155 lines
4.4 KiB
Plaintext
155 lines
4.4 KiB
Plaintext
[/
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Copyright Oliver Kowalke 2013.
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Distributed under the Boost Software License, Version 1.0.
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(See accompanying file LICENSE_1_0.txt or copy at
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http://www.boost.org/LICENSE_1_0.txt
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]
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[#class_promise]
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[section:promise Template `promise<>`]
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A __promise__ provides a mechanism to store a value (or exception) that can
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later be retrieved from the corresponding __future__ object. `promise<>` and
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`future<>` communicate via their underlying [link shared_state shared state].
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#include <boost/fiber/future/promise.hpp>
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namespace boost {
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namespace fibers {
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template< typename R >
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class promise {
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public:
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promise();
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template< typename __Allocator__ >
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promise( __allocator_arg_t__, Allocator);
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promise( promise &&) noexcept;
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promise & operator=( promise &&) noexcept;
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promise( promise const&) = delete;
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promise & operator=( promise const&) = delete;
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~promise();
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void swap( promise &) noexcept;
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future< R > get_future();
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void set_value( R const&); // member only of generic promise template
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void set_value( R &&); // member only of generic promise template
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void set_value( R &); // member only of promise< R & > template
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void set_value(); // member only of promise< void > template
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void set_exception( std::exception_ptr p);
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};
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template< typename R >
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void swap( promise< R > &, promise< R > &) noexcept;
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}
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[heading Default constructor]
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promise();
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[variablelist
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[[Effects:] [Creates a promise with an empty [link shared_state shared state].]]
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[[Throws:] [Exceptions caused by memory allocation.]]
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]
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[heading Constructor]
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template< typename __Allocator__ >
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promise( __allocator_arg_t__, Allocator alloc);
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[variablelist
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[[Effects:] [Creates a promise with an empty [link shared_state shared state] by using `alloc`.]]
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[[Throws:] [Exceptions caused by memory allocation.]]
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[[See also:] [__allocator_arg_t__]]
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]
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[heading Move constructor]
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promise( promise && other) noexcept;
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[variablelist
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[[Effects:] [Creates a promise by moving the [link shared_state shared state] from `other`.]]
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[[Postcondition:] [`other` contains no valid shared state.]]
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[[Throws:] [Nothing.]]
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]
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[heading Destructor]
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~promise();
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[variablelist
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[[Effects:] [Destroys `*this` and abandons the [link shared_state shared
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state] if shared state is ready; otherwise stores __future_error__ with error
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condition __broken_promise__ as if by [member_link promise..set_exception]:
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the shared state is set ready.]]
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]
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[operator_heading promise..operator_assign..operator=]
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promise & operator=( promise && other) noexcept;
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[variablelist
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[[Effects:] [Transfers the ownership of [link shared_state shared state] to `*this`.]]
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[[Postcondition:] [`other` contains no valid shared state.]]
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[[Throws:] [Nothing.]]
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]
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[member_heading promise..swap]
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void swap( promise & other) noexcept;
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[variablelist
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[[Effects:] [Swaps the [link shared_state shared state] between other and `*this`.]]
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[[Throws:] [Nothing.]]
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]
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[member_heading promise..get_future]
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future< R > get_future();
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[variablelist
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[[Returns:] [A __future__ with the same [link shared_state shared state].]]
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[[Throws:] [__future_error__ with __already_retrieved__ or __no_state__.]]
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]
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[member_heading promise..set_value]
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void set_value( R const& value); // member only of generic promise template
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void set_value( R && value); // member only of generic promise template
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void set_value( R & value); // member only of promise< R & > template
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void set_value(); // member only of promise< void > template
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[variablelist
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[[Effects:] [Store the result in the [link shared_state shared state] and marks the state as ready.]]
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[[Throws:] [__future_error__ with __already_satisfied__ or __no_state__.]]
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]
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[member_heading promise..set_exception]
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void set_exception( std::exception_ptr);
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[variablelist
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[[Effects:] [Store an exception pointer in the [link shared_state shared state] and marks the state as ready.]]
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[[Throws:] [__future_error__ with __already_satisfied__ or __no_state__.]]
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]
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[function_heading_for swap..promise]
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template< typename R >
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void swap( promise< R > & l, promise< R > & r) noexcept;
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[variablelist
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[[Effects:] [Same as `l.swap( r)`.]]
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]
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[endsect]
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