type_traits

Reverse engineered types traits classes from C++11 plus several ETL extensions.

This file is generated from type_traits_generator.h. See Generators

Not all traits have been defined as some rely on compiler intrinsics that are not available on all compiler platforms.

See type_traits for more information

integral_constant

remove_reference

add_reference

remove_pointer

add_pointer

is_const

remove_const

add_const

is_volatile

remove_volatile

add_volatile

remove_cv

add_cv

add_volatile

remove_cvref 20.17.0

is_integral

is_signed

is_unsigned

is_floating_point

is_same

is_void

is_arithmetic

is_fundamental

is_compound

is_array

is_pointer

is_reference

is_base_of

make_signed

make_unsigned

enable_if

conditional

extent

remove_extent

remove_all_extents

rank

decay

alignment_of

conjunction 20.14.0

disjunction 20.14.0

negation

is_lvalue_assignable

void_t 20.28.0

declvar 20.28.0

common_type

is_enum 20.30.0 C++11

underlying_type 20.42.0

Unless the ETL is set to use builtins, the user must specialise the templte for their enumerations.

The definitions will wrap those defined in C++11's <type_traits> if available.

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The following will be defined according to the C++ standard and user defined macros.

is_assignable

is_constructible

is_copy_constructible

is_move_constructible

is_trivially_constructible

is_trivially_copy_constructible

is_trivially_destructible

is_trivially_copy_assignable

is_trivially_copyable

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Scenario: Using C++11 or above and the STL.

If ETL_CPP11_SUPPORTED and ETL_USING_STL == 1 and !defined(ETL_USE_TYPE_TRAITS_BUILTINS)

and !defined(ETL_USER_DEFINED_TYPE_TRAITS) and ((!defined(ARDUINO) && ETL_NOT_USING_STLPORT) or

defined(ETL_GCC_V5_TYPE_TRAITS_SUPPORTED))

The ETL's definitions wrap the STL definitions, except in the following case.

if ETL_CPP11_TYPE_TRAITS_IS_TRIVIAL_SUPPORTED is not defined then they will be defined as in the

ETL_USER_DEFINED_TYPE_TRAITS option.

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Scenario: Not using the STL but the compiler has type trait built-ins.

If the user has defined ETL_USE_TYPE_TRAITS_BUILTINS then the ETL will use the generally available compiler built-ins.

This option is useful for when you are not using the STL, but are using a compatible compiler.

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Scenario: Not using the STL and have the compiler has no type trait built-ins.

If the user has defined ETL_USER_DEFINED_TYPE_TRAITS then the ETL will define these type traits for arithmetic and

pointer types only. For all other types the traits will be undefined, unless the user explicitly specialises them.

struct Copyable

{

Copyable() {}

Copyable(const Copyable& other) {}

Copyable& operator =(const Copyable& rhs) { return *this; }

Copyable(Copyable&& other) = delete;

Copyable& operator =(Copyable& rhs) = delete;

};

using etl::is_assignable;

using etl::is_constructible;

using etl::is_copy_constructible;

using etl::is_move_constructible;

template <>

struct etl::is_assignable<Copyable, Copyable> : public etl::true_type

{

};

template <>

struct etl::is_constructible<Copyable> : public etl::true_type

{

};

template <>

struct etl::is_copy_constructible<Copyable> : public etl::true_type

{

};

template <>

struct etl::is_move_constructible<Copyable> : public etl::false_type

{

};

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Scenario: Not using the STL, the compiler has no type trait built-ins, and no user define specialisations are defined.

The ETL will define these type traits as true for arithmetic and pointer types only. For all other types the traits will have

a value of false.

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is_one_of

ETL extension

C++03

template <typename T,

typename T1, typename T2 = void, typename T3 = void, typename T4 = void,

typename T5 = void, typename T6 = void, typename T7 = void, typename T8 = void,

typename T9 = void, typename T10 = void, typename T11 = void, typename T12 = void,

typename T13 = void, typename T14 = void, typename T15 = void, typename T16 = void>

struct is_one_of

By default the ETL allows up the 16 types. This may be changed by running the type traits generator.

See Generators

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C++11 or above

template <typename T, typename... TTypelist>

struct is_one_of

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Members

value

Set to true if the first template type is one of the subsequent types, otherwise false.

If C++17 is supported then this definition available

template <typename T>

constexpr bool is_one_of_v = etl::is_one_of<T, TRest...>::value;

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Example

bool isOK;

isOK = etl::is_one_of<int, char, short, int, long>::value; // Sets 'isOK' to true.

isOK = etl::is_one_of<double, char, short, int, long>::value; // Sets 'isOK' to false.

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are_all_same

ETL extension

C++11 or above

template <typename T, typename... TTypelist>

struct are_all_same

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Members

value

Set to true if all of the template types are the same, otherwise false.

If C++17 is supported then this definition available

template <typename T>

constexpr bool are_all_same_v = etl::is_one_of<T, TRest...>::value;

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Example

bool isOK;

isOK = etl::are_all_same<int, int, int, int>::value; // Sets 'isOK' to true.

isOK = etl::is_one_of<int, int, char, int>::value; // Sets 'isOK' to false.

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conditional_integral_constant

ETL extension

Members

value

Set to the constant determined by the condition.

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Example

int value;

value = etl::conditional_integral_constant<true, 1, 2>::value; // Sets value to 1

value = etl::conditional_integral_constant<false, 1, 2>::value; // Sets value to 2

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types

ETL extension

Extracts the basic types from a template type.

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type

The underlying type.

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reference

A reference to the underlying type.

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const_reference

A const reference to the underlying type.

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pointer

A pointer to the underlying type.

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const_pointer

A const pointer to the underlying type.

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Example

typedef const int* const MyType;

etl::types<MyType>::type int

etl::types<MyType>::reference int&

etl::types<MyType>::const_reference const int&

etl::types<MyType>::pointer int*

etl::types<MyType>::const_pointer const int*

etl::types<MyType>::const_pointer_const const int* const

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unsigned_type

ETL extension

20.29.0

template <typename T>

struct unsigned_type

Defines one of five unsigned types that has the same size as T.

Defines one of unsigned char, unsigned short, unsigned int, unsigned long, unsigned long long.

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template <typename T>

using unsigned_type_t = typename unsigned_type<T>::type;

C++11

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signed_type

ETL extension

20.29.0

template <typename T>

struct signed_type

Defines one of five signed types that has the same size as T.

Defines one of char, short, int, long, long long.

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template <typename T>

using signed_type_t = typename signed_type<T>::type;

C++11

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has_duplicates

ETL extension

20.39.1

C++11 or above

template <typename... TTypes>

struct has_duplicates

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Members

value

Set to true if the typelist TTypes contains any duplicate types, otherwise false.

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If C++17 is supported then this definition is available

template <typname... TTypes>

constexpr bool has_duplicates_v = etl::has_duplicates<TTypes...>::value;

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has_duplicates_of

ETL extension

20.39.1

C++11 or above

template <typename T, typename... TTypes>

struct has_duplicates_of

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Members

value

Set to true if the typelist TTypes contains duplicates of types T, otherwise false.

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If C++17 is supported then this definition is available

template <typename T, typname... TTypes>

constexpr bool has_duplicates_of_v = etl::has_duplicates_of<T, TTypes...>::value;

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count_of

ETL extension

20.39.1

C++11 or above

template <typename T, typename... TTypes>

struct count_of

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Members

value

The count of the occurences of type T in the typelist TTypes.

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If C++17 is supported then this definition is available

template <typename T, typname... TTypes>

constexpr bool count_of_v = etl::count_of<T, TTypes...>::value;

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conjunction

20.40.1

template <typename... Types>

struct conjunction;

Forms the logical conjunction (AND) of Types...

The result is found in the member value.

template <typename... Types>

inline constexpr bool conjunction_v;

Forms the logical conjunction (AND) of Types...

C++17

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disjunction

20.40.1

template <typename... Types>

struct disjunction;

Forms the logical disjunction (OR) of Types...

The result is found in the member value.

template <typename... Types>

inline constexpr bool disjunction_v;

Forms the logical disjunction (OR) of Types...

C++17

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exclusive_disjunction

20.40.1

template <typename... Types>

struct exclusive_disjunction;

Forms the logical exclusive disjunction (XOR) of Types...

The result is found in the member value.

template <typename... Types>

inline constexpr bool exclusive_disjunction_v;

Forms the logical exclusive disjunction (XOR) of Types...

C++17

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unwrap_reference

unwrap_ref_decay

20.40.1

template <class T>

struct unwrap_reference;

Unwraps any etl::reference_wrapper, changing etl::reference_wrapper<U> to U&.

If T is a specialisation of etl::reference_wrapper, unwraps it, otherwise T remains the same.

template <typename T>

using unwrap_reference_t;

C++11

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template <typename T>

struct unwrap_ref_decay;

Unwraps any etl::reference_wrapper, changing etl::reference_wrapper<U> to U&.

If decayed T is a specialisation of etl::reference_wrapper, unwraps it, otherwise T is decayed.

template <typename T>

using unwrap_ref_decay_t;

C++11

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is_specialization

20.41.0

template <typename T, template <typename...> class Template>

struct is_specialization

Checks if T is a specialization of template type Template.

The result is found in the member value.

C++11

template <typename T, template <typename...> class Template>

inline constexpr bool is_specialization_v = etl::is_specialization<T, Template>::value;

C++17

type_traits.h