type-traits.h File

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

Included Headers

#include "math.h" #include <string_view> #include <type_traits> #include "inlines/type-traits-inlines.h"

Namespaces Index

namespace	micro_os_plus
	The primary namespace for the µOS++ framework. More...
namespace	micro_test_plus
	Primary namespace for the µTest++ testing framework. More...
namespace	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, Extra>
	Struct template for compile-time type identity. More...
struct	integral_constant<N>
	Struct template representing a generic integral constant. More...
struct	list<Types>
	Struct template representing a compile-time type list. More...
struct	op
	Empty base struct for all operator types. More...
struct	value<T>
	Struct template representing a generic value, accessible via a getter. More...
struct	value<T>
	Struct template representing a floating point value with precision control. More...
struct	value_base_<T>
	Base struct template providing common storage and accessors for runtime value-wrapper types. More...

Concepts Index

concept	any_op
	C++20 concept satisfied when at least one of two types derives from op. More...
concept	checkable
	C++20 concept satisfied when a type can be used as a test expression in expect() or assume(). More...
concept	container_like
	C++20 concept satisfied when T provides both begin() and end() member functions. More...
concept	has_epsilon
	C++20 concept satisfied when T provides an epsilon member. More...
concept	has_npos
	C++20 concept satisfied when T provides a npos member. More...
concept	has_value
	C++20 concept satisfied when T provides a value member. More...
concept	is_floating_point
	C++20 concept satisfied when T is a standard floating point type. More...
concept	is_op
	C++20 concept satisfied when a type derives from op. More...
concept	printable
	C++20 concept satisfied when a type can be appended to the deferred reporter's output via operator<<. More...

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.

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/).

3 * Copyright (c) 2021-2026 Liviu Ionescu. All rights reserved.

4 *

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

6 * 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 be

9 * 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 */

15

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

17

47

48#ifndef MICRO_OS_PLUS_MICRO_TEST_PLUS_TYPE_TRAITS_H_

49#define MICRO_OS_PLUS_MICRO_TEST_PLUS_TYPE_TRAITS_H_

50

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

52

53#if defined(__cplusplus)

54

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

56

57#if __has_include("micro-os-plus/project-config.h")

58#include "micro-os-plus/project-config.h"

59#endif // __has_include("micro-os-plus/project-config.h")

60

61#if __has_include("micro-os-plus/micro-test-plus-defines.h")

62#include "micro-os-plus/micro-test-plus-defines.h"

63#endif // __has_include("micro-os-plus/micro-test-plus-defines.h")

64

65#include "math.h"

66

67#include <string_view>

68#include <type_traits>

69

70// ----------------------------------------------------------------------------

71

72#if defined(__GNUC__)

73#pragma GCC diagnostic push

74

75#if defined(__clang__)

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

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

78#endif // defined(__clang__)

79#endif // defined(__GNUC__)

80

81// ============================================================================

82

83namespace micro_os_plus::micro_test_plus

84{

85 // --------------------------------------------------------------------------

86

111 namespace type_traits

112 {

131 template <class... Types>

132 struct list

133 {

134 };

135

157 template <class T, class... Extra>

158 struct identity

159 {

163 using type = T;

164 };

165

166#if defined(__DOXYGEN__)

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

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

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

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

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

172#else

193 template <class T>

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

195 {

196 };

197#endif // defined(__DOXYGEN__)

198

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

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

220 {

224 using result_type = R;

225

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

230 };

231

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

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

253 {

257 using result_type = R;

258

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

263 };

264

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

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

287 {

291 using result_type = R;

292

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

297 };

298

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

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

322 {

326 using result_type = R;

327

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

332 };

333

334 // ------------------------------------------------------------------------

335

352 struct op

353 {

354 };

355

356 // ------------------------------------------------------------------------

357 // Concepts.

358

371 template <class T>

372 concept container_like = requires (const T& t) {

373 t.begin ();

374 t.end ();

375 };

376

388 template <class T>

389 concept has_npos = requires { T::npos; };

390

402 template <class T>

403 concept has_value = requires (const T& t) { t.value; };

404

416 template <class T>

417 concept has_epsilon = requires (const T& t) { t.epsilon; };

418

431 template <class T>

432 concept is_floating_point = std::is_floating_point_v<T>;

433

445 template <class T>

446 concept is_op = std::is_base_of_v<type_traits::op, T>;

447

462 template <class Lhs_T, class Rhs_T>

463 concept any_op = is_op<Lhs_T> or is_op<Rhs_T>;

464

478 template <class T>

479 concept checkable = is_op<T> or std::convertible_to<T, bool>;

480

494 template <class T>

495 concept printable = std::is_arithmetic_v<T>

496 or std::is_convertible_v<T, std::string_view>;

497

498 // ------------------------------------------------------------------------

499

517 template <class T>

518 struct value_base_ : op

519 {

523 using value_type = T;

524

530 constexpr explicit value_base_ (const T& v) noexcept;

531

537 [[nodiscard]] constexpr explicit

538 operator T () const noexcept;

539

547 [[nodiscard]] constexpr T

548 get (void) const noexcept;

549

553 T value_{};

554 };

555

574 template <auto N>

575 struct integral_constant : value_base_<decltype (N)>

576 {

580 static constexpr auto value = N;

581

585 constexpr integral_constant () noexcept;

586

592 [[nodiscard]] constexpr auto

593 operator- () const noexcept;

594 };

595

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

625 struct floating_point_constant : op

626 {

627 static_assert (P == 1 || P == -1,

628 "floating_point_constant: P must be 1 or -1");

629

633 using value_type = T;

634

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

642

649 static constexpr auto value

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

651

657 [[nodiscard]] constexpr explicit

658 operator T () const noexcept;

659

667 [[nodiscard]] constexpr T

668 get (void) const noexcept;

669

675 [[nodiscard]] constexpr auto

676 operator- () const noexcept;

677 };

678

691 template <class T>

692 struct genuine_integral_value : value_base_<T>

693 {

699 constexpr genuine_integral_value (const T& _value) noexcept;

700 };

701

715 template <class T>

716 struct value : value_base_<T>

717 {

726 constexpr value (const T& _value) noexcept;

727 };

728

751 template <class T>

752 requires is_floating_point<T>

753 struct value<T> : value_base_<T>

754 {

765 T epsilon = T{};

766

767 // Note: These constructor bodies are defined inline rather than

768 // out-of-line in type-traits-inlines.h. Clang 16 has a deficiency

769 // where it fails to match out-of-line constructor definitions to a

770 // `requires`-constrained partial specialisation: it either rejects

771 // the `requires` clause on the definition as differing from the

772 // declaration, or — when the clause is omitted — incorrectly matches

773 // the definition against the primary template instead of this

774 // specialisation. Keeping the bodies here avoids both failure modes.

775

786 constexpr value (const T& _value, const T precision) noexcept

787 : value_base_<T>{ _value }, epsilon{ precision }

788 {

789 }

790

800 constexpr value (const T& val)

801 : value{ val,

802 T (1)

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

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

805 {

806 }

807 };

808

809 // ------------------------------------------------------------------------

810 } // namespace type_traits

811

812 // --------------------------------------------------------------------------

813} // namespace micro_os_plus::micro_test_plus

814

815#if defined(__GNUC__)

816#pragma GCC diagnostic pop

817#endif // defined(__GNUC__)

818

819// ----------------------------------------------------------------------------

820

821#endif // defined(__cplusplus)

822

823// ============================================================================

824// Templates, inlines & constexpr implementations.

825

826#include "inlines/type-traits-inlines.h"

827

828// ----------------------------------------------------------------------------

829

830#endif // MICRO_OS_PLUS_MICRO_TEST_PLUS_TYPE_TRAITS_H_

831

832// ----------------------------------------------------------------------------

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