整理

include/boost/pfr/tuple_size.hpp

@@ -0,0 +1,58 @@
+// Copyright (c) 2016-2025 Antony Polukhin
+//
+// 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 BOOST_PFR_TUPLE_SIZE_HPP
+#define BOOST_PFR_TUPLE_SIZE_HPP
+#pragma once
+
+#include <boost/pfr/detail/config.hpp>
+
+#if !defined(BOOST_USE_MODULES) || defined(BOOST_PFR_INTERFACE_UNIT)
+
+#include <boost/pfr/detail/sequence_tuple.hpp>
+#include <boost/pfr/detail/fields_count.hpp>
+
+#if !defined(BOOST_PFR_INTERFACE_UNIT)
+#include <type_traits>
+#include <utility>      // metaprogramming stuff
+#endif
+
+/// \file boost/pfr/tuple_size.hpp
+/// Contains tuple-like interfaces to get fields count \forcedlink{tuple_size}, \forcedlink{tuple_size_v}.
+///
+/// \b Synopsis:
+namespace boost { namespace pfr {
+
+BOOST_PFR_BEGIN_MODULE_EXPORT
+
+/// Has a static const member variable `value` that contains fields count in a T.
+/// Works for any T that satisfies \aggregate.
+///
+/// \b Example:
+/// \code
+///     std::array<int, boost::pfr::tuple_size<my_structure>::value > a;
+/// \endcode
+template <class T>
+using tuple_size = detail::size_t_< boost::pfr::detail::fields_count<T>() >;
+
+
+/// `tuple_size_v` is a template variable that contains fields count in a T and
+/// works for any T that satisfies \aggregate.
+///
+/// \b Example:
+/// \code
+///     std::array<int, boost::pfr::tuple_size_v<my_structure> > a;
+/// \endcode
+template <class T>
+constexpr std::size_t tuple_size_v = tuple_size<T>::value;
+
+BOOST_PFR_END_MODULE_EXPORT
+
+}} // namespace boost::pfr
+
+#endif  // #if defined(BOOST_USE_MODULES) && !defined(BOOST_PFR_INTERFACE_UNIT)
+
+#endif // BOOST_PFR_TUPLE_SIZE_HPP