Class continuation

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### Class `continuation`

    #include <boost/context/continuation.hpp>

    class continuation {
    public:
        continuation() noexcept = default;

        ~continuation();

        continuation(continuation && other) noexcept;

        continuation & operator=(continuation && other) noexcept;

        continuation(continuation const& other) noexcept = delete;
        continuation & operator=(continuation const& other) noexcept = delete;

        continuation resume();

        template<typename Fn>
        continuation resume_with(Fn && fn);

        explicit operator bool() const noexcept;

        bool operator!() const noexcept;

        bool operator==(continuation const& other) const noexcept;

        bool operator!=(continuation const& other) const noexcept;

        bool operator<(continuation const& other) const noexcept;

        bool operator>(continuation const& other) const noexcept;

        bool operator<=(continuation const& other) const noexcept;

        bool operator>=(continuation const& other) const noexcept;

        template<typename charT,class traitsT>
        friend std::basic_ostream<charT,traitsT> &
        operator<<(std::basic_ostream<charT,traitsT> & os,continuation const& other) {

        void swap(continuation & other) noexcept;
    };

##### Constructor

    continuation() noexcept;

Effects:

  Creates a invalid continuation.

Throws:

  Nothing.

##### Destructor

    ~continuation();

Effects:

  Destructs the associated stack if `*this` is a valid continuation, e.g. continuation::operator bool() returns `true`.

Throws:

  Nothing.

##### Move constructor

    continuation(continuation && other) noexcept;

Effects:

  Moves underlying capture continuation to `*this`.

Throws:

  Nothing.

##### Move assignment operator

    continuation & operator=(continuation && other) noexcept;

Effects:

  Moves the state of `other` to `*this` using move semantics.

Throws:

  Nothing.

##### Member function `operator()`()

    continuation resume();

    template<typename Fn>
    continuation resume_with(Fn && fn);

Effects:

  Captures current continuation and resumes `*this`. The function `resume_with`, is used to execute function `fn` in the execution context of `*this` (e.g. the stack frame of `fn` is allocated on stack of `*this`).

Returns:

  The continuation representing the continuation that has been suspended.

Note:

  Function `fn` needs to return `continuation`.

Note:

  The returned continuation indicates if the suspended continuation has terminated (return from context-function) via `bool operator()`.

##### Member function `operator bool`()

    explicit operator bool() const noexcept;

Returns:

  `true` if `*this` points to a captured continuation.

Throws:

  Nothing.

##### Member function `operator!`()

    bool operator!() const noexcept;

Returns:

  `true` if `*this` does not point to a captured continuation.

Throws:

  Nothing.

##### Member function `operator==`()

    bool operator==(continuation const& other) const noexcept;

Returns:

  `true` if `*this` and `other` represent the same continuation, `false` otherwise.

Throws:

  Nothing.

##### Member function `operator!=`()

    bool operator!=(continuation const& other) const noexcept;

Returns:

  `! (other == * this)`

Throws:

  Nothing.

##### Member function `operator<`()

    bool operator<(continuation const& other) const noexcept;

Returns:

  `true` if `*this != other` is true and the implementation-defined total order of `continuation` values places `*this` before `other`, false otherwise.

Throws:

  Nothing.

##### Member function `operator>`()

    bool operator>(continuation const& other) const noexcept;

Returns:

  `other < * this`

Throws:

  Nothing.

##### Member function `operator<=`()

    bool operator<=(continuation const& other) const noexcept;

Returns:

  `! (other < * this)`

Throws:

  Nothing.

##### Member function `operator>=`()

    bool operator>=(continuation const& other) const noexcept;

Returns:

  `! (* this < other)`

Throws:

  Nothing.

##### Non-member function `operator<<()`

    template<typename charT,class traitsT>
    std::basic_ostream<charT,traitsT> &
    operator<<(std::basic_ostream<charT,traitsT> & os,continuation const& other);

Effects:

  Writes the representation of `other` to stream `os`.

Returns:

  `os`

##### Call with current continuation

    #include <boost/context/continuation.hpp>

    template<typename Fn>
    continuation callcc(Fn && fn);

    template<typename StackAlloc,typename Fn>
    continuation callcc(std::allocator_arg_t,StackAlloc salloc,Fn && fn);

    template<typename StackAlloc,typename Fn>
    continuation callcc(std::allocator_arg_t,preallocated palloc,StackAlloc salloc,Fn && fn);

Effects:

  Captures current continuation and creates a new continuation prepared to execute `fn`. `fixedsize_stack` is used as default stack allocator (stack size == fixedsize_stack::traits::default_size()). The function with argument type `preallocated`, is used to create a user defined data (for instance additional control structures) on top of the stack.

Returns:

  The continuation representing the contexcontinuation that has been suspended.

Note:

  The returned continuation indicates if the suspended continuation has terminated (return from context-function) via `bool operator()`.