Initial Commit

include/asio/execution/executor.hpp

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+//
+// execution/executor.hpp
+// ~~~~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2025 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_EXECUTION_EXECUTOR_HPP
+#define ASIO_EXECUTION_EXECUTOR_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/execution/invocable_archetype.hpp"
+#include "asio/traits/equality_comparable.hpp"
+#include "asio/traits/execute_member.hpp"
+
+#if defined(ASIO_HAS_DEDUCED_EXECUTE_MEMBER_TRAIT) \
+  && defined(ASIO_HAS_DEDUCED_EQUALITY_COMPARABLE_TRAIT)
+# define ASIO_HAS_DEDUCED_EXECUTION_IS_EXECUTOR_TRAIT 1
+#endif // defined(ASIO_HAS_DEDUCED_EXECUTE_MEMBER_TRAIT)
+       //   && defined(ASIO_HAS_DEDUCED_EQUALITY_COMPARABLE_TRAIT)
+
+#include "asio/detail/push_options.hpp"
+
+namespace asio {
+namespace execution {
+namespace detail {
+
+template <typename T, typename F,
+    typename = void, typename = void, typename = void, typename = void,
+    typename = void, typename = void, typename = void, typename = void>
+struct is_executor_of_impl : false_type
+{
+};
+
+template <typename T, typename F>
+struct is_executor_of_impl<T, F,
+  enable_if_t<
+    traits::execute_member<add_const_t<T>, F>::is_valid
+  >,
+  void_t<
+    result_of_t<decay_t<F>&()>
+  >,
+  enable_if_t<
+    is_constructible<decay_t<F>, F>::value
+  >,
+  enable_if_t<
+    is_move_constructible<decay_t<F>>::value
+  >,
+  enable_if_t<
+    is_nothrow_copy_constructible<T>::value
+  >,
+  enable_if_t<
+    is_nothrow_destructible<T>::value
+  >,
+  enable_if_t<
+    traits::equality_comparable<T>::is_valid
+  >,
+  enable_if_t<
+    traits::equality_comparable<T>::is_noexcept
+  >> : true_type
+{
+};
+
+} // namespace detail
+
+/// The is_executor trait detects whether a type T satisfies the
+/// execution::executor concept.
+/**
+ * Class template @c is_executor is a UnaryTypeTrait that is derived from @c
+ * true_type if the type @c T meets the concept definition for an executor,
+ * otherwise @c false_type.
+ */
+template <typename T>
+struct is_executor :
+#if defined(GENERATING_DOCUMENTATION)
+  integral_constant<bool, automatically_determined>
+#else // defined(GENERATING_DOCUMENTATION)
+  detail::is_executor_of_impl<T, invocable_archetype>
+#endif // defined(GENERATING_DOCUMENTATION)
+{
+};
+
+#if defined(ASIO_HAS_VARIABLE_TEMPLATES)
+
+template <typename T>
+constexpr const bool is_executor_v = is_executor<T>::value;
+
+#endif // defined(ASIO_HAS_VARIABLE_TEMPLATES)
+
+#if defined(ASIO_HAS_CONCEPTS)
+
+template <typename T>
+ASIO_CONCEPT executor = is_executor<T>::value;
+
+#define ASIO_EXECUTION_EXECUTOR ::asio::execution::executor
+
+#else // defined(ASIO_HAS_CONCEPTS)
+
+#define ASIO_EXECUTION_EXECUTOR typename
+
+#endif // defined(ASIO_HAS_CONCEPTS)
+
+} // namespace execution
+} // namespace asio
+
+#include "asio/detail/pop_options.hpp"
+
+#endif // ASIO_EXECUTION_EXECUTOR_HPP