static void assignment (LexState *ls, struct LHS_assign *lh, int nvars) {
expdesc e;
check_condition(ls, VLOCAL <= lh->v.k && lh->v.k <= VINDEXED,
"syntax error");
if (testnext(ls, ',')) { /* assignment -> `,' primaryexp assignment */
struct LHS_assign nv;
nv.prev = lh;
primaryexp(ls, &nv.v);
if (nv.v.k == VLOCAL)
check_conflict(ls, lh, &nv.v);
assignment(ls, &nv, nvars+1);
}
else { /* assignment -> `=' explist1 */
int nexps;
check(ls, '=');
nexps = explist1(ls, &e);
if (nexps != nvars) {
adjust_assign(ls, nvars, nexps, &e);
if (nexps > nvars)
ls->fs->freereg -= nexps - nvars; /* remove extra values */
}
else {
luaK_setcallreturns(ls->fs, &e, 1); /* 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 void retstat (LexState *ls) {
/* stat -> RETURN explist */
FuncState *fs = ls->fs;
expdesc e;
int first, nret; /* registers with returned values */
next(ls); /* skip RETURN */
if (block_follow(ls->t.token) || ls->t.token == ';')
first = nret = 0; /* return no values */
else {
nret = explist1(ls, &e); /* optional return values */
if (e.k == VCALL) {
luaK_setcallreturns(fs, &e, LUA_MULTRET);
if (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_codeABC(fs, OP_RETURN, first, nret+1, 0);
}
void luaK_tostack (LexState *ls, expdesc *v, int onlyone) {
FuncState *fs = ls->fs;
if (!discharge(fs, v)) { /* `v' is an expression? */
OpCode previous = GET_OPCODE(fs->f->code[fs->pc-1]);
if (!ISJUMP(previous) && v->u.l.f == NO_JUMP && v->u.l.t == NO_JUMP) {
/* expression has no jumps */
if (onlyone)
luaK_setcallreturns(fs, 1); /* call must return 1 value */
}
else { /* expression has jumps */
int final; /* position after whole expression */
int j = NO_JUMP; /* eventual jump over values */
int p_nil = NO_JUMP; /* position of an eventual PUSHNIL */
int p_1 = NO_JUMP; /* position of an eventual PUSHINT */
if (ISJUMP(previous) || need_value(fs, v->u.l.f, OP_JMPONF)
|| need_value(fs, v->u.l.t, OP_JMPONT)) {
/* expression needs values */
if (ISJUMP(previous))
luaK_concat(fs, &v->u.l.t, fs->pc-1); /* put `previous' in t. list */
else {
j = code_label(fs, OP_JMP, NO_JUMP); /* to jump over both pushes */
/* correct stack for compiler and symbolic execution */
luaK_adjuststack(fs, 1);
}
p_nil = code_label(fs, OP_PUSHNILJMP, 0);
p_1 = code_label(fs, OP_PUSHINT, 1);
luaK_patchlist(fs, j, luaK_getlabel(fs));
}
final = luaK_getlabel(fs);
luaK_patchlistaux(fs, v->u.l.f, p_nil, OP_JMPONF, final);
luaK_patchlistaux(fs, v->u.l.t, p_1, OP_JMPONT, final);
v->u.l.f = v->u.l.t = NO_JUMP;
}
static void lastlistfield (FuncState *fs, struct ConsControl *cc) {
if (cc->tostore == 0) return;
if (cc->v.k == VCALL) {
luaK_setcallreturns(fs, &cc->v, LUA_MULTRET);
luaK_codeABx(fs, OP_SETLISTO, cc->t->info, cc->na-1);
}
else {
if (cc->v.k != VVOID)
luaK_exp2nextreg(fs, &cc->v);
luaK_codeABx(fs, OP_SETLIST, cc->t->info, cc->na-1);
}
fs->freereg = cc->t->info + 1; /* free registers */
}
static void exprstat (LexState *ls) {
/* stat -> func | assignment */
FuncState *fs = ls->fs;
struct LHS_assign v;
primaryexp(ls, &v.v);
if (v.v.k == VCALL) { /* stat -> func */
luaK_setcallreturns(fs, &v.v, 0); /* call statement uses no results */
}
else { /* stat -> assignment */
v.prev = NULL;
assignment(ls, &v, 1);
}
}
static void funcargs (LexState *ls, expdesc *f) {
FuncState *fs = ls->fs;
expdesc args;
int base, nparams;
int line = ls->linenumber;
switch (ls->t.token) {
case '(': { /* funcargs -> `(' [ explist1 ] `)' */
if (line != ls->lastline)
luaX_syntaxerror(ls,"ambiguous syntax (function call x new statement)");
next(ls);
if (ls->t.token == ')') /* arg list is empty? */
args.k = VVOID;
else {
explist1(ls, &args);
luaK_setcallreturns(fs, &args, LUA_MULTRET);
}
check_match(ls, ')', '(', line);
break;
}
case '{': { /* funcargs -> constructor */
constructor(ls, &args);
break;
}
case TK_STRING: { /* funcargs -> STRING */
codestring(ls, &args, ls->t.seminfo.ts);
next(ls); /* must use `seminfo' before `next' */
break;
}
default: {
luaX_syntaxerror(ls, "function arguments expected");
return;
}
}
lua_assert(f->k == VNONRELOC);
base = f->info; /* base register for call */
if (args.k == VCALL)
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 */
}
static void adjust_assign (LexState *ls, int nvars, int nexps, expdesc *e) {
FuncState *fs = ls->fs;
int extra = nvars - nexps;
if (e->k == VCALL) {
extra++; /* includes call itself */
if (extra <= 0) extra = 0;
else luaK_reserveregs(fs, extra-1);
luaK_setcallreturns(fs, e, extra); /* call provides the difference */
}
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 discharge1 (FuncState *fs, expdesc *var) {
discharge(fs, var);
/* if it has jumps then it is already discharged */
if (var->u.l.t == NO_JUMP && var->u.l.f == NO_JUMP)
luaK_setcallreturns(fs, 1); /* call must return 1 value */
}
