }

   else {

     int v = searchvar(fs, n);  /* look up at current level */

     if (v >= 0) {

       init_exp(var, VLOCAL, v);

       if (!base)

         markupval(fs, v);  /* local will be used as an upval */

       return VLOCAL;

     }

     else {  /* not found at current level; try upper one */

       if (singlevaraux(fs->prev, n, var, 0) == VGLOBAL)

         return VGLOBAL;

       var->u.s.info = indexupvalue(fs, n, var);  /* else was LOCAL or UPVAL */

       var->k = VUPVAL;  /* upvalue in this level */

       return VUPVAL;

     }

   }

 }

 

 

 static void singlevar (LexState *ls, expdesc *var) {

   TString *varname = str_checkname(ls);

   FuncState *fs = ls->fs;

   if (singlevaraux(fs, varname, var, 1) == VGLOBAL)

     var->u.s.info = luaK_stringK(fs, varname);  /* info points to global name */

 }

 

 

 static void adjust_assign (LexState *ls, int nvars, int nexps, expdesc *e) {

   FuncState *fs = ls->fs;

   int extra = nvars - nexps;

   if (hasmultret(e->k)) {

     extra++;  /* includes call itself */

     if (extra < 0) extra = 0;

     luaK_setreturns(fs, e, extra);  /* last exp. provides the difference */

     if (extra > 1) luaK_reserveregs(fs, extra-1);

   }

   else {

     if (e->k != VVOID) luaK_exp2nextreg(fs, e);  /* close last expression */

     if (extra > 0) {

       int reg = fs->freereg;

       luaK_reserveregs(fs, extra);

       luaK_nil(fs, reg, extra);

     }

   }

 }

 

 

 static void enterlevel (LexState *ls) {

   if (++ls->L->nCcalls > LUAI_MAXCCALLS)

 	luaX_lexerror(ls, "chunk has too many syntax levels", 0);

 }

 

 

 #define leavelevel(ls)	((ls)->L->nCcalls--)

 

 

 static void enterblock (FuncState *fs, BlockCnt *bl, lu_byte isbreakable) {

   bl->breaklist = NO_JUMP;

   bl->isbreakable = isbreakable;

   bl->nactvar = fs->nactvar;

   bl->upval = 0;

   bl->previous = fs->bl;

   fs->bl = bl;

   lua_assert(fs->freereg == fs->nactvar);

 }

 

 

 static void leaveblock (FuncState *fs) {

   BlockCnt *bl = fs->bl;

   fs->bl = bl->previous;

   removevars(fs->ls, bl->nactvar);

   if (bl->upval)

     luaK_codeABC(fs, OP_CLOSE, bl->nactvar, 0, 0);

   /* a block either controls scope or breaks (never both) */

   lua_assert(!bl->isbreakable || !bl->upval);

   lua_assert(bl->nactvar == fs->nactvar);

   fs->freereg = fs->nactvar;  /* free registers */

   luaK_patchtohere(fs, bl->breaklist);

 }

 

 

 static void pushclosure (LexState *ls, FuncState *func, expdesc *v) {

   FuncState *fs = ls->fs;

   Proto *f = fs->f;

   int oldsize = f->sizep;

   int i;

   luaM_growvector(ls->L, f->p, fs->np, f->sizep, Proto *,

                   MAXARG_Bx, "constant table overflow");

   while (oldsize < f->sizep) f->p[oldsize++] = NULL;

   f->p[fs->np++] = func->f;

   luaC_objbarrier(ls->L, f, func->f);

   init_exp(v, VRELOCABLE, luaK_codeABx(fs, OP_CLOSURE, 0, fs->np-1));

   for (i=0; i<func->f->nups; i++) {

     OpCode o = (func->upvalues[i].k == VLOCAL) ? OP_MOVE : OP_GETUPVAL;

     luaK_codeABC(fs, o, 0, func->upvalues[i].info, 0);

   }

 }

 

 

 static void open_func (LexState *ls, FuncState *fs) {

   lua_State *L = ls->L;

   Proto *f = luaF_newproto(L);

   fs->f = f;

   fs->prev = ls->fs;  /* linked list of funcstates */

   fs->ls = ls;

   fs->L = L;

   ls->fs = fs;

   fs->pc = 0;

   fs->lasttarget = -1;

   fs->jpc = NO_JUMP;

   fs->freereg = 0;

   fs->nk = 0;

   fs->np = 0;

   fs->nlocvars = 0;

   fs->nactvar = 0;

   fs->bl = NULL;

   f->source = ls->source;

   f->maxstacksize = 2;  /* registers 0/1 are always valid */

   fs->h = luaH_new(L, 0, 0);

   /* anchor table of constants and prototype (to avoid being collected) */

   sethvalue2s(L, L->top, fs->h);

   incr_top(L);

   setptvalue2s(L, L->top, f);

   incr_top(L);

 }

 

 

 static void close_func (LexState *ls) {

   lua_State *L = ls->L;

   FuncState *fs = ls->fs;

   Proto *f = fs->f;

   removevars(ls, 0);

   luaK_ret(fs, 0, 0);  /* final return */

   luaM_reallocvector(L, f->code, f->sizecode, fs->pc, Instruction);

   f->sizecode = fs->pc;

   luaM_reallocvector(L, f->lineinfo, f->sizelineinfo, fs->pc, int);

   f->sizelineinfo = fs->pc;

   luaM_reallocvector(L, f->k, f->sizek, fs->nk, TValue);

   f->sizek = fs->nk;

   luaM_reallocvector(L, f->p, f->sizep, fs->np, Proto *);

   f->sizep = fs->np;

   luaM_reallocvector(L, f->locvars, f->sizelocvars, fs->nlocvars, LocVar);

   f->sizelocvars = fs->nlocvars;

   luaM_reallocvector(L, f->upvalues, f->sizeupvalues, f->nups, TString *);

   f->sizeupvalues = f->nups;

   lua_assert(luaG_checkcode(f));

   lua_assert(fs->bl == NULL);

   ls->fs = fs->prev;

   L->top -= 2;  /* remove table and prototype from the stack */

   /* last token read was anchored in defunct function; must reanchor it */

   if (fs) anchor_token(ls);

 }

 

 

 Proto *luaY_parser (lua_State *L, ZIO *z, Mbuffer *buff, const char *name) {

   struct LexState lexstate;

   struct FuncState funcstate;

   lexstate.buff = buff;

   luaX_setinput(L, &lexstate, z, luaS_new(L, name));

   open_func(&lexstate, &funcstate);

   funcstate.f->is_vararg = VARARG_ISVARARG;  /* main func. is always vararg */

   luaX_next(&lexstate);  /* read first token */

   chunk(&lexstate);

   check(&lexstate, TK_EOS);

   close_func(&lexstate);

   lua_assert(funcstate.prev == NULL);

   lua_assert(funcstate.f->nups == 0);

   lua_assert(lexstate.fs == NULL);

   return funcstate.f;

 }

 

 

 

 /*============================================================*/

 /* GRAMMAR RULES */

 /*============================================================*/

 

 

 static void field (LexState *ls, expdesc *v) {

   /* field -> ['.' | ':'] NAME */

   FuncState *fs = ls->fs;

   expdesc key;

   luaK_exp2anyreg(fs, v);

   luaX_next(ls);  /* skip the dot or colon */

   checkname(ls, &key);

   luaK_indexed(fs, v, &key);

 }

 

 

 static void yindex (LexState *ls, expdesc *v) {

   /* index -> '[' expr ']' */

   luaX_next(ls);  /* skip the '[' */

   expr(ls, v);

   luaK_exp2val(ls->fs, v);

   checknext(ls, ']');

 }

 

 

 /*

 ** {======================================================================

 ** Rules for Constructors

 ** =======================================================================

 */

 

 

 struct ConsControl {

   expdesc v;  /* last list item read */

   expdesc *t;  /* table descriptor */

   int nh;  /* total number of `record' elements */

   int na;  /* total number of array elements */

   int tostore;  /* number of array elements pending to be stored */

 };

 

 

 static void recfield (LexState *ls, struct ConsControl *cc) {

   /* recfield -> (NAME | `['exp1`]') = exp1 */

   FuncState *fs = ls->fs;

   int reg = ls->fs->freereg;

   expdesc key, val;

   int rkkey;

   if (ls->t.token == TK_NAME) {

     luaY_checklimit(fs, cc->nh, MAX_INT, "items in a constructor");

     checkname(ls, &key);

   }

   else  /* ls->t.token == '[' */

     yindex(ls, &key);

   cc->nh++;

   checknext(ls, '=');

   rkkey = luaK_exp2RK(fs, &key);

   expr(ls, &val);

   luaK_codeABC(fs, OP_SETTABLE, cc->t->u.s.info, rkkey, luaK_exp2RK(fs, &val));

   fs->freereg = reg;  /* free registers */

 }

 

 

 static void closelistfield (FuncState *fs, struct ConsControl *cc) {

   if (cc->v.k == VVOID) return;  /* there is no list item */

   luaK_exp2nextreg(fs, &cc->v);

   cc->v.k = VVOID;

   if (cc->tostore == LFIELDS_PER_FLUSH) {

     luaK_setlist(fs, cc->t->u.s.info, cc->na, cc->tostore);  /* flush */

     cc->tostore = 0;  /* no more items pending */

   }

 }

 

 

 static void lastlistfield (FuncState *fs, struct ConsControl *cc) {

   if (cc->tostore == 0) return;

   if (hasmultret(cc->v.k)) {

     luaK_setmultret(fs, &cc->v);

     luaK_setlist(fs, cc->t->u.s.info, cc->na, LUA_MULTRET);

     cc->na--;  /* do not count last expression (unknown number of elements) */

   }

   else {

     if (cc->v.k != VVOID)

       luaK_exp2nextreg(fs, &cc->v);

     luaK_setlist(fs, cc->t->u.s.info, cc->na, cc->tostore);

   }

 }

 

 

 static void listfield (LexState *ls, struct ConsControl *cc) {

   expr(ls, &cc->v);

   luaY_checklimit(ls->fs, cc->na, MAX_INT, "items in a constructor");

   cc->na++;

   cc->tostore++;

 }

 

 

 static void constructor (LexState *ls, expdesc *t) {

   /* constructor -> ?? */

   FuncState *fs = ls->fs;

   int line = ls->linenumber;

   int pc = luaK_codeABC(fs, OP_NEWTABLE, 0, 0, 0);

   struct ConsControl cc;

   cc.na = cc.nh = cc.tostore = 0;

   cc.t = t;

   init_exp(t, VRELOCABLE, pc);

   init_exp(&cc.v, VVOID, 0);  /* no value (yet) */

   luaK_exp2nextreg(ls->fs, t);  /* fix it at stack top (for gc) */

   checknext(ls, '{');

   do {

     lua_assert(cc.v.k == VVOID || cc.tostore > 0);

     if (ls->t.token == '}') break;

     closelistfield(fs, &cc);

     switch(ls->t.token) {

       case TK_NAME: {  /* may be listfields or recfields */

         luaX_lookahead(ls);

         if (ls->lookahead.token != '=')  /* expression? */

           listfield(ls, &cc);

         else

           recfield(ls, &cc);

         break;

       }

       case '[': {  /* constructor_item -> recfield */

         recfield(ls, &cc);

         break;

       }

       default: {  /* constructor_part -> listfield */

         listfield(ls, &cc);

         break;

       }

     }

   } while (testnext(ls, ',') || testnext(ls, ';'));

   check_match(ls, '}', '{', line);

   lastlistfield(fs, &cc);

   SETARG_B(fs->f->code[pc], luaO_int2fb(cc.na)); /* set initial array size */

   SETARG_C(fs->f->code[pc], luaO_int2fb(cc.nh));  /* set initial table size */

 }

 

 /* }====================================================================== */

 

 

 

 static void parlist (LexState *ls) {

   /* parlist -> [ param { `,' param } ] */

   FuncState *fs = ls->fs;

   Proto *f = fs->f;

   int nparams = 0;

   f->is_vararg = 0;

   if (ls->t.token != ')') {  /* is `parlist' not empty? */

     do {

       switch (ls->t.token) {

         case TK_NAME: {  /* param -> NAME */

           new_localvar(ls, str_checkname(ls), nparams++);

           break;

         }

         case TK_DOTS: {  /* param -> `...' */

           luaX_next(ls);

 #if defined(LUA_COMPAT_VARARG)

           /* use `arg' as default name */

           new_localvarliteral(ls, "arg", nparams++);

           f->is_vararg = VARARG_HASARG | VARARG_NEEDSARG;

 #endif

           f->is_vararg |= VARARG_ISVARARG;

           break;

         }

         default: luaX_syntaxerror(ls, "<name> or " LUA_QL("...") " expected");

       }

     } while (!f->is_vararg && testnext(ls, ','));

   }

   adjustlocalvars(ls, nparams);

   f->numparams = cast_byte(fs->nactvar - (f->is_vararg & VARARG_HASARG));

   luaK_reserveregs(fs, fs->nactvar);  /* reserve register for parameters */

 }

 

 

 static void body (LexState *ls, expdesc *e, int needself, int line) {

   /* body ->  `(' parlist `)' chunk END */

   FuncState new_fs;

   open_func(ls, &new_fs);

   new_fs.f->linedefined = line;

   checknext(ls, '(');

   if (needself) {

     new_localvarliteral(ls, "self", 0);

     adjustlocalvars(ls, 1);

   }

   parlist(ls);

   checknext(ls, ')');

   chunk(ls);

   new_fs.f->lastlinedefined = ls->linenumber;

   check_match(ls, TK_END, TK_FUNCTION, line);

   close_func(ls);

   pushclosure(ls, &new_fs, e);

 }

 

 

 static int explist1 (LexState *ls, expdesc *v) {

   /* explist1 -> expr { `,' expr } */

   int n = 1;  /* at least one expression */

   expr(ls, v);

   while (testnext(ls, ',')) {

     luaK_exp2nextreg(ls->fs, v);

     expr(ls, v);

     n++;

   }

   return n;

 }

 

 

 static void funcargs (LexState *ls, expdesc *f) {

   FuncState *fs = ls->fs;

   expdesc args;

   int base, nparams;

   int line = ls->linenumber;

   switch (ls->t.token) {

     case '(': {  /* funcargs -> `(' [ explist1 ] `)' */

       if (line != ls->lastline)

         luaX_syntaxerror(ls,"ambiguous syntax (function call x new statement)");

       luaX_next(ls);

       if (ls->t.token == ')')  /* arg list is empty? */

         args.k = VVOID;

       else {

         explist1(ls, &args);

         luaK_setmultret(fs, &args);

       }

       check_match(ls, ')', '(', line);

       break;

     }

     case '{': {  /* funcargs -> constructor */

       constructor(ls, &args);

       break;

     }

     case TK_STRING: {  /* funcargs -> STRING */

       codestring(ls, &args, ls->t.seminfo.ts);

       luaX_next(ls);  /* must use `seminfo' before `next' */

       break;

     }

     default: {

       luaX_syntaxerror(ls, "function arguments expected");

       return;

     }

   }

   lua_assert(f->k == VNONRELOC);

   base = f->u.s.info;  /* base register for call */

   if (hasmultret(args.k))

     nparams = LUA_MULTRET;  /* open call */

   else {

     if (args.k != VVOID)

       luaK_exp2nextreg(fs, &args);  /* close last argument */

     nparams = fs->freereg - (base+1);

   }

   init_exp(f, VCALL, luaK_codeABC(fs, OP_CALL, base, nparams+1, 2));

   luaK_fixline(fs, line);

   fs->freereg = base+1;  /* call remove function and arguments and leaves

                             (unless changed) one result */

 }

 

 

 

 

 /*

 ** {======================================================================

 ** Expression parsing

 ** =======================================================================

 */

 

 

 static void prefixexp (LexState *ls, expdesc *v) {

   /* prefixexp -> NAME | '(' expr ')' */

   switch (ls->t.token) {

     case '(': {

       int line = ls->linenumber;

       luaX_next(ls);

       expr(ls, v);

       check_match(ls, ')', '(', line);

       luaK_dischargevars(ls->fs, v);

       return;

     }

     case TK_NAME: {

       singlevar(ls, v);

       return;

     }

     default: {

       luaX_syntaxerror(ls, "unexpected symbol");

       return;

     }

   }

 }

 

 

 static void primaryexp (LexState *ls, expdesc *v) {

   /* primaryexp ->

         prefixexp { `.' NAME | `[' exp `]' | `:' NAME funcargs | funcargs } */

   FuncState *fs = ls->fs;

   prefixexp(ls, v);

   for (;;) {

     switch (ls->t.token) {

       case '.': {  /* field */

         field(ls, v);

         break;

       }

       case '[': {  /* `[' exp1 `]' */

         expdesc key;

         luaK_exp2anyreg(fs, v);

         yindex(ls, &key);

         luaK_indexed(fs, v, &key);

         break;

       }

       case ':': {  /* `:' NAME funcargs */

         expdesc key;

         luaX_next(ls);

         checkname(ls, &key);

         luaK_self(fs, v, &key);

         funcargs(ls, v);

         break;

       }

       case '(': case TK_STRING: case '{': {  /* funcargs */

         luaK_exp2nextreg(fs, v);

         funcargs(ls, v);

         break;

       }

       default: return;

     }

   }

 }

 

 

 static void simpleexp (LexState *ls, expdesc *v) {

   /* simpleexp -> NUMBER | STRING | NIL | true | false | ... |

                   constructor | FUNCTION body | primaryexp */

   switch (ls->t.token) {

     case TK_NUMBER: {

       init_exp(v, VKNUM, 0);

       v->u.nval = ls->t.seminfo.r;

       break;

     }

     case TK_STRING: {

       codestring(ls, v, ls->t.seminfo.ts);

       break;

     }

     case TK_NIL: {

       init_exp(v, VNIL, 0);

       break;

     }

     case TK_TRUE: {

       init_exp(v, VTRUE, 0);

       break;

     }

     case TK_FALSE: {

       init_exp(v, VFALSE, 0);

       break;

     }

     case TK_DOTS: {  /* vararg */

       FuncState *fs = ls->fs;

       check_condition(ls, fs->f->is_vararg,

                       "cannot use " LUA_QL("...") " outside a vararg function");

       fs->f->is_vararg &= ~VARARG_NEEDSARG;  /* don't need 'arg' */

       init_exp(v, VVARARG, luaK_codeABC(fs, OP_VARARG, 0, 1, 0));

       break;

     }

     case '{': {  /* constructor */

       constructor(ls, v);

       return;

     }

     case TK_FUNCTION: {

       luaX_next(ls);

       body(ls, v, 0, ls->linenumber);

       return;

     }

     default: {

       primaryexp(ls, v);

       return;

     }

   }

   luaX_next(ls);

 }

 

 

 static UnOpr getunopr (int op) {

   switch (op) {

     case TK_NOT: return OPR_NOT;

     case '-': return OPR_MINUS;

     case '#': return OPR_LEN;

     default: return OPR_NOUNOPR;

   }

 }

 

 

 static BinOpr getbinopr (int op) {

   switch (op) {

     case '+': return OPR_ADD;

     case '-': return OPR_SUB;

     case '*': return OPR_MUL;

     case '/': return OPR_DIV;

     case '%': return OPR_MOD;

     case '^': return OPR_POW;

     case TK_CONCAT: return OPR_CONCAT;

     case TK_NE: return OPR_NE;

     case TK_EQ: return OPR_EQ;

     case '<': return OPR_LT;

     case TK_LE: return OPR_LE;

     case '>': return OPR_GT;

     case TK_GE: return OPR_GE;

     case TK_AND: return OPR_AND;

     case TK_OR: return OPR_OR;

     default: return OPR_NOBINOPR;

   }

 }

 

 

 static const struct {

   lu_byte left;  /* left priority for each binary operator */

   lu_byte right; /* right priority */

 } priority[] = {  /* ORDER OPR */

    {6, 6}, {6, 6}, {7, 7}, {7, 7}, {7, 7},  /* `+' `-' `/' `%' */

    {10, 9}, {5, 4},                 /* power and concat (right associative) */

    {3, 3}, {3, 3},                  /* equality and inequality */

    {3, 3}, {3, 3}, {3, 3}, {3, 3},  /* order */

    {2, 2}, {1, 1}                   /* logical (and/or) */

 };

 

 #define UNARY_PRIORITY	8  /* priority for unary operators */

 

 

 /*

 ** subexpr -> (simpleexp | unop subexpr) { binop subexpr }

 ** where `binop' is any binary operator with a priority higher than `limit'

 */

 static BinOpr subexpr (LexState *ls, expdesc *v, unsigned int limit) {

   BinOpr op;

   UnOpr uop;

   enterlevel(ls);

   uop = getunopr(ls->t.token);

   if (uop != OPR_NOUNOPR) {

     luaX_next(ls);

     subexpr(ls, v, UNARY_PRIORITY);

     luaK_prefix(ls->fs, uop, v);

   }

   else simpleexp(ls, v);

   /* expand while operators have priorities higher than `limit' */

   op = getbinopr(ls->t.token);

   while (op != OPR_NOBINOPR && priority[op].left > limit) {

     expdesc v2;

     BinOpr nextop;

     luaX_next(ls);

     luaK_infix(ls->fs, op, v);

     /* read sub-expression with higher priority */

     nextop = subexpr(ls, &v2, priority[op].right);

     luaK_posfix(ls->fs, op, v, &v2);

     op = nextop;

   }

   leavelevel(ls);

   return op;  /* return first untreated operator */

 }

 

 

 static void expr (LexState *ls, expdesc *v) {

   subexpr(ls, v, 0);

 }

 

 /* }==================================================================== */

 

 

 

 /*

 ** {======================================================================

 ** Rules for Statements

 ** =======================================================================

 */

 

 

 static int block_follow (int token) {

   switch (token) {

     case TK_ELSE: case TK_ELSEIF: case TK_END:

     case TK_UNTIL: case TK_EOS:

       return 1;

     default: return 0;

   }

 }

 

 

 static void block (LexState *ls) {

   /* block -> chunk */

   FuncState *fs = ls->fs;

   BlockCnt bl;

   enterblock(fs, &bl, 0);

   chunk(ls);

   lua_assert(bl.breaklist == NO_JUMP);

   leaveblock(fs);

 }

 

 

 /*

 ** structure to chain all variables in the left-hand side of an

 ** assignment

 */

 struct LHS_assign {

   struct LHS_assign *prev;

   expdesc v;  /* variable (global, local, upvalue, or indexed) */

 };

 

 

 /*

 ** check whether, in an assignment to a local variable, the local variable

 ** is needed in a previous assignment (to a table). If so, save original

 ** local value in a safe place and use this safe copy in the previous

 ** assignment.

 */

 static void check_conflict (LexState *ls, struct LHS_assign *lh, expdesc *v) {

   FuncState *fs = ls->fs;

   int extra = fs->freereg;  /* eventual position to save local variable */

   int conflict = 0;

   for (; lh; lh = lh->prev) {

     if (lh->v.k == VINDEXED) {

       if (lh->v.u.s.info == v->u.s.info) {  /* conflict? */

         conflict = 1;

         lh->v.u.s.info = extra;  /* previous assignment will use safe copy */

       }

       if (lh->v.u.s.aux == v->u.s.info) {  /* conflict? */

         conflict = 1;

         lh->v.u.s.aux = extra;  /* previous assignment will use safe copy */

       }

     }

   }

   if (conflict) {

     luaK_codeABC(fs, OP_MOVE, fs->freereg, v->u.s.info, 0);  /* make copy */

     luaK_reserveregs(fs, 1);

   }

 }

 

 

 static void assignment (LexState *ls, struct LHS_assign *lh, int nvars) {

   expdesc e;

   check_condition(ls, VLOCAL <= lh->v.k && lh->v.k <= VINDEXED,

                       "syntax error");

   if (testnext(ls, ',')) {  /* assignment -> `,' primaryexp assignment */

     struct LHS_assign nv;

     nv.prev = lh;

     primaryexp(ls, &nv.v);

     if (nv.v.k == VLOCAL)

       check_conflict(ls, lh, &nv.v);

     luaY_checklimit(ls->fs, nvars, LUAI_MAXCCALLS - ls->L->nCcalls,

                     "variables in assignment");

     assignment(ls, &nv, nvars+1);

   }

   else {  /* assignment -> `=' explist1 */

     int nexps;

     checknext(ls, '=');

     nexps = explist1(ls, &e);

     if (nexps != nvars) {

       adjust_assign(ls, nvars, nexps, &e);

       if (nexps > nvars)

         ls->fs->freereg -= nexps - nvars;  /* remove extra values */

     }

     else {

       luaK_setoneret(ls->fs, &e);  /* close last expression */

       luaK_storevar(ls->fs, &lh->v, &e);

       return;  /* avoid default */

     }

   }

   init_exp(&e, VNONRELOC, ls->fs->freereg-1);  /* default assignment */

   luaK_storevar(ls->fs, &lh->v, &e);

 }

 

 

 static int cond (LexState *ls) {

   /* cond -> exp */

   expdesc v;

   expr(ls, &v);  /* read condition */

   if (v.k == VNIL) v.k = VFALSE;  /* `falses' are all equal here */

   luaK_goiftrue(ls->fs, &v);

   return v.f;

 }

 

 

 static void breakstat (LexState *ls) {

   FuncState *fs = ls->fs;

   BlockCnt *bl = fs->bl;

   int upval = 0;

   while (bl && !bl->isbreakable) {

     upval |= bl->upval;

     bl = bl->previous;

   }

   if (!bl)

     luaX_syntaxerror(ls, "no loop to break");

   if (upval)

     luaK_codeABC(fs, OP_CLOSE, bl->nactvar, 0, 0);

   luaK_concat(fs, &bl->breaklist, luaK_jump(fs));

 }

 

 

 static void whilestat (LexState *ls, int line) {

   /* whilestat -> WHILE cond DO block END */

   FuncState *fs = ls->fs;

   int whileinit;

   int condexit;

   BlockCnt bl;

   luaX_next(ls);  /* skip WHILE */

   whileinit = luaK_getlabel(fs);

   condexit = cond(ls);

   enterblock(fs, &bl, 1);

   checknext(ls, TK_DO);

   block(ls);

   luaK_patchlist(fs, luaK_jump(fs), whileinit);

   check_match(ls, TK_END, TK_WHILE, line);

   leaveblock(fs);

   luaK_patchtohere(fs, condexit);  /* false conditions finish the loop */

 }

 

 

 static void repeatstat (LexState *ls, int line) {

   /* repeatstat -> REPEAT block UNTIL cond */

   int condexit;

   FuncState *fs = ls->fs;

   int repeat_init = luaK_getlabel(fs);

   BlockCnt bl1, bl2;

   enterblock(fs, &bl1, 1);  /* loop block */

   enterblock(fs, &bl2, 0);  /* scope block */

   luaX_next(ls);  /* skip REPEAT */

   chunk(ls);

   check_match(ls, TK_UNTIL, TK_REPEAT, line);

   condexit = cond(ls);  /* read condition (inside scope block) */

   if (!bl2.upval) {  /* no upvalues? */

     leaveblock(fs);  /* finish scope */

     luaK_patchlist(ls->fs, condexit, repeat_init);  /* close the loop */

   }

   else {  /* complete semantics when there are upvalues */

     breakstat(ls);  /* if condition then break */

     luaK_patchtohere(ls->fs, condexit);  /* else... */

     leaveblock(fs);  /* finish scope... */

     luaK_patchlist(ls->fs, luaK_jump(fs), repeat_init);  /* and repeat */

   }

   leaveblock(fs);  /* finish loop */

 }

 

 

 static int exp1 (LexState *ls) {

   expdesc e;

   int k;

   expr(ls, &e);

   k = e.k;

   luaK_exp2nextreg(ls->fs, &e);

   return k;

 }

 

 

 static void forbody (LexState *ls, int base, int line, int nvars, int isnum) {

   /* forbody -> DO block */

   BlockCnt bl;

   FuncState *fs = ls->fs;

   int prep, endfor;

   adjustlocalvars(ls, 3);  /* control variables */

   checknext(ls, TK_DO);

   prep = isnum ? luaK_codeAsBx(fs, OP_FORPREP, base, NO_JUMP) : luaK_jump(fs);

   enterblock(fs, &bl, 0);  /* scope for declared variables */

   adjustlocalvars(ls, nvars);

   luaK_reserveregs(fs, nvars);

   block(ls);

   leaveblock(fs);  /* end of scope for declared variables */

   luaK_patchtohere(fs, prep);

   endfor = (isnum) ? luaK_codeAsBx(fs, OP_FORLOOP, base, NO_JUMP) :

                      luaK_codeABC(fs, OP_TFORLOOP, base, 0, nvars);

   luaK_fixline(fs, line);  /* pretend that `OP_FOR' starts the loop */

   luaK_patchlist(fs, (isnum ? endfor : luaK_jump(fs)), prep + 1);

 }

 

 

 static void fornum (LexState *ls, TString *varname, int line) {

   /* fornum -> NAME = exp1,exp1[,exp1] forbody */

   FuncState *fs = ls->fs;

   int base = fs->freereg;

   new_localvarliteral(ls, "(for index)", 0);

   new_localvarliteral(ls, "(for limit)", 1);

   new_localvarliteral(ls, "(for step)", 2);

   new_localvar(ls, varname, 3);

   checknext(ls, '=');

   exp1(ls);  /* initial value */

   checknext(ls, ',');

   exp1(ls);  /* limit */

   if (testnext(ls, ','))

     exp1(ls);  /* optional step */

   else {  /* default step = 1 */

     luaK_codeABx(fs, OP_LOADK, fs->freereg, luaK_numberK(fs, 1));

     luaK_reserveregs(fs, 1);

   }

   forbody(ls, base, line, 1, 1);

 }

 

 

 static void forlist (LexState *ls, TString *indexname) {

   /* forlist -> NAME {,NAME} IN explist1 forbody */

   FuncState *fs = ls->fs;

   expdesc e;

   int nvars = 0;

   int line;

   int base = fs->freereg;

   /* create control variables */

   new_localvarliteral(ls, "(for generator)", nvars++);

   new_localvarliteral(ls, "(for state)", nvars++);

   new_localvarliteral(ls, "(for control)", nvars++);

   /* create declared variables */

   new_localvar(ls, indexname, nvars++);

   while (testnext(ls, ','))

     new_localvar(ls, str_checkname(ls), nvars++);

   checknext(ls, TK_IN);

   line = ls->linenumber;

   adjust_assign(ls, 3, explist1(ls, &e), &e);

   luaK_checkstack(fs, 3);  /* extra space to call generator */

   forbody(ls, base, line, nvars - 3, 0);

 }

 

 

 static void forstat (LexState *ls, int line) {

   /* forstat -> FOR (fornum | forlist) END */

   FuncState *fs = ls->fs;

   TString *varname;

   BlockCnt bl;

   enterblock(fs, &bl, 1);  /* scope for loop and control variables */

   luaX_next(ls);  /* skip `for' */

   varname = str_checkname(ls);  /* first variable name */

   switch (ls->t.token) {

     case '=': fornum(ls, varname, line); break;

     case ',': case TK_IN: forlist(ls, varname); break;

     default: luaX_syntaxerror(ls, LUA_QL("=") " or " LUA_QL("in") " expected");

   }

   check_match(ls, TK_END, TK_FOR, line);

   leaveblock(fs);  /* loop scope (`break' jumps to this point) */

 }

 

 

 static int test_then_block (LexState *ls) {

   /* test_then_block -> [IF | ELSEIF] cond THEN block */

   int condexit;

   luaX_next(ls);  /* skip IF or ELSEIF */

   condexit = cond(ls);

   checknext(ls, TK_THEN);

   block(ls);  /* `then' part */

   return condexit;

 }

 

 

 static void ifstat (LexState *ls, int line) {

   /* ifstat -> IF cond THEN block {ELSEIF cond THEN block} [ELSE block] END */

   FuncState *fs = ls->fs;

   int flist;

   int escapelist = NO_JUMP;

   flist = test_then_block(ls);  /* IF cond THEN block */

   while (ls->t.token == TK_ELSEIF) {

     luaK_concat(fs, &escapelist, luaK_jump(fs));

     luaK_patchtohere(fs, flist);

     flist = test_then_block(ls);  /* ELSEIF cond THEN block */

   }

   if (ls->t.token == TK_ELSE) {

     luaK_concat(fs, &escapelist, luaK_jump(fs));

     luaK_patchtohere(fs, flist);

     luaX_next(ls);  /* skip ELSE (after patch, for correct line info) */

     block(ls);  /* `else' part */

   }

   else

     luaK_concat(fs, &escapelist, flist);

   luaK_patchtohere(fs, escapelist);

   check_match(ls, TK_END, TK_IF, line);

 }

 

 

 static void localfunc (LexState *ls) {

   expdesc v, b;

   FuncState *fs = ls->fs;

   new_localvar(ls, str_checkname(ls), 0);

   init_exp(&v, VLOCAL, fs->freereg);

   luaK_reserveregs(fs, 1);

   adjustlocalvars(ls, 1);

   body(ls, &b, 0, ls->linenumber);

   luaK_storevar(fs, &v, &b);

   /* debug information will only see the variable after this point! */

   getlocvar(fs, fs->nactvar - 1).startpc = fs->pc;

 }

 

 

 static void localstat (LexState *ls) {

   /* stat -> LOCAL NAME {`,' NAME} [`=' explist1] */

   int nvars = 0;

   int nexps;

   expdesc e;

   do {

     new_localvar(ls, str_checkname(ls), nvars++);

   } while (testnext(ls, ','));

   if (testnext(ls, '='))

     nexps = explist1(ls, &e);

   else {

     e.k = VVOID;

     nexps = 0;

   }

   adjust_assign(ls, nvars, nexps, &e);

   adjustlocalvars(ls, nvars);

 }

 

 

 static int funcname (LexState *ls, expdesc *v) {

   /* funcname -> NAME {field} [`:' NAME] */

   int needself = 0;

   singlevar(ls, v);

   while (ls->t.token == '.')

     field(ls, v);

   if (ls->t.token == ':') {

     needself = 1;

     field(ls, v);

   }

   return needself;

 }

 

 

 static void funcstat (LexState *ls, int line) {

   /* funcstat -> FUNCTION funcname body */

   int needself;

   expdesc v, b;

   luaX_next(ls);  /* skip FUNCTION */

   needself = funcname(ls, &v);

   body(ls, &b, needself, line);

   luaK_storevar(ls->fs, &v, &b);

   luaK_fixline(ls->fs, line);  /* definition `happens' in the first line */

 }

 

 

 static void exprstat (LexState *ls) {

   /* stat -> func | assignment */

   FuncState *fs = ls->fs;

   struct LHS_assign v;

   primaryexp(ls, &v.v);

   if (v.v.k == VCALL)  /* stat -> func */

     SETARG_C(getcode(fs, &v.v), 1);  /* call statement uses no results */

   else {  /* stat -> assignment */

     v.prev = NULL;

     assignment(ls, &v, 1);

   }

 }

 

 

 static void retstat (LexState *ls) {

   /* stat -> RETURN explist */

   FuncState *fs = ls->fs;

   expdesc e;

   int first, nret;  /* registers with returned values */

   luaX_next(ls);  /* skip RETURN */

   if (block_follow(ls->t.token) || ls->t.token == ';')

     first = nret = 0;  /* return no values */

   else {

     nret = explist1(ls, &e);  /* optional return values */

     if (hasmultret(e.k)) {

       luaK_setmultret(fs, &e);

       if (e.k == VCALL && nret == 1) {  /* tail call? */

         SET_OPCODE(getcode(fs,&e), OP_TAILCALL);

         lua_assert(GETARG_A(getcode(fs,&e)) == fs->nactvar);

       }

       first = fs->nactvar;

       nret = LUA_MULTRET;  /* return all values */

     }

     else {

       if (nret == 1)  /* only one single value? */

         first = luaK_exp2anyreg(fs, &e);

       else {

         luaK_exp2nextreg(fs, &e);  /* values must go to the `stack' */

         first = fs->nactvar;  /* return all `active' values */

         lua_assert(nret == fs->freereg - first);

       }

     }

   }

   luaK_ret(fs, first, nret);

 }

 

 

 static int statement (LexState *ls) {

   int line = ls->linenumber;  /* may be needed for error messages */

   switch (ls->t.token) {

     case TK_IF: {  /* stat -> ifstat */

       ifstat(ls, line);

       return 0;

     }

     case TK_WHILE: {  /* stat -> whilestat */

       whilestat(ls, line);

       return 0;

     }

     case TK_DO: {  /* stat -> DO block END */

       luaX_next(ls);  /* skip DO */

       block(ls);

       check_match(ls, TK_END, TK_DO, line);

       return 0;

     }

     case TK_FOR: {  /* stat -> forstat */

       forstat(ls, line);

       return 0;

     }

     case TK_REPEAT: {  /* stat -> repeatstat */

       repeatstat(ls, line);

       return 0;

     }

     case TK_FUNCTION: {

       funcstat(ls, line);  /* stat -> funcstat */

       return 0;

     }

     case TK_LOCAL: {  /* stat -> localstat */

       luaX_next(ls);  /* skip LOCAL */

       if (testnext(ls, TK_FUNCTION))  /* local function? */

         localfunc(ls);

       else

         localstat(ls);

       return 0;

     }

     case TK_RETURN: {  /* stat -> retstat */

       retstat(ls);

       return 1;  /* must be last statement */

     }

     case TK_BREAK: {  /* stat -> breakstat */

       luaX_next(ls);  /* skip BREAK */

       breakstat(ls);

       return 1;  /* must be last statement */

     }

     default: {

       exprstat(ls);

       return 0;  /* to avoid warnings */

     }

   }

 }

 

 

 static void chunk (LexState *ls) {

   /* chunk -> { stat [`;'] } */

   int islast = 0;

   enterlevel(ls);

   while (!islast && !block_follow(ls->t.token)) {

     islast = statement(ls);

     testnext(ls, ';');

     lua_assert(ls->fs->f->maxstacksize >= ls->fs->freereg &&

                ls->fs->freereg >= ls->fs->nactvar);

     ls->fs->freereg = ls->fs->nactvar;  /* free registers */

   }

   leavelevel(ls);

 }

 

 /* }====================================================================== */