//
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// Copyright (c) 2016-2019 Vinnie Falco (vinnie dot falco at gmail 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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// Official repository: https://github.com/boostorg/beast
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//
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#ifndef BOOST_BEAST_IMPL_READ_SIZE_HPP
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#define BOOST_BEAST_IMPL_READ_SIZE_HPP
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#include <boost/asio/buffer.hpp>
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#include <boost/assert.hpp>
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#include <stdexcept>
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#include <type_traits>
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namespace boost {
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namespace beast {
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namespace detail {
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template<class T, class = void>
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struct has_read_size_helper : std::false_type {};
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template<class T>
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struct has_read_size_helper<T, decltype(
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read_size_helper(std::declval<T&>(), 512),
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(void)0)> : std::true_type
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{
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};
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template<class DynamicBuffer>
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std::size_t
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read_size(DynamicBuffer& buffer,
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std::size_t max_size, std::true_type)
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{
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return read_size_helper(buffer, max_size);
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}
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template<class DynamicBuffer>
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std::size_t
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read_size(DynamicBuffer& buffer,
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std::size_t max_size, std::false_type)
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{
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static_assert(
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net::is_dynamic_buffer<DynamicBuffer>::value,
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"DynamicBuffer type requirements not met");
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auto const size = buffer.size();
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auto const limit = buffer.max_size() - size;
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BOOST_ASSERT(size <= buffer.max_size());
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return std::min<std::size_t>(
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std::max<std::size_t>(512, buffer.capacity() - size),
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std::min<std::size_t>(max_size, limit));
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}
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} // detail
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template<class DynamicBuffer>
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std::size_t
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read_size(
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DynamicBuffer& buffer, std::size_t max_size)
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{
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return detail::read_size(buffer, max_size,
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detail::has_read_size_helper<DynamicBuffer>{});
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}
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template<class DynamicBuffer>
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std::size_t
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read_size_or_throw(
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DynamicBuffer& buffer, std::size_t max_size)
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{
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auto const n = read_size(buffer, max_size);
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if(n == 0)
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BOOST_THROW_EXCEPTION(std::length_error{
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"buffer overflow"});
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return n;
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}
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} // beast
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} // boost
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#endif
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