+// <future> -*- C++ -*-
+
+// Copyright (C) 2009 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library. This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+
+// Under Section 7 of GPL version 3, you are granted additional
+// permissions described in the GCC Runtime Library Exception, version
+// 3.1, as published by the Free Software Foundation.
+
+// You should have received a copy of the GNU General Public License and
+// a copy of the GCC Runtime Library Exception along with this program;
+// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
+// <http://www.gnu.org/licenses/>.
+
+/** @file future
+ * This is a Standard C++ Library header.
+ */
+
+#ifndef _GLIBCXX_FUTURE
+#define _GLIBCXX_FUTURE 1
+
+#pragma GCC system_header
+
+#ifndef __GXX_EXPERIMENTAL_CXX0X__
+# include <c++0x_warning.h>
+#else
+
+#include <functional>
+#include <memory>
+#include <mutex>
+#include <condition_variable>
+#include <system_error>
+#include <exception>
+#include <cstdatomic>
+
+#if defined(_GLIBCXX_HAS_GTHREADS) && defined(_GLIBCXX_USE_C99_STDINT_TR1) \
+ && defined(_GLIBCXX_ATOMIC_BUILTINS_4)
+
+namespace std
+{
+ /**
+ * @defgroup futures Futures
+ * @ingroup concurrency
+ *
+ * Classes for futures support.
+ * @{
+ */
+
+ /// Error code for futures
+ enum class future_errc
+ { broken_promise, future_already_retrieved, promise_already_satisfied };
+
+ // TODO: requires concepts
+ // concept_map ErrorCodeEnum<future_errc> { }
+ template<>
+ struct is_error_code_enum<future_errc> : public true_type { };
+
+ /// Points to a statically-allocated object derived from error_category.
+ extern const error_category* const future_category;
+
+ // TODO: requires constexpr
+ inline error_code make_error_code(future_errc __errc)
+ { return error_code(static_cast<int>(__errc), *future_category); }
+
+ // TODO: requires constexpr
+ inline error_condition make_error_condition(future_errc __errc)
+ { return error_condition(static_cast<int>(__errc), *future_category); }
+
+ /// Exception type thrown by futures.
+ class future_error : public logic_error
+ {
+ public:
+ explicit future_error(future_errc __ec)
+ : logic_error("std::future_error"), _M_code(make_error_code(__ec))
+ { }
+
+ const error_code& code() const throw() { return _M_code; }
+
+ const char* what() const throw() { return _M_code.message().c_str(); }
+
+ private:
+ error_code _M_code;
+ };
+
+ // Holds the result of a future
+ struct _Future_result_base
+ {
+ _Future_result_base() = default;
+ _Future_result_base(const _Future_result_base&) = delete;
+ _Future_result_base& operator=(const _Future_result_base&) = delete;
+
+ exception_ptr _M_error;
+
+ // _M_destroy() allows derived classes to control deallocation,
+ // which will be needed when allocator support is added to promise.
+ // See http://gcc.gnu.org/ml/libstdc++/2009-06/msg00032.html
+ virtual void _M_destroy() = 0;
+ struct _Deleter
+ {
+ void operator()(_Future_result_base* __fr) const { __fr->_M_destroy(); }
+ };
+
+ protected:
+ ~_Future_result_base() = default;
+ };
+
+ // TODO: use template alias when available
+ /*
+ template<typename _Res>
+ using _Future_ptr = unique_ptr<_Res, _Future_result_base::_Deleter>;
+ */
+ template<typename _Res>
+ struct _Future_ptr
+ {
+ typedef unique_ptr<_Res, _Future_result_base::_Deleter> type;
+ };
+
+ // State shared between a promise and one or more associated futures.
+ class _Future_state
+ {
+ typedef _Future_ptr<_Future_result_base>::type _Future_ptr_type;
+
+ public:
+ _Future_state() : _M_result(), _M_retrieved(false) { }
+
+ _Future_state(const _Future_state&) = delete;
+ _Future_state& operator=(const _Future_state&) = delete;
+
+ bool
+ is_ready()
+ { return _M_get() != 0; }
+
+ bool
+ has_exception()
+ {
+ _Future_result_base* const __res = _M_get();
+ return __res && !(__res->_M_error == 0);
+ }
+
+ bool
+ has_value()
+ {
+ _Future_result_base* const __res = _M_get();
+ return __res && (__res->_M_error == 0);
+ }
+
+ _Future_result_base&
+ wait()
+ {
+ unique_lock<mutex> __lock(_M_mutex);
+ if (!_M_ready())
+ _M_cond.wait(__lock, std::bind(&_Future_state::_M_ready, this));
+ return *_M_result;
+ }
+
+ template<typename _Rep, typename _Period>
+ bool
+ wait_for(const chrono::duration<_Rep, _Period>& __rel)
+ {
+ unique_lock<mutex> __lock(_M_mutex);
+ return _M_ready() || _M_cond.wait_for(__lock, __rel,
+ std::bind(&_Future_state::_M_ready, this));
+ }
+
+ template<typename _Clock, typename _Duration>
+ bool
+ wait_until(const chrono::time_point<_Clock, _Duration>& __abs)
+ {
+ unique_lock<mutex> __lock(_M_mutex);
+ return _M_ready() || _M_cond.wait_until(__lock, __abs,
+ std::bind(&_Future_state::_M_ready, this));
+ }
+
+ void
+ _M_set_result(_Future_ptr_type __res)
+ {
+ {
+ lock_guard<mutex> __lock(_M_mutex);
+ if (_M_ready())
+ throw future_error(future_errc::promise_already_satisfied);
+ _M_result.swap(__res);
+ }
+ _M_cond.notify_all();
+ }
+
+ void
+ _M_break_promise(_Future_ptr_type __res)
+ {
+ if (static_cast<bool>(__res))
+ {
+ __res->_M_error
+ = std::copy_exception(future_error(future_errc::broken_promise));
+ {
+ lock_guard<mutex> __lock(_M_mutex);
+ _M_result.swap(__res);
+ }
+ _M_cond.notify_all();
+ }
+ }
+
+ // called when this object is passed to a unique_future
+ void
+ _M_set_retrieved_flag()
+ {
+ if (_M_retrieved.test_and_set())
+ throw future_error(future_errc::future_already_retrieved);
+ }
+
+ private:
+ _Future_result_base*
+ _M_get()
+ {
+ lock_guard<mutex> __lock(_M_mutex);
+ return _M_result.get();
+ }
+
+ bool _M_ready() const { return static_cast<bool>(_M_result); }
+
+ _Future_ptr_type _M_result;
+ mutex _M_mutex;
+ condition_variable _M_cond;
+ atomic_flag _M_retrieved;
+ };
+
+ // workaround for CWG issue 664 and c++/34022
+ template<typename _Result, bool = is_scalar<_Result>::value>
+ struct _Move_future_result
+ {
+ typedef _Result&& __rval_type;
+ static _Result&& _S_move(_Result& __res) { return std::move(__res); }
+ };
+
+ // specialization for scalar types returns rvalue not rvalue-reference
+ template<typename _Result>
+ struct _Move_future_result<_Result, true>
+ {
+ typedef _Result __rval_type;
+ static _Result _S_move(_Result __res) { return __res; }
+ };
+
+ template<typename _Result>
+ struct _Future_result : _Future_result_base
+ {
+ _Future_result() : _M_initialized() { }
+
+ ~_Future_result()
+ {
+ if (_M_initialized)
+ _M_value().~_Result();
+ }
+
+ // return lvalue, future will add const or rvalue-reference
+ _Result& _M_value()
+ { return *static_cast<_Result*>(_M_addr()); }
+
+ void
+ _M_set(const _Result& __res)
+ {
+ ::new (_M_addr()) _Result(__res);
+ _M_initialized = true;
+ }
+
+ void
+ _M_set(_Result&& __res)
+ {
+ typedef _Move_future_result<_Result> _Mover;
+ ::new (_M_addr()) _Result(_Mover::_S_move(__res));
+ _M_initialized = true;
+ }
+
+ private:
+ void _M_destroy() { delete this; }
+
+ void* _M_addr() { return static_cast<void*>(&_M_storage); }
+
+ typename aligned_storage<sizeof(_Result),
+ alignment_of<_Result>::value>::type _M_storage;
+ bool _M_initialized;
+ };
+
+ template<typename _Result>
+ struct _Future_result<_Result&> : _Future_result_base
+ {
+ _Future_result() : _M_value_ptr() { }
+
+ _Result* _M_value_ptr;
+
+ void _M_destroy() { delete this; }
+ };
+
+ template<>
+ struct _Future_result<void> : _Future_result_base
+ {
+ void _M_destroy() { delete this; }
+ };
+
+ /// unique_future
+ template<typename _Result>
+ class unique_future;
+
+ /// shared_future
+ template<typename _Result>
+ class shared_future;
+
+ // common implementation for unique_future and shared_future
+ template<typename _Result>
+ class _Future_impl
+ {
+ public:
+ // disable copying
+ _Future_impl(const _Future_impl&) = delete;
+ _Future_impl& operator=(const _Future_impl&) = delete;
+
+ // functions to check state and wait for ready
+ bool is_ready() const { return this->_M_state->is_ready(); }
+
+ bool has_exception() const { return this->_M_state->has_exception(); }
+
+ bool has_value() const { return this->_M_state->has_value(); }
+
+ void wait() const { this->_M_state->wait(); }
+
+ template<typename _Rep, typename _Period>
+ bool
+ wait_for(const chrono::duration<_Rep, _Period>& __rel) const
+ { return this->_M_state->wait_for(__rel); }
+
+ template<typename _Clock, typename _Duration>
+ bool
+ wait_until(const chrono::time_point<_Clock, _Duration>& __abs) const
+ { return this->_M_state->wait_until(__abs); }
+
+ protected:
+ // wait for the state to be ready and rethrow any stored exception
+ _Future_result<_Result>&
+ _M_get_result()
+ {
+ _Future_result_base& __res = this->_M_state->wait();
+ if (!(__res._M_error == 0))
+ rethrow_exception(__res._M_error);
+ return static_cast<_Future_result<_Result>&>(__res);
+ }
+
+ typedef shared_ptr<_Future_state> _State_ptr;
+
+ // construction of a unique_future by promise::get_future()
+ explicit
+ _Future_impl(const _State_ptr& __state)
+ : _M_state(__state)
+ {
+ if (static_cast<bool>(this->_M_state))
+ this->_M_state->_M_set_retrieved_flag();
+ else
+ throw future_error(future_errc::future_already_retrieved);
+ }
+
+ // copy construction from a shared_future
+ explicit
+ _Future_impl(const shared_future<_Result>&);
+
+ // move construction from a unique_future
+ explicit
+ _Future_impl(unique_future<_Result>&&);
+
+ _State_ptr _M_state;
+ };
+
+ /// promise
+ template<typename _Result>
+ class promise;
+
+ // primary template for unique_future
+ template<typename _Result>
+ class unique_future : public _Future_impl<_Result>
+ {
+ typedef _Move_future_result<_Result> _Mover;
+
+ public:
+ /// Move constructor
+ unique_future(unique_future&& __uf) : _Base_type(std::move(__uf)) { }
+
+ // disable copying
+ unique_future(const unique_future&) = delete;
+ unique_future& operator=(const unique_future&) = delete;
+
+ // retrieving the value
+ typename _Mover::__rval_type
+ get()
+ { return _Mover::_S_move(this->_M_get_result()._M_value()); }
+
+ private:
+ typedef _Future_impl<_Result> _Base_type;
+ typedef typename _Base_type::_State_ptr _State_ptr;
+
+ friend class promise<_Result>;
+
+ explicit
+ unique_future(const _State_ptr& __state) : _Base_type(__state) { }
+ };
+
+ // partial specialization for unique_future<R&>
+ template<typename _Result>
+ class unique_future<_Result&> : public _Future_impl<_Result&>
+ {
+ public:
+ /// Move constructor
+ unique_future(unique_future&& __uf) : _Base_type(std::move(__uf)) { }
+
+ // disable copying
+ unique_future(const unique_future&) = delete;
+ unique_future& operator=(const unique_future&) = delete;
+
+ // retrieving the value
+ _Result& get() { return *this->_M_get_result()._M_value_ptr; }
+
+ private:
+ typedef _Future_impl<_Result&> _Base_type;
+ typedef typename _Base_type::_State_ptr _State_ptr;
+
+ friend class promise<_Result&>;
+
+ explicit
+ unique_future(const _State_ptr& __state) : _Base_type(__state) { }
+ };
+
+ // specialization for unique_future<void>
+ template<>
+ class unique_future<void> : public _Future_impl<void>
+ {
+ public:
+ /// Move constructor
+ unique_future(unique_future&& __uf) : _Base_type(std::move(__uf)) { }
+
+ // disable copying
+ unique_future(const unique_future&) = delete;
+ unique_future& operator=(const unique_future&) = delete;
+
+ // retrieving the value
+ void get() { this->_M_get_result(); }
+
+ private:
+ typedef _Future_impl<void> _Base_type;
+ typedef _Base_type::_State_ptr _State_ptr;
+
+ friend class promise<void>;
+
+ explicit
+ unique_future(const _State_ptr& __state) : _Base_type(__state) { }
+ };
+
+ // primary template for unique_future
+ template<typename _Result>
+ class shared_future : public _Future_impl<_Result>
+ {
+ public:
+ /// Copy constructor
+ shared_future(const shared_future& __sf) : _Base_type(__sf) { }
+
+ /// Construct from a unique_future rvalue
+ shared_future(unique_future<_Result>&& __uf)
+ : _Base_type(std::move(__uf))
+ { }
+
+ shared_future& operator=(const shared_future&) = delete;
+
+ // retrieving the value
+ const _Result&
+ get()
+ { return this->_M_get_result()._M_value(); }
+
+ private:
+ typedef _Future_impl<_Result> _Base_type;
+ };
+
+ // partial specialization for shared_future<R&>
+ template<typename _Result>
+ class shared_future<_Result&> : public _Future_impl<_Result&>
+ {
+ public:
+ /// Copy constructor
+ shared_future(const shared_future& __sf) : _Base_type(__sf) { }
+
+ /// Construct from a unique_future rvalue
+ shared_future(unique_future<_Result&>&& __uf)
+ : _Base_type(std::move(__uf))
+ { }
+
+ shared_future& operator=(const shared_future&) = delete;
+
+ // retrieving the value
+ _Result& get() { return *this->_M_get_result()._M_value_ptr; }
+
+ private:
+ typedef _Future_impl<_Result&> _Base_type;
+ };
+
+ // specialization for shared_future<void>
+ template<>
+ class shared_future<void> : public _Future_impl<void>
+ {
+ public:
+ /// Copy constructor
+ shared_future(const shared_future& __sf) : _Base_type(__sf) { }
+
+ /// Construct from a unique_future rvalue
+ shared_future(unique_future<void>&& __uf)
+ : _Base_type(std::move(__uf))
+ { }
+
+ shared_future& operator=(const shared_future&) = delete;
+
+ // retrieving the value
+ void get() { this->_M_get_result(); }
+
+ private:
+ typedef _Future_impl<void> _Base_type;
+ };
+
+ // now we can define the protected _Future_impl constructors
+
+ template<typename _Result>
+ _Future_impl<_Result>::_Future_impl(const shared_future<_Result>& __sf)
+ : _M_state(__sf._M_state)
+ { }
+
+ template<typename _Result>
+ _Future_impl<_Result>::_Future_impl(unique_future<_Result>&& __uf)
+ : _M_state(std::move(__uf._M_state))
+ { }
+
+ template<typename> class packaged_task; // undefined
+
+ // primary template for promise
+ template<typename _Result>
+ class promise
+ {
+ public:
+ promise()
+ : _M_future(std::make_shared<_Future_state>()),
+ _M_storage(new _Future_result<_Result>())
+ { }
+
+ promise(promise&& __rhs)
+ : _M_future(std::move(__rhs._M_future)),
+ _M_storage(std::move(__rhs._M_storage))
+ { }
+
+ // TODO: requires allocator concepts
+ /*
+ template<typename _Allocator>
+ promise(allocator_arg_t, const _Allocator& __a);
+
+ template<typename _Allocator>
+ promise(allocator_arg_t, const _Allocator&, promise&& __rhs);
+ */
+
+ promise(const promise&) = delete;
+
+ ~promise()
+ {
+ if (static_cast<bool>(_M_future) && !_M_future.unique())
+ _M_future->_M_break_promise(std::move(_M_storage));
+ }
+
+ // assignment
+ promise&
+ operator=(promise&& __rhs)
+ {
+ promise(std::move(__rhs)).swap(*this);
+ return *this;
+ }
+
+ promise& operator=(const promise&) = delete;
+
+ void
+ swap(promise& __rhs)
+ {
+ _M_future.swap(__rhs._M_future);
+ _M_storage.swap(__rhs._M_storage);
+ }
+
+ // retrieving the result
+ unique_future<_Result>
+ get_future()
+ { return unique_future<_Result>(_M_future); }
+
+ // setting the result
+ void
+ set_value(const _Result& __r)
+ {
+ if (!_M_satisfied())
+ _M_storage->_M_set(__r);
+ _M_future->_M_set_result(std::move(_M_storage));
+ }
+
+ void
+ set_value(_Result&& __r)
+ {
+ if (!_M_satisfied())
+ _M_storage->_M_set(_Mover::_S_move(__r));
+ _M_future->_M_set_result(std::move(_M_storage));
+ }
+
+ void
+ set_exception(exception_ptr __p)
+ {
+ if (!_M_satisfied())
+ _M_storage->_M_error = __p;
+ _M_future->_M_set_result(std::move(_M_storage));
+ }
+
+ private:
+ template<typename> friend class packaged_task;
+ typedef _Move_future_result<_Result> _Mover;
+ bool _M_satisfied() { return !static_cast<bool>(_M_storage); }
+ shared_ptr<_Future_state> _M_future;
+ typename _Future_ptr<_Future_result<_Result>>::type _M_storage;
+ };
+
+ // partial specialization for promise<R&>
+ template<typename _Result>
+ class promise<_Result&>
+ {
+ public:
+ promise()
+ : _M_future(std::make_shared<_Future_state>()),
+ _M_storage(new _Future_result<_Result&>())
+ { }
+
+ promise(promise&& __rhs)
+ : _M_future(std::move(__rhs._M_future)),
+ _M_storage(std::move(__rhs._M_storage))
+ { }
+
+ // TODO: requires allocator concepts
+ /*
+ template<typename _Allocator>
+ promise(allocator_arg_t, const _Allocator& __a);
+
+ template<typename _Allocator>
+ promise(allocator_arg_t, const _Allocator&, promise&& __rhs);
+ */
+
+ promise(const promise&) = delete;
+
+ ~promise()
+ {
+ if (static_cast<bool>(_M_future) && !_M_future.unique())
+ _M_future->_M_break_promise(std::move(_M_storage));
+ }
+
+ // assignment
+ promise&
+ operator=(promise&& __rhs)
+ {
+ promise(std::move(__rhs)).swap(*this);
+ return *this;
+ }
+
+ promise& operator=(const promise&) = delete;
+
+ void
+ swap(promise& __rhs)
+ {
+ _M_future.swap(__rhs._M_future);
+ _M_storage.swap(__rhs._M_storage);
+ }
+
+ // retrieving the result
+ unique_future<_Result&>
+ get_future()
+ { return unique_future<_Result&>(_M_future); }
+
+ // setting the result
+ void
+ set_value(_Result& __r)
+ {
+ if (!_M_satisfied())
+ _M_storage->_M_value_ptr = &__r;
+ _M_future->_M_set_result(std::move(_M_storage));
+ }
+
+ void
+ set_exception(exception_ptr __p)
+ {
+ if (!_M_satisfied())
+ _M_storage->_M_error = __p;
+ _M_future->_M_set_result(std::move(_M_storage));
+ }
+
+ private:
+ template<typename> friend class packaged_task;
+ bool _M_satisfied() { return !static_cast<bool>(_M_storage); }
+ shared_ptr<_Future_state> _M_future;
+ typename _Future_ptr<_Future_result<_Result&>>::type _M_storage;
+ };
+
+ // specialization for promise<void>
+ template<>
+ class promise<void>
+ {
+ public:
+ promise()
+ : _M_future(std::make_shared<_Future_state>()),
+ _M_storage(new _Future_result<void>())
+ { }
+
+ promise(promise&& __rhs)
+ : _M_future(std::move(__rhs._M_future)),
+ _M_storage(std::move(__rhs._M_storage))
+ { }
+
+ // TODO: requires allocator concepts
+ /*
+ template<typename _Allocator>
+ promise(allocator_arg_t, const _Allocator& __a);
+
+ template<typename _Allocator>
+ promise(allocator_arg_t, const _Allocator&, promise&& __rhs);
+ */
+
+ promise(const promise&) = delete;
+
+ ~promise()
+ {
+ if (static_cast<bool>(_M_future) && !_M_future.unique())
+ _M_future->_M_break_promise(std::move(_M_storage));
+ }
+
+ // assignment
+ promise&
+ operator=(promise&& __rhs)
+ {
+ promise(std::move(__rhs)).swap(*this);
+ return *this;
+ }
+
+ promise& operator=(const promise&) = delete;
+
+ void
+ swap(promise& __rhs)
+ {
+ _M_future.swap(__rhs._M_future);
+ _M_storage.swap(__rhs._M_storage);
+ }
+
+ // retrieving the result
+ unique_future<void>
+ get_future()
+ { return unique_future<void>(_M_future); }
+
+ // setting the result
+ void
+ set_value()
+ {
+ _M_future->_M_set_result(std::move(_M_storage));
+ }
+
+ void
+ set_exception(exception_ptr __p)
+ {
+ if (!_M_satisfied())
+ _M_storage->_M_error = __p;
+ _M_future->_M_set_result(std::move(_M_storage));
+ }
+
+ private:
+ template<typename> friend class packaged_task;
+ bool _M_satisfied() { return !static_cast<bool>(_M_storage); }
+ shared_ptr<_Future_state> _M_future;
+ _Future_ptr<_Future_result<void>>::type _M_storage;
+ };
+
+ // TODO: requires allocator concepts
+ /*
+ template<typename _Result, class Alloc>
+ concept_map UsesAllocator<promise<_Result>, Alloc>
+ {
+ typedef Alloc allocator_type;
+ }
+ */
+
+ template<typename _Result, typename... _ArgTypes>
+ struct _Run_task
+ {
+ static void
+ _S_run(promise<_Result>& __p, function<_Result(_ArgTypes...)>& __f,
+ _ArgTypes... __args)
+ {
+ __p.set_value(__f(std::forward<_ArgTypes>(__args)...));
+ }
+ };
+
+ // specialization used by packaged_task<void(...)>
+ template<typename... _ArgTypes>
+ struct _Run_task<void, _ArgTypes...>
+ {
+ static void
+ _S_run(promise<void>& __p, function<void(_ArgTypes...)>& __f,
+ _ArgTypes... __args)
+ {
+ __f(std::forward<_ArgTypes>(__args)...);
+ __p.set_value();
+ }
+ };
+
+ template<typename _Result, typename... _ArgTypes>
+ class packaged_task<_Result(_ArgTypes...)>
+ {
+ public:
+ typedef _Result result_type;
+
+ // construction and destruction
+ packaged_task() { }
+
+ template<typename _Fn>
+ explicit
+ packaged_task(const _Fn& __fn) : _M_task(__fn) { }
+
+ template<typename _Fn>
+ explicit
+ packaged_task(_Fn&& __fn) : _M_task(std::move(__fn)) { }
+
+ explicit
+ packaged_task(_Result(*__fn)(_ArgTypes...)) : _M_task(__fn) { }
+
+ // TODO: requires allocator concepts
+ /*
+ template<typename _Fn, typename _Allocator>
+ explicit
+ packaged_task(allocator_arg_t __tag, const _Allocator& __a, _Fn __fn)
+ : _M_task(__tag, __a, __fn), _M_promise(__tag, __a)
+ { }
+
+ template<typename _Fn, typename _Allocator>
+ explicit
+ packaged_task(allocator_arg_t __tag, const _Allocator& __a, _Fn&& __fn)
+ : _M_task(__tag, __a, std::move(__fn)), _M_promise(__tag, __a)
+ { }
+ */
+
+ ~packaged_task() = default;
+
+ // no copy
+ packaged_task(packaged_task&) = delete;
+ packaged_task& operator=(packaged_task&) = delete;
+
+ // move support
+ packaged_task(packaged_task&& __other)
+ { this->swap(__other); }
+
+ packaged_task& operator=(packaged_task&& __other)
+ {
+ packaged_task(std::move(__other)).swap(*this);
+ return *this;
+ }
+
+ void
+ swap(packaged_task& __other)
+ {
+ _M_task.swap(__other._M_task);
+ _M_promise.swap(__other._M_promise);
+ }
+
+ explicit operator bool() const { return static_cast<bool>(_M_task); }
+
+ // result retrieval
+ unique_future<_Result>
+ get_future()
+ {
+ try
+ {
+ return _M_promise.get_future();
+ }
+ catch (const future_error& __e)
+ {
+ if (__e.code() == future_errc::future_already_retrieved)
+ throw std::bad_function_call();
+ throw;
+ }
+ }
+
+ // execution
+ void
+ operator()(_ArgTypes... __args)
+ {
+ if (!static_cast<bool>(_M_task) || _M_promise._M_satisfied())
+ throw std::bad_function_call();
+ try
+ {
+ _Run_task<_Result, _ArgTypes...>::_S_run(_M_promise, _M_task,
+ std::forward<_ArgTypes>(__args)...);
+ }
+ catch (...)
+ {
+ _M_promise.set_exception(current_exception());
+ }
+ }
+
+ void reset() { promise<_Result>().swap(_M_promise); }
+
+ private:
+ function<_Result(_ArgTypes...)> _M_task;
+ promise<_Result> _M_promise;
+ };
+
+ // @} group futures
+}
+
+#endif // _GLIBCXX_HAS_GTHREADS && _GLIBCXX_USE_C99_STDINT_TR1
+ // && _GLIBCXX_ATOMIC_BUILTINS_4
+
+#endif // __GXX_EXPERIMENTAL_CXX0X__
+
+#endif // _GLIBCXX_FUTURE