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+//
+// buffers_iterator.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_BUFFERS_ITERATOR_HPP
+#define ASIO_BUFFERS_ITERATOR_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 <iterator>
+#include "asio/buffer.hpp"
+#include "asio/detail/assert.hpp"
+#include "asio/detail/type_traits.hpp"
+
+#include "asio/detail/push_options.hpp"
+
+namespace asio {
+
+namespace detail
+{
+ template <bool IsMutable>
+ struct buffers_iterator_types_helper;
+
+ template <>
+ struct buffers_iterator_types_helper<false>
+ {
+ typedef const_buffer buffer_type;
+ template <typename ByteType>
+ struct byte_type
+ {
+ typedef typename add_const<ByteType>::type type;
+ };
+ };
+
+ template <>
+ struct buffers_iterator_types_helper<true>
+ {
+ typedef mutable_buffer buffer_type;
+ template <typename ByteType>
+ struct byte_type
+ {
+ typedef ByteType type;
+ };
+ };
+
+ template <typename BufferSequence, typename ByteType>
+ struct buffers_iterator_types
+ {
+ enum
+ {
+ is_mutable = is_convertible<
+ typename BufferSequence::value_type,
+ mutable_buffer>::value
+ };
+ typedef buffers_iterator_types_helper<is_mutable> helper;
+ typedef typename helper::buffer_type buffer_type;
+ typedef typename helper::template byte_type<ByteType>::type byte_type;
+ typedef typename BufferSequence::const_iterator const_iterator;
+ };
+
+ template <typename ByteType>
+ struct buffers_iterator_types<mutable_buffer, ByteType>
+ {
+ typedef mutable_buffer buffer_type;
+ typedef ByteType byte_type;
+ typedef const mutable_buffer* const_iterator;
+ };
+
+ template <typename ByteType>
+ struct buffers_iterator_types<const_buffer, ByteType>
+ {
+ typedef const_buffer buffer_type;
+ typedef typename add_const<ByteType>::type byte_type;
+ typedef const const_buffer* const_iterator;
+ };
+
+#if !defined(ASIO_NO_DEPRECATED)
+
+ template <typename ByteType>
+ struct buffers_iterator_types<mutable_buffers_1, ByteType>
+ {
+ typedef mutable_buffer buffer_type;
+ typedef ByteType byte_type;
+ typedef const mutable_buffer* const_iterator;
+ };
+
+ template <typename ByteType>
+ struct buffers_iterator_types<const_buffers_1, ByteType>
+ {
+ typedef const_buffer buffer_type;
+ typedef typename add_const<ByteType>::type byte_type;
+ typedef const const_buffer* const_iterator;
+ };
+
+#endif // !defined(ASIO_NO_DEPRECATED)
+}
+
+/// A random access iterator over the bytes in a buffer sequence.
+template <typename BufferSequence, typename ByteType = char>
+class buffers_iterator
+{
+private:
+ typedef typename detail::buffers_iterator_types<
+ BufferSequence, ByteType>::buffer_type buffer_type;
+
+ typedef typename detail::buffers_iterator_types<BufferSequence,
+ ByteType>::const_iterator buffer_sequence_iterator_type;
+
+public:
+ /// The type used for the distance between two iterators.
+ typedef std::ptrdiff_t difference_type;
+
+ /// The type of the value pointed to by the iterator.
+ typedef ByteType value_type;
+
+#if defined(GENERATING_DOCUMENTATION)
+ /// The type of the result of applying operator->() to the iterator.
+ /**
+ * If the buffer sequence stores buffer objects that are convertible to
+ * mutable_buffer, this is a pointer to a non-const ByteType. Otherwise, a
+ * pointer to a const ByteType.
+ */
+ typedef const_or_non_const_ByteType* pointer;
+#else // defined(GENERATING_DOCUMENTATION)
+ typedef typename detail::buffers_iterator_types<
+ BufferSequence, ByteType>::byte_type* pointer;
+#endif // defined(GENERATING_DOCUMENTATION)
+
+#if defined(GENERATING_DOCUMENTATION)
+ /// The type of the result of applying operator*() to the iterator.
+ /**
+ * If the buffer sequence stores buffer objects that are convertible to
+ * mutable_buffer, this is a reference to a non-const ByteType. Otherwise, a
+ * reference to a const ByteType.
+ */
+ typedef const_or_non_const_ByteType& reference;
+#else // defined(GENERATING_DOCUMENTATION)
+ typedef typename detail::buffers_iterator_types<
+ BufferSequence, ByteType>::byte_type& reference;
+#endif // defined(GENERATING_DOCUMENTATION)
+
+ /// The iterator category.
+ typedef std::random_access_iterator_tag iterator_category;
+
+ /// Default constructor. Creates an iterator in an undefined state.
+ buffers_iterator()
+ : current_buffer_(),
+ current_buffer_position_(0),
+ begin_(),
+ current_(),
+ end_(),
+ position_(0)
+ {
+ }
+
+ /// Construct an iterator representing the beginning of the buffers' data.
+ static buffers_iterator begin(const BufferSequence& buffers)
+#if defined(__GNUC__) && (__GNUC__ == 4) && (__GNUC_MINOR__ == 3)
+ __attribute__ ((__noinline__))
+#endif // defined(__GNUC__) && (__GNUC__ == 4) && (__GNUC_MINOR__ == 3)
+ {
+ buffers_iterator new_iter;
+ new_iter.begin_ = asio::buffer_sequence_begin(buffers);
+ new_iter.current_ = asio::buffer_sequence_begin(buffers);
+ new_iter.end_ = asio::buffer_sequence_end(buffers);
+ while (new_iter.current_ != new_iter.end_)
+ {
+ new_iter.current_buffer_ = *new_iter.current_;
+ if (new_iter.current_buffer_.size() > 0)
+ break;
+ ++new_iter.current_;
+ }
+ return new_iter;
+ }
+
+ /// Construct an iterator representing the end of the buffers' data.
+ static buffers_iterator end(const BufferSequence& buffers)
+#if defined(__GNUC__) && (__GNUC__ == 4) && (__GNUC_MINOR__ == 3)
+ __attribute__ ((__noinline__))
+#endif // defined(__GNUC__) && (__GNUC__ == 4) && (__GNUC_MINOR__ == 3)
+ {
+ buffers_iterator new_iter;
+ new_iter.begin_ = asio::buffer_sequence_begin(buffers);
+ new_iter.current_ = asio::buffer_sequence_begin(buffers);
+ new_iter.end_ = asio::buffer_sequence_end(buffers);
+ while (new_iter.current_ != new_iter.end_)
+ {
+ buffer_type buffer = *new_iter.current_;
+ new_iter.position_ += buffer.size();
+ ++new_iter.current_;
+ }
+ return new_iter;
+ }
+
+ /// Dereference an iterator.
+ reference operator*() const
+ {
+ return dereference();
+ }
+
+ /// Dereference an iterator.
+ pointer operator->() const
+ {
+ return &dereference();
+ }
+
+ /// Access an individual element.
+ reference operator[](std::ptrdiff_t difference) const
+ {
+ buffers_iterator tmp(*this);
+ tmp.advance(difference);
+ return *tmp;
+ }
+
+ /// Increment operator (prefix).
+ buffers_iterator& operator++()
+ {
+ increment();
+ return *this;
+ }
+
+ /// Increment operator (postfix).
+ buffers_iterator operator++(int)
+ {
+ buffers_iterator tmp(*this);
+ ++*this;
+ return tmp;
+ }
+
+ /// Decrement operator (prefix).
+ buffers_iterator& operator--()
+ {
+ decrement();
+ return *this;
+ }
+
+ /// Decrement operator (postfix).
+ buffers_iterator operator--(int)
+ {
+ buffers_iterator tmp(*this);
+ --*this;
+ return tmp;
+ }
+
+ /// Addition operator.
+ buffers_iterator& operator+=(std::ptrdiff_t difference)
+ {
+ advance(difference);
+ return *this;
+ }
+
+ /// Subtraction operator.
+ buffers_iterator& operator-=(std::ptrdiff_t difference)
+ {
+ advance(-difference);
+ return *this;
+ }
+
+ /// Addition operator.
+ friend buffers_iterator operator+(const buffers_iterator& iter,
+ std::ptrdiff_t difference)
+ {
+ buffers_iterator tmp(iter);
+ tmp.advance(difference);
+ return tmp;
+ }
+
+ /// Addition operator.
+ friend buffers_iterator operator+(std::ptrdiff_t difference,
+ const buffers_iterator& iter)
+ {
+ buffers_iterator tmp(iter);
+ tmp.advance(difference);
+ return tmp;
+ }
+
+ /// Subtraction operator.
+ friend buffers_iterator operator-(const buffers_iterator& iter,
+ std::ptrdiff_t difference)
+ {
+ buffers_iterator tmp(iter);
+ tmp.advance(-difference);
+ return tmp;
+ }
+
+ /// Subtraction operator.
+ friend std::ptrdiff_t operator-(const buffers_iterator& a,
+ const buffers_iterator& b)
+ {
+ return b.distance_to(a);
+ }
+
+ /// Test two iterators for equality.
+ friend bool operator==(const buffers_iterator& a, const buffers_iterator& b)
+ {
+ return a.equal(b);
+ }
+
+ /// Test two iterators for inequality.
+ friend bool operator!=(const buffers_iterator& a, const buffers_iterator& b)
+ {
+ return !a.equal(b);
+ }
+
+ /// Compare two iterators.
+ friend bool operator<(const buffers_iterator& a, const buffers_iterator& b)
+ {
+ return a.distance_to(b) > 0;
+ }
+
+ /// Compare two iterators.
+ friend bool operator<=(const buffers_iterator& a, const buffers_iterator& b)
+ {
+ return !(b < a);
+ }
+
+ /// Compare two iterators.
+ friend bool operator>(const buffers_iterator& a, const buffers_iterator& b)
+ {
+ return b < a;
+ }
+
+ /// Compare two iterators.
+ friend bool operator>=(const buffers_iterator& a, const buffers_iterator& b)
+ {
+ return !(a < b);
+ }
+
+private:
+ // Dereference the iterator.
+ reference dereference() const
+ {
+ return static_cast<pointer>(
+ current_buffer_.data())[current_buffer_position_];
+ }
+
+ // Compare two iterators for equality.
+ bool equal(const buffers_iterator& other) const
+ {
+ return position_ == other.position_;
+ }
+
+ // Increment the iterator.
+ void increment()
+ {
+ ASIO_ASSERT(current_ != end_ && "iterator out of bounds");
+ ++position_;
+
+ // Check if the increment can be satisfied by the current buffer.
+ ++current_buffer_position_;
+ if (current_buffer_position_ != current_buffer_.size())
+ return;
+
+ // Find the next non-empty buffer.
+ ++current_;
+ current_buffer_position_ = 0;
+ while (current_ != end_)
+ {
+ current_buffer_ = *current_;
+ if (current_buffer_.size() > 0)
+ return;
+ ++current_;
+ }
+ }
+
+ // Decrement the iterator.
+ void decrement()
+ {
+ ASIO_ASSERT(position_ > 0 && "iterator out of bounds");
+ --position_;
+
+ // Check if the decrement can be satisfied by the current buffer.
+ if (current_buffer_position_ != 0)
+ {
+ --current_buffer_position_;
+ return;
+ }
+
+ // Find the previous non-empty buffer.
+ buffer_sequence_iterator_type iter = current_;
+ while (iter != begin_)
+ {
+ --iter;
+ buffer_type buffer = *iter;
+ std::size_t buffer_size = buffer.size();
+ if (buffer_size > 0)
+ {
+ current_ = iter;
+ current_buffer_ = buffer;
+ current_buffer_position_ = buffer_size - 1;
+ return;
+ }
+ }
+ }
+
+ // Advance the iterator by the specified distance.
+ void advance(std::ptrdiff_t n)
+ {
+ if (n > 0)
+ {
+ ASIO_ASSERT(current_ != end_ && "iterator out of bounds");
+ for (;;)
+ {
+ std::ptrdiff_t current_buffer_balance
+ = current_buffer_.size() - current_buffer_position_;
+
+ // Check if the advance can be satisfied by the current buffer.
+ if (current_buffer_balance > n)
+ {
+ position_ += n;
+ current_buffer_position_ += n;
+ return;
+ }
+
+ // Update position.
+ n -= current_buffer_balance;
+ position_ += current_buffer_balance;
+
+ // Move to next buffer. If it is empty then it will be skipped on the
+ // next iteration of this loop.
+ if (++current_ == end_)
+ {
+ ASIO_ASSERT(n == 0 && "iterator out of bounds");
+ current_buffer_ = buffer_type();
+ current_buffer_position_ = 0;
+ return;
+ }
+ current_buffer_ = *current_;
+ current_buffer_position_ = 0;
+ }
+ }
+ else if (n < 0)
+ {
+ std::size_t abs_n = -n;
+ ASIO_ASSERT(position_ >= abs_n && "iterator out of bounds");
+ for (;;)
+ {
+ // Check if the advance can be satisfied by the current buffer.
+ if (current_buffer_position_ >= abs_n)
+ {
+ position_ -= abs_n;
+ current_buffer_position_ -= abs_n;
+ return;
+ }
+
+ // Update position.
+ abs_n -= current_buffer_position_;
+ position_ -= current_buffer_position_;
+
+ // Check if we've reached the beginning of the buffers.
+ if (current_ == begin_)
+ {
+ ASIO_ASSERT(abs_n == 0 && "iterator out of bounds");
+ current_buffer_position_ = 0;
+ return;
+ }
+
+ // Find the previous non-empty buffer.
+ buffer_sequence_iterator_type iter = current_;
+ while (iter != begin_)
+ {
+ --iter;
+ buffer_type buffer = *iter;
+ std::size_t buffer_size = buffer.size();
+ if (buffer_size > 0)
+ {
+ current_ = iter;
+ current_buffer_ = buffer;
+ current_buffer_position_ = buffer_size;
+ break;
+ }
+ }
+ }
+ }
+ }
+
+ // Determine the distance between two iterators.
+ std::ptrdiff_t distance_to(const buffers_iterator& other) const
+ {
+ return other.position_ - position_;
+ }
+
+ buffer_type current_buffer_;
+ std::size_t current_buffer_position_;
+ buffer_sequence_iterator_type begin_;
+ buffer_sequence_iterator_type current_;
+ buffer_sequence_iterator_type end_;
+ std::size_t position_;
+};
+
+/// Construct an iterator representing the beginning of the buffers' data.
+template <typename BufferSequence>
+inline buffers_iterator<BufferSequence> buffers_begin(
+ const BufferSequence& buffers)
+{
+ return buffers_iterator<BufferSequence>::begin(buffers);
+}
+
+/// Construct an iterator representing the end of the buffers' data.
+template <typename BufferSequence>
+inline buffers_iterator<BufferSequence> buffers_end(
+ const BufferSequence& buffers)
+{
+ return buffers_iterator<BufferSequence>::end(buffers);
+}
+
+} // namespace asio
+
+#include "asio/detail/pop_options.hpp"
+
+#endif // ASIO_BUFFERS_ITERATOR_HPP
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