lua-5.2.3/src/lparser.c

/*
** $Id: lparser.c,v 2.130.1.1 2013/04/12 18:48:47 roberto Exp $
** Lua Parser
** See Copyright Notice in lua.h
*/

#include <string.h>

#define lparser_c
#define LUA_CORE

#include "lua.h"

#include "lcode.h"
#include "ldebug.h"
#include "ldo.h"
#include "lfunc.h"
#include "llex.h"
#include "lmem.h"
#include "lobject.h"
#include "lopcodes.h"
#include "lparser.h"
#include "lstate.h"
#include "lstring.h"
#include "ltable.h"

/* 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)

/*
** nodes for block list (list of active blocks)
*/
typedef struct BlockCnt
{
	struct BlockCnt *previous; /* chain */
	short firstlabel;          /* index of first label in this block */
	short 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);

static void anchor_token(LexState *ls)
{
	/* last token from outer function must be EOS */
	lua_assert(ls->fs != NULL || ls->t.token == TK_EOS);
	if (ls->t.token == TK_NAME || ls->t.token == TK_STRING)
	{
		TString *ts = ls->t.seminfo.ts;
		luaX_newstring(ls, getstr(ts), ts->tsv.len);
	}
}

/* semantic error */
static l_noret semerror(LexState *ls, const char *msg)
{
	ls->t.token = 0; /* remove 'near to' 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 (luaS_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 (luaS_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 int singlevaraux(FuncState *fs, TString *n, expdesc *var, int base)
{
	if (fs == NULL)   /* no more levels? */
		return VVOID; /* 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 */
			return VLOCAL;
		}
		else
		{                                   /* not found as local at current level; try upvalues */
			int idx = searchupvalue(fs, n); /* try existing upvalues */
			if (idx < 0)
			{                                                   /* not found? */
				if (singlevaraux(fs->prev, n, var, 0) == VVOID) /* try upper levels */
					return VVOID;                               /* not found; is a global */
				/* else was LOCAL or UPVAL */
				idx = newupvalue(fs, n, var); /* will be a new upvalue */
			}
			init_exp(var, VUPVAL, idx);
			return VUPVAL;
		}
	}
}

static void singlevar(LexState *ls, expdesc *var)
{
	TString *varname = str_checkname(ls);
	FuncState *fs = ls->fs;
	if (singlevaraux(fs, varname, var, 1) == VVOID)
	{ /* global name? */
		expdesc key;
		singlevaraux(fs, ls->envn, var, 1); /* get environment variable */
		lua_assert(var->k == VLOCAL || var->k == VUPVAL);
		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);
		}
	}
}

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(luaS_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 " LUA_QS,
										   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 (luaS_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++;
	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 (luaS_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 " LUA_QS " 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)
{
	lua_State *L = ls->L;
	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 */
	fs->h = luaH_new(L);
	/* anchor table of constants (to avoid being collected) */
	sethvalue2s(L, L->top, fs->h);
	incr_top(L);
	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;
	/* last token read was anchored in defunct function; must re-anchor it */
	anchor_token(ls);
	L->top--; /* pop table of constants */
	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 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;
					break;
				}
				default:
					luaX_syntaxerror(ls, "<name> or " LUA_QL("...") " expected");
			}
		} while (!f->is_vararg && testnext(ls, ','));
	}
	adjustlocalvars(ls, nparams);
	f->numparams = cast_byte(fs->nactvar);
	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 -> NUMBER | STRING | NIL | TRUE | FALSE | ... |
                  constructor | FUNCTION body | suffixedexp */
	switch (ls->t.token)
	{
		case TK_NUMBER:
		{
			init_exp(v, VKNUM, 0);
			v->u.nval = ls->t.seminfo.r;
			break;
		}
		case TK_STRING:
		{
			codestring(ls, v, ls->t.seminfo.ts);
			break;
		}
		case TK_NIL:
		{
			init_exp(v, VNIL, 0);
			break;
		}
		case TK_TRUE:
		{
			init_exp(v, VTRUE, 0);
			break;
		}
		case TK_FALSE:
		{
			init_exp(v, VFALSE, 0);
			break;
		}
		case TK_DOTS:
		{ /* vararg */
			FuncState *fs = ls->fs;
			check_condition(ls, fs->f->is_vararg,
							"cannot use " LUA_QL("...") " outside a vararg function");
			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_LEN;
		default:
			return OPR_NOUNOPR;
	}
}

static BinOpr getbinopr(int op)
{
	switch (op)
	{
		case '+':
			return OPR_ADD;
		case '-':
			return OPR_SUB;
		case '*':
			return OPR_MUL;
		case '/':
			return OPR_DIV;
		case '%':
			return OPR_MOD;
		case '^':
			return OPR_POW;
		case TK_CONCAT:
			return OPR_CONCAT;
		case TK_NE:
			return OPR_NE;
		case TK_EQ:
			return OPR_EQ;
		case '<':
			return OPR_LT;
		case TK_LE:
			return OPR_LE;
		case '>':
			return OPR_GT;
		case TK_GE:
			return OPR_GE;
		case TK_AND:
			return OPR_AND;
		case TK_OR:
			return OPR_OR;
		default:
			return OPR_NOBINOPR;
	}
}

static const struct
{
	lu_byte left;  /* left priority for each binary operator */
	lu_byte right; /* right priority */
} priority[] = {
	/* ORDER OPR */
	{6, 6},
	{6, 6},
	{7, 7},
	{7, 7},
	{7, 7}, /* `+' `-' `*' `/' `%' */
	{10, 9},
	{5, 4}, /* ^, .. (right associative) */
	{3, 3},
	{3, 3},
	{3, 3}, /* ==, <, <= */
	{3, 3},
	{3, 3},
	{3, 3}, /* ~=, >, >= */
	{2, 2},
	{1, 1} /* and, or */
};

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

/*
** subexpr -> (simpleexp | unop subexpr) { binop subexpr }
** where `binop' is any binary operator with a priority higher than `limit'
*/
static BinOpr subexpr(LexState *ls, expdesc *v, 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);
			if (nexps > nvars)
				ls->fs->freereg -= nexps - nvars; /* remove extra values */
		}
		else
		{
			luaK_setoneret(ls->fs, &e); /* close last expression */
			luaK_storevar(ls->fs, &lh->v, &e);
			return; /* avoid default */
		}
	}
	init_exp(&e, VNONRELOC, ls->fs->freereg - 1); /* default assignment */
	luaK_storevar(ls->fs, &lh->v, &e);
}

static int cond(LexState *ls)
{
	/* cond -> exp */
	expdesc v;
	expr(ls, &v);                  /* read condition */
	if (v.k == VNIL) v.k = VFALSE; /* `falses' are all equal here */
	luaK_goiftrue(ls->fs, &v);
	return v.f;
}

static void 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 (luaS_eqstr(label, ll->arr[i].name))
		{
			const char *msg = luaO_pushfstring(fs->ls->L,
											   "label " LUA_QS " 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, fs->pc);
	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_numberK(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, LUA_QL("=") " or " LUA_QL("in") " expected");
	}
	check_match(ls, TK_END, TK_FOR, line);
	leaveblock(fs); /* loop scope (`break' jumps to this point) */
}

static 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 */
		skipnoopstat(ls);           /* skip other no-op statements */
		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(getcode(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(getcode(fs, &e), OP_TAILCALL);
				lua_assert(GETARG_A(getcode(fs, &e)) == fs->nactvar);
			}
			first = fs->nactvar;
			nret = LUA_MULTRET; /* return all values */
		}
		else
		{
			if (nret == 1) /* only one single value? */
				first = luaK_exp2anyreg(fs, &e);
			else
			{
				luaK_exp2nextreg(fs, &e); /* values must go to the `stack' */
				first = fs->nactvar;      /* return all `active' values */
				lua_assert(nret == fs->freereg - first);
			}
		}
	}
	luaK_ret(fs, first, nret);
	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 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);
}

Closure *luaY_parser(lua_State *L, ZIO *z, Mbuffer *buff,
					 Dyndata *dyd, const char *name, int firstchar)
{
	LexState lexstate;
	FuncState funcstate;
	Closure *cl = luaF_newLclosure(L, 1); /* create main closure */
	/* anchor closure (to avoid being collected) */
	setclLvalue(L, L->top, cl);
	incr_top(L);
	funcstate.f = cl->l.p = luaF_newproto(L);
	funcstate.f->source = luaS_new(L, name); /* create and anchor TString */
	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);
	return cl; /* it's on the stack too */
}