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add comparison predicate for enum_cast

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This commit is contained in:
neargye 2020-04-02 17:08:42 +05:00
parent a76480629c
commit 306b1d0704
2 changed files with 74 additions and 47 deletions
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58
include/magic_enum.hpp
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@ -131,6 +131,12 @@ struct static_string<0> {
constexpr operator std::string_view() const noexcept { return {}; }
};
struct char_equal {
constexpr bool operator()(char lhs, char rhs) const noexcept {
return lhs == rhs;
}
};
constexpr std::string_view pretty_name(std::string_view name) noexcept {
for (std::size_t i = name.size(); i > 0; --i) {
if (!((name[i - 1] >= '0' && name[i - 1] <= '9') ||
@ -151,19 +157,33 @@ constexpr std::string_view pretty_name(std::string_view name) noexcept {
return {}; // Invalid name.
}
template <typename L, typename R>
constexpr bool mixed_sign_less(L lhs, R rhs) noexcept {
static_assert(std::is_integral_v<L> && std::is_integral_v<R>, "magic_enum::detail::mixed_sign_less requires integral type.");
template <typename BinaryPredicate>
constexpr bool cmp_equal(std::string_view lhs, std::string_view rhs, BinaryPredicate p) noexcept(std::is_nothrow_invocable_r_v<bool, BinaryPredicate, char, char>) {
if (lhs.size() != rhs.size()) {
return false;
}
const auto size = lhs.size();
for (std::size_t i = 0; i < size; ++i) {
if (!p(lhs[i], rhs[i])) {
return false;
}
}
return true;
}
if constexpr (std::is_signed_v<L> && std::is_unsigned_v<R>) {
// If 'left' is negative, then result is 'true', otherwise cast & compare.
return lhs < 0 || static_cast<std::make_unsigned_t<L>>(lhs) < rhs;
} else if constexpr (std::is_unsigned_v<L> && std::is_signed_v<R>) {
// If 'right' is negative, then result is 'false', otherwise cast & compare.
return rhs >= 0 && lhs < static_cast<std::make_unsigned_t<R>>(rhs);
} else {
template <typename L, typename R>
constexpr bool cmp_less(L lhs, R rhs) noexcept {
static_assert(std::is_integral_v<L> && std::is_integral_v<R>, "magic_enum::detail::cmp_less requires integral type.");
if constexpr (std::is_signed_v<L> == std::is_signed_v<R>) {
// If same signedness (both signed or both unsigned).
return lhs < rhs;
} else if constexpr (std::is_signed_v<R>) {
// If 'right' is negative, then result is 'false', otherwise cast & compare.
return rhs > 0 && lhs < static_cast<std::make_unsigned_t<R>>(rhs);
} else {
// If 'left' is negative, then result is 'true', otherwise cast & compare.
return lhs < 0 || static_cast<std::make_unsigned_t<L>>(lhs) < rhs;
}
}
@ -212,7 +232,7 @@ constexpr int reflected_min() noexcept {
static_assert(lhs > (std::numeric_limits<std::int16_t>::min)(), "magic_enum::enum_range requires min must be greater than INT16_MIN.");
constexpr auto rhs = (std::numeric_limits<std::underlying_type_t<E>>::min)();
return mixed_sign_less(lhs, rhs) ? rhs : lhs;
return cmp_less(lhs, rhs) ? rhs : lhs;
}
template <typename E>
@ -222,7 +242,7 @@ constexpr int reflected_max() noexcept {
static_assert(lhs < (std::numeric_limits<std::int16_t>::max)(), "magic_enum::enum_range requires max must be less than INT16_MAX.");
constexpr auto rhs = (std::numeric_limits<std::underlying_type_t<E>>::max)();
return mixed_sign_less(lhs, rhs) ? lhs : rhs;
return cmp_less(lhs, rhs) ? lhs : rhs;
}
template <typename E>
@ -443,19 +463,20 @@ using enum_traits = detail::enum_traits<std::decay_t<E>>;
// Obtains enum value from enum string name.
// Returns std::optional with enum value.
template <typename E>
[[nodiscard]] constexpr auto enum_cast(std::string_view value) noexcept -> detail::enable_if_enum_t<E, std::optional<std::decay_t<E>>> {
template <typename E, typename BinaryPredicate>
[[nodiscard]] constexpr auto enum_cast(std::string_view value, BinaryPredicate p) noexcept(std::is_nothrow_invocable_r_v<bool, BinaryPredicate, char, char>) -> detail::enable_if_enum_t<E, std::optional<std::decay_t<E>>> {
static_assert(std::is_invocable_r_v<bool, BinaryPredicate, char, char>, "magic_enum::enum_cast requires bool(char, char) invocable predicate.");
using D = std::decay_t<E>;
if constexpr (detail::range_size_v<D> > detail::count_v<D> * 2) {
for (std::size_t i = 0; i < enum_traits<D>::count; ++i) {
if (value == enum_traits<D>::names[i]) {
if (detail::cmp_equal(value, enum_traits<D>::names[i], p)) {
return enum_traits<D>::values[i];
}
}
} else {
for (auto i = detail::min_v<D>; i <= detail::max_v<D>; ++i) {
if (value == enum_traits<D>::name(static_cast<D>(i))) {
if (detail::cmp_equal(value, enum_traits<D>::name(static_cast<D>(i)), p)) {
return static_cast<D>(i);
}
}
@ -464,6 +485,11 @@ template <typename E>
return std::nullopt; // Invalid value or out of range.
}
template <typename E>
[[nodiscard]] constexpr auto enum_cast(std::string_view value) noexcept -> detail::enable_if_enum_t<E, std::optional<std::decay_t<E>>> {
return enum_cast<E>(value, detail::char_equal{});
}
// Obtains enum value from integer value.
// Returns std::optional with enum value.
template <typename E>