//
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// Copyright (c) 2016-2019 Vinnie Falco (vinnie dot falco at gmail dot com)
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//
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// Distributed under the Boost Software License, Version 1.0. (See accompanying
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// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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//
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// Official repository: https://github.com/boostorg/beast
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//
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#ifndef BOOST_BEAST_CORE_SAVED_HANDLER_HPP
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#define BOOST_BEAST_CORE_SAVED_HANDLER_HPP
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#include <boost/beast/core/detail/config.hpp>
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namespace boost {
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namespace beast {
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/** An invocable, nullary function object which holds a completion handler.
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This container can hold a type-erased instance of any completion
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handler, or it can be empty. When the container holds a value,
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the implementation maintains an instance of `net::executor_work_guard`
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for the handler's associated executor. Memory is dynamically allocated
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to store the completion handler, and the allocator may optionally
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be specified. Otherwise, the implementation uses the handler's
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associated allocator.
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*/
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class saved_handler
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{
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class base;
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template<class, class>
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class impl;
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base* p_ = nullptr;
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public:
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/// Default Constructor
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saved_handler() = default;
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/// Copy Constructor (deleted)
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saved_handler(saved_handler const&) = delete;
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/// Copy Assignment (deleted)
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saved_handler& operator=(saved_handler const&) = delete;
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/// Destructor
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BOOST_BEAST_DECL
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~saved_handler();
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/// Move Constructor
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BOOST_BEAST_DECL
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saved_handler(saved_handler&& other) noexcept;
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/// Move Assignment
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BOOST_BEAST_DECL
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saved_handler&
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operator=(saved_handler&& other) noexcept;
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/// Returns `true` if `*this` contains a completion handler.
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bool
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has_value() const noexcept
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{
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return p_ != nullptr;
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}
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/** Store a completion handler in the container.
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Requires `this->has_value() == false`.
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@param handler The completion handler to store.
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The implementation takes ownership of the handler by performing a decay-copy.
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@param alloc The allocator to use.
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*/
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template<class Handler, class Allocator>
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void
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emplace(Handler&& handler, Allocator const& alloc);
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/** Store a completion handler in the container.
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Requires `this->has_value() == false`. The
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implementation will use the handler's associated
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allocator to obtian storage.
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@param handler The completion handler to store.
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The implementation takes ownership of the handler by performing a decay-copy.
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*/
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template<class Handler>
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void
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emplace(Handler&& handler);
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/** Discard the saved handler, if one exists.
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If `*this` contains an object, it is destroyed.
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@returns `true` if an object was destroyed.
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*/
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BOOST_BEAST_DECL
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bool
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reset() noexcept;
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/** Unconditionally invoke the stored completion handler.
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Requires `this->has_value() == true`. Any dynamic memory
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used is deallocated before the stored completion handler
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is invoked. The executor work guard is also reset before
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the invocation.
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*/
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BOOST_BEAST_DECL
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void
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invoke();
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/** Conditionally invoke the stored completion handler.
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Invokes the stored completion handler if
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`this->has_value() == true`, otherwise does nothing. Any
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dynamic memory used is deallocated before the stored completion
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handler is invoked. The executor work guard is also reset before
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the invocation.
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@return `true` if the invocation took place.
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*/
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BOOST_BEAST_DECL
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bool
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maybe_invoke();
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};
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} // beast
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} // boost
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#include <boost/beast/core/impl/saved_handler.hpp>
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#ifdef BOOST_BEAST_HEADER_ONLY
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#include <boost/beast/core/impl/saved_handler.ipp>
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#endif
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#endif
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