type-traits.h

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/*
 * This file is part of the µOS++ project (https://micro-os-plus.github.io/).
 * Copyright (c) 2021-2026 Liviu Ionescu. All rights reserved.
 *
 * Permission to use, copy, modify, and/or distribute this software for any
 * purpose is hereby granted, under the terms of the MIT license.
 *
 * If a copy of the license was not distributed with this file, it can be
 * obtained from https://opensource.org/licenses/mit.
 *
 * Major parts of the code are inspired from v1.1.8 of the Boost UT project,
 * released under the terms of the Boost Version 1.0 Software License,
 * which can be obtained from https://www.boost.org/LICENSE_1_0.txt.
 */
 
// ----------------------------------------------------------------------------

 
#ifndef MICRO_OS_PLUS_MICRO_TEST_PLUS_TYPE_TRAITS_H_
#define MICRO_OS_PLUS_MICRO_TEST_PLUS_TYPE_TRAITS_H_
 
// ----------------------------------------------------------------------------
 
#if defined(__cplusplus)
 
// ----------------------------------------------------------------------------
 
#if __has_include("micro-os-plus/project-config.h")
#include "micro-os-plus/project-config.h"
#endif // __has_include("micro-os-plus/project-config.h")
 
#if __has_include("micro-os-plus/micro-test-plus-defines.h")
#include "micro-os-plus/micro-test-plus-defines.h"
#endif // __has_include("micro-os-plus/micro-test-plus-defines.h")
 
#include "math.h"
 
#include <string_view>
#include <type_traits>
 
// ----------------------------------------------------------------------------
 
#if defined(__GNUC__)
#pragma GCC diagnostic push
 
#if defined(__clang__)
#pragma clang diagnostic ignored "-Wc++98-compat"
#pragma clang diagnostic ignored "-Wc++98-compat-pedantic"
#endif // defined(__clang__)
#endif // defined(__GNUC__)
 
// ============================================================================
 
namespace micro_os_plus::micro_test_plus
{
  // --------------------------------------------------------------------------

  namespace type_traits
  {
    template <class... Types>
    struct list
    {
    };

    template <class T, class... Extra>
    struct identity
    {
      using type = T;
    };
 
#if defined(__DOXYGEN__)
    // error: Detected potential recursive class relation between class
    // micro_os_plus::micro_test_plus::type_traits::function_traits and base
    // class micro_os_plus::micro_test_plus::type_traits::function_traits<
    // decltype(&T::operator())>!
    // https://github.com/doxygen/doxygen/issues/9915
#else
    template <class T>
    struct function_traits : function_traits<decltype (&T::operator())>
    {
    };
#endif // defined(__DOXYGEN__)

    template <class R, class... Args_T>
    struct function_traits<R (*) (Args_T...)>
    {
      using result_type = R;

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

    template <class R, class... Args_T>
    struct function_traits<R (Args_T...)>
    {
      using result_type = R;

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

    template <class R, class T, class... Args_T>
    struct function_traits<R (T::*) (Args_T...)>
    {
      using result_type = R;

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

    template <class R, class T, class... Args_T>
    struct function_traits<R (T::*) (Args_T...) const>
    {
      using result_type = R;

      using args = list<Args_T...>;
    };
 
    // ------------------------------------------------------------------------

    struct op
    {
    };
 
    // ------------------------------------------------------------------------
    // Concepts.

    template <class T>
    concept container_like = requires (const T& t) {
      t.begin ();
      t.end ();
    };

    template <class T>
    concept has_npos = requires { T::npos; };

    template <class T>
    concept has_value = requires (const T& t) { t.value; };

    template <class T>
    concept has_epsilon = requires (const T& t) { t.epsilon; };

    template <class T>
    concept is_floating_point = std::is_floating_point_v<T>;

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

    template <class Lhs_T, class Rhs_T>
    concept any_op = is_op<Lhs_T> or is_op<Rhs_T>;

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

    template <class T>
    concept printable = std::is_arithmetic_v<T>
                        or std::is_convertible_v<T, std::string_view>;
 
    // ------------------------------------------------------------------------

    template <class T>
    struct value_base_ : op
    {
      using value_type = T;

      constexpr explicit value_base_ (const T& v) noexcept;

      [[nodiscard]] constexpr explicit
      operator T () const noexcept;

      [[nodiscard]] constexpr T
      get (void) const noexcept;

      T value_{};
    };

    template <auto N>
    struct integral_constant : value_base_<decltype (N)>
    {
      static constexpr auto value = N;

      constexpr integral_constant () noexcept;

      [[nodiscard]] constexpr auto
      operator- () const noexcept;
    };

    template <class T, auto N, auto D, auto Size, auto P = 1>
    struct floating_point_constant : op
    {
      static_assert (P == 1 || P == -1,
                     "floating_point_constant: P must be +1 or -1");

      using value_type = T;

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

      static constexpr auto value
          = T (P) * (T (N) + (T (D) / math::pow (T (10), Size)));

      [[nodiscard]] constexpr explicit
      operator T () const noexcept;

      [[nodiscard]] constexpr T
      get (void) const noexcept;

      [[nodiscard]] constexpr auto
      operator- () const noexcept;
    };

    template <class T>
    struct genuine_integral_value : value_base_<T>
    {
      constexpr genuine_integral_value (const T& _value) noexcept;
    };

    template <class T>
    struct value : value_base_<T>
    {
      constexpr value (const T& _value) noexcept;
    };

    template <class T>
      requires is_floating_point<T>
    struct value<T> : value_base_<T>
    {
      T epsilon = T{};
 
      // Note: These constructor bodies are defined inline rather than
      // out-of-line in type-traits-inlines.h. Clang 16 has a deficiency
      // where it fails to match out-of-line constructor definitions to a
      // `requires`-constrained partial specialisation: it either rejects
      // the `requires` clause on the definition as differing from the
      // declaration, or — when the clause is omitted — incorrectly matches
      // the definition against the primary template instead of this
      // specialisation. Keeping the bodies here avoids both failure modes.

      constexpr value (const T& _value, const T precision) noexcept
          : value_base_<T>{ _value }, epsilon{ precision }
      {
      }

      constexpr value (const T& val)
          : value{ val,
                   T (1)
                       / math::pow (T (10),
                                    math::den_size<unsigned long long> (val)) }
      {
      }
    };
 
    // ------------------------------------------------------------------------
  } // namespace type_traits
 
  // --------------------------------------------------------------------------
} // namespace micro_os_plus::micro_test_plus
 
#if defined(__GNUC__)
#pragma GCC diagnostic pop
#endif // defined(__GNUC__)
 
// ----------------------------------------------------------------------------
 
#endif // defined(__cplusplus)
 
// ============================================================================
// Templates, inlines & constexpr implementations.
 
#include "inlines/type-traits-inlines.h"
 
// ----------------------------------------------------------------------------
 
#endif // MICRO_OS_PLUS_MICRO_TEST_PLUS_TYPE_TRAITS_H_
 
// ----------------------------------------------------------------------------