move all enum_flags_* func to enum_flags.hpp

include/magic_enum_flags.hpp

@@ -36,13 +36,137 @@
 
 namespace magic_enum {
 
+// Returns name from enum-flags value.
+// If enum-flags value does not have name or value out of range, returns empty string.
+template <typename E>
+[[nodiscard]] auto enum_flags_name(E value, char_type sep = static_cast<char_type>('|')) -> detail::enable_if_t<E, string> {
+  using D = std::decay_t<E>;
+  using U = underlying_type_t<D>;
+  constexpr auto S = detail::enum_subtype::flags;
+
+  string name;
+  auto check_value = U{0};
+  for (std::size_t i = 0; i < detail::count_v<D, S>; ++i) {
+    if (const auto v = static_cast<U>(enum_value<D, S>(i)); (static_cast<U>(value) & v) != 0) {
+      check_value |= v;
+      const auto n = detail::names_v<D, S>[i];
+      if (!name.empty()) {
+        name.append(1, sep);
+      }
+      name.append(n.data(), n.size());
+    }
+  }
+
+  if (check_value != 0 && check_value == static_cast<U>(value)) {
+    return name;
+  }
+  return {}; // Invalid value or out of range.
+}
+
+// Obtains enum-flags value from integer value.
+// Returns optional with enum-flags value.
+template <typename E>
+[[nodiscard]] constexpr auto enum_flags_cast(underlying_type_t<E> value) noexcept -> detail::enable_if_t<E, optional<std::decay_t<E>>> {
+  using D = std::decay_t<E>;
+  using U = underlying_type_t<D>;
+  constexpr auto S = detail::enum_subtype::flags;
+
+  if constexpr (detail::count_v<D, S> == 0) {
+    static_cast<void>(value);
+    return {}; // Empty enum.
+  } else {
+    if constexpr (detail::is_sparse_v<D, S>) {
+      auto check_value = U{0};
+      for (std::size_t i = 0; i < detail::count_v<D, S>; ++i) {
+        if (const auto v = static_cast<U>(enum_value<D, S>(i)); (value & v) != 0) {
+          check_value |= v;
+        }
+      }
+
+      if (check_value != 0 && check_value == value) {
+        return static_cast<D>(value);
+      }
+    } else {
+      constexpr auto min = detail::min_v<D, S>;
+      constexpr auto max = detail::values_ors<D, S>();
+
+      if (value >= min && value <= max) {
+        return static_cast<D>(value);
+      }
+    }
+    return {}; // Invalid value or out of range.
+  }
+}
+
+// Obtains enum-flags value from name.
+// Returns optional with enum-flags value.
+template <typename E, typename BinaryPredicate = std::equal_to<>>
+[[nodiscard]] constexpr auto enum_flags_cast(string_view value, [[maybe_unused]] BinaryPredicate p = {}) noexcept(detail::is_nothrow_invocable<BinaryPredicate>()) -> detail::enable_if_t<E, optional<std::decay_t<E>>, BinaryPredicate> {
+  using D = std::decay_t<E>;
+  using U = underlying_type_t<D>;
+  constexpr auto S = detail::enum_subtype::flags;
+
+  if constexpr (detail::count_v<D, S> == 0) {
+    static_cast<void>(value);
+    return {}; // Empty enum.
+  } else {
+    auto result = U{0};
+    while (!value.empty()) {
+      const auto d = detail::find(value, '|');
+      const auto s = (d == string_view::npos) ? value : value.substr(0, d);
+      auto f = U{0};
+      for (std::size_t i = 0; i < detail::count_v<D, S>; ++i) {
+        if (detail::cmp_equal(s, detail::names_v<D, S>[i], p)) {
+          f = static_cast<U>(enum_value<D, S>(i));
+          result |= f;
+          break;
+        }
+      }
+      if (f == U{0}) {
+        return {}; // Invalid value or out of range.
+      }
+      value.remove_prefix((d == string_view::npos) ? value.size() : d + 1);
+    }
+
+    if (result != U{0}) {
+      return static_cast<D>(result);
+    }
+    return {}; // Invalid value or out of range.
+  }
+}
+
+// Checks whether enum-flags contains value with such value.
+template <typename E>
+[[nodiscard]] constexpr auto enum_flags_contains(E value) noexcept -> detail::enable_if_t<E, bool> {
+  using D = std::decay_t<E>;
+  using U = underlying_type_t<D>;
+
+  return static_cast<bool>(enum_flags_cast<D>(static_cast<U>(value)));
+}
+
+// Checks whether enum-flags contains value with such integer value.
+template <typename E>
+[[nodiscard]] constexpr auto enum_flags_contains(underlying_type_t<E> value) noexcept -> detail::enable_if_t<E, bool> {
+  using D = std::decay_t<E>;
+
+  return static_cast<bool>(enum_flags_cast<D>(value));
+}
+
+// Checks whether enum-flags contains enumerator with such name.
+template <typename E, typename BinaryPredicate = std::equal_to<>>
+[[nodiscard]] constexpr auto enum_flags_contains(string_view value, BinaryPredicate p = {}) noexcept(detail::is_nothrow_invocable<BinaryPredicate>()) -> detail::enable_if_t<E, bool, BinaryPredicate> {
+  using D = std::decay_t<E>;
+
+  return static_cast<bool>(enum_flags_cast<D>(value, std::move(p)));
+}
+
 // Checks whether `flags set` contains `flag`.
 // Note: If `flag` equals 0, it returns false, as 0 is not a flag.
 template <typename E>
 constexpr auto enum_flags_test(E flags, E flag) noexcept -> detail::enable_if_t<E, bool> {
   using U = underlying_type_t<E>;
 
-  return static_cast<bool>(static_cast<U>(flags) & static_cast<U>(flag));
+  return static_cast<U>(flag) && ((static_cast<U>(flags) & static_cast<U>(flag)) == static_cast<U>(flag));
 }
 
 // Checks whether `lhs flags set` and `rhs flags set` have common flags.