core/detail/buffers_pair.hpp

0001 //
0002 // Copyright (c) 2016-2019 Vinnie Falco (vinnie dot falco at gmail dot com)
0003 //
0004 // Distributed under the Boost Software License, Version 1.0. (See accompanying
0005 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
0006 //
0007 // Official repository: https://github.com/boostorg/beast
0008 //
0009
0010 #ifndef BOOST_BEAST_DETAIL_BUFFERS_PAIR_HPP
0011 #define BOOST_BEAST_DETAIL_BUFFERS_PAIR_HPP
0012
0013 #include <boost/asio/buffer.hpp>
0014 #include <boost/assert.hpp>
0015 #include <boost/config/workaround.hpp>
0016 #include <type_traits>
0017
0018 namespace boost {
0019 namespace beast {
0020 namespace detail {
0021
0022 #if BOOST_WORKAROUND(BOOST_MSVC, < 1910)
0023 # pragma warning (push)
0024 # pragma warning (disable: 4521) // multiple copy constructors specified
0025 # pragma warning (disable: 4522) // multiple assignment operators specified
0026 #endif
0027
0028 template<bool isMutable>
0029 class buffers_pair
0030 {
0031 public:
0032     // VFALCO: This type is public otherwise
0033     //         asio::buffers_iterator won't compile.
0034     using value_type = typename
0035         std::conditional<isMutable,
0036             net::mutable_buffer,
0037             net::const_buffer>::type;
0038
0039     using const_iterator = value_type const*;
0040
0041     buffers_pair() = default;
0042
0043 #if BOOST_WORKAROUND(BOOST_MSVC, < 1910)
0044     buffers_pair(buffers_pair const& other)
0045         : buffers_pair(
0046             *other.begin(), *(other.begin() + 1))
0047     {
0048     }
0049
0050     buffers_pair&
0051     operator=(buffers_pair const& other)
0052     {
0053         b_[0] = *other.begin();
0054         b_[1] = *(other.begin() + 1);
0055         return *this;
0056     }
0057 #else
0058     buffers_pair(buffers_pair const& other) = default;
0059     buffers_pair& operator=(buffers_pair const& other) = default;
0060 #endif
0061
0062     template<
0063         bool isMutable_ = isMutable,
0064         class = typename std::enable_if<
0065             ! isMutable_>::type>
0066     buffers_pair(buffers_pair<true> const& other)
0067         : buffers_pair(
0068             *other.begin(), *(other.begin() + 1))
0069     {
0070     }
0071
0072     template<
0073         bool isMutable_ = isMutable,
0074         class = typename std::enable_if<
0075             ! isMutable_>::type>
0076     buffers_pair&
0077     operator=(buffers_pair<true> const& other)
0078     {
0079         b_[0] = *other.begin();
0080         b_[1] = *(other.begin() + 1);
0081         return *this;
0082     }
0083
0084     buffers_pair(value_type b0, value_type b1)
0085         : b_{b0, b1}
0086     {
0087     }
0088
0089     const_iterator
0090     begin() const noexcept
0091     {
0092         return &b_[0];
0093     }
0094
0095     const_iterator
0096     end() const noexcept
0097     {
0098         if(b_[1].size() > 0)
0099             return &b_[2];
0100         return &b_[1];
0101     }
0102
0103 private:
0104     value_type b_[2];
0105 };
0106
0107 #if BOOST_WORKAROUND(BOOST_MSVC, < 1910)
0108 # pragma warning (pop)
0109 #endif
0110
0111 } // detail
0112 } // beast
0113 } // boost
0114
0115 #endif