565 lines
16 KiB
Markdown
565 lines
16 KiB
Markdown
# Reference
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* [`enum_cast` obtains enum value from string or integer.](#enum_cast)
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* [`enum_value` returns enum value at specified index.](#enum_value)
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* [`enum_values` obtains enum value sequence.](#enum_values)
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* [`enum_count` returns number of enum values.](#enum_count)
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* [`enum_integer` obtains integer value from enum value.](#enum_integer)
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* [`enum_name` returns name from enum value.](#enum_name)
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* [`enum_names` obtains string enum name sequence.](#enum_names)
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* [`enum_entries` obtains pair (value enum, string enum name) sequence.](#enum_entries)
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* [`enum_index` obtains index in enum value sequence from enum value.](#enum_index)
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* [`enum_contains` checks whether enum contains enumerator with such value.](#enum_contains)
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* [`enum_type_name` returns type name of enum.](#enum_type_name)
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* [`enum_fuse` returns a bijective mix of enum values.](#enum_fuse)
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* [`enum_switch` allows runtime enum value transformation to constexpr context.](#enum_switch)
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* [`enum_for_each` calls a function with all enum constexpr value.](#enum_for_each)
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* [`enum_flags` API from enum-flags.](#enum_flags)
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* [`is_unscoped_enum` checks whether type is an Unscoped enumeration.](#is_unscoped_enum)
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* [`is_scoped_enum` checks whether type is an Scoped enumeration.](#is_scoped_enum)
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* [`underlying_type` improved UB-free "SFINAE-friendly" underlying_type.](#underlying_type)
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* [`ostream_operators` ostream operators for enums.](#ostream_operators)
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* [`bitwise_operators` bitwise operators for enums.](#bitwise_operators)
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## Synopsis
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* Before use, read the [limitations](limitations.md) of functionality.
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* To check is magic_enum supported compiler use macro `MAGIC_ENUM_SUPPORTED` or constexpr constant `magic_enum::is_magic_enum_supported`.</br>
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If magic_enum used on unsupported compiler, occurs the compilation error. To suppress error define macro `MAGIC_ENUM_NO_CHECK_SUPPORT`.
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* To add custom enum or type names see the [example](../example/example_custom_name.cpp).
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* To change the type of strings or ortional, use special macros:
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```cpp
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#include <my_lib/string.hpp>
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#include <my_lib/string_view.hpp>
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#define MAGIC_ENUM_USING_ALIAS_STRING using string = my_lib::String;
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#define MAGIC_ENUM_USING_ALIAS_STRING_VIEW using string_view = my_lib::StringView;
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#define MAGIC_ENUM_USING_ALIAS_OPTIONAL template <typename T> using optional = my_lib::Optional<T>;
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#include <magic_enum.hpp>
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```
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* Optionally define `MAGIC_ENUM_CONFIG_FILE` i.e., in your build system, with path to header file with defined
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macros or constants, for example:
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```cpp
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#define MAGIC_ENUM_CONFIG_FILE "my_magic_enum_cfg.hpp"
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```
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my_magic_enum_cfg.hpp:
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```cpp
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#include <my_lib/string.hpp>
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#include <my_lib/string_view.hpp>
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#define MAGIC_ENUM_USING_ALIAS_STRING using string = my_lib::String;
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#define MAGIC_ENUM_USING_ALIAS_STRING_VIEW using string_view = my_lib::StringView;
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#define MAGIC_ENUM_USING_ALIAS_OPTIONAL template <typename T> using optional = my_lib::Optional<T>;
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#define MAGIC_ENUM_RANGE_MIN 0
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#define MAGIC_ENUM_RANGE_MAX 255
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```
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* To add support for non-ASCII enumeration identifier, use special macros:
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```cpp
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#define MAGIC_ENUM_ENABLE_NONASCII
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#include <magic_enum.hpp>
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```
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## `enum_cast`
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```cpp
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template <typename E>
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constexpr optional<E> enum_cast(underlying_type_t<E> value) noexcept;
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template <typename E>
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constexpr optional<E> enum_cast(string_view value) noexcept;
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template <typename E, typename BinaryPredicate>
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constexpr optional<E> enum_cast(string_view value, BinaryPredicate p) noexcept(is_nothrow_invocable_v<BinaryPredicate>);
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```
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* Obtains enum value from string or integer.
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* Returns `optional<E>`, using `has_value()` to check contains enum value and `value()` to get the enum value.
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* If argument does not enum value, returns empty `optional`.
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* Examples
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* String to enum value.
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```cpp
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string color_name{"GREEN"};
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auto color = magic_enum::enum_cast<Color>(color_name);
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if (color.has_value()) {
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// color.value() -> Color::GREEN
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}
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auto color_or_default = magic_enum::enum_cast<Color>(value).value_or(Color::NONE);
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```
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* Integer to enum value.
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```cpp
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int color_integer = 2;
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auto color = magic_enum::enum_cast<Color>(color_integer);
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if (color.has_value()) {
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// color.value() -> Color::RED
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}
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auto color_or_default = magic_enum::enum_cast<Color>(value).value_or(Color::NONE);
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```
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## `enum_value`
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```cpp
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template <typename E>
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constexpr E enum_value(size_t index) noexcept;
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template <typename E, size_t I>
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constexpr E enum_value() noexcept;
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```
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* Returns enum value at specified index.
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* `enum_value(value)` no bounds checking is performed: the behavior is undefined if `index >= number of enum values`.
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* `enum_value<value>()` check if `I >= number of enum values`, occurs the compilation error `magic_enum::enum_value out of range`.
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* Examples
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```cpp
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int i = 1;
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Color color = magic_enum::enum_value<Color>(i);
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// color -> Color::BLUE
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```
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```cpp
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Color color = magic_enum::enum_value<Color, 1>();
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// color -> Color::BLUE
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```
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## `enum_values`
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```cpp
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template <typename E>
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constexpr array<E, N> enum_values() noexcept;
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```
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* Returns `array<E, N>` with all enum values where `N = number of enum values`, sorted by enum value.
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* Examples
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```cpp
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constexpr auto colors = magic_enum::enum_values<Color>();
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// colors -> {Color::RED, Color::BLUE, Color::GREEN}
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// colors[0] -> Color::RED
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```
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## `enum_count`
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```cpp
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template <typename E>
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constexpr size_t enum_count() noexcept;
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```
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* Returns number of enum values.
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* Examples
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```cpp
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constexpr auto color_count = magic_enum::enum_count<Color>();
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// color_count -> 3
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```
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## `enum_integer`
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```cpp
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template <typename E>
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constexpr underlying_type_t<E> enum_integer(E value) noexcept;
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template <typename E>
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constexpr underlying_type_t<E> enum_underlying(E value) noexcept;
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```
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* Returns integer value from enum value.
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* Examples
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```cpp
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Color color = Color::RED;
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auto color_integer = magic_enum::enum_integer(color);
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// color -> 2
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```
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## `enum_name`
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```cpp
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template <typename E>
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constexpr string_view enum_name(E value) noexcept;
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template <auto V>
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constexpr string_view enum_name() noexcept;
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```
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* Returns name from enum value as `string_view` with null-terminated string.
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* If enum value does not have name or [out of range](limitations.md), `enum_name(value)` returns empty string.
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* If enum value does not have name, `enum_name<value>()` occurs the compilation error `magic_enum::enum_name enum value does not have a name`.
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* `enum_name<value>()` is much lighter on the compile times and is not restricted to the enum_range [limitation](limitations.md).
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* Examples
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```cpp
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Color color = Color::RED;
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auto color_name = magic_enum::enum_name(color);
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// color_name -> "RED"
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```
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```cpp
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constexpr Color color = Color::BLUE;
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constexpr auto color_name = magic_enum::enum_name<color>();
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// color_name -> "BLUE"
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```
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## `enum_names`
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```cpp
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template <typename E>
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constexpr array<string_view, N> enum_names() noexcept;
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```
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* Returns `array<string_view, N>` with all names where `N = number of enum values`, sorted by enum value.
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* Examples
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```cpp
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constexpr auto color_names = magic_enum::enum_names<Color>();
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// color_names -> {"RED", "BLUE", "GREEN"}
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// color_names[0] -> "RED"
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```
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## `enum_entries`
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```cpp
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template <typename E>
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constexpr array<pair<E, string_view>, N> enum_entries() noexcept;
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```
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* Returns `array<pair<E, string_view>, N>` with all pairs (value, name) where `N = number of enum values`, sorted by enum value.
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* Examples
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```cpp
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constexpr auto color_entries = magic_enum::enum_entries<Color>();
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// color_entries -> {{Color::RED, "RED"}, {Color::BLUE, "BLUE"}, {Color::GREEN, "GREEN"}}
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// color_entries[0].first -> Color::RED
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// color_entries[0].second -> "RED"
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```
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## `enum_index`
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```cpp
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template <typename E>
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constexpr optional<size_t> enum_index(E value) noexcept;
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template <auto V>
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constexpr size_t enum_index() noexcept;
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```
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* Obtains index in enum values from enum value.
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* `enum_index(value)` returns `optional<size_t>` with index.
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* `enum_index<value>()` returns index. If enum value does not have a index, occurs the compilation error `magic_enum::enum_index enum value does not have a index`.
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* Examples
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```cpp
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constexpr auto color_index = magic_enum::enum_index(Color::BLUE);
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// color_index.value() -> 1
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// color_index.has_value() -> true
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```
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```cpp
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constexpr auto color_index = magic_enum::enum_index<Color::BLUE>();
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// color_index -> 1
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```
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## `enum_contains`
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```cpp
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template <typename E>
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constexpr bool enum_contains(E value) noexcept;
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template <typename E>
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constexpr bool enum_contains(underlying_type_t<E> value) noexcept;
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template <typename E>
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constexpr bool enum_contains(string_view value) noexcept;
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template <typename E, typename BinaryPredicate>
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constexpr optional<E> enum_contains(string_view value, BinaryPredicate p) noexcept(is_nothrow_invocable_v<BinaryPredicate>);
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```
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* Checks whether enum contains enumerator with such value.
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* Returns true is enum contains value, otherwise false.
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* Examples
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```cpp
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magic_enum::enum_contains(Color::GREEN); // -> true
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magic_enum::enum_contains<Color>(2); // -> true
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magic_enum::enum_contains<Color>(123); // -> false
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magic_enum::enum_contains<Color>("GREEN"); // -> true
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magic_enum::enum_contains<Color>("fda"); // -> false
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```
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## `enum_type_name`
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```cpp
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template <typename E>
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constexpr string_view enum_type_name() noexcept;
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```
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* Returns type name of enum as `string_view` null-terminated string.
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* Examples
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```cpp
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Color color = Color::RED;
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auto type_name = magic_enum::enum_type_name<decltype(color)>();
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// color_name -> "Color"
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```
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## `enum_fuse`
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```cpp
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template <typename... Es>
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[[nodiscard]] constexpr optional<enum_fuse_t> enum_fuse(Es... values) noexcept;
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```
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* You should add the required file `<magic_enum_fuse.hpp>`.
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* Returns a typesafe bijective mix of several enum values. This can be used to emulate 2D switch/case statements.
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* Return type is `optional<enum_fuse_t>` where `enum_fuse_t` is an incomplete enum, it is unique for any given combination of `Es...`.
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* Switch/case statement over an incomplete enum is a Visual Studio warning C4064
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* You have to silent (/wd4064) or ignore it.
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* Alternatively, define `MAGIC_ENUM_NO_TYPESAFE_ENUM_FUSE` to disable type-safety (`enum_fuse_t` equals `uintmax_t`).
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* Examples
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```cpp
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switch (magic_enum::enum_fuse(color, direction).value()) {
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case magic_enum::enum_fuse(Color::RED, Directions::Up).value(): // ...
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case magic_enum::enum_fuse(Color::BLUE, Directions::Down).value(): // ...
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case magic_enum::enum_fuse(Directions::BLUE, Color::Down).value(): // Compilation error
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// ...
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}
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```
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## `enum_switch`
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```cpp
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template <typename Result = void, typename E, typename Lambda>
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constexpr Result enum_switch(Lambda&& lambda, E value);
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template <typename Result, typename E, typename Lambda>
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constexpr Result enum_switch(Lambda&& lambda, E value, Result&& result);
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```
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* You should add the required file `<magic_enum_switch.hpp>`.
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* Examples
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```cpp
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Color color = Color::RED;
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magic_enum::enum_switch([] (auto val) {
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constexpr Color c_color = val;
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// ...
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}, color);
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```
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## `enum_for_each`
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```cpp
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template <typename E, typename Lambda>
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constexpr auto enum_for_each(Lambda&& lambda);
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```
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* Examples
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```cpp
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magic_enum::enum_for_each<Color>([] (auto val) {
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constexpr Color c_color = val;
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// ...
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});
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```
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## `enum_flags`
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```cpp
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template <typename E>
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string enum_flags_name(E value);
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template <typename E>
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constexpr optional<E> enum_flags_cast(underlying_type_t<E> value) noexcept;
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template <typename E>
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constexpr optional<E> enum_flags_cast(string_view value) noexcept;
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template <typename E, typename BinaryPredicate>
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constexpr optional<E> enum_flags_cast(string_view value, BinaryPredicate p) noexcept(is_nothrow_invocable_v<BinaryPredicate>);
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template <typename E>
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constexpr bool enum_flags_contains(E value) noexcept;
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template <typename E>
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constexpr bool enum_flags_contains(underlying_type_t<E> value) noexcept;
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template <typename E>
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constexpr bool enum_flags_contains(string_view value) noexcept;
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template <typename E, typename BinaryPredicate>
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constexpr optional<E> enum_flags_contains(string_view value, BinaryPredicate p) noexcept(is_nothrow_invocable_v<BinaryPredicate>);
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```
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* Examples
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```cpp
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auto directions_name = magic_enum::enum_flags_name(Directions::Up | Directions::Right);
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// directions_name -> "Directions::Up | Directions::Right"
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```
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## `is_unscoped_enum`
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```cpp
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template <typename T>
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struct is_unscoped_enum;
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template <typename T>
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inline constexpr bool is_unscoped_enum_v = is_unscoped_enum<T>::value;
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```
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* Checks whether type is an [Unscoped enumeration](https://en.cppreference.com/w/cpp/language/enum#Unscoped_enumeration).
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* Provides the member constant value which is equal to true, if T is an [Unscoped enumeration](https://en.cppreference.com/w/cpp/language/enum#Unscoped_enumeration) type.</br>
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Otherwise, value is equal to false.
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* Examples
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```cpp
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magic_enum::is_unscoped_enum<color>::value -> true
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magic_enum::is_unscoped_enum<Direction>::value -> false
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// Helper variable template.
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magic_enum::is_unscoped_enum_v<color> -> true
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```
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## `is_scoped_enum`
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```cpp
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template <typename T>
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struct is_scoped_enum;
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template <typename T>
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inline constexpr bool is_scoped_enum_v = is_scoped_enum<T>::value;
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```
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* Checks whether type is an [Scoped enumeration](https://en.cppreference.com/w/cpp/language/enum#Scoped_enumerations).
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* Provides the member constant value which is equal to true, if T is an [Scoped enumeration](https://en.cppreference.com/w/cpp/language/enum#Scoped_enumerations) type.</br>
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Otherwise, value is equal to false.
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* Examples
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```cpp
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magic_enum::is_scoped_enum<color>::value -> false
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magic_enum::is_scoped_enum<Direction>::value -> true
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// Helper variable template.
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magic_enum::is_scoped_enum_v<Direction> -> true
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```
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## `underlying_type`
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```cpp
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template <typename T>
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struct underlying_type;
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template <typename T>
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using underlying_type_t = typename underlying_type<T>::type;
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```
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* Improved UB-free "SFINAE-friendly" [underlying_type](https://en.cppreference.com/w/cpp/types/underlying_type).
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* If T is a complete enumeration type, provides a member typedef type that names the underlying type of T.</br>
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Otherwise, if T is not an enumeration type, there is no member type.</br>
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Otherwise (T is an incomplete enumeration type), the program is ill-formed.
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* Examples
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```cpp
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magic_enum::underlying_type<color>::type -> int
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// Helper types.
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magic_enum::underlying_type_t<Direction> -> int
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```
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## `ostream_operators`
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```cpp
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template <typename Char, typename Traits, typename E>
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basic_ostream<Char, Traits>& operator<<(basic_ostream<Char, Traits>& os, E value);
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template <typename Char, typename Traits, typename E>
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basic_ostream<Char, Traits>& operator<<(basic_ostream<Char, Traits>& os, optional<E> value);
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```
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* Out-of-the-box ostream operators for all enums.
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* Examples
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```cpp
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using namespace magic_enum::ostream_operators; // out-of-the-box ostream operators for enums.
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Color color = Color::BLUE;
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std::cout << color << std::endl; // "BLUE"
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|
```
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|
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|
## `bitwise_operators`
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|
|
|
```cpp
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|
template <typename E>
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|
constexpr E operator~(E rhs) noexcept;
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|
|
|
template <typename E>
|
|
constexpr E operator|(E lhs, E rhs) noexcept;
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|
|
|
template <typename E>
|
|
constexpr E operator&(E lhs, E rhs) noexcept;
|
|
|
|
template <typename E>
|
|
constexpr E operator^(E lhs, E rhs) noexcept;
|
|
|
|
template <typename E>
|
|
constexpr E& operator|=(E& lhs, E rhs) noexcept;
|
|
|
|
template <typename E>
|
|
constexpr E& operator&=(E& lhs, E rhs) noexcept;
|
|
|
|
template <typename E>
|
|
constexpr E& operator^=(E& lhs, E rhs) noexcept;
|
|
```
|
|
|
|
* Out-of-the-box bitwise operators for all enums.
|
|
|
|
* Examples
|
|
|
|
```cpp
|
|
enum class Flags { A = 1 << 0, B = 1 << 1, C = 1 << 2, D = 1 << 3 };
|
|
using namespace magic_enum::bitwise_operators; // out-of-the-box bitwise operators for enums.
|
|
// Support operators: ~, |, &, ^, |=, &=, ^=.
|
|
Flags flags = Flags::A | Flags::B & ~Flags::C;
|
|
```
|