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//
// completion_condition.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_COMPLETION_CONDITION_HPP
#define ASIO_COMPLETION_CONDITION_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/detail/push_options.hpp"
namespace asio {
namespace detail {
// The default maximum number of bytes to transfer in a single operation.
enum default_max_transfer_size_t { default_max_transfer_size = 65536 };
// Adapt result of old-style completion conditions (which had a bool result
// where true indicated that the operation was complete).
inline std::size_t adapt_completion_condition_result(bool result)
{
return result ? 0 : default_max_transfer_size;
}
// Adapt result of current completion conditions (which have a size_t result
// where 0 means the operation is complete, and otherwise the result is the
// maximum number of bytes to transfer on the next underlying operation).
inline std::size_t adapt_completion_condition_result(std::size_t result)
{
return result;
}
class transfer_all_t
{
public:
typedef std::size_t result_type;
template <typename Error>
std::size_t operator()(const Error& err, std::size_t)
{
return !!err ? 0 : default_max_transfer_size;
}
};
class transfer_at_least_t
{
public:
typedef std::size_t result_type;
explicit transfer_at_least_t(std::size_t minimum)
: minimum_(minimum)
{
}
template <typename Error>
std::size_t operator()(const Error& err, std::size_t bytes_transferred)
{
return (!!err || bytes_transferred >= minimum_)
? 0 : default_max_transfer_size;
}
private:
std::size_t minimum_;
};
class transfer_exactly_t
{
public:
typedef std::size_t result_type;
explicit transfer_exactly_t(std::size_t size)
: size_(size)
{
}
template <typename Error>
std::size_t operator()(const Error& err, std::size_t bytes_transferred)
{
return (!!err || bytes_transferred >= size_) ? 0 :
(size_ - bytes_transferred < default_max_transfer_size
? size_ - bytes_transferred : std::size_t(default_max_transfer_size));
}
private:
std::size_t size_;
};
} // namespace detail
/**
* @defgroup completion_condition Completion Condition Function Objects
*
* Function objects used for determining when a read or write operation should
* complete.
*/
/*@{*/
/// Return a completion condition function object that indicates that a read or
/// write operation should continue until all of the data has been transferred,
/// or until an error occurs.
/**
* This function is used to create an object, of unspecified type, that meets
* CompletionCondition requirements.
*
* @par Example
* Reading until a buffer is full:
* @code
* boost::array<char, 128> buf;
* asio::error_code ec;
* std::size_t n = asio::read(
* sock, asio::buffer(buf),
* asio::transfer_all(), ec);
* if (ec)
* {
* // An error occurred.
* }
* else
* {
* // n == 128
* }
* @endcode
*/
#if defined(GENERATING_DOCUMENTATION)
unspecified transfer_all();
#else
inline detail::transfer_all_t transfer_all()
{
return detail::transfer_all_t();
}
#endif
/// Return a completion condition function object that indicates that a read or
/// write operation should continue until a minimum number of bytes has been
/// transferred, or until an error occurs.
/**
* This function is used to create an object, of unspecified type, that meets
* CompletionCondition requirements.
*
* @par Example
* Reading until a buffer is full or contains at least 64 bytes:
* @code
* boost::array<char, 128> buf;
* asio::error_code ec;
* std::size_t n = asio::read(
* sock, asio::buffer(buf),
* asio::transfer_at_least(64), ec);
* if (ec)
* {
* // An error occurred.
* }
* else
* {
* // n >= 64 && n <= 128
* }
* @endcode
*/
#if defined(GENERATING_DOCUMENTATION)
unspecified transfer_at_least(std::size_t minimum);
#else
inline detail::transfer_at_least_t transfer_at_least(std::size_t minimum)
{
return detail::transfer_at_least_t(minimum);
}
#endif
/// Return a completion condition function object that indicates that a read or
/// write operation should continue until an exact number of bytes has been
/// transferred, or until an error occurs.
/**
* This function is used to create an object, of unspecified type, that meets
* CompletionCondition requirements.
*
* @par Example
* Reading until a buffer is full or contains exactly 64 bytes:
* @code
* boost::array<char, 128> buf;
* asio::error_code ec;
* std::size_t n = asio::read(
* sock, asio::buffer(buf),
* asio::transfer_exactly(64), ec);
* if (ec)
* {
* // An error occurred.
* }
* else
* {
* // n == 64
* }
* @endcode
*/
#if defined(GENERATING_DOCUMENTATION)
unspecified transfer_exactly(std::size_t size);
#else
inline detail::transfer_exactly_t transfer_exactly(std::size_t size)
{
return detail::transfer_exactly_t(size);
}
#endif
/*@}*/
} // namespace asio
#include "asio/detail/pop_options.hpp"
#endif // ASIO_COMPLETION_CONDITION_HPP
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