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141 lines
4.2 KiB
C++
141 lines
4.2 KiB
C++
//
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// Copyright (c) 2013-2016 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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#ifndef BEAST_CONSUMING_BUFFERS_HPP
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#define BEAST_CONSUMING_BUFFERS_HPP
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#include <beast/core/buffer_concepts.hpp>
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#include <boost/asio/buffer.hpp>
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#include <cstdint>
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#include <iterator>
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#include <type_traits>
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#include <utility>
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namespace beast {
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/** Adapter to trim the front of a `BufferSequence`.
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This adapter wraps a buffer sequence to create a new sequence
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which may be incrementally consumed. Bytes consumed are removed
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from the front of the buffer. The underlying memory is not changed,
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instead the adapter efficiently iterates through a subset of
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the buffers wrapped.
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The wrapped buffer is not modified, a copy is made instead.
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Ownership of the underlying memory is not transferred, the application
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is still responsible for managing its lifetime.
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@tparam BufferSequence The buffer sequence to wrap.
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@tparam ValueType The type of buffer of the final buffer sequence. This
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can be different from the buffer type of the wrapped sequence. For
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example, a `MutableBufferSequence` can be transformed into a
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consumable `ConstBufferSequence`. Violations of buffer const safety
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are not permitted, and will result in a compile error.
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*/
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template<class BufferSequence,
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class ValueType = typename BufferSequence::value_type>
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class consuming_buffers
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{
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using iter_type =
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typename BufferSequence::const_iterator;
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static_assert(is_BufferSequence<BufferSequence, ValueType>::value,
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"BufferSequence requirements not met");
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static_assert(std::is_constructible<ValueType,
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typename std::iterator_traits<iter_type>::value_type>::value,
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"ValueType requirements not met");
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BufferSequence bs_;
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iter_type begin_;
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std::size_t skip_ = 0;
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template<class Deduced>
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consuming_buffers(Deduced&& other, std::size_t nbegin)
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: bs_(std::forward<Deduced>(other).bs_)
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, begin_(std::next(bs_.begin(), nbegin))
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, skip_(other.skip_)
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{
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}
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public:
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/// The type for each element in the list of buffers.
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using value_type = ValueType;
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#if GENERATING_DOCS
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/// A bidirectional iterator type that may be used to read elements.
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using const_iterator = implementation_defined;
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#else
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class const_iterator;
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#endif
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/// Move constructor.
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consuming_buffers(consuming_buffers&&);
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/// Copy constructor.
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consuming_buffers(consuming_buffers const&);
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/// Move assignment.
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consuming_buffers& operator=(consuming_buffers&&);
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/// Copy assignment.
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consuming_buffers& operator=(consuming_buffers const&);
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/** Construct to represent a buffer sequence.
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A copy of the buffer sequence is made. Ownership of the
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underlying memory is not transferred or copied.
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*/
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explicit
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consuming_buffers(BufferSequence const& buffers);
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/// Get a bidirectional iterator to the first element.
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const_iterator
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begin() const;
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/// Get a bidirectional iterator for one past the last element.
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const_iterator
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end() const;
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/** Remove bytes from the beginning of the sequence.
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@param n The number of bytes to remove. If this is
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larger than the number of bytes remaining, all the
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bytes remaining are removed.
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*/
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void
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consume(std::size_t n);
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};
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/** Returns a new, consumed buffer sequence.
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This function returns a new buffer sequence which when iterated,
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efficiently represents the portion of the original buffer sequence
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with `n` bytes removed from the beginning.
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Copies will be made of the buffer sequence passed, but ownership
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of the underlying memory is not transferred.
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@param buffers The buffer sequence to consume.
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@param n The number of bytes to remove from the front. If this is
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larger than the size of the buffer sequence, an empty buffer sequence
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is returned.
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*/
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template<class BufferSequence>
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consuming_buffers<BufferSequence, typename BufferSequence::value_type>
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consumed_buffers(BufferSequence const& buffers, std::size_t n);
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} // beast
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#include <beast/core/impl/consuming_buffers.ipp>
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#endif
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