56 lines
1.4 KiB
C++
56 lines
1.4 KiB
C++
//
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// cpp14/require_free.cpp
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// ~~~~~~~~~~~~~~~~~~~~~~
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//
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// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
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//
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// Distributed under the Boost Software License, Version 1.0. (See accompanying
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// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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//
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#include <boost/asio/require.hpp>
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#include <cassert>
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template <int>
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struct prop
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{
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template <typename> static constexpr bool is_applicable_property_v = true;
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static constexpr bool is_requirable = true;
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};
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template <int>
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struct object
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{
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template <int N>
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friend constexpr object<N> require(const object&, prop<N>)
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{
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return object<N>();
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}
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};
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int main()
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{
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object<1> o1 = {};
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object<2> o2 = boost::asio::require(o1, prop<2>());
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object<3> o3 = boost::asio::require(o1, prop<2>(), prop<3>());
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object<4> o4 = boost::asio::require(o1, prop<2>(), prop<3>(), prop<4>());
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(void)o2;
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(void)o3;
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(void)o4;
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const object<1> o5 = {};
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object<2> o6 = boost::asio::require(o5, prop<2>());
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object<3> o7 = boost::asio::require(o5, prop<2>(), prop<3>());
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object<4> o8 = boost::asio::require(o5, prop<2>(), prop<3>(), prop<4>());
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(void)o6;
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(void)o7;
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(void)o8;
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constexpr object<2> o9 = boost::asio::require(object<1>(), prop<2>());
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constexpr object<3> o10 = boost::asio::require(object<1>(), prop<2>(), prop<3>());
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constexpr object<4> o11 = boost::asio::require(object<1>(), prop<2>(), prop<3>(), prop<4>());
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(void)o9;
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(void)o10;
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(void)o11;
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}
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