text:
/*
** $Id: lparser.c,v 2.155.1.2 2017/04/29 18:11:40 roberto Exp $
** Lua Parser
** See Copyright Notice in lua.h
*/

#define lparser_c
#define LUA_CORE

#include "lprefix.h"

#include <string.h>

#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"

/* maximum number of local variables per function (must be smaller
   than 250, due to the bytecode format) */
#define MAXVARS		200

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

/* because all strings are unified by the scanner, the parser
   can use pointer equality for string equality */
#define eqstr(a,b)	((a) == (b))

/*
** nodes for block list (list of active blocks)
*/
typedef struct BlockCnt {
  struct BlockCnt *previous;  /* chain */
  int firstlabel;  /* index of first label in this block */
  int firstgoto;  /* index of first pending goto in this block */
  lu_byte nactvar;  /* # active locals outside the block */
  lu_byte upval;  /* true if some variable in the block is an upvalue */
  lu_byte isloop;  /* true if 'block' is a loop */
} BlockCnt;

/*
** prototypes for recursive non-terminal functions
*/
static void statement (LexState *ls);
static void expr (LexState *ls, expdesc *v);

/* semantic error */
static l_noret semerror (LexState *ls, const char *msg) {
  ls->t.token = 0;  /* remove "near <token>" from final message */
  luaX_syntaxerror(ls, msg);
}

static l_noret error_expected (LexState *ls, int token) {
  luaX_syntaxerror(ls,
      luaO_pushfstring(ls->L, "%s expected", luaX_token2str(ls, token)));
}

static l_noret errorlimit (FuncState *fs, int limit, const char *what) {
  lua_State *L = fs->ls->L;
  const char *msg;
  int line = fs->f->linedefined;
  const char *where = (line == 0)
                      ? "main function"
                      : luaO_pushfstring(L, "function at line %d", line);
  msg = luaO_pushfstring(L, "too many %s (limit is %d) in %s",
                             what, limit, where);
  luaX_syntaxerror(fs->ls, msg);
}

static void checklimit (FuncState *fs, int v, int l, const char *what) {
  if (v > l) errorlimit(fs, l, what);
}

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,
             "%s expected (to close %s 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.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, "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++;
}

static void new_localvar (LexState *ls, TString *name) {
  FuncState *fs = ls->fs;
  Dyndata *dyd = ls->dyd;
  int reg = registerlocalvar(ls, name);
  checklimit(fs, dyd->actvar.n + 1 - fs->firstlocal,
                  MAXVARS, "local variables");
  luaM_growvector(ls->L, dyd->actvar.arr, dyd->actvar.n + 1,
                  dyd->actvar.size, Vardesc, MAX_INT, "local variables");
  dyd->actvar.arr[dyd->actvar.n++].idx = cast(short, reg);
}

static void new_localvarliteral_ (LexState *ls, const char *name, size_t sz) {
  new_localvar(ls, luaX_newstring(ls, name, sz));
}

#define new_localvarliteral(ls,v) \
	new_localvarliteral_(ls, "" v, (sizeof(v)/sizeof(char))-1)

static LocVar *getlocvar (FuncState *fs, int i) {
  int idx = fs->ls->dyd->actvar.arr[fs->firstlocal + i].idx;
  lua_assert(idx < fs->nlocvars);
  return &fs->f->locvars[idx];
}

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 (FuncState *fs, int tolevel) {
  fs->ls->dyd->actvar.n -= (fs->nactvar - tolevel);
  while (fs->nactvar > tolevel)
    getlocvar(fs, --fs->nactvar)->endpc = fs->pc;
}

static int searchupvalue (FuncState *fs, TString *name) {
  int i;
  Upvaldesc *up = fs->f->upvalues;
  for (i = 0; i < fs->nups; i++) {
    if (eqstr(up[i].name, name)) return i;
  }
  return -1;  /* not found */
}

static int newupvalue (FuncState *fs, TString *name, expdesc *v) {
  Proto *f = fs->f;
  int oldsize = f->sizeupvalues;
  checklimit(fs, fs->nups + 1, MAXUPVAL, "upvalues");
  luaM_growvector(fs->ls->L, f->upvalues, fs->nups, f->sizeupvalues,
                  Upvaldesc, MAXUPVAL, "upvalues");
  while (oldsize < f->sizeupvalues)
    f->upvalues[oldsize++].name = NULL;
  f->upvalues[fs->nups].instack = (v->k == VLOCAL);
  f->upvalues[fs->nups].idx = cast_byte(v->u.info);
  f->upvalues[fs->nups].name = name;
  luaC_objbarrier(fs->ls->L, f, name);
  return fs->nups++;
}

static int searchvar (FuncState *fs, TString *n) {
  int i;
  for (i = cast_int(fs->nactvar) - 1; i >= 0; i--) {
    if (eqstr(n, getlocvar(fs, i)->varname))
      return i;
  }
  return -1;  /* not found */
}

/*
  Mark block where variable at given level was defined
  (to emit close instructions later).
*/
static void markupval (FuncState *fs, int level) {
  BlockCnt *bl = fs->bl;
  while (bl->nactvar > level)
    bl = bl->previous;
  bl->upval = 1;
}

/*
  Find variable with given name 'n'. If it is an upvalue, add this
  upvalue into all intermediate functions.
*/
static void singlevaraux (FuncState *fs, TString *n, expdesc *var, int base) {
  if (fs == NULL)  /* no more levels? */
    init_exp(var, VVOID, 0);  /* default is global */
  else {
    int v = searchvar(fs, n);  /* look up locals at current level */
    if (v >= 0) {  /* found? */
      init_exp(var, VLOCAL, v);  /* variable is local */
      if (!base)
        markupval(fs, v);  /* local will be used as an upval */
    }
    else {  /* not found as local at current level; try upvalues */
      int idx = searchupvalue(fs, n);  /* try existing upvalues */
      if (idx < 0) {  /* not found? */
        singlevaraux(fs->prev, n, var, 0);  /* try upper levels */
        if (var->k == VVOID)  /* not found? */
          return;  /* it is a global */
        /* else was LOCAL or UPVAL */
        idx  = newupvalue(fs, n, var);  /* will be a new upvalue */
      }
      init_exp(var, VUPVAL, idx);  /* new or old upvalue */
    }
  }
}

static void singlevar (LexState *ls, expdesc *var) {
  TString *varname = str_checkname(ls);
  FuncState *fs = ls->fs;
  singlevaraux(fs, varname, var, 1);
  if (var->k == VVOID) {  /* global name? */
    expdesc key;
    singlevaraux(fs, ls->envn, var, 1);  /* get environment variable */
    lua_assert(var->k != VVOID);  /* this one must exist */
    codestring(ls, &key, varname);  /* key is variable name */
    luaK_indexed(fs, var, &key);  /* env[varname] */
  }
}

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);
    }
  }
  if (nexps > nvars)
    ls->fs->freereg -= nexps - nvars;  /* remove extra values */
}

static void enterlevel (LexState *ls) {
  lua_State *L = ls->L;
  ++L->nCcalls;
  checklimit(ls->fs, L->nCcalls, LUAI_MAXCCALLS, "C levels");
}

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

static void closegoto (LexState *ls, int g, Labeldesc *label) {
  int i;
  FuncState *fs = ls->fs;
  Labellist *gl = &ls->dyd->gt;
  Labeldesc *gt = &gl->arr[g];
  lua_assert(eqstr(gt->name, label->name));
  if (gt->nactvar < label->nactvar) {
    TString *vname = getlocvar(fs, gt->nactvar)->varname;
    const char *msg = luaO_pushfstring(ls->L,
      "<goto %s> at line %d jumps into the scope of local '%s'",
      getstr(gt->name), gt->line, getstr(vname));
    semerror(ls, msg);
  }
  luaK_patchlist(fs, gt->pc, label->pc);
  /* remove goto from pending list */
  for (i = g; i < gl->n - 1; i++)
    gl->arr[i] = gl->arr[i + 1];
  gl->n--;
}

/*
** try to close a goto with existing labels; this solves backward jumps
*/
static int findlabel (LexState *ls, int g) {
  int i;
  BlockCnt *bl = ls->fs->bl;
  Dyndata *dyd = ls->dyd;
  Labeldesc *gt = &dyd->gt.arr[g];
  /* check labels in current block for a match */
  for (i = bl->firstlabel; i < dyd->label.n; i++) {
    Labeldesc *lb = &dyd->label.arr[i];
    if (eqstr(lb->name, gt->name)) {  /* correct label? */
      if (gt->nactvar > lb->nactvar &&
          (bl->upval || dyd->label.n > bl->firstlabel))
        luaK_patchclose(ls->fs, gt->pc, lb->nactvar);
      closegoto(ls, g, lb);  /* close it */
      return 1;
    }
  }
  return 0;  /* label not found; cannot close goto */
}

static int newlabelentry (LexState *ls, Labellist *l, TString *name,
                          int line, int pc) {
  int n = l->n;
  luaM_growvector(ls->L, l->arr, n, l->size,
                  Labeldesc, SHRT_MAX, "labels/gotos");
  l->arr[n].name = name;
  l->arr[n].line = line;
  l->arr[n].nactvar = ls->fs->nactvar;
  l->arr[n].pc = pc;
  l->n = n + 1;
  return n;
}

/*
** check whether new label 'lb' matches any pending gotos in current
** block; solves forward jumps
*/
static void findgotos (LexState *ls, Labeldesc *lb) {
  Labellist *gl = &ls->dyd->gt;
  int i = ls->fs->bl->firstgoto;
  while (i < gl->n) {
    if (eqstr(gl->arr[i].name, lb->name))
      closegoto(ls, i, lb);
    else
      i++;
  }
}

/*
** export pending gotos to outer level, to check them against
** outer labels; if the block being exited has upvalues, and
** the goto exits the scope of any variable (which can be the
** upvalue), close those variables being exited.
*/
static void movegotosout (FuncState *fs, BlockCnt *bl) {
  int i = bl->firstgoto;
  Labellist *gl = &fs->ls->dyd->gt;
  /* correct pending gotos to current block and try to close it
     with visible labels */
  while (i < gl->n) {
    Labeldesc *gt = &gl->arr[i];
    if (gt->nactvar > bl->nactvar) {
      if (bl->upval)
        luaK_patchclose(fs, gt->pc, bl->nactvar);
      gt->nactvar = bl->nactvar;
    }
    if (!findlabel(fs->ls, i))
      i++;  /* move to next one */
  }
}

static void enterblock (FuncState *fs, BlockCnt *bl, lu_byte isloop) {
  bl->isloop = isloop;
  bl->nactvar = fs->nactvar;
  bl->firstlabel = fs->ls->dyd->label.n;
  bl->firstgoto = fs->ls->dyd->gt.n;
  bl->upval = 0;
  bl->previous = fs->bl;
  fs->bl = bl;
  lua_assert(fs->freereg == fs->nactvar);
}

/*
** create a label named 'break' to resolve break statements
*/
static void breaklabel (LexState *ls) {
  TString *n = luaS_new(ls->L, "break");
  int l = newlabelentry(ls, &ls->dyd->label, n, 0, ls->fs->pc);
  findgotos(ls, &ls->dyd->label.arr[l]);
}

/*
** generates an error for an undefined 'goto'; choose appropriate
** message when label name is a reserved word (which can only be 'break')
*/
static l_noret undefgoto (LexState *ls, Labeldesc *gt) {
  const char *msg = isreserved(gt->name)
                    ? "<%s> at line %d not inside a loop"
                    : "no visible label '%s' for <goto> at line %d";
  msg = luaO_pushfstring(ls->L, msg, getstr(gt->name), gt->line);
  semerror(ls, msg);
}

static void leaveblock (FuncState *fs) {
  BlockCnt *bl = fs->bl;
  LexState *ls = fs->ls;
  if (bl->previous && bl->upval) {
    /* create a 'jump to here' to close upvalues */
    int j = luaK_jump(fs);
    luaK_patchclose(fs, j, bl->nactvar);
    luaK_patchtohere(fs, j);
  }
  if (bl->isloop)
    breaklabel(ls);  /* close pending breaks */
  fs->bl = bl->previous;
  removevars(fs, bl->nactvar);
  lua_assert(bl->nactvar == fs->nactvar);
  fs->freereg = fs->nactvar;  /* free registers */
  ls->dyd->label.n = bl->firstlabel;  /* remove local labels */
  if (bl->previous)  /* inner block? */
    movegotosout(fs, bl);  /* update pending gotos to outer block */
  else if (bl->firstgoto < ls->dyd->gt.n)  /* pending gotos in outer block? */
    undefgoto(ls, &ls->dyd->gt.arr[bl->firstgoto]);  /* error */
}

/*
** adds a new prototype into list of prototypes
*/
static Proto *addprototype (LexState *ls) {
  Proto *clp;
  lua_State *L = ls->L;
  FuncState *fs = ls->fs;
  Proto *f = fs->f;  /* prototype of current function */
  if (fs->np >= f->sizep) {
    int oldsize = f->sizep;
    luaM_growvector(L, f->p, fs->np, f->sizep, Proto *, MAXARG_Bx, "functions");
    while (oldsize < f->sizep)
      f->p[oldsize++] = NULL;
  }
  f->p[fs->np++] = clp = luaF_newproto(L);
  luaC_objbarrier(L, f, clp);
  return clp;
}

/*
** codes instruction to create new closure in parent function.
** The OP_CLOSURE instruction must use the last available register,
** so that, if it invokes the GC, the GC knows which registers
** are in use at that time.
*/
static void codeclosure (LexState *ls, expdesc *v) {
  FuncState *fs = ls->fs->prev;
  init_exp(v, VRELOCABLE, luaK_codeABx(fs, OP_CLOSURE, 0, fs->np - 1));
  luaK_exp2nextreg(fs, v);  /* fix it at the last register */
}

static void open_func (LexState *ls, FuncState *fs, BlockCnt *bl) {
  Proto *f;
  fs->prev = ls->fs;  /* linked list of funcstates */
  fs->ls = ls;
  ls->fs = fs;
  fs->pc = 0;
  fs->lasttarget = 0;
  fs->jpc = NO_JUMP;
  fs->freereg = 0;
  fs->nk = 0;
  fs->np = 0;
  fs->nups = 0;
  fs->nlocvars = 0;
  fs->nactvar = 0;
  fs->firstlocal = ls->dyd->actvar.n;
  fs->bl = NULL;
  f = fs->f;
  f->source = ls->source;
  f->maxstacksize = 2;  /* registers 0/1 are always valid */
  enterblock(fs, bl, 0);
}

static void close_func (LexState *ls) {
  lua_State *L = ls->L;
  FuncState *fs = ls->fs;
  Proto *f = fs->f;
  luaK_ret(fs, 0, 0);  /* final return */
  leaveblock(fs);
  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, fs->nups, Upvaldesc);
  f->sizeupvalues = fs->nups;
  lua_assert(fs->bl == NULL);
  ls->fs = fs->prev;
  luaC_checkGC(L);
}

/*============================================================*/
/* GRAMMAR RULES */
/*============================================================*/

/*
** check whether current token is in the follow set of a block.
** 'until' closes syntactical blocks, but do not close scope,
** so it is handled in separate.
*/
static int block_follow (LexState *ls, int withuntil) {
  switch (ls->t.token) {
    case TK_ELSE: case TK_ELSEIF:
    case TK_END: case TK_EOS:
      return 1;
    case TK_UNTIL: return withuntil;
    default: return 0;
  }
}

static void statlist (LexState *ls) {
  /* statlist -> { stat [';'] } */
  while (!block_follow(ls, 1)) {
    if (ls->t.token == TK_RETURN) {
      statement(ls);
      return;  /* 'return' must be last statement */
    }
    statement(ls);
  }
}

static void fieldsel (LexState *ls, expdesc *v) {
  /* fieldsel -> ['.' | ':'] NAME */
  FuncState *fs = ls->fs;
  expdesc key;
  luaK_exp2anyregup(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) {
    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.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.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.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.info, cc->na, cc->tostore);
  }
}

static void listfield (LexState *ls, struct ConsControl *cc) {
  /* listfield -> exp */
  expr(ls, &cc->v);
  checklimit(ls->fs, cc->na, MAX_INT, "items in a constructor");
  cc->na++;
  cc->tostore++;
}

static void field (LexState *ls, struct ConsControl *cc) {
  /* field -> listfield | recfield */
  switch(ls->t.token) {
    case TK_NAME: {  /* may be 'listfield' or 'recfield' */
      if (luaX_lookahead(ls) != '=')  /* expression? */
        listfield(ls, cc);
      else
        recfield(ls, cc);
      break;
    }
    case '[': {
      recfield(ls, cc);
      break;
    }
    default: {
      listfield(ls, cc);
      break;
    }
  }
}

static void constructor (LexState *ls, expdesc *t) {
  /* constructor -> '{' [ field { sep field } [sep] ] '}'
     sep -> ',' | ';' */
  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 */
  checknext(ls, '{');
  do {
    lua_assert(cc.v.k == VVOID || cc.tostore > 0);
    if (ls->t.token == '}') break;
    closelistfield(fs, &cc);
    field(ls, &cc);
  } 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);
          f->is_vararg = 1;  /* declared vararg */
          break;
        }
        default: luaX_syntaxerror(ls, "<name> or '...' expected");
      }
    } while (!f->is_vararg && testnext(ls, ','));
  }
  adjustlocalvars(ls, nparams);
  f->numparams = cast_byte(fs->nactvar);
  luaK_reserveregs(fs, fs->nactvar);  /* reserve register for parameters */
}

static void body (LexState *ls, expdesc *e, int ismethod, int line) {
  /* body ->  '(' parlist ')' block END */
  FuncState new_fs;
  BlockCnt bl;
  new_fs.f = addprototype(ls);
  new_fs.f->linedefined = line;
  open_func(ls, &new_fs, &bl);
  checknext(ls, '(');
  if (ismethod) {
    new_localvarliteral(ls, "self");  /* create 'self' parameter */
    adjustlocalvars(ls, 1);
  }
  parlist(ls);
  checknext(ls, ')');
  statlist(ls);
  new_fs.f->lastlinedefined = ls->linenumber;
  check_match(ls, TK_END, TK_FUNCTION, line);
  codeclosure(ls, e);
  close_func(ls);
}

static int explist (LexState *ls, expdesc *v) {
  /* explist -> 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, int line) {
  FuncState *fs = ls->fs;
  expdesc args;
  int base, nparams;
  switch (ls->t.token) {
    case '(': {  /* funcargs -> '(' [ explist ] ')' */
      luaX_next(ls);
      if (ls->t.token == ')')  /* arg list is empty? */
        args.k = VVOID;
      else {
        explist(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");
    }
  }
  lua_assert(f->k == VNONRELOC);
  base = f->u.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 primaryexp (LexState *ls, expdesc *v) {
  /* primaryexp -> 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");
    }
  }
}

static void suffixedexp (LexState *ls, expdesc *v) {
  /* suffixedexp ->
       primaryexp { '.' NAME | '[' exp ']' | ':' NAME funcargs | funcargs } */
  FuncState *fs = ls->fs;
  int line = ls->linenumber;
  primaryexp(ls, v);
  for (;;) {
    switch (ls->t.token) {
      case '.': {  /* fieldsel */
        fieldsel(ls, v);
        break;
      }
      case '[': {  /* '[' exp1 ']' */
        expdesc key;
        luaK_exp2anyregup(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, line);
        break;
      }
      case '(': case TK_STRING: case '{': {  /* funcargs */
        luaK_exp2nextreg(fs, v);
        funcargs(ls, v, line);
        break;
      }
      default: return;
    }
  }
}

static void simpleexp (LexState *ls, expdesc *v) {
  /* simpleexp -> FLT | INT | STRING | NIL | TRUE | FALSE | ... |
                  constructor | FUNCTION body | suffixedexp */
  switch (ls->t.token) {
    case TK_FLT: {
      init_exp(v, VKFLT, 0);
      v->u.nval = ls->t.seminfo.r;
      break;
    }
    case TK_INT: {
      init_exp(v, VKINT, 0);
      v->u.ival = ls->t.seminfo.i;
      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 '...' outside a vararg function");
      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: {
      suffixedexp(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_BNOT;
    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_MOD;
    case '^': return OPR_POW;
    case '/': return OPR_DIV;
    case TK_IDIV: return OPR_IDIV;
    case '&': return OPR_BAND;
    case '|': return OPR_BOR;
    case '~': return OPR_BXOR;
    case TK_SHL: return OPR_SHL;
    case TK_SHR: return OPR_SHR;
    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 */
   {10, 10}, {10, 10},           /* '+' '-' */
   {11, 11}, {11, 11},           /* '*' '%' */
   {14, 13},                  /* '^' (right associative) */
   {11, 11}, {11, 11},           /* '/' '//' */
   {6, 6}, {4, 4}, {5, 5},   /* '&' '|' '~' */
   {7, 7}, {7, 7},           /* '<<' '>>' */
   {9, 8},                   /* '..' (right associative) */
   {3, 3}, {3, 3}, {3, 3},   /* ==, <, <= */
   {3, 3}, {3, 3}, {3, 3},   /* ~=, >, >= */
   {2, 2}, {1, 1}            /* and, or */
};

#define UNARY_PRIORITY	12  /* 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, int limit) {
  BinOpr op;
  UnOpr uop;
  enterlevel(ls);
  uop = getunopr(ls->t.token);
  if (uop != OPR_NOUNOPR) {
    int line = ls->linenumber;
    luaX_next(ls);
    subexpr(ls, v, UNARY_PRIORITY);
    luaK_prefix(ls->fs, uop, v, line);
  }
  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;
    int line = ls->linenumber;
    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, line);
    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 void block (LexState *ls) {
  /* block -> statlist */
  FuncState *fs = ls->fs;
  BlockCnt bl;
  enterblock(fs, &bl, 0);
  statlist(ls);
  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 an upvalue/local variable, the
** upvalue/local variable is begin used in a previous assignment to a
** table. If so, save original upvalue/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) {  /* check all previous assignments */
    if (lh->v.k == VINDEXED) {  /* assigning to a table? */
      /* table is the upvalue/local being assigned now? */
      if (lh->v.u.ind.vt == v->k && lh->v.u.ind.t == v->u.info) {
        conflict = 1;
        lh->v.u.ind.vt = VLOCAL;
        lh->v.u.ind.t = extra;  /* previous assignment will use safe copy */
      }
      /* index is the local being assigned? (index cannot be upvalue) */
      if (v->k == VLOCAL && lh->v.u.ind.idx == v->u.info) {
        conflict = 1;
        lh->v.u.ind.idx = extra;  /* previous assignment will use safe copy */
      }
    }
  }
  if (conflict) {
    /* copy upvalue/local value to a temporary (in position 'extra') */
    OpCode op = (v->k == VLOCAL) ? OP_MOVE : OP_GETUPVAL;
    luaK_codeABC(fs, op, extra, v->u.info, 0);
    luaK_reserveregs(fs, 1);
  }
}

static void assignment (LexState *ls, struct LHS_assign *lh, int nvars) {
  expdesc e;
  check_condition(ls, vkisvar(lh->v.k), "syntax error");
  if (testnext(ls, ',')) {  /* assignment -> ',' suffixedexp assignment */
    struct LHS_assign nv;
    nv.prev = lh;
    suffixedexp(ls, &nv.v);
    if (nv.v.k != VINDEXED)
      check_conflict(ls, lh, &nv.v);
    checklimit(ls->fs, nvars + ls->L->nCcalls, LUAI_MAXCCALLS,
                    "C levels");
    assignment(ls, &nv, nvars+1);
  }
  else {  /* assignment -> '=' explist */
    int nexps;
    checknext(ls, '=');
    nexps = explist(ls, &e);
    if (nexps != nvars)
      adjust_assign(ls, nvars, nexps, &e);
    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 gotostat (LexState *ls, int pc) {
  int line = ls->linenumber;
  TString *label;
  int g;
  if (testnext(ls, TK_GOTO))
    label = str_checkname(ls);
  else {
    luaX_next(ls);  /* skip break */
    label = luaS_new(ls->L, "break");
  }
  g = newlabelentry(ls, &ls->dyd->gt, label, line, pc);
  findlabel(ls, g);  /* close it if label already defined */
}

/* check for repeated labels on the same block */
static void checkrepeated (FuncState *fs, Labellist *ll, TString *label) {
  int i;
  for (i = fs->bl->firstlabel; i < ll->n; i++) {
    if (eqstr(label, ll->arr[i].name)) {
      const char *msg = luaO_pushfstring(fs->ls->L,
                          "label '%s' already defined on line %d",
                          getstr(label), ll->arr[i].line);
      semerror(fs->ls, msg);
    }
  }
}

/* skip no-op statements */
static void skipnoopstat (LexState *ls) {
  while (ls->t.token == ';' || ls->t.token == TK_DBCOLON)
    statement(ls);
}

static void labelstat (LexState *ls, TString *label, int line) {
  /* label -> '::' NAME '::' */
  FuncState *fs = ls->fs;
  Labellist *ll = &ls->dyd->label;
  int l;  /* index of new label being created */
  checkrepeated(fs, ll, label);  /* check for repeated labels */
  checknext(ls, TK_DBCOLON);  /* skip double colon */
  /* create new entry for this label */
  l = newlabelentry(ls, ll, label, line, luaK_getlabel(fs));
  skipnoopstat(ls);  /* skip other no-op statements */
  if (block_follow(ls, 0)) {  /* label is last no-op statement in the block? */
    /* assume that locals are already out of scope */
    ll->arr[l].nactvar = fs->bl->nactvar;
  }
  findgotos(ls, &ll->arr[l]);
}

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_jumpto(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 */
  statlist(ls);
  check_match(ls, TK_UNTIL, TK_REPEAT, line);
  condexit = cond(ls);  /* read condition (inside scope block) */
  if (bl2.upval)  /* upvalues? */
    luaK_patchclose(fs, condexit, bl2.nactvar);
  leaveblock(fs);  /* finish scope */
  luaK_patchlist(fs, condexit, repeat_init);  /* close the loop */
  leaveblock(fs);  /* finish loop */
}

static int exp1 (LexState *ls) {
  expdesc e;
  int reg;
  expr(ls, &e);
  luaK_exp2nextreg(ls->fs, &e);
  lua_assert(e.k == VNONRELOC);
  reg = e.u.info;
  return reg;
}

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);
  if (isnum)  /* numeric for? */
    endfor = luaK_codeAsBx(fs, OP_FORLOOP, base, NO_JUMP);
  else {  /* generic for */
    luaK_codeABC(fs, OP_TFORCALL, base, 0, nvars);
    luaK_fixline(fs, line);
    endfor = luaK_codeAsBx(fs, OP_TFORLOOP, base + 2, NO_JUMP);
  }
  luaK_patchlist(fs, endfor, prep + 1);
  luaK_fixline(fs, line);
}

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)");
  new_localvarliteral(ls, "(for limit)");
  new_localvarliteral(ls, "(for step)");
  new_localvar(ls, varname);
  checknext(ls, '=');
  exp1(ls);  /* initial value */
  checknext(ls, ',');
  exp1(ls);  /* limit */
  if (testnext(ls, ','))
    exp1(ls);  /* optional step */
  else {  /* default step = 1 */
    luaK_codek(fs, fs->freereg, luaK_intK(fs, 1));
    luaK_reserveregs(fs, 1);
  }
  forbody(ls, base, line, 1, 1);
}

static void forlist (LexState *ls, TString *indexname) {
  /* forlist -> NAME {,NAME} IN explist forbody */
  FuncState *fs = ls->fs;
  expdesc e;
  int nvars = 4;  /* gen, state, control, plus at least one declared var */
  int line;
  int base = fs->freereg;
  /* create control variables */
  new_localvarliteral(ls, "(for generator)");
  new_localvarliteral(ls, "(for state)");
  new_localvarliteral(ls, "(for control)");
  /* create declared variables */
  new_localvar(ls, indexname);
  while (testnext(ls, ',')) {
    new_localvar(ls, str_checkname(ls));
    nvars++;
  }
  checknext(ls, TK_IN);
  line = ls->linenumber;
  adjust_assign(ls, 3, explist(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, "'=' or 'in' expected");
  }
  check_match(ls, TK_END, TK_FOR, line);
  leaveblock(fs);  /* loop scope ('break' jumps to this point) */
}

static void test_then_block (LexState *ls, int *escapelist) {
  /* test_then_block -> [IF | ELSEIF] cond THEN block */
  BlockCnt bl;
  FuncState *fs = ls->fs;
  expdesc v;
  int jf;  /* instruction to skip 'then' code (if condition is false) */
  luaX_next(ls);  /* skip IF or ELSEIF */
  expr(ls, &v);  /* read condition */
  checknext(ls, TK_THEN);
  if (ls->t.token == TK_GOTO || ls->t.token == TK_BREAK) {
    luaK_goiffalse(ls->fs, &v);  /* will jump to label if condition is true */
    enterblock(fs, &bl, 0);  /* must enter block before 'goto' */
    gotostat(ls, v.t);  /* handle goto/break */
    while (testnext(ls, ';')) {}  /* skip colons */
    if (block_follow(ls, 0)) {  /* 'goto' is the entire block? */
      leaveblock(fs);
      return;  /* and that is it */
    }
    else  /* must skip over 'then' part if condition is false */
      jf = luaK_jump(fs);
  }
  else {  /* regular case (not goto/break) */
    luaK_goiftrue(ls->fs, &v);  /* skip over block if condition is false */
    enterblock(fs, &bl, 0);
    jf = v.f;
  }
  statlist(ls);  /* 'then' part */
  leaveblock(fs);
  if (ls->t.token == TK_ELSE ||
      ls->t.token == TK_ELSEIF)  /* followed by 'else'/'elseif'? */
    luaK_concat(fs, escapelist, luaK_jump(fs));  /* must jump over it */
  luaK_patchtohere(fs, jf);
}

static void ifstat (LexState *ls, int line) {
  /* ifstat -> IF cond THEN block {ELSEIF cond THEN block} [ELSE block] END */
  FuncState *fs = ls->fs;
  int escapelist = NO_JUMP;  /* exit list for finished parts */
  test_then_block(ls, &escapelist);  /* IF cond THEN block */
  while (ls->t.token == TK_ELSEIF)
    test_then_block(ls, &escapelist);  /* ELSEIF cond THEN block */
  if (testnext(ls, TK_ELSE))
    block(ls);  /* 'else' part */
  check_match(ls, TK_END, TK_IF, line);
  luaK_patchtohere(fs, escapelist);  /* patch escape list to 'if' end */
}

static void localfunc (LexState *ls) {
  expdesc b;
  FuncState *fs = ls->fs;
  new_localvar(ls, str_checkname(ls));  /* new local variable */
  adjustlocalvars(ls, 1);  /* enter its scope */
  body(ls, &b, 0, ls->linenumber);  /* function created in next register */
  /* debug information will only see the variable after this point! */
  getlocvar(fs, b.u.info)->startpc = fs->pc;
}

static void localstat (LexState *ls) {
  /* stat -> LOCAL NAME {',' NAME} ['=' explist] */
  int nvars = 0;
  int nexps;
  expdesc e;
  do {
    new_localvar(ls, str_checkname(ls));
    nvars++;
  } while (testnext(ls, ','));
  if (testnext(ls, '='))
    nexps = explist(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 {fieldsel} [':' NAME] */
  int ismethod = 0;
  singlevar(ls, v);
  while (ls->t.token == '.')
    fieldsel(ls, v);
  if (ls->t.token == ':') {
    ismethod = 1;
    fieldsel(ls, v);
  }
  return ismethod;
}

static void funcstat (LexState *ls, int line) {
  /* funcstat -> FUNCTION funcname body */
  int ismethod;
  expdesc v, b;
  luaX_next(ls);  /* skip FUNCTION */
  ismethod = funcname(ls, &v);
  body(ls, &b, ismethod, 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;
  suffixedexp(ls, &v.v);
  if (ls->t.token == '=' || ls->t.token == ',') { /* stat -> assignment ? */
    v.prev = NULL;
    assignment(ls, &v, 1);
  }
  else {  /* stat -> func */
    check_condition(ls, v.v.k == VCALL, "syntax error");
    SETARG_C(getinstruction(fs, &v.v), 1);  /* call statement uses no results */
  }
}

static void retstat (LexState *ls) {
  /* stat -> RETURN [explist] [';'] */
  FuncState *fs = ls->fs;
  expdesc e;
  int first, nret;  /* registers with returned values */
  if (block_follow(ls, 1) || ls->t.token == ';')
    first = nret = 0;  /* return no values */
  else {
    nret = explist(ls, &e);  /* optional return values */
    if (hasmultret(e.k)) {
      luaK_setmultret(fs, &e);
      if (e.k == VCALL && nret == 1) {  /* tail call? */
        SET_OPCODE(getinstruction(fs,&e), OP_TAILCALL);
        lua_assert(GETARG_A(getinstruction(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);
  testnext(ls, ';');  /* skip optional semicolon */
}

static void statement (LexState *ls) {
  int line = ls->linenumber;  /* may be needed for error messages */
  enterlevel(ls);
  switch (ls->t.token) {
    case ';': {  /* stat -> ';' (empty statement) */
      luaX_next(ls);  /* skip ';' */
      break;
    }
    case TK_IF: {  /* stat -> ifstat */
      ifstat(ls, line);
      break;
    }
    case TK_WHILE: {  /* stat -> whilestat */
      whilestat(ls, line);
      break;
    }
    case TK_DO: {  /* stat -> DO block END */
      luaX_next(ls);  /* skip DO */
      block(ls);
      check_match(ls, TK_END, TK_DO, line);
      break;
    }
    case TK_FOR: {  /* stat -> forstat */
      forstat(ls, line);
      break;
    }
    case TK_REPEAT: {  /* stat -> repeatstat */
      repeatstat(ls, line);
      break;
    }
    case TK_FUNCTION: {  /* stat -> funcstat */
      funcstat(ls, line);
      break;
    }
    case TK_LOCAL: {  /* stat -> localstat */
      luaX_next(ls);  /* skip LOCAL */
      if (testnext(ls, TK_FUNCTION))  /* local function? */
        localfunc(ls);
      else
        localstat(ls);
      break;
    }
    case TK_DBCOLON: {  /* stat -> label */
      luaX_next(ls);  /* skip double colon */
      labelstat(ls, str_checkname(ls), line);
      break;
    }
    case TK_RETURN: {  /* stat -> retstat */
      luaX_next(ls);  /* skip RETURN */
      retstat(ls);
      break;
    }
    case TK_BREAK:   /* stat -> breakstat */
    case TK_GOTO: {  /* stat -> 'goto' NAME */
      gotostat(ls, luaK_jump(ls->fs));
      break;
    }
    default: {  /* stat -> func | assignment */
      exprstat(ls);
      break;
    }
  }
  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);
}

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

/*
** compiles the main function, which is a regular vararg function with an
** upvalue named LUA_ENV
*/
static void mainfunc (LexState *ls, FuncState *fs) {
  BlockCnt bl;
  expdesc v;
  open_func(ls, fs, &bl);
  fs->f->is_vararg = 1;  /* main function is always declared vararg */
  init_exp(&v, VLOCAL, 0);  /* create and... */
  newupvalue(fs, ls->envn, &v);  /* ...set environment upvalue */
  luaX_next(ls);  /* read first token */
  statlist(ls);  /* parse main body */
  check(ls, TK_EOS);
  close_func(ls);
}

LClosure *luaY_parser (lua_State *L, ZIO *z, Mbuffer *buff,
                       Dyndata *dyd, const char *name, int firstchar) {
  LexState lexstate;
  FuncState funcstate;
  LClosure *cl = luaF_newLclosure(L, 1);  /* create main closure */
  setclLvalue(L, L->top, cl);  /* anchor it (to avoid being collected) */
  luaD_inctop(L);
  lexstate.h = luaH_new(L);  /* create table for scanner */
  sethvalue(L, L->top, lexstate.h);  /* anchor it */
  luaD_inctop(L);
  funcstate.f = cl->p = luaF_newproto(L);
  funcstate.f->source = luaS_new(L, name);  /* create and anchor TString */
  lua_assert(iswhite(funcstate.f));  /* do not need barrier here */
  lexstate.buff = buff;
  lexstate.dyd = dyd;
  dyd->actvar.n = dyd->gt.n = dyd->label.n = 0;
  luaX_setinput(L, &lexstate, z, funcstate.f->source, firstchar);
  mainfunc(&lexstate, &funcstate);
  lua_assert(!funcstate.prev && funcstate.nups == 1 && !lexstate.fs);
  /* all scopes should be correctly finished */
  lua_assert(dyd->actvar.n == 0 && dyd->gt.n == 0 && dyd->label.n == 0);
  L->top--;  /* remove scanner's table */
  return cl;  /* closure is on the stack, too */
}


text:
/*
** $Id: ldo.c,v 2.157.1.1 2017/04/19 17:20:42 roberto Exp $
** Stack and Call structure of Lua
** See Copyright Notice in lua.h
*/

#define ldo_c
#define LUA_CORE

#include "lprefix.h"

#include <setjmp.h>
#include <stdlib.h>
#include <string.h>

#include "lua.h"

#include "lapi.h"
#include "ldebug.h"
#include "ldo.h"
#include "lfunc.h"
#include "lgc.h"
#include "lmem.h"
#include "lobject.h"
#include "lopcodes.h"
#include "lparser.h"
#include "lstate.h"
#include "lstring.h"
#include "ltable.h"
#include "ltm.h"
#include "lundump.h"
#include "lvm.h"
#include "lzio.h"

#define errorstatus(s)	((s) > LUA_YIELD)

/*
** {======================================================
** Error-recovery functions
** =======================================================
*/

/*
** LUAI_THROW/LUAI_TRY define how Lua does exception handling. By
** default, Lua handles errors with exceptions when compiling as
** C++ code, with _longjmp/_setjmp when asked to use them, and with
** longjmp/setjmp otherwise.
*/
#if !defined(LUAI_THROW)				/* { */

#if defined(__cplusplus) && !defined(LUA_USE_LONGJMP)	/* { */

/* C++ exceptions */
#define LUAI_THROW(L,c)		throw(c)
#define LUAI_TRY(L,c,a) \
	try { a } catch(...) { if ((c)->status == 0) (c)->status = -1; }
#define luai_jmpbuf		int  /* dummy variable */

#elif defined(LUA_USE_POSIX)				/* }{ */

/* in POSIX, try _longjmp/_setjmp (more efficient) */
#define LUAI_THROW(L,c)		_longjmp((c)->b, 1)
#define LUAI_TRY(L,c,a)		if (_setjmp((c)->b) == 0) { a }
#define luai_jmpbuf		jmp_buf

#else							/* }{ */

/* ISO C handling with long jumps */
#define LUAI_THROW(L,c)		longjmp((c)->b, 1)
#define LUAI_TRY(L,c,a)		if (setjmp((c)->b) == 0) { a }
#define luai_jmpbuf		jmp_buf

#endif							/* } */

#endif							/* } */

/* chain list of long jump buffers */
struct lua_longjmp {
  struct lua_longjmp *previous;
  luai_jmpbuf b;
  volatile int status;  /* error code */
};

static void seterrorobj (lua_State *L, int errcode, StkId oldtop) {
  switch (errcode) {
    case LUA_ERRMEM: {  /* memory error? */
      setsvalue2s(L, oldtop, G(L)->memerrmsg); /* reuse preregistered msg. */
      break;
    }
    case LUA_ERRERR: {
      setsvalue2s(L, oldtop, luaS_newliteral(L, "error in error handling"));
      break;
    }
    default: {
      setobjs2s(L, oldtop, L->top - 1);  /* error message on current top */
      break;
    }
  }
  L->top = oldtop + 1;
}

l_noret luaD_throw (lua_State *L, int errcode) {
  if (L->errorJmp) {  /* thread has an error handler? */
    L->errorJmp->status = errcode;  /* set status */
    LUAI_THROW(L, L->errorJmp);  /* jump to it */
  }
  else {  /* thread has no error handler */
    global_State *g = G(L);
    L->status = cast_byte(errcode);  /* mark it as dead */
    if (g->mainthread->errorJmp) {  /* main thread has a handler? */
      setobjs2s(L, g->mainthread->top++, L->top - 1);  /* copy error obj. */
      luaD_throw(g->mainthread, errcode);  /* re-throw in main thread */
    }
    else {  /* no handler at all; abort */
      if (g->panic) {  /* panic function? */
        seterrorobj(L, errcode, L->top);  /* assume EXTRA_STACK */
        if (L->ci->top < L->top)
          L->ci->top = L->top;  /* pushing msg. can break this invariant */
        lua_unlock(L);
        g->panic(L);  /* call panic function (last chance to jump out) */
      }
      abort();
    }
  }
}

int luaD_rawrunprotected (lua_State *L, Pfunc f, void *ud) {
  unsigned short oldnCcalls = L->nCcalls;
  struct lua_longjmp lj;
  lj.status = LUA_OK;
  lj.previous = L->errorJmp;  /* chain new error handler */
  L->errorJmp = &lj;
  LUAI_TRY(L, &lj,
    (*f)(L, ud);
  );
  L->errorJmp = lj.previous;  /* restore old error handler */
  L->nCcalls = oldnCcalls;
  return lj.status;
}

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

/*
** {==================================================================
** Stack reallocation
** ===================================================================
*/
static void correctstack (lua_State *L, TValue *oldstack) {
  CallInfo *ci;
  UpVal *up;
  L->top = (L->top - oldstack) + L->stack;
  for (up = L->openupval; up != NULL; up = up->u.open.next)
    up->v = (up->v - oldstack) + L->stack;
  for (ci = L->ci; ci != NULL; ci = ci->previous) {
    ci->top = (ci->top - oldstack) + L->stack;
    ci->func = (ci->func - oldstack) + L->stack;
    if (isLua(ci))
      ci->u.l.base = (ci->u.l.base - oldstack) + L->stack;
  }
}

/* some space for error handling */
#define ERRORSTACKSIZE	(LUAI_MAXSTACK + 200)

void luaD_reallocstack (lua_State *L, int newsize) {
  TValue *oldstack = L->stack;
  int lim = L->stacksize;
  lua_assert(newsize <= LUAI_MAXSTACK || newsize == ERRORSTACKSIZE);
  lua_assert(L->stack_last - L->stack == L->stacksize - EXTRA_STACK);
  luaM_reallocvector(L, L->stack, L->stacksize, newsize, TValue);
  for (; lim < newsize; lim++)
    setnilvalue(L->stack + lim); /* erase new segment */
  L->stacksize = newsize;
  L->stack_last = L->stack + newsize - EXTRA_STACK;
  correctstack(L, oldstack);
}

void luaD_growstack (lua_State *L, int n) {
  int size = L->stacksize;
  if (size > LUAI_MAXSTACK)  /* error after extra size? */
    luaD_throw(L, LUA_ERRERR);
  else {
    int needed = cast_int(L->top - L->stack) + n + EXTRA_STACK;
    int newsize = 2 * size;
    if (newsize > LUAI_MAXSTACK) newsize = LUAI_MAXSTACK;
    if (newsize < needed) newsize = needed;
    if (newsize > LUAI_MAXSTACK) {  /* stack overflow? */
      luaD_reallocstack(L, ERRORSTACKSIZE);
      luaG_runerror(L, "stack overflow");
    }
    else
      luaD_reallocstack(L, newsize);
  }
}

static int stackinuse (lua_State *L) {
  CallInfo *ci;
  StkId lim = L->top;
  for (ci = L->ci; ci != NULL; ci = ci->previous) {
    if (lim < ci->top) lim = ci->top;
  }
  lua_assert(lim <= L->stack_last);
  return cast_int(lim - L->stack) + 1;  /* part of stack in use */
}

void luaD_shrinkstack (lua_State *L) {
  int inuse = stackinuse(L);
  int goodsize = inuse + (inuse / 8) + 2*EXTRA_STACK;
  if (goodsize > LUAI_MAXSTACK)
    goodsize = LUAI_MAXSTACK;  /* respect stack limit */
  if (L->stacksize > LUAI_MAXSTACK)  /* had been handling stack overflow? */
    luaE_freeCI(L);  /* free all CIs (list grew because of an error) */
  else
    luaE_shrinkCI(L);  /* shrink list */
  /* if thread is currently not handling a stack overflow and its
     good size is smaller than current size, shrink its stack */
  if (inuse <= (LUAI_MAXSTACK - EXTRA_STACK) &&
      goodsize < L->stacksize)
    luaD_reallocstack(L, goodsize);
  else  /* don't change stack */
    condmovestack(L,{},{});  /* (change only for debugging) */
}

void luaD_inctop (lua_State *L) {
  luaD_checkstack(L, 1);
  L->top++;
}

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

/*
** Call a hook for the given event. Make sure there is a hook to be
** called. (Both 'L->hook' and 'L->hookmask', which triggers this
** function, can be changed asynchronously by signals.)
*/
void luaD_hook (lua_State *L, int event, int line) {
  lua_Hook hook = L->hook;
  if (hook && L->allowhook) {  /* make sure there is a hook */
    CallInfo *ci = L->ci;
    ptrdiff_t top = savestack(L, L->top);
    ptrdiff_t ci_top = savestack(L, ci->top);
    lua_Debug ar;
    ar.event = event;
    ar.currentline = line;
    ar.i_ci = ci;
    luaD_checkstack(L, LUA_MINSTACK);  /* ensure minimum stack size */
    ci->top = L->top + LUA_MINSTACK;
    lua_assert(ci->top <= L->stack_last);
    L->allowhook = 0;  /* cannot call hooks inside a hook */
    ci->callstatus |= CIST_HOOKED;
    lua_unlock(L);
    (*hook)(L, &ar);
    lua_lock(L);
    lua_assert(!L->allowhook);
    L->allowhook = 1;
    ci->top = restorestack(L, ci_top);
    L->top = restorestack(L, top);
    ci->callstatus &= ~CIST_HOOKED;
  }
}

static void callhook (lua_State *L, CallInfo *ci) {
  int hook = LUA_HOOKCALL;
  ci->u.l.savedpc++;  /* hooks assume 'pc' is already incremented */
  if (isLua(ci->previous) &&
      GET_OPCODE(*(ci->previous->u.l.savedpc - 1)) == OP_TAILCALL) {
    ci->callstatus |= CIST_TAIL;
    hook = LUA_HOOKTAILCALL;
  }
  luaD_hook(L, hook, -1);
  ci->u.l.savedpc--;  /* correct 'pc' */
}

static StkId adjust_varargs (lua_State *L, Proto *p, int actual) {
  int i;
  int nfixargs = p->numparams;
  StkId base, fixed;
  /* move fixed parameters to final position */
  fixed = L->top - actual;  /* first fixed argument */
  base = L->top;  /* final position of first argument */
  for (i = 0; i < nfixargs && i < actual; i++) {
    setobjs2s(L, L->top++, fixed + i);
    setnilvalue(fixed + i);  /* erase original copy (for GC) */
  }
  for (; i < nfixargs; i++)
    setnilvalue(L->top++);  /* complete missing arguments */
  return base;
}

/*
** Check whether __call metafield of 'func' is a function. If so, put
** it in stack below original 'func' so that 'luaD_precall' can call
** it. Raise an error if __call metafield is not a function.
*/
static void tryfuncTM (lua_State *L, StkId func) {
  const TValue *tm = luaT_gettmbyobj(L, func, TM_CALL);
  StkId p;
  if (!ttisfunction(tm))
    luaG_typeerror(L, func, "call");
  /* Open a hole inside the stack at 'func' */
  for (p = L->top; p > func; p--)
    setobjs2s(L, p, p-1);
  L->top++;  /* slot ensured by caller */
  setobj2s(L, func, tm);  /* tag method is the new function to be called */
}

/*
** Given 'nres' results at 'firstResult', move 'wanted' of them to 'res'.
** Handle most typical cases (zero results for commands, one result for
** expressions, multiple results for tail calls/single parameters)
** separated.
*/
static int moveresults (lua_State *L, const TValue *firstResult, StkId res,
                                      int nres, int wanted) {
  switch (wanted) {  /* handle typical cases separately */
    case 0: break;  /* nothing to move */
    case 1: {  /* one result needed */
      if (nres == 0)   /* no results? */
        firstResult = luaO_nilobject;  /* adjust with nil */
      setobjs2s(L, res, firstResult);  /* move it to proper place */
      break;
    }
    case LUA_MULTRET: {
      int i;
      for (i = 0; i < nres; i++)  /* move all results to correct place */
        setobjs2s(L, res + i, firstResult + i);
      L->top = res + nres;
      return 0;  /* wanted == LUA_MULTRET */
    }
    default: {
      int i;
      if (wanted <= nres) {  /* enough results? */
        for (i = 0; i < wanted; i++)  /* move wanted results to correct place */
          setobjs2s(L, res + i, firstResult + i);
      }
      else {  /* not enough results; use all of them plus nils */
        for (i = 0; i < nres; i++)  /* move all results to correct place */
          setobjs2s(L, res + i, firstResult + i);
        for (; i < wanted; i++)  /* complete wanted number of results */
          setnilvalue(res + i);
      }
      break;
    }
  }
  L->top = res + wanted;  /* top points after the last result */
  return 1;
}

/*
** Finishes a function call: calls hook if necessary, removes CallInfo,
** moves current number of results to proper place; returns 0 iff call
** wanted multiple (variable number of) results.
*/
int luaD_poscall (lua_State *L, CallInfo *ci, StkId firstResult, int nres) {
  StkId res;
  int wanted = ci->nresults;
  if (L->hookmask & (LUA_MASKRET | LUA_MASKLINE)) {
    if (L->hookmask & LUA_MASKRET) {
      ptrdiff_t fr = savestack(L, firstResult);  /* hook may change stack */
      luaD_hook(L, LUA_HOOKRET, -1);
      firstResult = restorestack(L, fr);
    }
    L->oldpc = ci->previous->u.l.savedpc;  /* 'oldpc' for caller function */
  }
  res = ci->func;  /* res == final position of 1st result */
  L->ci = ci->previous;  /* back to caller */
  /* move results to proper place */
  return moveresults(L, firstResult, res, nres, wanted);
}

#define next_ci(L) (L->ci = (L->ci->next ? L->ci->next : luaE_extendCI(L)))

/* macro to check stack size, preserving 'p' */
#define checkstackp(L,n,p)  \
  luaD_checkstackaux(L, n, \
    ptrdiff_t t__ = savestack(L, p);  /* save 'p' */ \
    luaC_checkGC(L),  /* stack grow uses memory */ \
    p = restorestack(L, t__))  /* 'pos' part: restore 'p' */

/*
** Prepares a function call: checks the stack, creates a new CallInfo
** entry, fills in the relevant information, calls hook if needed.
** If function is a C function, does the call, too. (Otherwise, leave
** the execution ('luaV_execute') to the caller, to allow stackless
** calls.) Returns true iff function has been executed (C function).
*/
int luaD_precall (lua_State *L, StkId func, int nresults) {
  lua_CFunction f;
  CallInfo *ci;
  switch (ttype(func)) {
    case LUA_TCCL:  /* C closure */
      f = clCvalue(func)->f;
      goto Cfunc;
    case LUA_TLCF:  /* light C function */
      f = fvalue(func);
     Cfunc: {
      int n;  /* number of returns */
      checkstackp(L, LUA_MINSTACK, func);  /* ensure minimum stack size */
      ci = next_ci(L);  /* now 'enter' new function */
      ci->nresults = nresults;
      ci->func = func;
      ci->top = L->top + LUA_MINSTACK;
      lua_assert(ci->top <= L->stack_last);
      ci->callstatus = 0;
      if (L->hookmask & LUA_MASKCALL)
        luaD_hook(L, LUA_HOOKCALL, -1);
      lua_unlock(L);
      n = (*f)(L);  /* do the actual call */
      lua_lock(L);
      api_checknelems(L, n);
      luaD_poscall(L, ci, L->top - n, n);
      return 1;
    }
    case LUA_TLCL: {  /* Lua function: prepare its call */
      StkId base;
      Proto *p = clLvalue(func)->p;
      int n = cast_int(L->top - func) - 1;  /* number of real arguments */
      int fsize = p->maxstacksize;  /* frame size */
      checkstackp(L, fsize, func);
      if (p->is_vararg)
        base = adjust_varargs(L, p, n);
      else {  /* non vararg function */
        for (; n < p->numparams; n++)
          setnilvalue(L->top++);  /* complete missing arguments */
        base = func + 1;
      }
      ci = next_ci(L);  /* now 'enter' new function */
      ci->nresults = nresults;
      ci->func = func;
      ci->u.l.base = base;
      L->top = ci->top = base + fsize;
      lua_assert(ci->top <= L->stack_last);
      ci->u.l.savedpc = p->code;  /* starting point */
      ci->callstatus = CIST_LUA;
      if (L->hookmask & LUA_MASKCALL)
        callhook(L, ci);
      return 0;
    }
    default: {  /* not a function */
      checkstackp(L, 1, func);  /* ensure space for metamethod */
      tryfuncTM(L, func);  /* try to get '__call' metamethod */
      return luaD_precall(L, func, nresults);  /* now it must be a function */
    }
  }
}

/*
** Check appropriate error for stack overflow ("regular" overflow or
** overflow while handling stack overflow). If 'nCalls' is larger than
** LUAI_MAXCCALLS (which means it is handling a "regular" overflow) but
** smaller than 9/8 of LUAI_MAXCCALLS, does not report an error (to
** allow overflow handling to work)
*/
static void stackerror (lua_State *L) {
  if (L->nCcalls == LUAI_MAXCCALLS)
    luaG_runerror(L, "C stack overflow");
  else if (L->nCcalls >= (LUAI_MAXCCALLS + (LUAI_MAXCCALLS>>3)))
    luaD_throw(L, LUA_ERRERR);  /* error while handing stack error */
}

/*
** Call a function (C or Lua). The function to be called is at *func.
** The arguments are on the stack, right after the function.
** When returns, all the results are on the stack, starting at the original
** function position.
*/
void luaD_call (lua_State *L, StkId func, int nResults) {
  if (++L->nCcalls >= LUAI_MAXCCALLS)
    stackerror(L);
  if (!luaD_precall(L, func, nResults))  /* is a Lua function? */
    luaV_execute(L);  /* call it */
  L->nCcalls--;
}

/*
** Similar to 'luaD_call', but does not allow yields during the call
*/
void luaD_callnoyield (lua_State *L, StkId func, int nResults) {
  L->nny++;
  luaD_call(L, func, nResults);
  L->nny--;
}

/*
** Completes the execution of an interrupted C function, calling its
** continuation function.
*/
static void finishCcall (lua_State *L, int status) {
  CallInfo *ci = L->ci;
  int n;
  /* must have a continuation and must be able to call it */
  lua_assert(ci->u.c.k != NULL && L->nny == 0);
  /* error status can only happen in a protected call */
  lua_assert((ci->callstatus & CIST_YPCALL) || status == LUA_YIELD);
  if (ci->callstatus & CIST_YPCALL) {  /* was inside a pcall? */
    ci->callstatus &= ~CIST_YPCALL;  /* continuation is also inside it */
    L->errfunc = ci->u.c.old_errfunc;  /* with the same error function */
  }
  /* finish 'lua_callk'/'lua_pcall'; CIST_YPCALL and 'errfunc' already
     handled */
  adjustresults(L, ci->nresults);
  lua_unlock(L);
  n = (*ci->u.c.k)(L, status, ci->u.c.ctx);  /* call continuation function */
  lua_lock(L);
  api_checknelems(L, n);
  luaD_poscall(L, ci, L->top - n, n);  /* finish 'luaD_precall' */
}

/*
** Executes "full continuation" (everything in the stack) of a
** previously interrupted coroutine until the stack is empty (or another
** interruption long-jumps out of the loop). If the coroutine is
** recovering from an error, 'ud' points to the error status, which must
** be passed to the first continuation function (otherwise the default
** status is LUA_YIELD).
*/
static void unroll (lua_State *L, void *ud) {
  if (ud != NULL)  /* error status? */
    finishCcall(L, *(int *)ud);  /* finish 'lua_pcallk' callee */
  while (L->ci != &L->base_ci) {  /* something in the stack */
    if (!isLua(L->ci))  /* C function? */
      finishCcall(L, LUA_YIELD);  /* complete its execution */
    else {  /* Lua function */
      luaV_finishOp(L);  /* finish interrupted instruction */
      luaV_execute(L);  /* execute down to higher C 'boundary' */
    }
  }
}

/*
** Try to find a suspended protected call (a "recover point") for the
** given thread.
*/
static CallInfo *findpcall (lua_State *L) {
  CallInfo *ci;
  for (ci = L->ci; ci != NULL; ci = ci->previous) {  /* search for a pcall */
    if (ci->callstatus & CIST_YPCALL)
      return ci;
  }
  return NULL;  /* no pending pcall */
}

/*
** Recovers from an error in a coroutine. Finds a recover point (if
** there is one) and completes the execution of the interrupted
** 'luaD_pcall'. If there is no recover point, returns zero.
*/
static int recover (lua_State *L, int status) {
  StkId oldtop;
  CallInfo *ci = findpcall(L);
  if (ci == NULL) return 0;  /* no recovery point */
  /* "finish" luaD_pcall */
  oldtop = restorestack(L, ci->extra);
  luaF_close(L, oldtop);
  seterrorobj(L, status, oldtop);
  L->ci = ci;
  L->allowhook = getoah(ci->callstatus);  /* restore original 'allowhook' */
  L->nny = 0;  /* should be zero to be yieldable */
  luaD_shrinkstack(L);
  L->errfunc = ci->u.c.old_errfunc;
  return 1;  /* continue running the coroutine */
}

/*
** Signal an error in the call to 'lua_resume', not in the execution
** of the coroutine itself. (Such errors should not be handled by any
** coroutine error handler and should not kill the coroutine.)
*/
static int resume_error (lua_State *L, const char *msg, int narg) {
  L->top -= narg;  /* remove args from the stack */
  setsvalue2s(L, L->top, luaS_new(L, msg));  /* push error message */
  api_incr_top(L);
  lua_unlock(L);
  return LUA_ERRRUN;
}

/*
** Do the work for 'lua_resume' in protected mode. Most of the work
** depends on the status of the coroutine: initial state, suspended
** inside a hook, or regularly suspended (optionally with a continuation
** function), plus erroneous cases: non-suspended coroutine or dead
** coroutine.
*/
static void resume (lua_State *L, void *ud) {
  int n = *(cast(int*, ud));  /* number of arguments */
  StkId firstArg = L->top - n;  /* first argument */
  CallInfo *ci = L->ci;
  if (L->status == LUA_OK) {  /* starting a coroutine? */
    if (!luaD_precall(L, firstArg - 1, LUA_MULTRET))  /* Lua function? */
      luaV_execute(L);  /* call it */
  }
  else {  /* resuming from previous yield */
    lua_assert(L->status == LUA_YIELD);
    L->status = LUA_OK;  /* mark that it is running (again) */
    ci->func = restorestack(L, ci->extra);
    if (isLua(ci))  /* yielded inside a hook? */
      luaV_execute(L);  /* just continue running Lua code */
    else {  /* 'common' yield */
      if (ci->u.c.k != NULL) {  /* does it have a continuation function? */
        lua_unlock(L);
        n = (*ci->u.c.k)(L, LUA_YIELD, ci->u.c.ctx); /* call continuation */
        lua_lock(L);
        api_checknelems(L, n);
        firstArg = L->top - n;  /* yield results come from continuation */
      }
      luaD_poscall(L, ci, firstArg, n);  /* finish 'luaD_precall' */
    }
    unroll(L, NULL);  /* run continuation */
  }
}

LUA_API int lua_resume (lua_State *L, lua_State *from, int nargs) {
  int status;
  unsigned short oldnny = L->nny;  /* save "number of non-yieldable" calls */
  lua_lock(L);
  if (L->status == LUA_OK) {  /* may be starting a coroutine */
    if (L->ci != &L->base_ci)  /* not in base level? */
      return resume_error(L, "cannot resume non-suspended coroutine", nargs);
  }
  else if (L->status != LUA_YIELD)
    return resume_error(L, "cannot resume dead coroutine", nargs);
  L->nCcalls = (from) ? from->nCcalls + 1 : 1;
  if (L->nCcalls >= LUAI_MAXCCALLS)
    return resume_error(L, "C stack overflow", nargs);
  luai_userstateresume(L, nargs);
  L->nny = 0;  /* allow yields */
  api_checknelems(L, (L->status == LUA_OK) ? nargs + 1 : nargs);
  status = luaD_rawrunprotected(L, resume, &nargs);
  if (status == -1)  /* error calling 'lua_resume'? */
    status = LUA_ERRRUN;
  else {  /* continue running after recoverable errors */
    while (errorstatus(status) && recover(L, status)) {
      /* unroll continuation */
      status = luaD_rawrunprotected(L, unroll, &status);
    }
    if (errorstatus(status)) {  /* unrecoverable error? */
      L->status = cast_byte(status);  /* mark thread as 'dead' */
      seterrorobj(L, status, L->top);  /* push error message */
      L->ci->top = L->top;
    }
    else lua_assert(status == L->status);  /* normal end or yield */
  }
  L->nny = oldnny;  /* restore 'nny' */
  L->nCcalls--;
  lua_assert(L->nCcalls == ((from) ? from->nCcalls : 0));
  lua_unlock(L);
  return status;
}

LUA_API int lua_isyieldable (lua_State *L) {
  return (L->nny == 0);
}

LUA_API int lua_yieldk (lua_State *L, int nresults, lua_KContext ctx,
                        lua_KFunction k) {
  CallInfo *ci = L->ci;
  luai_userstateyield(L, nresults);
  lua_lock(L);
  api_checknelems(L, nresults);
  if (L->nny > 0) {
    if (L != G(L)->mainthread)
      luaG_runerror(L, "attempt to yield across a C-call boundary");
    else
      luaG_runerror(L, "attempt to yield from outside a coroutine");
  }
  L->status = LUA_YIELD;
  ci->extra = savestack(L, ci->func);  /* save current 'func' */
  if (isLua(ci)) {  /* inside a hook? */
    api_check(L, k == NULL, "hooks cannot continue after yielding");
  }
  else {
    if ((ci->u.c.k = k) != NULL)  /* is there a continuation? */
      ci->u.c.ctx = ctx;  /* save context */
    ci->func = L->top - nresults - 1;  /* protect stack below results */
    luaD_throw(L, LUA_YIELD);
  }
  lua_assert(ci->callstatus & CIST_HOOKED);  /* must be inside a hook */
  lua_unlock(L);
  return 0;  /* return to 'luaD_hook' */
}

int luaD_pcall (lua_State *L, Pfunc func, void *u,
                ptrdiff_t old_top, ptrdiff_t ef) {
  int status;
  CallInfo *old_ci = L->ci;
  lu_byte old_allowhooks = L->allowhook;
  unsigned short old_nny = L->nny;
  ptrdiff_t old_errfunc = L->errfunc;
  L->errfunc = ef;
  status = luaD_rawrunprotected(L, func, u);
  if (status != LUA_OK) {  /* an error occurred? */
    StkId oldtop = restorestack(L, old_top);
    luaF_close(L, oldtop);  /* close possible pending closures */
    seterrorobj(L, status, oldtop);
    L->ci = old_ci;
    L->allowhook = old_allowhooks;
    L->nny = old_nny;
    luaD_shrinkstack(L);
  }
  L->errfunc = old_errfunc;
  return status;
}

/*
** Execute a protected parser.
*/
struct SParser {  /* data to 'f_parser' */
  ZIO *z;
  Mbuffer buff;  /* dynamic structure used by the scanner */
  Dyndata dyd;  /* dynamic structures used by the parser */
  const char *mode;
  const char *name;
};

static void checkmode (lua_State *L, const char *mode, const char *x) {
  if (mode && strchr(mode, x[0]) == NULL) {
    luaO_pushfstring(L,
       "attempt to load a %s chunk (mode is '%s')", x, mode);
    luaD_throw(L, LUA_ERRSYNTAX);
  }
}

static void f_parser (lua_State *L, void *ud) {
  LClosure *cl;
  struct SParser *p = cast(struct SParser *, ud);
  int c = zgetc(p->z);  /* read first character */
  if (c == LUA_SIGNATURE[0]) {
    checkmode(L, p->mode, "binary");
    cl = luaU_undump(L, p->z, p->name);
  }
  else {
    checkmode(L, p->mode, "text");
    cl = luaY_parser(L, p->z, &p->buff, &p->dyd, p->name, c);
  }
  lua_assert(cl->nupvalues == cl->p->sizeupvalues);
  luaF_initupvals(L, cl);
}

int luaD_protectedparser (lua_State *L, ZIO *z, const char *name,
                                        const char *mode) {
  struct SParser p;
  int status;
  L->nny++;  /* cannot yield during parsing */
  p.z = z; p.name = name; p.mode = mode;
  p.dyd.actvar.arr = NULL; p.dyd.actvar.size = 0;
  p.dyd.gt.arr = NULL; p.dyd.gt.size = 0;
  p.dyd.label.arr = NULL; p.dyd.label.size = 0;
  luaZ_initbuffer(L, &p.buff);
  status = luaD_pcall(L, f_parser, &p, savestack(L, L->top), L->errfunc);
  luaZ_freebuffer(L, &p.buff);
  luaM_freearray(L, p.dyd.actvar.arr, p.dyd.actvar.size);
  luaM_freearray(L, p.dyd.gt.arr, p.dyd.gt.size);
  luaM_freearray(L, p.dyd.label.arr, p.dyd.label.size);
  L->nny--;
  return status;
}

mime_type: text/plain


text:
/*
** $Id: lvm.h,v 2.41.1.1 2017/04/19 17:20:42 roberto Exp $
** Lua virtual machine
** See Copyright Notice in lua.h
*/

#ifndef lvm_h
#define lvm_h

#include "ldo.h"
#include "lobject.h"
#include "ltm.h"

#if !defined(LUA_NOCVTN2S)
#define cvt2str(o)	ttisnumber(o)
#else
#define cvt2str(o)	0	/* no conversion from numbers to strings */
#endif

#if !defined(LUA_NOCVTS2N)
#define cvt2num(o)	ttisstring(o)
#else
#define cvt2num(o)	0	/* no conversion from strings to numbers */
#endif

/*
** You can define LUA_FLOORN2I if you want to convert floats to integers
** by flooring them (instead of raising an error if they are not
** integral values)
*/
#if !defined(LUA_FLOORN2I)
#define LUA_FLOORN2I		0
#endif

#define tonumber(o,n) \
	(ttisfloat(o) ? (*(n) = fltvalue(o), 1) : luaV_tonumber_(o,n))

#define tointeger(o,i) \
    (ttisinteger(o) ? (*(i) = ivalue(o), 1) : luaV_tointeger(o,i,LUA_FLOORN2I))

#define intop(op,v1,v2) l_castU2S(l_castS2U(v1) op l_castS2U(v2))

#define luaV_rawequalobj(t1,t2)		luaV_equalobj(NULL,t1,t2)

/*
** fast track for 'gettable': if 't' is a table and 't[k]' is not nil,
** return 1 with 'slot' pointing to 't[k]' (final result).  Otherwise,
** return 0 (meaning it will have to check metamethod) with 'slot'
** pointing to a nil 't[k]' (if 't' is a table) or NULL (otherwise).
** 'f' is the raw get function to use.
*/
#define luaV_fastget(L,t,k,slot,f) \
  (!ttistable(t)  \
   ? (slot = NULL, 0)  /* not a table; 'slot' is NULL and result is 0 */  \
   : (slot = f(hvalue(t), k),  /* else, do raw access */  \
      !ttisnil(slot)))  /* result not nil? */

/*
** standard implementation for 'gettable'
*/
#define luaV_gettable(L,t,k,v) { const TValue *slot; \
  if (luaV_fastget(L,t,k,slot,luaH_get)) { setobj2s(L, v, slot); } \
  else luaV_finishget(L,t,k,v,slot); }

/*
** Fast track for set table. If 't' is a table and 't[k]' is not nil,
** call GC barrier, do a raw 't[k]=v', and return true; otherwise,
** return false with 'slot' equal to NULL (if 't' is not a table) or
** 'nil'. (This is needed by 'luaV_finishget'.) Note that, if the macro
** returns true, there is no need to 'invalidateTMcache', because the
** call is not creating a new entry.
*/
#define luaV_fastset(L,t,k,slot,f,v) \
  (!ttistable(t) \
   ? (slot = NULL, 0) \
   : (slot = f(hvalue(t), k), \
     ttisnil(slot) ? 0 \
     : (luaC_barrierback(L, hvalue(t), v), \
        setobj2t(L, cast(TValue *,slot), v), \
        1)))

#define luaV_settable(L,t,k,v) { const TValue *slot; \
  if (!luaV_fastset(L,t,k,slot,luaH_get,v)) \
    luaV_finishset(L,t,k,v,slot); }

LUAI_FUNC int luaV_equalobj (lua_State *L, const TValue *t1, const TValue *t2);
LUAI_FUNC int luaV_lessthan (lua_State *L, const TValue *l, const TValue *r);
LUAI_FUNC int luaV_lessequal (lua_State *L, const TValue *l, const TValue *r);
LUAI_FUNC int luaV_tonumber_ (const TValue *obj, lua_Number *n);
LUAI_FUNC int luaV_tointeger (const TValue *obj, lua_Integer *p, int mode);
LUAI_FUNC void luaV_finishget (lua_State *L, const TValue *t, TValue *key,
                               StkId val, const TValue *slot);
LUAI_FUNC void luaV_finishset (lua_State *L, const TValue *t, TValue *key,
                               StkId val, const TValue *slot);
LUAI_FUNC void luaV_finishOp (lua_State *L);
LUAI_FUNC void luaV_execute (lua_State *L);
LUAI_FUNC void luaV_concat (lua_State *L, int total);
LUAI_FUNC lua_Integer luaV_div (lua_State *L, lua_Integer x, lua_Integer y);
LUAI_FUNC lua_Integer luaV_mod (lua_State *L, lua_Integer x, lua_Integer y);
LUAI_FUNC lua_Integer luaV_shiftl (lua_Integer x, lua_Integer y);
LUAI_FUNC void luaV_objlen (lua_State *L, StkId ra, const TValue *rb);

#endif


text:
/*
** $Id: lctype.h,v 1.12.1.1 2013/04/12 18:48:47 roberto Exp $
** 'ctype' functions for Lua
** See Copyright Notice in lua.h
*/

#ifndef lctype_h
#define lctype_h

#include "lua.h"

/*
** WARNING: the functions defined here do not necessarily correspond
** to the similar functions in the standard C ctype.h. They are
** optimized for the specific needs of Lua
*/

#if !defined(LUA_USE_CTYPE)

#if 'A' == 65 && '0' == 48
/* ASCII case: can use its own tables; faster and fixed */
#define LUA_USE_CTYPE	0
#else
/* must use standard C ctype */
#define LUA_USE_CTYPE	1
#endif

#endif

#if !LUA_USE_CTYPE	/* { */

#include <limits.h>

#include "llimits.h"

#define ALPHABIT	0
#define DIGITBIT	1
#define PRINTBIT	2
#define SPACEBIT	3
#define XDIGITBIT	4

#define MASK(B)		(1 << (B))

/*
** add 1 to char to allow index -1 (EOZ)
*/
#define testprop(c,p)	(luai_ctype_[(c)+1] & (p))

/*
** 'lalpha' (Lua alphabetic) and 'lalnum' (Lua alphanumeric) both include '_'
*/
#define lislalpha(c)	testprop(c, MASK(ALPHABIT))
#define lislalnum(c)	testprop(c, (MASK(ALPHABIT) | MASK(DIGITBIT)))
#define lisdigit(c)	testprop(c, MASK(DIGITBIT))
#define lisspace(c)	testprop(c, MASK(SPACEBIT))
#define lisprint(c)	testprop(c, MASK(PRINTBIT))
#define lisxdigit(c)	testprop(c, MASK(XDIGITBIT))

/*
** this 'ltolower' only works for alphabetic characters
*/
#define ltolower(c)	((c) | ('A' ^ 'a'))

/* two more entries for 0 and -1 (EOZ) */
LUAI_DDEC const lu_byte luai_ctype_[UCHAR_MAX + 2];

#else			/* }{ */

/*
** use standard C ctypes
*/

#include <ctype.h>

#define lislalpha(c)	(isalpha(c) || (c) == '_')
#define lislalnum(c)	(isalnum(c) || (c) == '_')
#define lisdigit(c)	(isdigit(c))
#define lisspace(c)	(isspace(c))
#define lisprint(c)	(isprint(c))
#define lisxdigit(c)	(isxdigit(c))

#define ltolower(c)	(tolower(c))

#endif			/* } */

#endif


text:
/*
** $Id: lzio.h,v 1.31.1.1 2017/04/19 17:20:42 roberto Exp $
** Buffered streams
** See Copyright Notice in lua.h
*/

#ifndef lzio_h
#define lzio_h

#include "lua.h"

#include "lmem.h"

#define EOZ	(-1)			/* end of stream */

typedef struct Zio ZIO;

#define zgetc(z)  (((z)->n--)>0 ?  cast_uchar(*(z)->p++) : luaZ_fill(z))

typedef struct Mbuffer {
  char *buffer;
  size_t n;
  size_t buffsize;
} Mbuffer;

#define luaZ_initbuffer(L, buff) ((buff)->buffer = NULL, (buff)->buffsize = 0)

#define luaZ_buffer(buff)	((buff)->buffer)
#define luaZ_sizebuffer(buff)	((buff)->buffsize)
#define luaZ_bufflen(buff)	((buff)->n)

#define luaZ_buffremove(buff,i)	((buff)->n -= (i))
#define luaZ_resetbuffer(buff) ((buff)->n = 0)

#define luaZ_resizebuffer(L, buff, size) \
	((buff)->buffer = luaM_reallocvchar(L, (buff)->buffer, \
				(buff)->buffsize, size), \
	(buff)->buffsize = size)

#define luaZ_freebuffer(L, buff)	luaZ_resizebuffer(L, buff, 0)

LUAI_FUNC void luaZ_init (lua_State *L, ZIO *z, lua_Reader reader,
                                        void *data);
LUAI_FUNC size_t luaZ_read (ZIO* z, void *b, size_t n);	/* read next n bytes */

/* --------- Private Part ------------------ */

struct Zio {
  size_t n;			/* bytes still unread */
  const char *p;		/* current position in buffer */
  lua_Reader reader;		/* reader function */
  void *data;			/* additional data */
  lua_State *L;			/* Lua state (for reader) */
};

LUAI_FUNC int luaZ_fill (ZIO *z);

#endif


text:
/*
** $Id: lstate.c,v 2.133.1.1 2017/04/19 17:39:34 roberto Exp $
** Global State
** See Copyright Notice in lua.h
*/

#define lstate_c
#define LUA_CORE

#include "lprefix.h"

#include <stddef.h>
#include <string.h>

#include "lua.h"

#include "lapi.h"
#include "ldebug.h"
#include "ldo.h"
#include "lfunc.h"
#include "lgc.h"
#include "llex.h"
#include "lmem.h"
#include "lstate.h"
#include "lstring.h"
#include "ltable.h"
#include "ltm.h"

#if !defined(LUAI_GCPAUSE)
#define LUAI_GCPAUSE	200  /* 200% */
#endif

#if !defined(LUAI_GCMUL)
#define LUAI_GCMUL	200 /* GC runs 'twice the speed' of memory allocation */
#endif

/*
** a macro to help the creation of a unique random seed when a state is
** created; the seed is used to randomize hashes.
*/
#if !defined(luai_makeseed)
#include <time.h>
#define luai_makeseed()		cast(unsigned int, time(NULL))
#endif

/*
** thread state + extra space
*/
typedef struct LX {
  lu_byte extra_[LUA_EXTRASPACE];
  lua_State l;
} LX;

/*
** Main thread combines a thread state and the global state
*/
typedef struct LG {
  LX l;
  global_State g;
} LG;

#define fromstate(L)	(cast(LX *, cast(lu_byte *, (L)) - offsetof(LX, l)))

/*
** Compute an initial seed as random as possible. Rely on Address Space
** Layout Randomization (if present) to increase randomness..
*/
#define addbuff(b,p,e) \
  { size_t t = cast(size_t, e); \
    memcpy(b + p, &t, sizeof(t)); p += sizeof(t); }

static unsigned int makeseed (lua_State *L) {
  char buff[4 * sizeof(size_t)];
  unsigned int h = luai_makeseed();
  int p = 0;
  addbuff(buff, p, L);  /* heap variable */
  addbuff(buff, p, &h);  /* local variable */
  addbuff(buff, p, luaO_nilobject);  /* global variable */
  addbuff(buff, p, &lua_newstate);  /* public function */
  lua_assert(p == sizeof(buff));
  return luaS_hash(buff, p, h);
}

/*
** set GCdebt to a new value keeping the value (totalbytes + GCdebt)
** invariant (and avoiding underflows in 'totalbytes')
*/
void luaE_setdebt (global_State *g, l_mem debt) {
  l_mem tb = gettotalbytes(g);
  lua_assert(tb > 0);
  if (debt < tb - MAX_LMEM)
    debt = tb - MAX_LMEM;  /* will make 'totalbytes == MAX_LMEM' */
  g->totalbytes = tb - debt;
  g->GCdebt = debt;
}

CallInfo *luaE_extendCI (lua_State *L) {
  CallInfo *ci = luaM_new(L, CallInfo);
  lua_assert(L->ci->next == NULL);
  L->ci->next = ci;
  ci->previous = L->ci;
  ci->next = NULL;
  L->nci++;
  return ci;
}

/*
** free all CallInfo structures not in use by a thread
*/
void luaE_freeCI (lua_State *L) {
  CallInfo *ci = L->ci;
  CallInfo *next = ci->next;
  ci->next = NULL;
  while ((ci = next) != NULL) {
    next = ci->next;
    luaM_free(L, ci);
    L->nci--;
  }
}

/*
** free half of the CallInfo structures not in use by a thread
*/
void luaE_shrinkCI (lua_State *L) {
  CallInfo *ci = L->ci;
  CallInfo *next2;  /* next's next */
  /* while there are two nexts */
  while (ci->next != NULL && (next2 = ci->next->next) != NULL) {
    luaM_free(L, ci->next);  /* free next */
    L->nci--;
    ci->next = next2;  /* remove 'next' from the list */
    next2->previous = ci;
    ci = next2;  /* keep next's next */
  }
}

static void stack_init (lua_State *L1, lua_State *L) {
  int i; CallInfo *ci;
  /* initialize stack array */
  L1->stack = luaM_newvector(L, BASIC_STACK_SIZE, TValue);
  L1->stacksize = BASIC_STACK_SIZE;
  for (i = 0; i < BASIC_STACK_SIZE; i++)
    setnilvalue(L1->stack + i);  /* erase new stack */
  L1->top = L1->stack;
  L1->stack_last = L1->stack + L1->stacksize - EXTRA_STACK;
  /* initialize first ci */
  ci = &L1->base_ci;
  ci->next = ci->previous = NULL;
  ci->callstatus = 0;
  ci->func = L1->top;
  setnilvalue(L1->top++);  /* 'function' entry for this 'ci' */
  ci->top = L1->top + LUA_MINSTACK;
  L1->ci = ci;
}

static void freestack (lua_State *L) {
  if (L->stack == NULL)
    return;  /* stack not completely built yet */
  L->ci = &L->base_ci;  /* free the entire 'ci' list */
  luaE_freeCI(L);
  lua_assert(L->nci == 0);
  luaM_freearray(L, L->stack, L->stacksize);  /* free stack array */
}

/*
** Create registry table and its predefined values
*/
static void init_registry (lua_State *L, global_State *g) {
  TValue temp;
  /* create registry */
  Table *registry = luaH_new(L);
  sethvalue(L, &g->l_registry, registry);
  luaH_resize(L, registry, LUA_RIDX_LAST, 0);
  /* registry[LUA_RIDX_MAINTHREAD] = L */
  setthvalue(L, &temp, L);  /* temp = L */
  luaH_setint(L, registry, LUA_RIDX_MAINTHREAD, &temp);
  /* registry[LUA_RIDX_GLOBALS] = table of globals */
  sethvalue(L, &temp, luaH_new(L));  /* temp = new table (global table) */
  luaH_setint(L, registry, LUA_RIDX_GLOBALS, &temp);
}

/*
** open parts of the state that may cause memory-allocation errors.
** ('g->version' != NULL flags that the state was completely build)
*/
static void f_luaopen (lua_State *L, void *ud) {
  global_State *g = G(L);
  UNUSED(ud);
  stack_init(L, L);  /* init stack */
  init_registry(L, g);
  luaS_init(L);
  luaT_init(L);
  luaX_init(L);
  g->gcrunning = 1;  /* allow gc */
  g->version = lua_version(NULL);
  luai_userstateopen(L);
}

/*
** preinitialize a thread with consistent values without allocating
** any memory (to avoid errors)
*/
static void preinit_thread (lua_State *L, global_State *g) {
  G(L) = g;
  L->stack = NULL;
  L->ci = NULL;
  L->nci = 0;
  L->stacksize = 0;
  L->twups = L;  /* thread has no upvalues */
  L->errorJmp = NULL;
  L->nCcalls = 0;
  L->hook = NULL;
  L->hookmask = 0;
  L->basehookcount = 0;
  L->allowhook = 1;
  resethookcount(L);
  L->openupval = NULL;
  L->nny = 1;
  L->status = LUA_OK;
  L->errfunc = 0;
}

static void close_state (lua_State *L) {
  global_State *g = G(L);
  luaF_close(L, L->stack);  /* close all upvalues for this thread */
  luaC_freeallobjects(L);  /* collect all objects */
  if (g->version)  /* closing a fully built state? */
    luai_userstateclose(L);
  luaM_freearray(L, G(L)->strt.hash, G(L)->strt.size);
  freestack(L);
  lua_assert(gettotalbytes(g) == sizeof(LG));
  (*g->frealloc)(g->ud, fromstate(L), sizeof(LG), 0);  /* free main block */
}

LUA_API lua_State *lua_newthread (lua_State *L) {
  global_State *g = G(L);
  lua_State *L1;
  lua_lock(L);
  luaC_checkGC(L);
  /* create new thread */
  L1 = &cast(LX *, luaM_newobject(L, LUA_TTHREAD, sizeof(LX)))->l;
  L1->marked = luaC_white(g);
  L1->tt = LUA_TTHREAD;
  /* link it on list 'allgc' */
  L1->next = g->allgc;
  g->allgc = obj2gco(L1);
  /* anchor it on L stack */
  setthvalue(L, L->top, L1);
  api_incr_top(L);
  preinit_thread(L1, g);
  L1->hookmask = L->hookmask;
  L1->basehookcount = L->basehookcount;
  L1->hook = L->hook;
  resethookcount(L1);
  /* initialize L1 extra space */
  memcpy(lua_getextraspace(L1), lua_getextraspace(g->mainthread),
         LUA_EXTRASPACE);
  luai_userstatethread(L, L1);
  stack_init(L1, L);  /* init stack */
  lua_unlock(L);
  return L1;
}

void luaE_freethread (lua_State *L, lua_State *L1) {
  LX *l = fromstate(L1);
  luaF_close(L1, L1->stack);  /* close all upvalues for this thread */
  lua_assert(L1->openupval == NULL);
  luai_userstatefree(L, L1);
  freestack(L1);
  luaM_free(L, l);
}

LUA_API lua_State *lua_newstate (lua_Alloc f, void *ud) {
  int i;
  lua_State *L;
  global_State *g;
  LG *l = cast(LG *, (*f)(ud, NULL, LUA_TTHREAD, sizeof(LG)));
  if (l == NULL) return NULL;
  L = &l->l.l;
  g = &l->g;
  L->next = NULL;
  L->tt = LUA_TTHREAD;
  g->currentwhite = bitmask(WHITE0BIT);
  L->marked = luaC_white(g);
  preinit_thread(L, g);
  g->frealloc = f;
  g->ud = ud;
  g->mainthread = L;
  g->seed = makeseed(L);
  g->gcrunning = 0;  /* no GC while building state */
  g->GCestimate = 0;
  g->strt.size = g->strt.nuse = 0;
  g->strt.hash = NULL;
  setnilvalue(&g->l_registry);
  g->panic = NULL;
  g->version = NULL;
  g->gcstate = GCSpause;
  g->gckind = KGC_NORMAL;
  g->allgc = g->finobj = g->tobefnz = g->fixedgc = NULL;
  g->sweepgc = NULL;
  g->gray = g->grayagain = NULL;
  g->weak = g->ephemeron = g->allweak = NULL;
  g->twups = NULL;
  g->totalbytes = sizeof(LG);
  g->GCdebt = 0;
  g->gcfinnum = 0;
  g->gcpause = LUAI_GCPAUSE;
  g->gcstepmul = LUAI_GCMUL;
  for (i=0; i < LUA_NUMTAGS; i++) g->mt[i] = NULL;
  if (luaD_rawrunprotected(L, f_luaopen, NULL) != LUA_OK) {
    /* memory allocation error: free partial state */
    close_state(L);
    L = NULL;
  }
  return L;
}

LUA_API void lua_close (lua_State *L) {
  L = G(L)->mainthread;  /* only the main thread can be closed */
  lua_lock(L);
  close_state(L);
}


text:
/*
** $Id: lgc.h,v 2.91.1.1 2017/04/19 17:39:34 roberto Exp $
** Garbage Collector
** See Copyright Notice in lua.h
*/

#ifndef lgc_h
#define lgc_h

#include "lobject.h"
#include "lstate.h"

/*
** Collectable objects may have one of three colors: white, which
** means the object is not marked; gray, which means the
** object is marked, but its references may be not marked; and
** black, which means that the object and all its references are marked.
** The main invariant of the garbage collector, while marking objects,
** is that a black object can never point to a white one. Moreover,
** any gray object must be in a "gray list" (gray, grayagain, weak,
** allweak, ephemeron) so that it can be visited again before finishing
** the collection cycle. These lists have no meaning when the invariant
** is not being enforced (e.g., sweep phase).
*/

/* how much to allocate before next GC step */
#if !defined(GCSTEPSIZE)
/* ~100 small strings */
#define GCSTEPSIZE	(cast_int(100 * sizeof(TString)))
#endif

/*
** Possible states of the Garbage Collector
*/
#define GCSpropagate	0
#define GCSatomic	1
#define GCSswpallgc	2
#define GCSswpfinobj	3
#define GCSswptobefnz	4
#define GCSswpend	5
#define GCScallfin	6
#define GCSpause	7

#define issweepphase(g)  \
	(GCSswpallgc <= (g)->gcstate && (g)->gcstate <= GCSswpend)

/*
** macro to tell when main invariant (white objects cannot point to black
** ones) must be kept. During a collection, the sweep
** phase may break the invariant, as objects turned white may point to
** still-black objects. The invariant is restored when sweep ends and
** all objects are white again.
*/

#define keepinvariant(g)	((g)->gcstate <= GCSatomic)

/*
** some useful bit tricks
*/
#define resetbits(x,m)		((x) &= cast(lu_byte, ~(m)))
#define setbits(x,m)		((x) |= (m))
#define testbits(x,m)		((x) & (m))
#define bitmask(b)		(1<<(b))
#define bit2mask(b1,b2)		(bitmask(b1) | bitmask(b2))
#define l_setbit(x,b)		setbits(x, bitmask(b))
#define resetbit(x,b)		resetbits(x, bitmask(b))
#define testbit(x,b)		testbits(x, bitmask(b))

/* Layout for bit use in 'marked' field: */
#define WHITE0BIT	0  /* object is white (type 0) */
#define WHITE1BIT	1  /* object is white (type 1) */
#define BLACKBIT	2  /* object is black */
#define FINALIZEDBIT	3  /* object has been marked for finalization */
/* bit 7 is currently used by tests (luaL_checkmemory) */

#define WHITEBITS	bit2mask(WHITE0BIT, WHITE1BIT)

#define iswhite(x)      testbits((x)->marked, WHITEBITS)
#define isblack(x)      testbit((x)->marked, BLACKBIT)
#define isgray(x)  /* neither white nor black */  \
	(!testbits((x)->marked, WHITEBITS | bitmask(BLACKBIT)))

#define tofinalize(x)	testbit((x)->marked, FINALIZEDBIT)

#define otherwhite(g)	((g)->currentwhite ^ WHITEBITS)
#define isdeadm(ow,m)	(!(((m) ^ WHITEBITS) & (ow)))
#define isdead(g,v)	isdeadm(otherwhite(g), (v)->marked)

#define changewhite(x)	((x)->marked ^= WHITEBITS)
#define gray2black(x)	l_setbit((x)->marked, BLACKBIT)

#define luaC_white(g)	cast(lu_byte, (g)->currentwhite & WHITEBITS)

/*
** Does one step of collection when debt becomes positive. 'pre'/'pos'
** allows some adjustments to be done only when needed. macro
** 'condchangemem' is used only for heavy tests (forcing a full
** GC cycle on every opportunity)
*/
#define luaC_condGC(L,pre,pos) \
	{ if (G(L)->GCdebt > 0) { pre; luaC_step(L); pos;}; \
	  condchangemem(L,pre,pos); }

/* more often than not, 'pre'/'pos' are empty */
#define luaC_checkGC(L)		luaC_condGC(L,(void)0,(void)0)

#define luaC_barrier(L,p,v) (  \
	(iscollectable(v) && isblack(p) && iswhite(gcvalue(v))) ?  \
	luaC_barrier_(L,obj2gco(p),gcvalue(v)) : cast_void(0))

#define luaC_barrierback(L,p,v) (  \
	(iscollectable(v) && isblack(p) && iswhite(gcvalue(v))) ? \
	luaC_barrierback_(L,p) : cast_void(0))

#define luaC_objbarrier(L,p,o) (  \
	(isblack(p) && iswhite(o)) ? \
	luaC_barrier_(L,obj2gco(p),obj2gco(o)) : cast_void(0))

#define luaC_upvalbarrier(L,uv) ( \
	(iscollectable((uv)->v) && !upisopen(uv)) ? \
         luaC_upvalbarrier_(L,uv) : cast_void(0))

LUAI_FUNC void luaC_fix (lua_State *L, GCObject *o);
LUAI_FUNC void luaC_freeallobjects (lua_State *L);
LUAI_FUNC void luaC_step (lua_State *L);
LUAI_FUNC void luaC_runtilstate (lua_State *L, int statesmask);
LUAI_FUNC void luaC_fullgc (lua_State *L, int isemergency);
LUAI_FUNC GCObject *luaC_newobj (lua_State *L, int tt, size_t sz);
LUAI_FUNC void luaC_barrier_ (lua_State *L, GCObject *o, GCObject *v);
LUAI_FUNC void luaC_barrierback_ (lua_State *L, Table *o);
LUAI_FUNC void luaC_upvalbarrier_ (lua_State *L, UpVal *uv);
LUAI_FUNC void luaC_checkfinalizer (lua_State *L, GCObject *o, Table *mt);
LUAI_FUNC void luaC_upvdeccount (lua_State *L, UpVal *uv);

#endif


text:
/*
** $Id: lstring.h,v 1.61.1.1 2017/04/19 17:20:42 roberto Exp $
** String table (keep all strings handled by Lua)
** See Copyright Notice in lua.h
*/

#ifndef lstring_h
#define lstring_h

#include "lgc.h"
#include "lobject.h"
#include "lstate.h"

#define sizelstring(l)  (sizeof(union UTString) + ((l) + 1) * sizeof(char))

#define sizeludata(l)	(sizeof(union UUdata) + (l))
#define sizeudata(u)	sizeludata((u)->len)

#define luaS_newliteral(L, s)	(luaS_newlstr(L, "" s, \
                                 (sizeof(s)/sizeof(char))-1))

/*
** test whether a string is a reserved word
*/
#define isreserved(s)	((s)->tt == LUA_TSHRSTR && (s)->extra > 0)

/*
** equality for short strings, which are always internalized
*/
#define eqshrstr(a,b)	check_exp((a)->tt == LUA_TSHRSTR, (a) == (b))

LUAI_FUNC unsigned int luaS_hash (const char *str, size_t l, unsigned int seed);
LUAI_FUNC unsigned int luaS_hashlongstr (TString *ts);
LUAI_FUNC int luaS_eqlngstr (TString *a, TString *b);
LUAI_FUNC void luaS_resize (lua_State *L, int newsize);
LUAI_FUNC void luaS_clearcache (global_State *g);
LUAI_FUNC void luaS_init (lua_State *L);
LUAI_FUNC void luaS_remove (lua_State *L, TString *ts);
LUAI_FUNC Udata *luaS_newudata (lua_State *L, size_t s);
LUAI_FUNC TString *luaS_newlstr (lua_State *L, const char *str, size_t l);
LUAI_FUNC TString *luaS_new (lua_State *L, const char *str);
LUAI_FUNC TString *luaS_createlngstrobj (lua_State *L, size_t l);

#endif


text:
/*
** $Id: lmem.h,v 1.43.1.1 2017/04/19 17:20:42 roberto Exp $
** Interface to Memory Manager
** See Copyright Notice in lua.h
*/

#ifndef lmem_h
#define lmem_h

#include <stddef.h>

#include "llimits.h"
#include "lua.h"

/*
** This macro reallocs a vector 'b' from 'on' to 'n' elements, where
** each element has size 'e'. In case of arithmetic overflow of the
** product 'n'*'e', it raises an error (calling 'luaM_toobig'). Because
** 'e' is always constant, it avoids the runtime division MAX_SIZET/(e).
**
** (The macro is somewhat complex to avoid warnings:  The 'sizeof'
** comparison avoids a runtime comparison when overflow cannot occur.
** The compiler should be able to optimize the real test by itself, but
** when it does it, it may give a warning about "comparison is always
** false due to limited range of data type"; the +1 tricks the compiler,
** avoiding this warning but also this optimization.)
*/
#define luaM_reallocv(L,b,on,n,e) \
  (((sizeof(n) >= sizeof(size_t) && cast(size_t, (n)) + 1 > MAX_SIZET/(e)) \
      ? luaM_toobig(L) : cast_void(0)) , \
   luaM_realloc_(L, (b), (on)*(e), (n)*(e)))

/*
** Arrays of chars do not need any test
*/
#define luaM_reallocvchar(L,b,on,n)  \
    cast(char *, luaM_realloc_(L, (b), (on)*sizeof(char), (n)*sizeof(char)))

#define luaM_freemem(L, b, s)	luaM_realloc_(L, (b), (s), 0)
#define luaM_free(L, b)		luaM_realloc_(L, (b), sizeof(*(b)), 0)
#define luaM_freearray(L, b, n)   luaM_realloc_(L, (b), (n)*sizeof(*(b)), 0)

#define luaM_malloc(L,s)	luaM_realloc_(L, NULL, 0, (s))
#define luaM_new(L,t)		cast(t *, luaM_malloc(L, sizeof(t)))
#define luaM_newvector(L,n,t) \
		cast(t *, luaM_reallocv(L, NULL, 0, n, sizeof(t)))

#define luaM_newobject(L,tag,s)	luaM_realloc_(L, NULL, tag, (s))

#define luaM_growvector(L,v,nelems,size,t,limit,e) \
          if ((nelems)+1 > (size)) \
            ((v)=cast(t *, luaM_growaux_(L,v,&(size),sizeof(t),limit,e)))

#define luaM_reallocvector(L, v,oldn,n,t) \
   ((v)=cast(t *, luaM_reallocv(L, v, oldn, n, sizeof(t))))

LUAI_FUNC l_noret luaM_toobig (lua_State *L);

/* not to be called directly */
LUAI_FUNC void *luaM_realloc_ (lua_State *L, void *block, size_t oldsize,
                                                          size_t size);
LUAI_FUNC void *luaM_growaux_ (lua_State *L, void *block, int *size,
                               size_t size_elem, int limit,
                               const char *what);

#endif