Open rpatters1 opened 9 months ago
Just to fill this out with a code example:
template <auto Start, auto End, auto Inc, class F>
constexpr void constexpr_for(F&& f)
{
if constexpr (Start < End)
{
f(std::integral_constant<decltype(Start), Start>());
constexpr_for<Start + Inc, End, Inc>(f);
}
}
enum APLHABITS
{
NONE = 0,
A = 0x0001,
B = 0x0002,
C = 0x0004,
D = 0x0008,
E = 0x0010,
F = 0x0020,
G = 0x0040,
H = 0x0080,
I = 0x0100,
J = 0x0200,
// K = 0x0300, // ignore this one, it's a typo
L = 0x0400,
M = 0x0800,
N = 0x1000,
O = 0x2000,
P = 0x4000,
Q = 0x8000
};
template <>
struct magic_enum::customize::enum_range<APLHABITS> {
static constexpr bool is_flags = true;
};
void myfunc()
{
constexpr std::size_t count = magic_enum::enum_count<APLHABITS>();
printf("%ld ", count);
constexpr auto names = magic_enum::enum_names<APLHABITS>();
constexpr_for<0, count, 1>([&](auto i)
{
printf("%s:%d ", names[i].data(), magic_enum::enum_value<APLHABITS, i>());
});
}
When you run my_func
it prints
16 A:1 B:2 C:4 D:8 E:16 F:32 G:64 H:128 I:256 J:512 L:1024 M:2048 N:4096 O:8192 P:16384 Q:32768
.
I would like it to print
17 NONE:0 A:1 B:2 C:4 D:8 E:16 F:32 G:64 H:128 I:256 J:512 L:1024 M:2048 N:4096 O:8192 P:16384 Q:32768
.
while keeping the is_flags
set for performance reasons. Is this possible?
In reading #314, it appears that it is not possible to fully iterate an
is_flags
enum that has a zero value. This seems like an unfortunate limitation. I have frequently encountered bit-sensitive enums that include a 0 value for clearing out the bits. My code simply needs to iterate the names and values to create Lua constants, and bit-sensitive values are resource-intensive if they don't setis_flags
.