core/detail/buffer_traits.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_BUFFER_TRAITS_HPP
0011 #define BOOST_BEAST_DETAIL_BUFFER_TRAITS_HPP
0012
0013 #include <boost/asio/buffer.hpp>
0014 #include <boost/config/workaround.hpp>
0015 #include <boost/type_traits/make_void.hpp>
0016 #include <cstdint>
0017 #include <type_traits>
0018
0019 namespace boost {
0020 namespace beast {
0021 namespace detail {
0022
0023 #if BOOST_WORKAROUND(BOOST_MSVC, < 1910)
0024
0025 template<class T>
0026 struct buffers_iterator_type_helper
0027 {
0028     using type = decltype(
0029         net::buffer_sequence_begin(
0030             std::declval<T const&>()));
0031 };
0032
0033 template<>
0034 struct buffers_iterator_type_helper<
0035     net::const_buffer>
0036 {
0037     using type = net::const_buffer const*;
0038 };
0039
0040 template<>
0041 struct buffers_iterator_type_helper<
0042     net::mutable_buffer>
0043 {
0044     using type = net::mutable_buffer const*;
0045 };
0046
0047 #endif
0048
0049 struct buffer_bytes_impl
0050 {
0051     std::size_t
0052     operator()(net::const_buffer b) const noexcept
0053     {
0054         return net::const_buffer(b).size();
0055     }
0056
0057     std::size_t
0058     operator()(net::mutable_buffer b) const noexcept
0059     {
0060         return net::mutable_buffer(b).size();
0061     }
0062
0063     template<
0064         class B,
0065         class = typename std::enable_if<
0066             net::is_const_buffer_sequence<B>::value>::type>
0067     std::size_t
0068     operator()(B const& b) const noexcept
0069     {
0070         using net::buffer_size;
0071         return buffer_size(b);
0072     }
0073 };
0074
0075 /** Return `true` if a buffer sequence is empty
0076
0077     This is sometimes faster than using @ref buffer_bytes
0078 */
0079 template<class ConstBufferSequence>
0080 bool
0081 buffers_empty(ConstBufferSequence const& buffers)
0082 {
0083     auto it = net::buffer_sequence_begin(buffers);
0084     auto end = net::buffer_sequence_end(buffers);
0085     while(it != end)
0086     {
0087         if(net::const_buffer(*it).size() > 0)
0088             return false;
0089         ++it;
0090     }
0091     return true;
0092 }
0093
0094 } // detail
0095 } // beast
0096 } // boost
0097
0098 #endif