multi_buffer.hpp

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//
// Copyright (c) 2016-2017 Vinnie Falco (vinnie dot falco at gmail dot com)
//
// 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)
//
// Official repository: https://github.com/boostorg/beast
//

#ifndef BOOST_BEAST_MULTI_BUFFER_HPP
#define BOOST_BEAST_MULTI_BUFFER_HPP

#include <boost/beast/config.hpp>
#include <boost/beast/core/detail/allocator.hpp>
#include <boost/beast/core/detail/empty_base_optimization.hpp>
#include <boost/asio/buffer.hpp>
#include <boost/intrusive/list.hpp>
#include <iterator>
#include <limits>
#include <memory>
#include <type_traits>

namespace boost {
namespace beast {

template<class Allocator>
class basic_multi_buffer
#if ! BOOST_BEAST_DOXYGEN
    : private detail::empty_base_optimization<
        typename detail::allocator_traits<Allocator>::
            template rebind_alloc<char>>
#endif
{
    using base_alloc_type = typename
        detail::allocator_traits<Allocator>::
            template rebind_alloc<char>;

    // Storage for the list of buffers representing the input
    // and output sequences. The allocation for each element
    // contains `element` followed by raw storage bytes.
    class element;

    using alloc_traits = detail::allocator_traits<base_alloc_type>;
    using list_type = typename boost::intrusive::make_list<element,
        boost::intrusive::constant_time_size<true>>::type;
    using iter = typename list_type::iterator;
    using const_iter = typename list_type::const_iterator;

    using size_type = typename alloc_traits::size_type;
    using const_buffer = boost::asio::const_buffer;
    using mutable_buffer = boost::asio::mutable_buffer;

    static_assert(std::is_base_of<std::bidirectional_iterator_tag,
        typename std::iterator_traits<iter>::iterator_category>::value,
            "BidirectionalIterator requirements not met");

    static_assert(std::is_base_of<std::bidirectional_iterator_tag,
        typename std::iterator_traits<const_iter>::iterator_category>::value,
            "BidirectionalIterator requirements not met");

    std::size_t max_ =
        (std::numeric_limits<std::size_t>::max)();
    list_type list_;        // list of allocated buffers
    iter out_;              // element that contains out_pos_
    size_type in_size_ = 0; // size of the input sequence
    size_type in_pos_ = 0;  // input offset in list_.front()
    size_type out_pos_ = 0; // output offset in *out_
    size_type out_end_ = 0; // output end offset in list_.back()

public:
    using allocator_type = Allocator;

#if BOOST_BEAST_DOXYGEN
    using const_buffers_type = implementation_defined;

    using mutable_buffers_type = implementation_defined;

#else
    class const_buffers_type;

    class mutable_buffers_type;

#endif

    ~basic_multi_buffer();

    basic_multi_buffer();

    explicit
    basic_multi_buffer(std::size_t limit);

    explicit
    basic_multi_buffer(Allocator const& alloc);

    basic_multi_buffer(
        std::size_t limit, Allocator const& alloc);

    basic_multi_buffer(basic_multi_buffer&& other);

    basic_multi_buffer(basic_multi_buffer&& other,
        Allocator const& alloc);

    basic_multi_buffer(basic_multi_buffer const& other);

    basic_multi_buffer(basic_multi_buffer const& other,
        Allocator const& alloc);

    template<class OtherAlloc>
    basic_multi_buffer(basic_multi_buffer<
        OtherAlloc> const& other);

    template<class OtherAlloc>
    basic_multi_buffer(basic_multi_buffer<
        OtherAlloc> const& other, allocator_type const& alloc);

    basic_multi_buffer&
    operator=(basic_multi_buffer&& other);

    basic_multi_buffer& operator=(basic_multi_buffer const& other);

    template<class OtherAlloc>
    basic_multi_buffer& operator=(
        basic_multi_buffer<OtherAlloc> const& other);

    allocator_type
    get_allocator() const
    {
        return this->member();
    }

    size_type
    size() const
    {
        return in_size_;
    }

    size_type
    max_size() const
    {
        return max_;
    }

    std::size_t
    capacity() const;

    const_buffers_type
    data() const;

    mutable_buffers_type
    prepare(size_type n);

    void
    commit(size_type n);

    void
    consume(size_type n);

    template<class Alloc>
    friend
    void
    swap(
        basic_multi_buffer<Alloc>& lhs,
        basic_multi_buffer<Alloc>& rhs);

private:
    template<class OtherAlloc>
    friend class basic_multi_buffer;

    void
    delete_list();

    void
    reset();

    template<class DynamicBuffer>
    void
    copy_from(DynamicBuffer const& other);

    void
    move_assign(basic_multi_buffer& other, std::false_type);

    void
    move_assign(basic_multi_buffer& other, std::true_type);

    void
    copy_assign(basic_multi_buffer const& other, std::false_type);

    void
    copy_assign(basic_multi_buffer const& other, std::true_type);

    void
    swap(basic_multi_buffer&);

    void
    swap(basic_multi_buffer&, std::true_type);

    void
    swap(basic_multi_buffer&, std::false_type);

    void
    debug_check() const;
};

using multi_buffer = basic_multi_buffer<std::allocator<char>>;

} // beast
} // boost

#include <boost/beast/core/impl/multi_buffer.ipp>

#endif