buffer.hpp

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//
// buffer.hpp
// ~~~~~~~~~~
//
// Copyright (c) 2003-2007 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_BUFFER_HPP
#define ASIO_BUFFER_HPP

#if defined(_MSC_VER) && (_MSC_VER >= 1200)
# pragma once
#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)

#include "asio/detail/push_options.hpp"

#include "asio/detail/push_options.hpp"
#include <cstddef>
#include <boost/config.hpp>
#include <boost/array.hpp>
#include <boost/type_traits/is_const.hpp>
#include <string>
#include <vector>
#include "asio/detail/pop_options.hpp"

#if defined(BOOST_MSVC)
# if defined(_HAS_ITERATOR_DEBUGGING) && (_HAS_ITERATOR_DEBUGGING != 0)
#  if !defined(ASIO_DISABLE_BUFFER_DEBUGGING)
#   define ASIO_ENABLE_BUFFER_DEBUGGING
#  endif // !defined(ASIO_DISABLE_BUFFER_DEBUGGING)
# endif // defined(_HAS_ITERATOR_DEBUGGING)
#endif // defined(BOOST_MSVC)

#if defined(__GNUC__)
# if defined(_GLIBCXX_DEBUG)
#  if !defined(ASIO_DISABLE_BUFFER_DEBUGGING)
#   define ASIO_ENABLE_BUFFER_DEBUGGING
#  endif // !defined(ASIO_DISABLE_BUFFER_DEBUGGING)
# endif // defined(_GLIBCXX_DEBUG)
#endif // defined(__GNUC__)

#if defined(ASIO_ENABLE_BUFFER_DEBUGGING)
# include "asio/detail/push_options.hpp"
# include <boost/function.hpp>
# include "asio/detail/pop_options.hpp"
#endif // ASIO_ENABLE_BUFFER_DEBUGGING

namespace asio {

class mutable_buffer;
class const_buffer;

namespace detail {
void* buffer_cast_helper(const mutable_buffer&);
const void* buffer_cast_helper(const const_buffer&);
std::size_t buffer_size_helper(const mutable_buffer&);
std::size_t buffer_size_helper(const const_buffer&);
} // namespace detail

/// Holds a buffer that can be modified.
/**
 * The mutable_buffer class provides a safe representation of a buffer that can
 * be modified. It does not own the underlying data, and so is cheap to copy or
 * assign.
 */
class mutable_buffer
{
public:
  /// Construct an empty buffer.
  mutable_buffer()
    : data_(0),
      size_(0)
  {
  }

  /// Construct a buffer to represent a given memory range.
  mutable_buffer(void* data, std::size_t size)
    : data_(data),
      size_(size)
  {
  }

#if defined(ASIO_ENABLE_BUFFER_DEBUGGING)
  mutable_buffer(void* data, std::size_t size,
      boost::function<void()> debug_check)
    : data_(data),
      size_(size),
      debug_check_(debug_check)
  {
  }

  const boost::function<void()>& get_debug_check() const
  {
    return debug_check_;
  }
#endif // ASIO_ENABLE_BUFFER_DEBUGGING

private:
  friend void* asio::detail::buffer_cast_helper(
      const mutable_buffer& b);
  friend std::size_t asio::detail::buffer_size_helper(
      const mutable_buffer& b);

  void* data_;
  std::size_t size_;

#if defined(ASIO_ENABLE_BUFFER_DEBUGGING)
  boost::function<void()> debug_check_;
#endif // ASIO_ENABLE_BUFFER_DEBUGGING
};

namespace detail {

inline void* buffer_cast_helper(const mutable_buffer& b)
{
#if defined(ASIO_ENABLE_BUFFER_DEBUGGING)
  if (b.size_ && b.debug_check_)
    b.debug_check_();
#endif // ASIO_ENABLE_BUFFER_DEBUGGING
  return b.data_;
}

inline std::size_t buffer_size_helper(const mutable_buffer& b)
{
  return b.size_;
}

} // namespace detail

/// Cast a non-modifiable buffer to a specified pointer to POD type.
/**
 * @relates mutable_buffer
 */
template <typename PointerToPodType>
inline PointerToPodType buffer_cast(const mutable_buffer& b)
{
  return static_cast<PointerToPodType>(detail::buffer_cast_helper(b));
}

/// Get the number of bytes in a non-modifiable buffer.
/**
 * @relates mutable_buffer
 */
inline std::size_t buffer_size(const mutable_buffer& b)
{
  return detail::buffer_size_helper(b);
}

/// Create a new modifiable buffer that is offset from the start of another.
/**
 * @relates mutable_buffer
 */
inline mutable_buffer operator+(const mutable_buffer& b, std::size_t start)
{
  if (start > buffer_size(b))
    return mutable_buffer();
  char* new_data = buffer_cast<char*>(b) + start;
  std::size_t new_size = buffer_size(b) - start;
  return mutable_buffer(new_data, new_size
#if defined(ASIO_ENABLE_BUFFER_DEBUGGING)
      , b.get_debug_check()
#endif // ASIO_ENABLE_BUFFER_DEBUGGING
      );
}

/// Create a new modifiable buffer that is offset from the start of another.
/**
 * @relates mutable_buffer
 */
inline mutable_buffer operator+(std::size_t start, const mutable_buffer& b)
{
  if (start > buffer_size(b))
    return mutable_buffer();
  char* new_data = buffer_cast<char*>(b) + start;
  std::size_t new_size = buffer_size(b) - start;
  return mutable_buffer(new_data, new_size
#if defined(ASIO_ENABLE_BUFFER_DEBUGGING)
      , b.get_debug_check()
#endif // ASIO_ENABLE_BUFFER_DEBUGGING
      );
}

/// Adapts a single modifiable buffer so that it meets the requirements of the
/// MutableBufferSequence concept.
class mutable_buffers_1
  : public mutable_buffer
{
public:
  /// The type for each element in the list of buffers.
  typedef mutable_buffer value_type;

  /// A random-access iterator type that may be used to read elements.
  typedef const mutable_buffer* const_iterator;

  /// Construct to represent a single modifiable buffer.
  explicit mutable_buffers_1(const mutable_buffer& b)
    : mutable_buffer(b)
  {
  }

  /// Get a random-access iterator to the first element.
  const_iterator begin() const
  {
    return this;
  }

  /// Get a random-access iterator for one past the last element.
  const_iterator end() const
  {
    return begin() + 1;
  }
};

/// Holds a buffer that cannot be modified.
/**
 * The const_buffer class provides a safe representation of a buffer that cannot
 * be modified. It does not own the underlying data, and so is cheap to copy or
 * assign.
 */
class const_buffer
{
public:
  /// Construct an empty buffer.
  const_buffer()
    : data_(0),
      size_(0)
  {
  }

  /// Construct a buffer to represent a given memory range.
  const_buffer(const void* data, std::size_t size)
    : data_(data),
      size_(size)
  {
  }

  /// Construct a non-modifiable buffer from a modifiable one.
  const_buffer(const mutable_buffer& b)
    : data_(asio::detail::buffer_cast_helper(b)),
      size_(asio::detail::buffer_size_helper(b))
#if defined(ASIO_ENABLE_BUFFER_DEBUGGING)
      , debug_check_(b.get_debug_check())
#endif // ASIO_ENABLE_BUFFER_DEBUGGING
  {
  }

#if defined(ASIO_ENABLE_BUFFER_DEBUGGING)
  const_buffer(const void* data, std::size_t size,
      boost::function<void()> debug_check)
    : data_(data),
      size_(size),
      debug_check_(debug_check)
  {
  }

  const boost::function<void()>& get_debug_check() const
  {
    return debug_check_;
  }
#endif // ASIO_ENABLE_BUFFER_DEBUGGING

private:
  friend const void* asio::detail::buffer_cast_helper(
      const const_buffer& b);
  friend std::size_t asio::detail::buffer_size_helper(
      const const_buffer& b);

  const void* data_;
  std::size_t size_;

#if defined(ASIO_ENABLE_BUFFER_DEBUGGING)
  boost::function<void()> debug_check_;
#endif // ASIO_ENABLE_BUFFER_DEBUGGING
};

namespace detail {

inline const void* buffer_cast_helper(const const_buffer& b)
{
#if defined(ASIO_ENABLE_BUFFER_DEBUGGING)
  if (b.size_ && b.debug_check_)
    b.debug_check_();
#endif // ASIO_ENABLE_BUFFER_DEBUGGING
  return b.data_;
}

inline std::size_t buffer_size_helper(const const_buffer& b)
{
  return b.size_;
}

} // namespace detail

/// Cast a non-modifiable buffer to a specified pointer to POD type.
/**
 * @relates const_buffer
 */
template <typename PointerToPodType>
inline PointerToPodType buffer_cast(const const_buffer& b)
{
  return static_cast<PointerToPodType>(detail::buffer_cast_helper(b));
}

/// Get the number of bytes in a non-modifiable buffer.
/**
 * @relates const_buffer
 */
inline std::size_t buffer_size(const const_buffer& b)
{
  return detail::buffer_size_helper(b);
}

/// Create a new non-modifiable buffer that is offset from the start of another.
/**
 * @relates const_buffer
 */
inline const_buffer operator+(const const_buffer& b, std::size_t start)
{
  if (start > buffer_size(b))
    return const_buffer();
  const char* new_data = buffer_cast<const char*>(b) + start;
  std::size_t new_size = buffer_size(b) - start;
  return const_buffer(new_data, new_size
#if defined(ASIO_ENABLE_BUFFER_DEBUGGING)
      , b.get_debug_check()
#endif // ASIO_ENABLE_BUFFER_DEBUGGING
      );
}

/// Create a new non-modifiable buffer that is offset from the start of another.
/**
 * @relates const_buffer
 */
inline const_buffer operator+(std::size_t start, const const_buffer& b)
{
  if (start > buffer_size(b))
    return const_buffer();
  const char* new_data = buffer_cast<const char*>(b) + start;
  std::size_t new_size = buffer_size(b) - start;
  return const_buffer(new_data, new_size
#if defined(ASIO_ENABLE_BUFFER_DEBUGGING)
      , b.get_debug_check()
#endif // ASIO_ENABLE_BUFFER_DEBUGGING
      );
}

/// Adapts a single non-modifiable buffer so that it meets the requirements of
/// the ConstBufferSequence concept.
class const_buffers_1
  : public const_buffer
{
public:
  /// The type for each element in the list of buffers.
  typedef const_buffer value_type;

  /// A random-access iterator type that may be used to read elements.
  typedef const const_buffer* const_iterator;

  /// Construct to represent a single non-modifiable buffer.
  explicit const_buffers_1(const const_buffer& b)
    : const_buffer(b)
  {
  }

  /// Get a random-access iterator to the first element.
  const_iterator begin() const
  {
    return this;
  }

  /// Get a random-access iterator for one past the last element.
  const_iterator end() const
  {
    return begin() + 1;
  }
};

#if defined(ASIO_ENABLE_BUFFER_DEBUGGING)
namespace detail {

template <typename Iterator>
class buffer_debug_check
{
public:
  buffer_debug_check(Iterator iter)
    : iter_(iter)
  {
  }

  ~buffer_debug_check()
  {
    iter_ = Iterator();
  }

  void operator()()
  {
    *iter_;