The `type-traits.h` File Reference

C++ header file with declarations for the µTest++ type trait utilities and metaprogramming support. More...

Included Headers

#include "math.h"

Namespaces Index

namespace	micro_os_plus
	The primary namespace for the µOS++ framework. More...

namespace	micro_os_plus::micro_test_plus
	Primary namespace for the µTest++ testing framework. More...

namespace	micro_os_plus::micro_test_plus::type_traits
	Type trait utilities and metaprogramming support for the µTest++ testing framework. More...

Classes Index

struct	floating_point_constant<T, N, D, Size, P>
	Struct template representing a generic floating point constant with custom size and precision. More...

struct	function_traits<R(*)(Args_T...)>
	Struct template specialisation for extracting function traits from function pointer types. More...

struct	function_traits<R(Args_T...)>
	Struct template specialisation for extracting function traits from plain function types. More...

struct	function_traits<R(T::*)(Args_T...) const>
	Struct template specialisation for extracting function traits from const member function types. More...

struct	function_traits<R(T::*)(Args_T...)>
	Struct template specialisation for extracting function traits from non-const member function types. More...

struct	genuine_integral_value<T>
	Struct template representing a genuine integral value. More...

struct	identity<T, class...>
	Struct template for compile-time type identity. More...

struct	integral_constant<N>
	Struct template representing a generic integral constant. More...

struct	list<class...>
	Struct template representing a compile-time type list. More...

struct	op
	Empty base struct for all operator types. More...

struct	requires_<bool>
	Struct template for SFINAE requirements. More...

struct	requires_<true>
	Specialisation of the requirements struct template for `true`. More...

struct	value<T, class>
	Struct template representing a generic value, accessible via a getter. More...

struct	value<T, type_traits::requires_t< type_traits::is_floating_point_v< T > >>
	Struct template representing a floating point value with precision control. More...

Typedefs Index

using	requires_t = typename requires_< Cond >::type
	Alias template for extracting the `type` member from `requires_`. More...

Variables Index

auto	has_epsilon_v = is_valid<T> ([] (auto t) -> decltype (void (t.epsilon)) {})
	Variable template to determine if a type provides an `epsilon` member. More...

auto	has_npos_v = is_valid<T> ([] (auto t) -> decltype (void (t.npos)) {})
	Variable template to determine if a type provides a static `npos` member. More...

auto	has_value_v = is_valid<T> ([] (auto t) -> decltype (void (t.value)) {})
	Variable template to determine if a type provides a `value` member. More...

auto	is_container_v = is_valid<T> ( [] (auto t) -> decltype (t.begin (), t.end (), void ()) {})
	Variable template to determine if a type models a container. More...

auto	is_convertible_v = is_convertible<From, To> (0)
	Variable template to determine if one type is convertible to another. More...

auto	is_floating_point_v = false
	Variable template to determine if a type is a floating point type. More...

auto	is_floating_point_v< double > = true
	Variable template specialisation indicating that `double` is a floating point type. More...

auto	is_floating_point_v< float > = true
	Variable template specialisation indicating that `float` is a floating point type. More...

auto	is_floating_point_v< long double > = true
	Variable template specialisation indicating that `long double` is a floating point type. More...

auto	is_op_v = __is_base_of (type_traits::op, T)
	Variable template to determine if a type derives from `op`. More...

Functions Index

T &&	declval (void)
	Utility function template to simulate std::declval for type deduction. More...

constexpr auto	is_convertible (...)
	Fallback function template for is_convertible, returns false if the conversion is not valid. More...

constexpr auto	is_convertible (int n) -> decltype(bool(To(declval< From >())))
	Function template to determine if one type is convertible to another. More...

constexpr bool	is_valid (...)
	Fallback function template for is_valid, returns false if the expression is not valid. More...

constexpr auto	is_valid (Expr_T expr) -> decltype(expr(declval< Ts... >()), bool())

Description

C++ header file with declarations for the µTest++ type trait utilities and metaprogramming support.

This header provides the declarations for the type trait utilities and metaprogramming constructs used within the µTest++ framework. It defines templates and variable traits for function traits, type lists, identity, value wrappers, compile-time checks for container and floating-point types, and type convertibility.

These utilities underpin advanced template programming, type deduction, and compile-time introspection, supporting the flexible and type-safe design of the framework. The provided traits and wrappers enable expressive and generic handling of types, values, and callable objects, facilitating robust and maintainable test code.

All definitions reside within the micro_os_plus::micro_test_plus::type_traits namespace, ensuring clear separation from user code and minimising the risk of naming conflicts.

All header files are organised within the include/micro-os-plus/micro-test-plus folder to maintain a structured and modular codebase.

This file is intended for internal use within the framework and should not be included directly by user code.

Typedefs

requires_t

template <bool Cond>

using micro_os_plus::micro_test_plus::type_traits::requires_t = typename requires_<Cond>::type

Alias template for extracting the type member from requires_.

Template Parameters

Cond	The boolean condition to be checked at compile time.

The requires_t alias template simplifies the use of the requires_ struct template by directly exposing the nested type member. It is commonly used to enforce compile-time requirements in template declarations.

Definition at line 662 of file type-traits.h.

Variables

has_epsilon_v

template <class T>

auto micro_os_plus::micro_test_plus::type_traits::has_epsilon_v = is_valid<T> ([] (auto t) -> decltype (void (t.epsilon)) {})

constexprstatic

Variable template to determine if a type provides an epsilon member.

Template Parameters

T	The type to be checked for the presence of an `epsilon` member.

Return Values

true	if `T` has a member named `epsilon`.
false	otherwise.

The has_epsilon_v variable template evaluates to true if the given type T defines a member named epsilon. This trait is determined at compile time using SFINAE and the is_valid utility, and is used throughout the µTest++ framework to enable generic handling of types that represent floating-point values or require precision control.

Definition at line 442 of file type-traits.h.

has_npos_v

template <class T>

auto micro_os_plus::micro_test_plus::type_traits::has_npos_v = is_valid<T> ([] (auto t) -> decltype (void (t.npos)) {})

constexprstatic

Variable template to determine if a type provides a static npos member.

Template Parameters

T	The type to be checked for the presence of a static `npos` member.

Return Values

true	if `T` has a static member named `npos`.
false	otherwise.

The has_npos_v variable template evaluates to true if the given type T defines a static member named npos. This trait is determined at compile time using SFINAE and the is_valid utility, and is used throughout the µTest++ framework to enable generic handling of types that follow the standard string or container conventions.

Definition at line 401 of file type-traits.h.

has_value_v

template <class T>

auto micro_os_plus::micro_test_plus::type_traits::has_value_v = is_valid<T> ([] (auto t) -> decltype (void (t.value)) {})

constexprstatic

Variable template to determine if a type provides a value member.

Template Parameters

T	The type to be checked for the presence of a `value` member.

Return Values

true	if `T` has a member named `value`.
false	otherwise.

The has_value_v variable template evaluates to true if the given type T defines a member named value. This trait is determined at compile time using SFINAE and the is_valid utility, and is used throughout the µTest++ framework to enable generic handling of types that encapsulate a value, such as wrappers or constant types.

Definition at line 421 of file type-traits.h.

is_container_v

template <class T>

auto micro_os_plus::micro_test_plus::type_traits::is_container_v = is_valid<T> ( [] (auto t) -> decltype (t.begin (), t.end (), void ()) {})

constexprstatic

Variable template to determine if a type models a container.

Template Parameters

T	The type to be checked for container-like behaviour.

Return Values

true	if `T` has both `begin()` and `end()` member functions.
false	otherwise.

The is_container_v variable template evaluates to true if the given type T provides both begin() and end() member functions, indicating that it models a standard container concept. This trait is determined at compile time using SFINAE and is_valid, and is used throughout the µTest++ framework to enable generic handling of container types in template metaprogramming.

Definition at line 380 of file type-traits.h.

is_convertible_v

template <class From, class To>

auto micro_os_plus::micro_test_plus::type_traits::is_convertible_v = is_convertible<From, To> (0)

constexpr

Variable template to determine if one type is convertible to another.

Template Parameters

From	The source type to be checked for convertibility.
To	The target type to which conversion is tested.

Return Values

true	if `From` is convertible to `To`.
false	otherwise.

The is_convertible_v variable template evaluates to true if the type From is implicitly convertible to the type To, and false otherwise. This trait is determined at compile time and is used throughout the µTest++ framework to enable type-safe conversions and requirements checking in template metaprogramming.

Definition at line 605 of file type-traits.h.

is_floating_point_v

template <class T>

auto micro_os_plus::micro_test_plus::type_traits::is_floating_point_v = false

constexpr

Variable template to determine if a type is a floating point type.

Template Parameters

T	The type to be checked for floating point classification.

Return Values

true	if `T` is a floating point type.
false	otherwise.

The is_floating_point_v variable template evaluates to true if the given type T is a floating point type (float, double, or long double). For all other types, it evaluates to false. This trait is used throughout the µTest++ framework to enable type-safe handling and specialisation for floating point types in template metaprogramming.

Specialisations are provided for float, double, and long double, each evaluating to true.

Definition at line 465 of file type-traits.h.

is_floating_point_v< double >

auto micro_os_plus::micro_test_plus::type_traits::is_floating_point_v< double > = true

constexpr

Variable template specialisation indicating that double is a floating point type.

This specialisation of the is_floating_point_v variable template evaluates to true for the double type, confirming that it is recognised as a floating point type within the µTest++ framework. This enables type-safe handling and specialisation for floating point types in template metaprogramming.

See Also: is_floating_point_v

Definition at line 497 of file type-traits.h.

is_floating_point_v< float >

auto micro_os_plus::micro_test_plus::type_traits::is_floating_point_v< float > = true

constexpr

Variable template specialisation indicating that float is a floating point type.

This specialisation of the is_floating_point_v variable template evaluates to true for the float type, confirming that it is recognised as a floating point type within the µTest++ framework. This enables type-safe handling and specialisation for floating point types in template metaprogramming.

See Also: is_floating_point_v

Definition at line 481 of file type-traits.h.

is_floating_point_v< long double >

auto micro_os_plus::micro_test_plus::type_traits::is_floating_point_v< long double > = true

constexpr

Variable template specialisation indicating that long double is a floating point type.

This specialisation of the is_floating_point_v variable template evaluates to true for the long double type, confirming that it is recognised as a floating point type within the µTest++ framework. This enables type-safe handling and specialisation for floating point types in template metaprogramming.

See Also: is_floating_point_v

Definition at line 513 of file type-traits.h.

is_op_v

template <class T>

auto micro_os_plus::micro_test_plus::type_traits::is_op_v = __is_base_of (type_traits::op, T)

constexpr

Variable template to determine if a type derives from op.

Template Parameters

T	The type to be checked for derivation from `op`.

Return Values

true	if `T` is derived from `type_traits::op`.
false	otherwise.

The is_op_v variable template evaluates to true if the given type T is derived from the type_traits::op base struct, and false otherwise. This trait is determined at compile time using compiler intrinsics and is used throughout the µTest++ framework to enable generic handling and detection of operator-like or value wrapper types in template metaprogramming.

Definition at line 946 of file type-traits.h.

Functions

declval()

template <class T>

T && micro_os_plus::micro_test_plus::type_traits::declval (void)

Utility function template to simulate std::declval for type deduction.

Template Parameters

T	The type for which an rvalue reference is required.

Parameters: None.

Returns: An rvalue reference to type T.

The declval function template provides a mechanism for obtaining an rvalue reference to a type T without requiring an actual object. This is primarily used in unevaluated contexts, such as within decltype, to deduce types during template metaprogramming in the µTest++ framework.

Definition at line 335 of file type-traits.h.

is_convertible()

template <class...>

auto micro_os_plus::micro_test_plus::type_traits::is_convertible (...)

constexpr

Fallback function template for is_convertible, returns false if the conversion is not valid.

Template Parameters

...Unused

Unused template parameters.

Return Values

false

indicating the conversion is not valid.

This overload is selected when the primary is_convertible template cannot be instantiated, providing a false result for invalid conversions.

Definition at line 582 of file type-traits.h.

is_convertible()

template <class From, class To>

decltype(bool(To(declval< From >()))) micro_os_plus::micro_test_plus::type_traits::is_convertible (int n)

constexpr

Function template to determine if one type is convertible to another.

Template Parameters

From	The source type to be checked for convertibility.
To	The target type to which conversion is tested.

Parameters

n	Dummy parameter used for overload resolution.

Return Values

true	if `From` is convertible to `To`.

The is_convertible function template checks, at compile time, whether a value of type From can be implicitly converted to type To. This is achieved using SFINAE and is primarily used as an implementation detail for the is_convertible_v variable template within the µTest++ framework.

If the conversion is valid, this overload is selected and returns true.

Definition at line 561 of file type-traits.h.

is_valid()

template <class...>

bool micro_os_plus::micro_test_plus::type_traits::is_valid (...)

constexpr

Fallback function template for is_valid, returns false if the expression is not valid.

Template Parameters

...Ts

The argument types to be tested.

Returns: false indicating the expression is not valid for the given argument types.

This overload is selected when the primary is_valid template cannot be instantiated, providing a false result for invalid expressions.

Definition at line 358 of file type-traits.h.

is_valid()

template <class... Ts, class Expr_T>

decltype(expr(declval< Ts... >()), bool()) micro_os_plus::micro_test_plus::type_traits::is_valid (Expr_T expr)

constexpr

Definition at line 338 of file type-traits.h.

File Listing

The file content with the documentation metadata removed is:

1/*

2 * This file is part of the µOS++ project (https://micro-os-plus.github.io/).

4 *

5 * Permission to use, copy, modify, and/or distribute this software

6 * for any purpose is hereby granted, under the terms of the MIT license.

7 *

8 * If a copy of the license was not distributed with this file, it can

9 * be obtained from https://opensource.org/licenses/mit.

10 *

11 * Major parts of the code are inspired from v1.1.8 of the Boost UT project,

12 * released under the terms of the Boost Version 1 Software License,

13 * which can be obtained from https://www.boost.org/LICENSE_1_0.txt.

14 */

16// ----------------------------------------------------------------------------

48#ifndef MICRO_TEST_PLUS_TYPE_TRAITS_H_

49#define MICRO_TEST_PLUS_TYPE_TRAITS_H_

51// ----------------------------------------------------------------------------

53#ifdef __cplusplus

55// ----------------------------------------------------------------------------

57#include "math.h"

59// ----------------------------------------------------------------------------

61#if defined(__GNUC__)

62#pragma GCC diagnostic push

63#if defined(__clang__)

64#pragma clang diagnostic ignored "-Wc++98-compat"

65#pragma clang diagnostic ignored "-Wc++98-compat-pedantic"

66#endif

67#endif

69namespace micro_os_plus::micro_test_plus

70{

71 // --------------------------------------------------------------------------

97 namespace type_traits

98 {

117 template <class...>

118 struct list

119 {

120 };

121

140 template <class T, class...>

141 struct identity

142 {

146 using type = T;

147 };

148

149#if defined(__DOXYGEN__)

150 // error: Detected potential recursive class relation between class

151 // micro_os_plus::micro_test_plus::type_traits::function_traits and base

152 // class micro_os_plus::micro_test_plus::type_traits::function_traits<

153 // decltype(&T::operator())>!

154 // https://github.com/doxygen/doxygen/issues/9915

155#else

176 template <class T>

177 struct function_traits : function_traits<decltype (&T::operator())>

178 {

179 };

180#endif

181

201 template <class R, class... Args_T>

202 struct function_traits<R (*) (Args_T...)>

203 {

207 using result_type = R;

208

212 using args = list<Args_T...>;

213 };

214

234 template <class R, class... Args_T>

235 struct function_traits<R (Args_T...)>

236 {

240 using result_type = R;

241

245 using args = list<Args_T...>;

246 };

247

268 template <class R, class T, class... Args_T>

269 struct function_traits<R (T::*) (Args_T...)>

270 {

274 using result_type = R;

275

279 using args = list<Args_T...>;

280 };

281

303 template <class R, class T, class... Args_T>

304 struct function_traits<R (T::*) (Args_T...) const>

305 {

309 using result_type = R;

310

314 using args = list<Args_T...>;

315 };

316

333 template <class T>

334 T&&

335 declval (void);

336 template <class... Ts, class Expr_T>

337 constexpr auto

338 is_valid (Expr_T expr) -> decltype (expr (declval<Ts...> ()), bool ())

339 {

340 return true;

341 }

342

356 template <class...>

357 constexpr auto

358 is_valid (...) -> bool

359 {

360 return false;

361 }

362

379 template <class T>

380 static constexpr auto is_container_v = is_valid<T> (

381 [] (auto t) -> decltype (t.begin (), t.end (), void ()) {});

382

400 template <class T>

401 static constexpr auto has_npos_v

402 = is_valid<T> ([] (auto t) -> decltype (void (t.npos)) {});

403

420 template <class T>

421 static constexpr auto has_value_v

422 = is_valid<T> ([] (auto t) -> decltype (void (t.value)) {});

423

441 template <class T>

442 static constexpr auto has_epsilon_v

443 = is_valid<T> ([] (auto t) -> decltype (void (t.epsilon)) {});

444

464 template <class T>

465 inline constexpr auto is_floating_point_v = false;

466

480 template <>

481 inline constexpr auto is_floating_point_v<float> = true;

482

496 template <>

497 inline constexpr auto is_floating_point_v<double> = true;

498

512 template <>

513 inline constexpr auto is_floating_point_v<long double> = true;

514

515#if defined(__clang__) or defined(_MSC_VER)

536 template <class From, class To>

537 static constexpr auto is_convertible_v = __is_convertible_to (From, To);

538#else

559 template <class From, class To>

560 constexpr auto

561 is_convertible (int n) -> decltype (bool (To (declval<From> ())))

562 {

563 (void)n; // Prevent the unused parameter warning.

564 return true;

565 }

566

580 template <class...>

581 constexpr auto

582 is_convertible (...)

583 {

584 return false;

585 }

586

604 template <class From, class To>

605 constexpr auto is_convertible_v = is_convertible<From, To> (0);

606#endif

607

626 template <bool>

627 struct requires_

628 {

629 };

630

641 template <>

642 struct requires_<true>

643 {

647 using type = int;

648 };

649

661 template <bool Cond>

662 using requires_t = typename requires_<Cond>::type;

663

680 struct op

681 {

682 };

683

702 template <auto N>

703 struct integral_constant : op

704 {

708 using value_type = decltype (N);

709

713 static constexpr auto value = N;

714

724 [[nodiscard]] constexpr auto

725 operator- () const

726 {

727 return integral_constant<-N>{};

728 }

729

740 [[nodiscard]] constexpr explicit

741 operator value_type (void) const

742 {

743 return N;

744 }

745

756 [[nodiscard]] constexpr auto

757 get (void) const

758 {

759 return N;

760 }

761 };

762

789 template <class T, auto N, auto D, auto Size, auto P = 1>

790 struct floating_point_constant : op

791 {

795 using value_type = T;

796

803 static constexpr auto epsilon = T (1) / math::pow (T (10), Size - 1);

804

811 static constexpr auto value

812 = T (P) * (T (N) + (T (D) / math::pow (T (10), Size)));

813

823 [[nodiscard]] constexpr auto

824 operator-() const

825 {

826 return floating_point_constant<T, N, D, Size, -1>{};

827 }

828

838 [[nodiscard]] constexpr explicit

839 operator value_type () const

840 {

841 return value;

842 }

843

852 [[nodiscard]] constexpr auto

853 get () const

854 {

855 return value;

856 }

857 };

858

878 template <class T>

879 struct genuine_integral_value : op

880 {

884 using value_type = T;

885

891 constexpr genuine_integral_value (const T& _value) : value_{ _value }

892 {

893 }

894

903 [[nodiscard]] constexpr explicit

904 operator T () const

905 {

906 return value_;

907 }

908

917 [[nodiscard]] constexpr decltype (auto)

918 get () const

919 {

920 return value_;

921 }

922

926 T value_{};

927 };

928

945 template <class T>

946 inline constexpr auto is_op_v = __is_base_of (type_traits::op, T);

947

970 template <class T, class = int>

971 struct value : type_traits::op

972 {

976 using value_type = T;

977

983 constexpr value (const T& _value) : value_{ _value }

984 {

985 }

986

995 [[nodiscard]] constexpr explicit

996 operator T () const

997 {

998 return value_;

999 }

1000

1011 [[nodiscard]] constexpr decltype (auto)

1012 get (void) const

1013 {

1014 return value_;

1015 }

1016

1020 T value_{};

1021 };

1022

1048 template <class T>

1049 struct value<T,

1050 type_traits::requires_t<type_traits::is_floating_point_v<T>>>

1051 : type_traits::op

1052 {

1056 using value_type = T;

1057

1066 static inline auto epsilon = T{}; // Why static?

1067

1074 constexpr value (const T& _value, const T precision) : value_{ _value }

1075 {

1076 epsilon = precision;

1077 }

1078

1088 constexpr /*explicit(false)*/ value (const T& val)

1089 : value{ val,

1090 T (1)

1091 / math::pow (T (10),

1092 math::den_size<unsigned long long> (val)) }

1093 {

1094 }

1095

1104 [[nodiscard]] constexpr explicit

1105 operator T () const

1106 {

1107 return value_;

1108 }

1109

1120 [[nodiscard]] constexpr decltype (auto)

1121 get (void) const

1122 {

1123 return value_;

1124 }

1125

1129 T value_{};

1130 };

1131

1132 // ------------------------------------------------------------------------

1133 } // namespace type_traits

1134

1135 // --------------------------------------------------------------------------

1136} // namespace micro_os_plus::micro_test_plus

1137

1138#if defined(__GNUC__)

1139#pragma GCC diagnostic pop

1140#endif

1141

1142// ----------------------------------------------------------------------------

1143

1144#endif // __cplusplus

1145

1146// ----------------------------------------------------------------------------

1147

1148#endif // MICRO_TEST_PLUS_TYPE_TRAITS_H_

1149

1150// ----------------------------------------------------------------------------

Generated via docusaurus-plugin-doxygen by Doxygen 1.14.0.

Included Headers​

Namespaces Index​

Classes Index​

Typedefs Index​

Variables Index​

Functions Index​

Description​

Typedefs​

requires_t​

Variables​

has_epsilon_v​

has_npos_v​

has_value_v​

is_container_v​

is_convertible_v​

is_floating_point_v​

is_floating_point_v< double >​

is_floating_point_v< float >​

is_floating_point_v< long double >​

is_op_v​

Functions​

declval()​

is_convertible()​

is_convertible()​

is_valid()​

is_valid()​

File Listing​

Included Headers

Namespaces Index

Classes Index

Typedefs Index

Variables Index

Functions Index

Description

Typedefs

requires_t

Variables

has_epsilon_v

has_npos_v

has_value_v

is_container_v

is_convertible_v

is_floating_point_v

is_floating_point_v< double >

is_floating_point_v< float >

is_floating_point_v< long double >

is_op_v

Functions

declval()

is_convertible()

is_convertible()

is_valid()

is_valid()

File Listing