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+//
+// detail/consuming_buffers.hpp
+// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2018 Christopher M. Kohlhoff (chris at kohlhoff 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)
+//
+
+#ifndef ASIO_DETAIL_CONSUMING_BUFFERS_HPP
+#define ASIO_DETAIL_CONSUMING_BUFFERS_HPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#include "asio/detail/config.hpp"
+#include <cstddef>
+#include "asio/buffer.hpp"
+#include "asio/detail/buffer_sequence_adapter.hpp"
+#include "asio/detail/limits.hpp"
+
+#include "asio/detail/push_options.hpp"
+
+namespace asio {
+namespace detail {
+
+// Helper template to determine the maximum number of prepared buffers.
+template <typename Buffers>
+struct prepared_buffers_max
+{
+ enum { value = buffer_sequence_adapter_base::max_buffers };
+};
+
+template <typename Elem, std::size_t N>
+struct prepared_buffers_max<boost::array<Elem, N> >
+{
+ enum { value = N };
+};
+
+#if defined(ASIO_HAS_STD_ARRAY)
+
+template <typename Elem, std::size_t N>
+struct prepared_buffers_max<std::array<Elem, N> >
+{
+ enum { value = N };
+};
+
+#endif // defined(ASIO_HAS_STD_ARRAY)
+
+// A buffer sequence used to represent a subsequence of the buffers.
+template <typename Buffer, std::size_t MaxBuffers>
+struct prepared_buffers
+{
+ typedef Buffer value_type;
+ typedef const Buffer* const_iterator;
+
+ enum { max_buffers = MaxBuffers < 16 ? MaxBuffers : 16 };
+
+ prepared_buffers() : count(0) {}
+ const_iterator begin() const { return elems; }
+ const_iterator end() const { return elems + count; }
+
+ Buffer elems[max_buffers];
+ std::size_t count;
+};
+
+// A proxy for a sub-range in a list of buffers.
+template <typename Buffer, typename Buffers, typename Buffer_Iterator>
+class consuming_buffers
+{
+public:
+ typedef prepared_buffers<Buffer, prepared_buffers_max<Buffers>::value>
+ prepared_buffers_type;
+
+ // Construct to represent the entire list of buffers.
+ explicit consuming_buffers(const Buffers& buffers)
+ : buffers_(buffers),
+ total_consumed_(0),
+ next_elem_(0),
+ next_elem_offset_(0)
+ {
+ using asio::buffer_size;
+ total_size_ = buffer_size(buffers);
+ }
+
+ // Determine if we are at the end of the buffers.
+ bool empty() const
+ {
+ return total_consumed_ >= total_size_;
+ }
+
+ // Get the buffer for a single transfer, with a size.
+ prepared_buffers_type prepare(std::size_t max_size)
+ {
+ prepared_buffers_type result;
+
+ Buffer_Iterator next = asio::buffer_sequence_begin(buffers_);
+ Buffer_Iterator end = asio::buffer_sequence_end(buffers_);
+
+ std::advance(next, next_elem_);
+ std::size_t elem_offset = next_elem_offset_;
+ while (next != end && max_size > 0 && (result.count) < result.max_buffers)
+ {
+ Buffer next_buf = Buffer(*next) + elem_offset;
+ result.elems[result.count] = asio::buffer(next_buf, max_size);
+ max_size -= result.elems[result.count].size();
+ elem_offset = 0;
+ if (result.elems[result.count].size() > 0)
+ ++result.count;
+ ++next;
+ }
+
+ return result;
+ }
+
+ // Consume the specified number of bytes from the buffers.
+ void consume(std::size_t size)
+ {
+ total_consumed_ += size;
+
+ Buffer_Iterator next = asio::buffer_sequence_begin(buffers_);
+ Buffer_Iterator end = asio::buffer_sequence_end(buffers_);
+
+ std::advance(next, next_elem_);
+ while (next != end && size > 0)
+ {
+ Buffer next_buf = Buffer(*next) + next_elem_offset_;
+ if (size < next_buf.size())
+ {
+ next_elem_offset_ += size;
+ size = 0;
+ }
+ else
+ {
+ size -= next_buf.size();
+ next_elem_offset_ = 0;
+ ++next_elem_;
+ ++next;
+ }
+ }
+ }
+
+ // Get the total number of bytes consumed from the buffers.
+ std::size_t total_consumed() const
+ {
+ return total_consumed_;
+ }
+
+private:
+ Buffers buffers_;
+ std::size_t total_size_;
+ std::size_t total_consumed_;
+ std::size_t next_elem_;
+ std::size_t next_elem_offset_;
+};
+
+// Base class of all consuming_buffers specialisations for single buffers.
+template <typename Buffer>
+class consuming_single_buffer
+{
+public:
+ // Construct to represent the entire list of buffers.
+ template <typename Buffer1>
+ explicit consuming_single_buffer(const Buffer1& buffer)
+ : buffer_(buffer),
+ total_consumed_(0)
+ {
+ }
+
+ // Determine if we are at the end of the buffers.
+ bool empty() const
+ {
+ return total_consumed_ >= buffer_.size();
+ }
+
+ // Get the buffer for a single transfer, with a size.
+ Buffer prepare(std::size_t max_size)
+ {
+ return asio::buffer(buffer_ + total_consumed_, max_size);
+ }
+
+ // Consume the specified number of bytes from the buffers.
+ void consume(std::size_t size)
+ {
+ total_consumed_ += size;
+ }
+
+ // Get the total number of bytes consumed from the buffers.
+ std::size_t total_consumed() const
+ {
+ return total_consumed_;
+ }
+
+private:
+ Buffer buffer_;
+ std::size_t total_consumed_;
+};
+
+template <>
+class consuming_buffers<mutable_buffer, mutable_buffer, const mutable_buffer*>
+ : public consuming_single_buffer<ASIO_MUTABLE_BUFFER>
+{
+public:
+ explicit consuming_buffers(const mutable_buffer& buffer)
+ : consuming_single_buffer<ASIO_MUTABLE_BUFFER>(buffer)
+ {
+ }
+};
+
+template <>
+class consuming_buffers<const_buffer, mutable_buffer, const mutable_buffer*>
+ : public consuming_single_buffer<ASIO_CONST_BUFFER>
+{
+public:
+ explicit consuming_buffers(const mutable_buffer& buffer)
+ : consuming_single_buffer<ASIO_CONST_BUFFER>(buffer)
+ {
+ }
+};
+
+template <>
+class consuming_buffers<const_buffer, const_buffer, const const_buffer*>
+ : public consuming_single_buffer<ASIO_CONST_BUFFER>
+{
+public:
+ explicit consuming_buffers(const const_buffer& buffer)
+ : consuming_single_buffer<ASIO_CONST_BUFFER>(buffer)
+ {
+ }
+};
+
+#if !defined(ASIO_NO_DEPRECATED)
+
+template <>
+class consuming_buffers<mutable_buffer,
+ mutable_buffers_1, const mutable_buffer*>
+ : public consuming_single_buffer<ASIO_MUTABLE_BUFFER>
+{
+public:
+ explicit consuming_buffers(const mutable_buffers_1& buffer)
+ : consuming_single_buffer<ASIO_MUTABLE_BUFFER>(buffer)
+ {
+ }
+};
+
+template <>
+class consuming_buffers<const_buffer, mutable_buffers_1, const mutable_buffer*>
+ : public consuming_single_buffer<ASIO_CONST_BUFFER>
+{
+public:
+ explicit consuming_buffers(const mutable_buffers_1& buffer)
+ : consuming_single_buffer<ASIO_CONST_BUFFER>(buffer)
+ {
+ }
+};
+
+template <>
+class consuming_buffers<const_buffer, const_buffers_1, const const_buffer*>
+ : public consuming_single_buffer<ASIO_CONST_BUFFER>
+{
+public:
+ explicit consuming_buffers(const const_buffers_1& buffer)
+ : consuming_single_buffer<ASIO_CONST_BUFFER>(buffer)
+ {
+ }
+};
+
+#endif // !defined(ASIO_NO_DEPRECATED)
+
+template <typename Buffer, typename Elem>
+class consuming_buffers<Buffer, boost::array<Elem, 2>,
+ typename boost::array<Elem, 2>::const_iterator>
+{
+public:
+ // Construct to represent the entire list of buffers.
+ explicit consuming_buffers(const boost::array<Elem, 2>& buffers)
+ : buffers_(buffers),
+ total_consumed_(0)
+ {
+ }
+
+ // Determine if we are at the end of the buffers.
+ bool empty() const
+ {
+ return total_consumed_ >=
+ Buffer(buffers_[0]).size() + Buffer(buffers_[1]).size();
+ }
+
+ // Get the buffer for a single transfer, with a size.
+ boost::array<Buffer, 2> prepare(std::size_t max_size)
+ {
+ boost::array<Buffer, 2> result = {{
+ Buffer(buffers_[0]), Buffer(buffers_[1]) }};
+ std::size_t buffer0_size = result[0].size();
+ result[0] = asio::buffer(result[0] + total_consumed_, max_size);
+ result[1] = asio::buffer(
+ result[1] + (total_consumed_ < buffer0_size
+ ? 0 : total_consumed_ - buffer0_size),
+ max_size - result[0].size());
+ return result;
+ }
+
+ // Consume the specified number of bytes from the buffers.
+ void consume(std::size_t size)
+ {
+ total_consumed_ += size;
+ }
+
+ // Get the total number of bytes consumed from the buffers.
+ std::size_t total_consumed() const
+ {
+ return total_consumed_;
+ }
+
+private:
+ boost::array<Elem, 2> buffers_;
+ std::size_t total_consumed_;
+};
+
+#if defined(ASIO_HAS_STD_ARRAY)
+
+template <typename Buffer, typename Elem>
+class consuming_buffers<Buffer, std::array<Elem, 2>,
+ typename std::array<Elem, 2>::const_iterator>
+{
+public:
+ // Construct to represent the entire list of buffers.
+ explicit consuming_buffers(const std::array<Elem, 2>& buffers)
+ : buffers_(buffers),
+ total_consumed_(0)
+ {
+ }
+
+ // Determine if we are at the end of the buffers.
+ bool empty() const
+ {
+ return total_consumed_ >=
+ Buffer(buffers_[0]).size() + Buffer(buffers_[1]).size();
+ }
+
+ // Get the buffer for a single transfer, with a size.
+ std::array<Buffer, 2> prepare(std::size_t max_size)
+ {
+ std::array<Buffer, 2> result = {{
+ Buffer(buffers_[0]), Buffer(buffers_[1]) }};
+ std::size_t buffer0_size = result[0].size();
+ result[0] = asio::buffer(result[0] + total_consumed_, max_size);
+ result[1] = asio::buffer(
+ result[1] + (total_consumed_ < buffer0_size
+ ? 0 : total_consumed_ - buffer0_size),
+ max_size - result[0].size());
+ return result;
+ }
+
+ // Consume the specified number of bytes from the buffers.
+ void consume(std::size_t size)
+ {
+ total_consumed_ += size;
+ }
+
+ // Get the total number of bytes consumed from the buffers.
+ std::size_t total_consumed() const
+ {
+ return total_consumed_;
+ }
+
+private:
+ std::array<Elem, 2> buffers_;
+ std::size_t total_consumed_;
+};
+
+#endif // defined(ASIO_HAS_STD_ARRAY)
+
+// Specialisation for null_buffers to ensure that the null_buffers type is
+// always passed through to the underlying read or write operation.
+template <typename Buffer>
+class consuming_buffers<Buffer, null_buffers, const mutable_buffer*>
+ : public asio::null_buffers
+{
+public:
+ consuming_buffers(const null_buffers&)
+ {
+ // No-op.
+ }
+
+ bool empty()
+ {
+ return false;
+ }
+
+ null_buffers prepare(std::size_t)
+ {
+ return null_buffers();
+ }
+
+ void consume(std::size_t)
+ {
+ // No-op.
+ }
+
+ std::size_t total_consumed() const
+ {
+ return 0;
+ }
+};
+
+} // namespace detail
+} // namespace asio
+
+#include "asio/detail/pop_options.hpp"
+
+#endif // ASIO_DETAIL_CONSUMING_BUFFERS_HPP
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