353 lines
9.9 KiB
C++
353 lines
9.9 KiB
C++
//
|
|
// require_concept.hpp
|
|
// ~~~~~~~~~~~~~~~~~~~
|
|
//
|
|
// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
|
|
//
|
|
// Distributed under the Boost Software License, Version 1.0. (See accompanying
|
|
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
|
|
//
|
|
|
|
#ifndef ASIO_REQUIRE_CONCEPT_HPP
|
|
#define ASIO_REQUIRE_CONCEPT_HPP
|
|
|
|
#if defined(_MSC_VER) && (_MSC_VER >= 1200)
|
|
# pragma once
|
|
#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
|
|
|
|
#include "asio/detail/config.hpp"
|
|
#include "asio/detail/type_traits.hpp"
|
|
#include "asio/is_applicable_property.hpp"
|
|
#include "asio/traits/require_concept_member.hpp"
|
|
#include "asio/traits/require_concept_free.hpp"
|
|
#include "asio/traits/static_require_concept.hpp"
|
|
|
|
#include "asio/detail/push_options.hpp"
|
|
|
|
#if defined(GENERATING_DOCUMENTATION)
|
|
|
|
namespace asio {
|
|
|
|
/// A customisation point that applies a concept-enforcing property to an
|
|
/// object.
|
|
/**
|
|
* The name <tt>require_concept</tt> denotes a customization point object. The
|
|
* expression <tt>asio::require_concept(E, P)</tt> for some
|
|
* subexpressions <tt>E</tt> and <tt>P</tt> (with types <tt>T =
|
|
* decay_t<decltype(E)></tt> and <tt>Prop = decay_t<decltype(P)></tt>) is
|
|
* expression-equivalent to:
|
|
*
|
|
* @li If <tt>is_applicable_property_v<T, Prop> &&
|
|
* Prop::is_requirable_concept</tt> is not a well-formed constant expression
|
|
* with value <tt>true</tt>, <tt>asio::require_concept(E, P)</tt> is
|
|
* ill-formed.
|
|
*
|
|
* @li Otherwise, <tt>E</tt> if the expression <tt>Prop::template
|
|
* static_query_v<T> == Prop::value()</tt> is a well-formed constant
|
|
* expression with value <tt>true</tt>.
|
|
*
|
|
* @li Otherwise, <tt>(E).require_concept(P)</tt> if the expression
|
|
* <tt>(E).require_concept(P)</tt> is well-formed.
|
|
*
|
|
* @li Otherwise, <tt>require_concept(E, P)</tt> if the expression
|
|
* <tt>require_concept(E, P)</tt> is a valid expression with overload
|
|
* resolution performed in a context that does not include the declaration
|
|
* of the <tt>require_concept</tt> customization point object.
|
|
*
|
|
* @li Otherwise, <tt>asio::require_concept(E, P)</tt> is ill-formed.
|
|
*/
|
|
inline constexpr unspecified require_concept = unspecified;
|
|
|
|
/// A type trait that determines whether a @c require_concept expression is
|
|
/// well-formed.
|
|
/**
|
|
* Class template @c can_require_concept is a trait that is derived from
|
|
* @c true_type if the expression
|
|
* <tt>asio::require_concept(std::declval<T>(),
|
|
* std::declval<Property>())</tt> is well formed; otherwise @c false_type.
|
|
*/
|
|
template <typename T, typename Property>
|
|
struct can_require_concept :
|
|
integral_constant<bool, automatically_determined>
|
|
{
|
|
};
|
|
|
|
/// A type trait that determines whether a @c require_concept expression will
|
|
/// not throw.
|
|
/**
|
|
* Class template @c is_nothrow_require_concept is a trait that is derived from
|
|
* @c true_type if the expression
|
|
* <tt>asio::require_concept(std::declval<T>(),
|
|
* std::declval<Property>())</tt> is @c noexcept; otherwise @c false_type.
|
|
*/
|
|
template <typename T, typename Property>
|
|
struct is_nothrow_require_concept :
|
|
integral_constant<bool, automatically_determined>
|
|
{
|
|
};
|
|
|
|
/// A type trait that determines the result type of a @c require_concept
|
|
/// expression.
|
|
/**
|
|
* Class template @c require_concept_result is a trait that determines the
|
|
* result type of the expression
|
|
* <tt>asio::require_concept(std::declval<T>(),
|
|
* std::declval<Property>())</tt>.
|
|
*/
|
|
template <typename T, typename Property>
|
|
struct require_concept_result
|
|
{
|
|
/// The result of the @c require_concept expression.
|
|
typedef automatically_determined type;
|
|
};
|
|
|
|
} // namespace asio
|
|
|
|
#else // defined(GENERATING_DOCUMENTATION)
|
|
|
|
namespace asio_require_concept_fn {
|
|
|
|
using asio::conditional;
|
|
using asio::decay;
|
|
using asio::declval;
|
|
using asio::enable_if;
|
|
using asio::is_applicable_property;
|
|
using asio::traits::require_concept_free;
|
|
using asio::traits::require_concept_member;
|
|
using asio::traits::static_require_concept;
|
|
|
|
void require_concept();
|
|
|
|
enum overload_type
|
|
{
|
|
identity,
|
|
call_member,
|
|
call_free,
|
|
ill_formed
|
|
};
|
|
|
|
template <typename Impl, typename T, typename Properties, typename = void,
|
|
typename = void, typename = void, typename = void, typename = void>
|
|
struct call_traits
|
|
{
|
|
ASIO_STATIC_CONSTEXPR(overload_type, overload = ill_formed);
|
|
ASIO_STATIC_CONSTEXPR(bool, is_noexcept = false);
|
|
typedef void result_type;
|
|
};
|
|
|
|
template <typename Impl, typename T, typename Property>
|
|
struct call_traits<Impl, T, void(Property),
|
|
typename enable_if<
|
|
is_applicable_property<
|
|
typename decay<T>::type,
|
|
typename decay<Property>::type
|
|
>::value
|
|
>::type,
|
|
typename enable_if<
|
|
decay<Property>::type::is_requirable_concept
|
|
>::type,
|
|
typename enable_if<
|
|
static_require_concept<T, Property>::is_valid
|
|
>::type>
|
|
{
|
|
ASIO_STATIC_CONSTEXPR(overload_type, overload = identity);
|
|
ASIO_STATIC_CONSTEXPR(bool, is_noexcept = true);
|
|
typedef ASIO_MOVE_ARG(T) result_type;
|
|
};
|
|
|
|
template <typename Impl, typename T, typename Property>
|
|
struct call_traits<Impl, T, void(Property),
|
|
typename enable_if<
|
|
is_applicable_property<
|
|
typename decay<T>::type,
|
|
typename decay<Property>::type
|
|
>::value
|
|
>::type,
|
|
typename enable_if<
|
|
decay<Property>::type::is_requirable_concept
|
|
>::type,
|
|
typename enable_if<
|
|
!static_require_concept<T, Property>::is_valid
|
|
>::type,
|
|
typename enable_if<
|
|
require_concept_member<
|
|
typename Impl::template proxy<T>::type,
|
|
Property
|
|
>::is_valid
|
|
>::type> :
|
|
require_concept_member<
|
|
typename Impl::template proxy<T>::type,
|
|
Property
|
|
>
|
|
{
|
|
ASIO_STATIC_CONSTEXPR(overload_type, overload = call_member);
|
|
};
|
|
|
|
template <typename Impl, typename T, typename Property>
|
|
struct call_traits<Impl, T, void(Property),
|
|
typename enable_if<
|
|
is_applicable_property<
|
|
typename decay<T>::type,
|
|
typename decay<Property>::type
|
|
>::value
|
|
>::type,
|
|
typename enable_if<
|
|
decay<Property>::type::is_requirable_concept
|
|
>::type,
|
|
typename enable_if<
|
|
!static_require_concept<T, Property>::is_valid
|
|
>::type,
|
|
typename enable_if<
|
|
!require_concept_member<
|
|
typename Impl::template proxy<T>::type,
|
|
Property
|
|
>::is_valid
|
|
>::type,
|
|
typename enable_if<
|
|
require_concept_free<T, Property>::is_valid
|
|
>::type> :
|
|
require_concept_free<T, Property>
|
|
{
|
|
ASIO_STATIC_CONSTEXPR(overload_type, overload = call_free);
|
|
};
|
|
|
|
struct impl
|
|
{
|
|
template <typename T>
|
|
struct proxy
|
|
{
|
|
#if defined(ASIO_HAS_DEDUCED_REQUIRE_CONCEPT_MEMBER_TRAIT)
|
|
struct type
|
|
{
|
|
template <typename P>
|
|
auto require_concept(ASIO_MOVE_ARG(P) p)
|
|
noexcept(
|
|
noexcept(
|
|
declval<typename conditional<true, T, P>::type>().require_concept(
|
|
ASIO_MOVE_CAST(P)(p))
|
|
)
|
|
)
|
|
-> decltype(
|
|
declval<typename conditional<true, T, P>::type>().require_concept(
|
|
ASIO_MOVE_CAST(P)(p))
|
|
);
|
|
};
|
|
#else // defined(ASIO_HAS_DEDUCED_REQUIRE_CONCEPT_MEMBER_TRAIT)
|
|
typedef T type;
|
|
#endif // defined(ASIO_HAS_DEDUCED_REQUIRE_CONCEPT_MEMBER_TRAIT)
|
|
};
|
|
|
|
template <typename T, typename Property>
|
|
ASIO_NODISCARD ASIO_CONSTEXPR typename enable_if<
|
|
call_traits<impl, T, void(Property)>::overload == identity,
|
|
typename call_traits<impl, T, void(Property)>::result_type
|
|
>::type
|
|
operator()(
|
|
ASIO_MOVE_ARG(T) t,
|
|
ASIO_MOVE_ARG(Property)) const
|
|
ASIO_NOEXCEPT_IF((
|
|
call_traits<impl, T, void(Property)>::is_noexcept))
|
|
{
|
|
return ASIO_MOVE_CAST(T)(t);
|
|
}
|
|
|
|
template <typename T, typename Property>
|
|
ASIO_NODISCARD ASIO_CONSTEXPR typename enable_if<
|
|
call_traits<impl, T, void(Property)>::overload == call_member,
|
|
typename call_traits<impl, T, void(Property)>::result_type
|
|
>::type
|
|
operator()(
|
|
ASIO_MOVE_ARG(T) t,
|
|
ASIO_MOVE_ARG(Property) p) const
|
|
ASIO_NOEXCEPT_IF((
|
|
call_traits<impl, T, void(Property)>::is_noexcept))
|
|
{
|
|
return ASIO_MOVE_CAST(T)(t).require_concept(
|
|
ASIO_MOVE_CAST(Property)(p));
|
|
}
|
|
|
|
template <typename T, typename Property>
|
|
ASIO_NODISCARD ASIO_CONSTEXPR typename enable_if<
|
|
call_traits<impl, T, void(Property)>::overload == call_free,
|
|
typename call_traits<impl, T, void(Property)>::result_type
|
|
>::type
|
|
operator()(
|
|
ASIO_MOVE_ARG(T) t,
|
|
ASIO_MOVE_ARG(Property) p) const
|
|
ASIO_NOEXCEPT_IF((
|
|
call_traits<impl, T, void(Property)>::is_noexcept))
|
|
{
|
|
return require_concept(
|
|
ASIO_MOVE_CAST(T)(t),
|
|
ASIO_MOVE_CAST(Property)(p));
|
|
}
|
|
};
|
|
|
|
template <typename T = impl>
|
|
struct static_instance
|
|
{
|
|
static const T instance;
|
|
};
|
|
|
|
template <typename T>
|
|
const T static_instance<T>::instance = {};
|
|
|
|
} // namespace asio_require_concept_fn
|
|
namespace asio {
|
|
namespace {
|
|
|
|
static ASIO_CONSTEXPR const asio_require_concept_fn::impl&
|
|
require_concept = asio_require_concept_fn::static_instance<>::instance;
|
|
|
|
} // namespace
|
|
|
|
typedef asio_require_concept_fn::impl require_concept_t;
|
|
|
|
template <typename T, typename Property>
|
|
struct can_require_concept :
|
|
integral_constant<bool,
|
|
asio_require_concept_fn::call_traits<
|
|
require_concept_t, T, void(Property)>::overload !=
|
|
asio_require_concept_fn::ill_formed>
|
|
{
|
|
};
|
|
|
|
#if defined(ASIO_HAS_VARIABLE_TEMPLATES)
|
|
|
|
template <typename T, typename Property>
|
|
constexpr bool can_require_concept_v
|
|
= can_require_concept<T, Property>::value;
|
|
|
|
#endif // defined(ASIO_HAS_VARIABLE_TEMPLATES)
|
|
|
|
template <typename T, typename Property>
|
|
struct is_nothrow_require_concept :
|
|
integral_constant<bool,
|
|
asio_require_concept_fn::call_traits<
|
|
require_concept_t, T, void(Property)>::is_noexcept>
|
|
{
|
|
};
|
|
|
|
#if defined(ASIO_HAS_VARIABLE_TEMPLATES)
|
|
|
|
template <typename T, typename Property>
|
|
constexpr bool is_nothrow_require_concept_v
|
|
= is_nothrow_require_concept<T, Property>::value;
|
|
|
|
#endif // defined(ASIO_HAS_VARIABLE_TEMPLATES)
|
|
|
|
template <typename T, typename Property>
|
|
struct require_concept_result
|
|
{
|
|
typedef typename asio_require_concept_fn::call_traits<
|
|
require_concept_t, T, void(Property)>::result_type type;
|
|
};
|
|
|
|
} // namespace asio
|
|
|
|
#endif // defined(GENERATING_DOCUMENTATION)
|
|
|
|
#include "asio/detail/pop_options.hpp"
|
|
|
|
#endif // ASIO_REQUIRE_CONCEPT_HPP
|