Chris@16: //
Chris@16: // buffers_iterator.hpp
Chris@16: // ~~~~~~~~~~~~~~~~~~~~
Chris@16: //
Chris@101: // Copyright (c) 2003-2015 Christopher M. Kohlhoff (chris at kohlhoff dot com)
Chris@16: //
Chris@16: // Distributed under the Boost Software License, Version 1.0. (See accompanying
Chris@16: // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
Chris@16: //
Chris@16: 
Chris@16: #ifndef BOOST_ASIO_BUFFERS_ITERATOR_HPP
Chris@16: #define BOOST_ASIO_BUFFERS_ITERATOR_HPP
Chris@16: 
Chris@16: #if defined(_MSC_VER) && (_MSC_VER >= 1200)
Chris@16: # pragma once
Chris@16: #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
Chris@16: 
Chris@16: #include <boost/asio/detail/config.hpp>
Chris@16: #include <cstddef>
Chris@16: #include <iterator>
Chris@16: #include <boost/asio/buffer.hpp>
Chris@16: #include <boost/asio/detail/assert.hpp>
Chris@16: #include <boost/asio/detail/type_traits.hpp>
Chris@16: 
Chris@16: #include <boost/asio/detail/push_options.hpp>
Chris@16: 
Chris@16: namespace boost {
Chris@16: namespace asio {
Chris@16: 
Chris@16: namespace detail
Chris@16: {
Chris@16:   template <bool IsMutable>
Chris@16:   struct buffers_iterator_types_helper;
Chris@16: 
Chris@16:   template <>
Chris@16:   struct buffers_iterator_types_helper<false>
Chris@16:   {
Chris@16:     typedef const_buffer buffer_type;
Chris@16:     template <typename ByteType>
Chris@16:     struct byte_type
Chris@16:     {
Chris@16:       typedef typename add_const<ByteType>::type type;
Chris@16:     };
Chris@16:   };
Chris@16: 
Chris@16:   template <>
Chris@16:   struct buffers_iterator_types_helper<true>
Chris@16:   {
Chris@16:     typedef mutable_buffer buffer_type;
Chris@16:     template <typename ByteType>
Chris@16:     struct byte_type
Chris@16:     {
Chris@16:       typedef ByteType type;
Chris@16:     };
Chris@16:   };
Chris@16: 
Chris@16:   template <typename BufferSequence, typename ByteType>
Chris@16:   struct buffers_iterator_types
Chris@16:   {
Chris@16:     enum
Chris@16:     {
Chris@16:       is_mutable = is_convertible<
Chris@16:           typename BufferSequence::value_type,
Chris@16:           mutable_buffer>::value
Chris@16:     };
Chris@16:     typedef buffers_iterator_types_helper<is_mutable> helper;
Chris@16:     typedef typename helper::buffer_type buffer_type;
Chris@16:     typedef typename helper::template byte_type<ByteType>::type byte_type;
Chris@16:   };
Chris@16: }
Chris@16: 
Chris@16: /// A random access iterator over the bytes in a buffer sequence.
Chris@16: template <typename BufferSequence, typename ByteType = char>
Chris@16: class buffers_iterator
Chris@16: {
Chris@16: private:
Chris@16:   typedef typename detail::buffers_iterator_types<
Chris@16:       BufferSequence, ByteType>::buffer_type buffer_type;
Chris@16: 
Chris@16: public:
Chris@16:   /// The type used for the distance between two iterators.
Chris@16:   typedef std::ptrdiff_t difference_type;
Chris@16: 
Chris@16:   /// The type of the value pointed to by the iterator.
Chris@16:   typedef ByteType value_type;
Chris@16: 
Chris@16: #if defined(GENERATING_DOCUMENTATION)
Chris@16:   /// The type of the result of applying operator->() to the iterator.
Chris@16:   /**
Chris@16:    * If the buffer sequence stores buffer objects that are convertible to
Chris@16:    * mutable_buffer, this is a pointer to a non-const ByteType. Otherwise, a
Chris@16:    * pointer to a const ByteType.
Chris@16:    */
Chris@16:   typedef const_or_non_const_ByteType* pointer;
Chris@16: #else // defined(GENERATING_DOCUMENTATION)
Chris@16:   typedef typename detail::buffers_iterator_types<
Chris@16:       BufferSequence, ByteType>::byte_type* pointer;
Chris@16: #endif // defined(GENERATING_DOCUMENTATION)
Chris@16: 
Chris@16: #if defined(GENERATING_DOCUMENTATION)
Chris@16:   /// The type of the result of applying operator*() to the iterator.
Chris@16:   /**
Chris@16:    * If the buffer sequence stores buffer objects that are convertible to
Chris@16:    * mutable_buffer, this is a reference to a non-const ByteType. Otherwise, a
Chris@16:    * reference to a const ByteType.
Chris@16:    */
Chris@16:   typedef const_or_non_const_ByteType& reference;
Chris@16: #else // defined(GENERATING_DOCUMENTATION)
Chris@16:   typedef typename detail::buffers_iterator_types<
Chris@16:       BufferSequence, ByteType>::byte_type& reference;
Chris@16: #endif // defined(GENERATING_DOCUMENTATION)
Chris@16: 
Chris@16:   /// The iterator category.
Chris@16:   typedef std::random_access_iterator_tag iterator_category;
Chris@16: 
Chris@16:   /// Default constructor. Creates an iterator in an undefined state.
Chris@16:   buffers_iterator()
Chris@16:     : current_buffer_(),
Chris@16:       current_buffer_position_(0),
Chris@16:       begin_(),
Chris@16:       current_(),
Chris@16:       end_(),
Chris@16:       position_(0)
Chris@16:   {
Chris@16:   }
Chris@16: 
Chris@16:   /// Construct an iterator representing the beginning of the buffers' data.
Chris@16:   static buffers_iterator begin(const BufferSequence& buffers)
Chris@16: #if defined(__GNUC__) && (__GNUC__ == 4) && (__GNUC_MINOR__ == 3)
Chris@16:     __attribute__ ((__noinline__))
Chris@16: #endif // defined(__GNUC__) && (__GNUC__ == 4) && (__GNUC_MINOR__ == 3)
Chris@16:   {
Chris@16:     buffers_iterator new_iter;
Chris@16:     new_iter.begin_ = buffers.begin();
Chris@16:     new_iter.current_ = buffers.begin();
Chris@16:     new_iter.end_ = buffers.end();
Chris@16:     while (new_iter.current_ != new_iter.end_)
Chris@16:     {
Chris@16:       new_iter.current_buffer_ = *new_iter.current_;
Chris@16:       if (boost::asio::buffer_size(new_iter.current_buffer_) > 0)
Chris@16:         break;
Chris@16:       ++new_iter.current_;
Chris@16:     }
Chris@16:     return new_iter;
Chris@16:   }
Chris@16: 
Chris@16:   /// Construct an iterator representing the end of the buffers' data.
Chris@16:   static buffers_iterator end(const BufferSequence& buffers)
Chris@16: #if defined(__GNUC__) && (__GNUC__ == 4) && (__GNUC_MINOR__ == 3)
Chris@16:     __attribute__ ((__noinline__))
Chris@16: #endif // defined(__GNUC__) && (__GNUC__ == 4) && (__GNUC_MINOR__ == 3)
Chris@16:   {
Chris@16:     buffers_iterator new_iter;
Chris@16:     new_iter.begin_ = buffers.begin();
Chris@16:     new_iter.current_ = buffers.begin();
Chris@16:     new_iter.end_ = buffers.end();
Chris@16:     while (new_iter.current_ != new_iter.end_)
Chris@16:     {
Chris@16:       buffer_type buffer = *new_iter.current_;
Chris@16:       new_iter.position_ += boost::asio::buffer_size(buffer);
Chris@16:       ++new_iter.current_;
Chris@16:     }
Chris@16:     return new_iter;
Chris@16:   }
Chris@16: 
Chris@16:   /// Dereference an iterator.
Chris@16:   reference operator*() const
Chris@16:   {
Chris@16:     return dereference();
Chris@16:   }
Chris@16: 
Chris@16:   /// Dereference an iterator.
Chris@16:   pointer operator->() const
Chris@16:   {
Chris@16:     return &dereference();
Chris@16:   }
Chris@16: 
Chris@16:   /// Access an individual element.
Chris@16:   reference operator[](std::ptrdiff_t difference) const
Chris@16:   {
Chris@16:     buffers_iterator tmp(*this);
Chris@16:     tmp.advance(difference);
Chris@16:     return *tmp;
Chris@16:   }
Chris@16: 
Chris@16:   /// Increment operator (prefix).
Chris@16:   buffers_iterator& operator++()
Chris@16:   {
Chris@16:     increment();
Chris@16:     return *this;
Chris@16:   }
Chris@16: 
Chris@16:   /// Increment operator (postfix).
Chris@16:   buffers_iterator operator++(int)
Chris@16:   {
Chris@16:     buffers_iterator tmp(*this);
Chris@16:     ++*this;
Chris@16:     return tmp;
Chris@16:   }
Chris@16: 
Chris@16:   /// Decrement operator (prefix).
Chris@16:   buffers_iterator& operator--()
Chris@16:   {
Chris@16:     decrement();
Chris@16:     return *this;
Chris@16:   }
Chris@16: 
Chris@16:   /// Decrement operator (postfix).
Chris@16:   buffers_iterator operator--(int)
Chris@16:   {
Chris@16:     buffers_iterator tmp(*this);
Chris@16:     --*this;
Chris@16:     return tmp;
Chris@16:   }
Chris@16: 
Chris@16:   /// Addition operator.
Chris@16:   buffers_iterator& operator+=(std::ptrdiff_t difference)
Chris@16:   {
Chris@16:     advance(difference);
Chris@16:     return *this;
Chris@16:   }
Chris@16: 
Chris@16:   /// Subtraction operator.
Chris@16:   buffers_iterator& operator-=(std::ptrdiff_t difference)
Chris@16:   {
Chris@16:     advance(-difference);
Chris@16:     return *this;
Chris@16:   }
Chris@16: 
Chris@16:   /// Addition operator.
Chris@16:   friend buffers_iterator operator+(const buffers_iterator& iter,
Chris@16:       std::ptrdiff_t difference)
Chris@16:   {
Chris@16:     buffers_iterator tmp(iter);
Chris@16:     tmp.advance(difference);
Chris@16:     return tmp;
Chris@16:   }
Chris@16: 
Chris@16:   /// Addition operator.
Chris@16:   friend buffers_iterator operator+(std::ptrdiff_t difference,
Chris@16:       const buffers_iterator& iter)
Chris@16:   {
Chris@16:     buffers_iterator tmp(iter);
Chris@16:     tmp.advance(difference);
Chris@16:     return tmp;
Chris@16:   }
Chris@16: 
Chris@16:   /// Subtraction operator.
Chris@16:   friend buffers_iterator operator-(const buffers_iterator& iter,
Chris@16:       std::ptrdiff_t difference)
Chris@16:   {
Chris@16:     buffers_iterator tmp(iter);
Chris@16:     tmp.advance(-difference);
Chris@16:     return tmp;
Chris@16:   }
Chris@16: 
Chris@16:   /// Subtraction operator.
Chris@16:   friend std::ptrdiff_t operator-(const buffers_iterator& a,
Chris@16:       const buffers_iterator& b)
Chris@16:   {
Chris@16:     return b.distance_to(a);
Chris@16:   }
Chris@16: 
Chris@16:   /// Test two iterators for equality.
Chris@16:   friend bool operator==(const buffers_iterator& a, const buffers_iterator& b)
Chris@16:   {
Chris@16:     return a.equal(b);
Chris@16:   }
Chris@16: 
Chris@16:   /// Test two iterators for inequality.
Chris@16:   friend bool operator!=(const buffers_iterator& a, const buffers_iterator& b)
Chris@16:   {
Chris@16:     return !a.equal(b);
Chris@16:   }
Chris@16: 
Chris@16:   /// Compare two iterators.
Chris@16:   friend bool operator<(const buffers_iterator& a, const buffers_iterator& b)
Chris@16:   {
Chris@16:     return a.distance_to(b) > 0;
Chris@16:   }
Chris@16: 
Chris@16:   /// Compare two iterators.
Chris@16:   friend bool operator<=(const buffers_iterator& a, const buffers_iterator& b)
Chris@16:   {
Chris@16:     return !(b < a);
Chris@16:   }
Chris@16: 
Chris@16:   /// Compare two iterators.
Chris@16:   friend bool operator>(const buffers_iterator& a, const buffers_iterator& b)
Chris@16:   {
Chris@16:     return b < a;
Chris@16:   }
Chris@16: 
Chris@16:   /// Compare two iterators.
Chris@16:   friend bool operator>=(const buffers_iterator& a, const buffers_iterator& b)
Chris@16:   {
Chris@16:     return !(a < b);
Chris@16:   }
Chris@16: 
Chris@16: private:
Chris@16:   // Dereference the iterator.
Chris@16:   reference dereference() const
Chris@16:   {
Chris@16:     return buffer_cast<pointer>(current_buffer_)[current_buffer_position_];
Chris@16:   }
Chris@16: 
Chris@16:   // Compare two iterators for equality.
Chris@16:   bool equal(const buffers_iterator& other) const
Chris@16:   {
Chris@16:     return position_ == other.position_;
Chris@16:   }
Chris@16: 
Chris@16:   // Increment the iterator.
Chris@16:   void increment()
Chris@16:   {
Chris@16:     BOOST_ASIO_ASSERT(current_ != end_ && "iterator out of bounds");
Chris@16:     ++position_;
Chris@16: 
Chris@16:     // Check if the increment can be satisfied by the current buffer.
Chris@16:     ++current_buffer_position_;
Chris@16:     if (current_buffer_position_ != boost::asio::buffer_size(current_buffer_))
Chris@16:       return;
Chris@16: 
Chris@16:     // Find the next non-empty buffer.
Chris@16:     ++current_;
Chris@16:     current_buffer_position_ = 0;
Chris@16:     while (current_ != end_)
Chris@16:     {
Chris@16:       current_buffer_ = *current_;
Chris@16:       if (boost::asio::buffer_size(current_buffer_) > 0)
Chris@16:         return;
Chris@16:       ++current_;
Chris@16:     }
Chris@16:   }
Chris@16: 
Chris@16:   // Decrement the iterator.
Chris@16:   void decrement()
Chris@16:   {
Chris@16:     BOOST_ASIO_ASSERT(position_ > 0 && "iterator out of bounds");
Chris@16:     --position_;
Chris@16: 
Chris@16:     // Check if the decrement can be satisfied by the current buffer.
Chris@16:     if (current_buffer_position_ != 0)
Chris@16:     {
Chris@16:       --current_buffer_position_;
Chris@16:       return;
Chris@16:     }
Chris@16: 
Chris@16:     // Find the previous non-empty buffer.
Chris@16:     typename BufferSequence::const_iterator iter = current_;
Chris@16:     while (iter != begin_)
Chris@16:     {
Chris@16:       --iter;
Chris@16:       buffer_type buffer = *iter;
Chris@16:       std::size_t buffer_size = boost::asio::buffer_size(buffer);
Chris@16:       if (buffer_size > 0)
Chris@16:       {
Chris@16:         current_ = iter;
Chris@16:         current_buffer_ = buffer;
Chris@16:         current_buffer_position_ = buffer_size - 1;
Chris@16:         return;
Chris@16:       }
Chris@16:     }
Chris@16:   }
Chris@16: 
Chris@16:   // Advance the iterator by the specified distance.
Chris@16:   void advance(std::ptrdiff_t n)
Chris@16:   {
Chris@16:     if (n > 0)
Chris@16:     {
Chris@16:       BOOST_ASIO_ASSERT(current_ != end_ && "iterator out of bounds");
Chris@16:       for (;;)
Chris@16:       {
Chris@16:         std::ptrdiff_t current_buffer_balance
Chris@16:           = boost::asio::buffer_size(current_buffer_)
Chris@16:           - current_buffer_position_;
Chris@16: 
Chris@16:         // Check if the advance can be satisfied by the current buffer.
Chris@16:         if (current_buffer_balance > n)
Chris@16:         {
Chris@16:           position_ += n;
Chris@16:           current_buffer_position_ += n;
Chris@16:           return;
Chris@16:         }
Chris@16: 
Chris@16:         // Update position.
Chris@16:         n -= current_buffer_balance;
Chris@16:         position_ += current_buffer_balance;
Chris@16: 
Chris@16:         // Move to next buffer. If it is empty then it will be skipped on the
Chris@16:         // next iteration of this loop.
Chris@16:         if (++current_ == end_)
Chris@16:         {
Chris@16:           BOOST_ASIO_ASSERT(n == 0 && "iterator out of bounds");
Chris@16:           current_buffer_ = buffer_type();
Chris@16:           current_buffer_position_ = 0;
Chris@16:           return;
Chris@16:         }
Chris@16:         current_buffer_ = *current_;
Chris@16:         current_buffer_position_ = 0;
Chris@16:       }
Chris@16:     }
Chris@16:     else if (n < 0)
Chris@16:     {
Chris@16:       std::size_t abs_n = -n;
Chris@16:       BOOST_ASIO_ASSERT(position_ >= abs_n && "iterator out of bounds");
Chris@16:       for (;;)
Chris@16:       {
Chris@16:         // Check if the advance can be satisfied by the current buffer.
Chris@16:         if (current_buffer_position_ >= abs_n)
Chris@16:         {
Chris@16:           position_ -= abs_n;
Chris@16:           current_buffer_position_ -= abs_n;
Chris@16:           return;
Chris@16:         }
Chris@16: 
Chris@16:         // Update position.
Chris@16:         abs_n -= current_buffer_position_;
Chris@16:         position_ -= current_buffer_position_;
Chris@16: 
Chris@16:         // Check if we've reached the beginning of the buffers.
Chris@16:         if (current_ == begin_)
Chris@16:         {
Chris@16:           BOOST_ASIO_ASSERT(abs_n == 0 && "iterator out of bounds");
Chris@16:           current_buffer_position_ = 0;
Chris@16:           return;
Chris@16:         }
Chris@16: 
Chris@16:         // Find the previous non-empty buffer.
Chris@16:         typename BufferSequence::const_iterator iter = current_;
Chris@16:         while (iter != begin_)
Chris@16:         {
Chris@16:           --iter;
Chris@16:           buffer_type buffer = *iter;
Chris@16:           std::size_t buffer_size = boost::asio::buffer_size(buffer);
Chris@16:           if (buffer_size > 0)
Chris@16:           {
Chris@16:             current_ = iter;
Chris@16:             current_buffer_ = buffer;
Chris@16:             current_buffer_position_ = buffer_size;
Chris@16:             break;
Chris@16:           }
Chris@16:         }
Chris@16:       }
Chris@16:     }
Chris@16:   }
Chris@16: 
Chris@16:   // Determine the distance between two iterators.
Chris@16:   std::ptrdiff_t distance_to(const buffers_iterator& other) const
Chris@16:   {
Chris@16:     return other.position_ - position_;
Chris@16:   }
Chris@16: 
Chris@16:   buffer_type current_buffer_;
Chris@16:   std::size_t current_buffer_position_;
Chris@16:   typename BufferSequence::const_iterator begin_;
Chris@16:   typename BufferSequence::const_iterator current_;
Chris@16:   typename BufferSequence::const_iterator end_;
Chris@16:   std::size_t position_;
Chris@16: };
Chris@16: 
Chris@16: /// Construct an iterator representing the beginning of the buffers' data.
Chris@16: template <typename BufferSequence>
Chris@16: inline buffers_iterator<BufferSequence> buffers_begin(
Chris@16:     const BufferSequence& buffers)
Chris@16: {
Chris@16:   return buffers_iterator<BufferSequence>::begin(buffers);
Chris@16: }
Chris@16: 
Chris@16: /// Construct an iterator representing the end of the buffers' data.
Chris@16: template <typename BufferSequence>
Chris@16: inline buffers_iterator<BufferSequence> buffers_end(
Chris@16:     const BufferSequence& buffers)
Chris@16: {
Chris@16:   return buffers_iterator<BufferSequence>::end(buffers);
Chris@16: }
Chris@16: 
Chris@16: } // namespace asio
Chris@16: } // namespace boost
Chris@16: 
Chris@16: #include <boost/asio/detail/pop_options.hpp>
Chris@16: 
Chris@16: #endif // BOOST_ASIO_BUFFERS_ITERATOR_HPP