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libs/lua-5.3.4/src/lparser.c
Vladislav Khorev 111d2de79b Added lua
2017-02-21 00:03:08 +03:00

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/*
** $Id: lparser.c,v 2.155 2016/08/01 19:51:24 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 */
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(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 */
}
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