void luaV_arith (lua_State *L, StkId ra, const TValue *rb,
const TValue *rc, TMS op) {
TValue tempb, tempc;
const TValue *b, *c;
if ((b = luaV_tonumber(rb, &tempb)) != NULL &&
(c = luaV_tonumber(rc, &tempc)) != NULL) {
lua_Number res = luaO_arith(op - TM_ADD + LUA_OPADD, nvalue(b), nvalue(c));
setnvalue(ra, res);
}
else if (!call_binTM(L, rb, rc, ra, op))
luaG_aritherror(L, rb, rc);
}
LUA_API void lua_arith (lua_State *L, int op) {
lua_lock(L);
if (op != LUA_OPUNM && op != LUA_OPBNOT)
api_checknelems(L, 2); /* all other operations expect two operands */
else { /* for unary operations, add fake 2nd operand */
api_checknelems(L, 1);
setobjs2s(L, L->top, L->top - 1);
L->top++;
}
/* first operand at top - 2, second at top - 1; result go to top - 2 */
luaO_arith(L, op, L->top - 2, L->top - 1, L->top - 2);
L->top--; /* remove second operand */
lua_unlock(L);
}
/*
** Try to "constant-fold" an operation; return 1 iff successful
*/
static int constfolding (FuncState *fs, int op, expdesc *e1, expdesc *e2) {
TValue v1, v2, res;
if (!tonumeral(e1, &v1) || !tonumeral(e2, &v2) || !validop(op, &v1, &v2))
return 0; /* non-numeric operands or not safe to fold */
luaO_arith(fs->ls->L, op, &v1, &v2, &res);
if (ttisinteger(&res)) {
e1->k = VKINT;
e1->u.ival = ivalue(&res);
}
else {
lua_Number n = fltvalue(&res);
if (luai_numisnan(n) || isminuszero(n))
return 0; /* folds neither NaN nor -0 */
e1->k = VKFLT;
e1->u.nval = n;
}
return 1;
}
LUA_API void lua_arith (lua_State *L, int op) {
StkId o1; /* 1st operand */
StkId o2; /* 2nd operand */
lua_lock(L);
if (op != LUA_OPUNM) /* all other operations expect two operands */
api_checknelems(L, 2);
else { /* for unary minus, add fake 2nd operand */
api_checknelems(L, 1);
setobjs2s(L, L->top, L->top - 1);
L->top++;
}
o1 = L->top - 2;
o2 = L->top - 1;
if (ttisnumber(o1) && ttisnumber(o2)) {
changenvalue(o1, luaO_arith(op, nvalue(o1), nvalue(o2)));
}
else
luaV_arith(L, o1, o1, o2, cast(TMS, op - LUA_OPADD + TM_ADD));
L->top--;
lua_unlock(L);
}
