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- //
- // completion_condition.hpp
- // ~~~~~~~~~~~~~~~~~~~~~~~~
- //
- // Copyright (c) 2003-2019 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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