Vendor import of llvm-project main 88e66fa60ae5, the last commit beforevendor/llvm-project/llvmorg-13-init-16847-g88e66fa60ae5vendor/llvm-project/llvmorg-12.0.1-rc2-0-ge7dac564cd0evendor/llvm-project/llvmorg-12.0.1-0-gfed41342a82f

the upstream release/13.x branch was created.

1 files changed, 2809 insertions, 0 deletions

diff --git a/libcxx/include/__functional/function.h b/libcxx/include/__functional/function.h
new file mode 100644
index 000000000000..ba629e1d145e
--- /dev/null
+++ b/libcxx/include/__functional/function.h
@@ -0,0 +1,2809 @@
+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___FUNCTIONAL_FUNCTION_H
+#define _LIBCPP___FUNCTIONAL_FUNCTION_H
+
+#include <__config>
+#include <__functional/binary_function.h>
+#include <__functional/invoke.h>
+#include <__functional/unary_function.h>
+#include <__iterator/iterator_traits.h>
+#include <__memory/allocator_traits.h>
+#include <__memory/compressed_pair.h>
+#include <__memory/shared_ptr.h>
+#include <exception>
+#include <memory> // TODO: replace with <__memory/__builtin_new_allocator.h>
+#include <type_traits>
+#include <utility>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+// bad_function_call
+
+class _LIBCPP_EXCEPTION_ABI bad_function_call
+    : public exception
+{
+#ifdef _LIBCPP_ABI_BAD_FUNCTION_CALL_KEY_FUNCTION
+public:
+    virtual ~bad_function_call() _NOEXCEPT;
+
+    virtual const char* what() const _NOEXCEPT;
+#endif
+};
+
+_LIBCPP_NORETURN inline _LIBCPP_INLINE_VISIBILITY
+void __throw_bad_function_call()
+{
+#ifndef _LIBCPP_NO_EXCEPTIONS
+    throw bad_function_call();
+#else
+    _VSTD::abort();
+#endif
+}
+
+#if defined(_LIBCPP_CXX03_LANG) && !defined(_LIBCPP_DISABLE_DEPRECATION_WARNINGS) && __has_attribute(deprecated)
+#   define _LIBCPP_DEPRECATED_CXX03_FUNCTION \
+        __attribute__((deprecated("Using std::function in C++03 is not supported anymore. Please upgrade to C++11 or later, or use a different type")))
+#else
+#   define _LIBCPP_DEPRECATED_CXX03_FUNCTION /* nothing */
+#endif
+
+template<class _Fp> class _LIBCPP_DEPRECATED_CXX03_FUNCTION _LIBCPP_TEMPLATE_VIS function; // undefined
+
+namespace __function
+{
+
+template<class _Rp>
+struct __maybe_derive_from_unary_function
+{
+};
+
+template<class _Rp, class _A1>
+struct __maybe_derive_from_unary_function<_Rp(_A1)>
+    : public unary_function<_A1, _Rp>
+{
+};
+
+template<class _Rp>
+struct __maybe_derive_from_binary_function
+{
+};
+
+template<class _Rp, class _A1, class _A2>
+struct __maybe_derive_from_binary_function<_Rp(_A1, _A2)>
+    : public binary_function<_A1, _A2, _Rp>
+{
+};
+
+template <class _Fp>
+_LIBCPP_INLINE_VISIBILITY
+bool __not_null(_Fp const&) { return true; }
+
+template <class _Fp>
+_LIBCPP_INLINE_VISIBILITY
+bool __not_null(_Fp* __ptr) { return __ptr; }
+
+template <class _Ret, class _Class>
+_LIBCPP_INLINE_VISIBILITY
+bool __not_null(_Ret _Class::*__ptr) { return __ptr; }
+
+template <class _Fp>
+_LIBCPP_INLINE_VISIBILITY
+bool __not_null(function<_Fp> const& __f) { return !!__f; }
+
+#ifdef _LIBCPP_HAS_EXTENSION_BLOCKS
+template <class _Rp, class ..._Args>
+_LIBCPP_INLINE_VISIBILITY
+bool __not_null(_Rp (^__p)(_Args...)) { return __p; }
+#endif
+
+} // namespace __function
+
+#ifndef _LIBCPP_CXX03_LANG
+
+namespace __function {
+
+// __alloc_func holds a functor and an allocator.
+
+template <class _Fp, class _Ap, class _FB> class __alloc_func;
+template <class _Fp, class _FB>
+class __default_alloc_func;
+
+template <class _Fp, class _Ap, class _Rp, class... _ArgTypes>
+class __alloc_func<_Fp, _Ap, _Rp(_ArgTypes...)>
+{
+    __compressed_pair<_Fp, _Ap> __f_;
+
+  public:
+    typedef _LIBCPP_NODEBUG_TYPE _Fp _Target;
+    typedef _LIBCPP_NODEBUG_TYPE _Ap _Alloc;
+
+    _LIBCPP_INLINE_VISIBILITY
+    const _Target& __target() const { return __f_.first(); }
+
+    // WIN32 APIs may define __allocator, so use __get_allocator instead.
+    _LIBCPP_INLINE_VISIBILITY
+    const _Alloc& __get_allocator() const { return __f_.second(); }
+
+    _LIBCPP_INLINE_VISIBILITY
+    explicit __alloc_func(_Target&& __f)
+        : __f_(piecewise_construct, _VSTD::forward_as_tuple(_VSTD::move(__f)),
+               _VSTD::forward_as_tuple())
+    {
+    }
+
+    _LIBCPP_INLINE_VISIBILITY
+    explicit __alloc_func(const _Target& __f, const _Alloc& __a)
+        : __f_(piecewise_construct, _VSTD::forward_as_tuple(__f),
+               _VSTD::forward_as_tuple(__a))
+    {
+    }
+
+    _LIBCPP_INLINE_VISIBILITY
+    explicit __alloc_func(const _Target& __f, _Alloc&& __a)
+        : __f_(piecewise_construct, _VSTD::forward_as_tuple(__f),
+               _VSTD::forward_as_tuple(_VSTD::move(__a)))
+    {
+    }
+
+    _LIBCPP_INLINE_VISIBILITY
+    explicit __alloc_func(_Target&& __f, _Alloc&& __a)
+        : __f_(piecewise_construct, _VSTD::forward_as_tuple(_VSTD::move(__f)),
+               _VSTD::forward_as_tuple(_VSTD::move(__a)))
+    {
+    }
+
+    _LIBCPP_INLINE_VISIBILITY
+    _Rp operator()(_ArgTypes&&... __arg)
+    {
+        typedef __invoke_void_return_wrapper<_Rp> _Invoker;
+        return _Invoker::__call(__f_.first(),
+                                _VSTD::forward<_ArgTypes>(__arg)...);
+    }
+
+    _LIBCPP_INLINE_VISIBILITY
+    __alloc_func* __clone() const
+    {
+        typedef allocator_traits<_Alloc> __alloc_traits;
+        typedef
+            typename __rebind_alloc_helper<__alloc_traits, __alloc_func>::type
+                _AA;
+        _AA __a(__f_.second());
+        typedef __allocator_destructor<_AA> _Dp;
+        unique_ptr<__alloc_func, _Dp> __hold(__a.allocate(1), _Dp(__a, 1));
+        ::new ((void*)__hold.get()) __alloc_func(__f_.first(), _Alloc(__a));
+        return __hold.release();
+    }
+
+    _LIBCPP_INLINE_VISIBILITY
+    void destroy() _NOEXCEPT { __f_.~__compressed_pair<_Target, _Alloc>(); }
+
+    static void __destroy_and_delete(__alloc_func* __f) {
+      typedef allocator_traits<_Alloc> __alloc_traits;
+      typedef typename __rebind_alloc_helper<__alloc_traits, __alloc_func>::type
+          _FunAlloc;
+      _FunAlloc __a(__f->__get_allocator());
+      __f->destroy();
+      __a.deallocate(__f, 1);
+    }
+};
+
+template <class _Fp, class _Rp, class... _ArgTypes>
+class __default_alloc_func<_Fp, _Rp(_ArgTypes...)> {
+  _Fp __f_;
+
+public:
+  typedef _LIBCPP_NODEBUG_TYPE _Fp _Target;
+
+  _LIBCPP_INLINE_VISIBILITY
+  const _Target& __target() const { return __f_; }
+
+  _LIBCPP_INLINE_VISIBILITY
+  explicit __default_alloc_func(_Target&& __f) : __f_(_VSTD::move(__f)) {}
+
+  _LIBCPP_INLINE_VISIBILITY
+  explicit __default_alloc_func(const _Target& __f) : __f_(__f) {}
+
+  _LIBCPP_INLINE_VISIBILITY
+  _Rp operator()(_ArgTypes&&... __arg) {
+    typedef __invoke_void_return_wrapper<_Rp> _Invoker;
+    return _Invoker::__call(__f_, _VSTD::forward<_ArgTypes>(__arg)...);
+  }
+
+  _LIBCPP_INLINE_VISIBILITY
+  __default_alloc_func* __clone() const {
+      __builtin_new_allocator::__holder_t __hold =
+        __builtin_new_allocator::__allocate_type<__default_alloc_func>(1);
+    __default_alloc_func* __res =
+        ::new ((void*)__hold.get()) __default_alloc_func(__f_);
+    (void)__hold.release();
+    return __res;
+  }
+
+  _LIBCPP_INLINE_VISIBILITY
+  void destroy() _NOEXCEPT { __f_.~_Target(); }
+
+  static void __destroy_and_delete(__default_alloc_func* __f) {
+    __f->destroy();
+      __builtin_new_allocator::__deallocate_type<__default_alloc_func>(__f, 1);
+  }
+};
+
+// __base provides an abstract interface for copyable functors.
+
+template<class _Fp> class _LIBCPP_TEMPLATE_VIS __base;
+
+template<class _Rp, class ..._ArgTypes>
+class __base<_Rp(_ArgTypes...)>
+{
+    __base(const __base&);
+    __base& operator=(const __base&);
+public:
+    _LIBCPP_INLINE_VISIBILITY __base() {}
+    _LIBCPP_INLINE_VISIBILITY virtual ~__base() {}
+    virtual __base* __clone() const = 0;
+    virtual void __clone(__base*) const = 0;
+    virtual void destroy() _NOEXCEPT = 0;
+    virtual void destroy_deallocate() _NOEXCEPT = 0;
+    virtual _Rp operator()(_ArgTypes&& ...) = 0;
+#ifndef _LIBCPP_NO_RTTI
+    virtual const void* target(const type_info&) const _NOEXCEPT = 0;
+    virtual const std::type_info& target_type() const _NOEXCEPT = 0;
+#endif // _LIBCPP_NO_RTTI
+};
+
+// __func implements __base for a given functor type.
+
+template<class _FD, class _Alloc, class _FB> class __func;
+
+template<class _Fp, class _Alloc, class _Rp, class ..._ArgTypes>
+class __func<_Fp, _Alloc, _Rp(_ArgTypes...)>
+    : public  __base<_Rp(_ArgTypes...)>
+{
+    __alloc_func<_Fp, _Alloc, _Rp(_ArgTypes...)> __f_;
+public:
+    _LIBCPP_INLINE_VISIBILITY
+    explicit __func(_Fp&& __f)
+        : __f_(_VSTD::move(__f)) {}
+
+    _LIBCPP_INLINE_VISIBILITY
+    explicit __func(const _Fp& __f, const _Alloc& __a)
+        : __f_(__f, __a) {}
+
+    _LIBCPP_INLINE_VISIBILITY
+    explicit __func(const _Fp& __f, _Alloc&& __a)
+        : __f_(__f, _VSTD::move(__a)) {}
+
+    _LIBCPP_INLINE_VISIBILITY
+    explicit __func(_Fp&& __f, _Alloc&& __a)
+        : __f_(_VSTD::move(__f), _VSTD::move(__a)) {}
+
+    virtual __base<_Rp(_ArgTypes...)>* __clone() const;
+    virtual void __clone(__base<_Rp(_ArgTypes...)>*) const;
+    virtual void destroy() _NOEXCEPT;
+    virtual void destroy_deallocate() _NOEXCEPT;
+    virtual _Rp operator()(_ArgTypes&&... __arg);
+#ifndef _LIBCPP_NO_RTTI
+    virtual const void* target(const type_info&) const _NOEXCEPT;
+    virtual const std::type_info& target_type() const _NOEXCEPT;
+#endif // _LIBCPP_NO_RTTI
+};
+
+template<class _Fp, class _Alloc, class _Rp, class ..._ArgTypes>
+__base<_Rp(_ArgTypes...)>*
+__func<_Fp, _Alloc, _Rp(_ArgTypes...)>::__clone() const
+{
+    typedef allocator_traits<_Alloc> __alloc_traits;
+    typedef typename __rebind_alloc_helper<__alloc_traits, __func>::type _Ap;
+    _Ap __a(__f_.__get_allocator());
+    typedef __allocator_destructor<_Ap> _Dp;
+    unique_ptr<__func, _Dp> __hold(__a.allocate(1), _Dp(__a, 1));
+    ::new ((void*)__hold.get()) __func(__f_.__target(), _Alloc(__a));
+    return __hold.release();
+}
+
+template<class _Fp, class _Alloc, class _Rp, class ..._ArgTypes>
+void
+__func<_Fp, _Alloc, _Rp(_ArgTypes...)>::__clone(__base<_Rp(_ArgTypes...)>* __p) const
+{
+    ::new ((void*)__p) __func(__f_.__target(), __f_.__get_allocator());
+}
+
+template<class _Fp, class _Alloc, class _Rp, class ..._ArgTypes>
+void
+__func<_Fp, _Alloc, _Rp(_ArgTypes...)>::destroy() _NOEXCEPT
+{
+    __f_.destroy();
+}
+
+template<class _Fp, class _Alloc, class _Rp, class ..._ArgTypes>
+void
+__func<_Fp, _Alloc, _Rp(_ArgTypes...)>::destroy_deallocate() _NOEXCEPT
+{
+    typedef allocator_traits<_Alloc> __alloc_traits;
+    typedef typename __rebind_alloc_helper<__alloc_traits, __func>::type _Ap;
+    _Ap __a(__f_.__get_allocator());
+    __f_.destroy();
+    __a.deallocate(this, 1);
+}
+
+template<class _Fp, class _Alloc, class _Rp, class ..._ArgTypes>
+_Rp
+__func<_Fp, _Alloc, _Rp(_ArgTypes...)>::operator()(_ArgTypes&& ... __arg)
+{
+    return __f_(_VSTD::forward<_ArgTypes>(__arg)...);
+}
+
+#ifndef _LIBCPP_NO_RTTI
+
+template<class _Fp, class _Alloc, class _Rp, class ..._ArgTypes>
+const void*
+__func<_Fp, _Alloc, _Rp(_ArgTypes...)>::target(const type_info& __ti) const _NOEXCEPT
+{
+    if (__ti == typeid(_Fp))
+        return &__f_.__target();
+    return nullptr;
+}
+
+template<class _Fp, class _Alloc, class _Rp, class ..._ArgTypes>
+const std::type_info&
+__func<_Fp, _Alloc, _Rp(_ArgTypes...)>::target_type() const _NOEXCEPT
+{
+    return typeid(_Fp);
+}
+
+#endif // _LIBCPP_NO_RTTI
+
+// __value_func creates a value-type from a __func.
+
+template <class _Fp> class __value_func;
+
+template <class _Rp, class... _ArgTypes> class __value_func<_Rp(_ArgTypes...)>
+{
+    typename aligned_storage<3 * sizeof(void*)>::type __buf_;
+
+    typedef __base<_Rp(_ArgTypes...)> __func;
+    __func* __f_;
+
+    _LIBCPP_NO_CFI static __func* __as_base(void* p)
+    {
+        return reinterpret_cast<__func*>(p);
+    }
+
+  public:
+    _LIBCPP_INLINE_VISIBILITY
+    __value_func() _NOEXCEPT : __f_(nullptr) {}
+
+    template <class _Fp, class _Alloc>
+    _LIBCPP_INLINE_VISIBILITY __value_func(_Fp&& __f, const _Alloc& __a)
+        : __f_(nullptr)
+    {
+        typedef allocator_traits<_Alloc> __alloc_traits;
+        typedef __function::__func<_Fp, _Alloc, _Rp(_ArgTypes...)> _Fun;
+        typedef typename __rebind_alloc_helper<__alloc_traits, _Fun>::type
+            _FunAlloc;
+
+        if (__function::__not_null(__f))
+        {
+            _FunAlloc __af(__a);
+            if (sizeof(_Fun) <= sizeof(__buf_) &&
+                is_nothrow_copy_constructible<_Fp>::value &&
+                is_nothrow_copy_constructible<_FunAlloc>::value)
+            {
+                __f_ =
+                    ::new ((void*)&__buf_) _Fun(_VSTD::move(__f), _Alloc(__af));
+            }
+            else
+            {
+                typedef __allocator_destructor<_FunAlloc> _Dp;
+                unique_ptr<__func, _Dp> __hold(__af.allocate(1), _Dp(__af, 1));
+                ::new ((void*)__hold.get()) _Fun(_VSTD::move(__f), _Alloc(__a));
+                __f_ = __hold.release();
+            }
+        }
+    }
+
+    template <class _Fp,
+        class = typename enable_if<!is_same<typename decay<_Fp>::type, __value_func>::value>::type>
+    _LIBCPP_INLINE_VISIBILITY explicit __value_func(_Fp&& __f)
+        : __value_func(_VSTD::forward<_Fp>(__f), allocator<_Fp>()) {}
+
+    _LIBCPP_INLINE_VISIBILITY
+    __value_func(const __value_func& __f)
+    {
+        if (__f.__f_ == nullptr)
+            __f_ = nullptr;
+        else if ((void*)__f.__f_ == &__f.__buf_)
+        {
+            __f_ = __as_base(&__buf_);
+            __f.__f_->__clone(__f_);
+        }
+        else
+            __f_ = __f.__f_->__clone();
+    }
+
+    _LIBCPP_INLINE_VISIBILITY
+    __value_func(__value_func&& __f) _NOEXCEPT
+    {
+        if (__f.__f_ == nullptr)
+            __f_ = nullptr;
+        else if ((void*)__f.__f_ == &__f.__buf_)
+        {
+            __f_ = __as_base(&__buf_);
+            __f.__f_->__clone(__f_);
+        }
+        else
+        {
+            __f_ = __f.__f_;
+            __f.__f_ = nullptr;
+        }
+    }
+
+    _LIBCPP_INLINE_VISIBILITY
+    ~__value_func()
+    {
+        if ((void*)__f_ == &__buf_)
+            __f_->destroy();
+        else if (__f_)
+            __f_->destroy_deallocate();
+    }
+
+    _LIBCPP_INLINE_VISIBILITY
+    __value_func& operator=(__value_func&& __f)
+    {
+        *this = nullptr;
+        if (__f.__f_ == nullptr)
+            __f_ = nullptr;
+        else if ((void*)__f.__f_ == &__f.__buf_)
+        {
+            __f_ = __as_base(&__buf_);
+            __f.__f_->__clone(__f_);
+        }
+        else
+        {
+            __f_ = __f.__f_;
+            __f.__f_ = nullptr;
+        }
+        return *this;
+    }
+
+    _LIBCPP_INLINE_VISIBILITY
+    __value_func& operator=(nullptr_t)
+    {
+        __func* __f = __f_;
+        __f_ = nullptr;
+        if ((void*)__f == &__buf_)
+            __f->destroy();
+        else if (__f)
+            __f->destroy_deallocate();
+        return *this;
+    }
+
+    _LIBCPP_INLINE_VISIBILITY
+    _Rp operator()(_ArgTypes&&... __args) const
+    {
+        if (__f_ == nullptr)
+            __throw_bad_function_call();
+        return (*__f_)(_VSTD::forward<_ArgTypes>(__args)...);
+    }
+
+    _LIBCPP_INLINE_VISIBILITY
+    void swap(__value_func& __f) _NOEXCEPT
+    {
+        if (&__f == this)
+            return;
+        if ((void*)__f_ == &__buf_ && (void*)__f.__f_ == &__f.__buf_)
+        {
+            typename aligned_storage<sizeof(__buf_)>::type __tempbuf;
+            __func* __t = __as_base(&__tempbuf);
+            __f_->__clone(__t);
+            __f_->destroy();
+            __f_ = nullptr;
+            __f.__f_->__clone(__as_base(&__buf_));
+            __f.__f_->destroy();
+            __f.__f_ = nullptr;
+            __f_ = __as_base(&__buf_);
+            __t->__clone(__as_base(&__f.__buf_));
+            __t->destroy();
+            __f.__f_ = __as_base(&__f.__buf_);
+        }
+        else if ((void*)__f_ == &__buf_)
+        {
+            __f_->__clone(__as_base(&__f.__buf_));
+            __f_->destroy();
+            __f_ = __f.__f_;
+            __f.__f_ = __as_base(&__f.__buf_);
+        }
+        else if ((void*)__f.__f_ == &__f.__buf_)
+        {
+            __f.__f_->__clone(__as_base(&__buf_));
+            __f.__f_->destroy();
+            __f.__f_ = __f_;
+            __f_ = __as_base(&__buf_);
+        }
+        else
+            _VSTD::swap(__f_, __f.__f_);
+    }
+
+    _LIBCPP_INLINE_VISIBILITY
+    explicit operator bool() const _NOEXCEPT { return __f_ != nullptr; }
+
+#ifndef _LIBCPP_NO_RTTI
+    _LIBCPP_INLINE_VISIBILITY
+    const std::type_info& target_type() const _NOEXCEPT
+    {
+        if (__f_ == nullptr)
+            return typeid(void);
+        return __f_->target_type();
+    }
+
+    template <typename _Tp>
+    _LIBCPP_INLINE_VISIBILITY const _Tp* target() const _NOEXCEPT
+    {
+        if (__f_ == nullptr)
+            return nullptr;
+        return (const _Tp*)__f_->target(typeid(_Tp));
+    }
+#endif // _LIBCPP_NO_RTTI
+};
+
+// Storage for a functor object, to be used with __policy to manage copy and
+// destruction.
+union __policy_storage
+{
+    mutable char __small[sizeof(void*) * 2];
+    void* __large;
+};
+
+// True if _Fun can safely be held in __policy_storage.__small.
+template <typename _Fun>
+struct __use_small_storage
+    : public integral_constant<
+          bool, sizeof(_Fun) <= sizeof(__policy_storage) &&
+                    _LIBCPP_ALIGNOF(_Fun) <= _LIBCPP_ALIGNOF(__policy_storage) &&
+                    is_trivially_copy_constructible<_Fun>::value &&
+                    is_trivially_destructible<_Fun>::value> {};
+
+// Policy contains information about how to copy, destroy, and move the
+// underlying functor. You can think of it as a vtable of sorts.
+struct __policy
+{
+    // Used to copy or destroy __large values. null for trivial objects.
+    void* (*const __clone)(const void*);
+    void (*const __destroy)(void*);
+
+    // True if this is the null policy (no value).
+    const bool __is_null;
+
+    // The target type. May be null if RTTI is disabled.
+    const std::type_info* const __type_info;
+
+    // Returns a pointer to a static policy object suitable for the functor
+    // type.
+    template <typename _Fun>
+    _LIBCPP_INLINE_VISIBILITY static const __policy* __create()
+    {
+        return __choose_policy<_Fun>(__use_small_storage<_Fun>());
+    }
+
+    _LIBCPP_INLINE_VISIBILITY
+    static const __policy* __create_empty()
+    {
+        static const _LIBCPP_CONSTEXPR __policy __policy_ = {nullptr, nullptr,
+                                                             true,
+#ifndef _LIBCPP_NO_RTTI
+                                                             &typeid(void)
+#else
+                                                             nullptr
+#endif
+        };
+        return &__policy_;
+    }
+
+  private:
+    template <typename _Fun> static void* __large_clone(const void* __s)
+    {
+        const _Fun* __f = static_cast<const _Fun*>(__s);
+        return __f->__clone();
+    }
+
+    template <typename _Fun>
+    static void __large_destroy(void* __s) {
+      _Fun::__destroy_and_delete(static_cast<_Fun*>(__s));
+    }
+
+    template <typename _Fun>
+    _LIBCPP_INLINE_VISIBILITY static const __policy*
+    __choose_policy(/* is_small = */ false_type) {
+      static const _LIBCPP_CONSTEXPR __policy __policy_ = {
+          &__large_clone<_Fun>, &__large_destroy<_Fun>, false,
+#ifndef _LIBCPP_NO_RTTI
+          &typeid(typename _Fun::_Target)
+#else
+          nullptr
+#endif
+      };
+        return &__policy_;
+    }
+
+    template <typename _Fun>
+    _LIBCPP_INLINE_VISIBILITY static const __policy*
+        __choose_policy(/* is_small = */ true_type)
+    {
+        static const _LIBCPP_CONSTEXPR __policy __policy_ = {
+            nullptr, nullptr, false,
+#ifndef _LIBCPP_NO_RTTI
+            &typeid(typename _Fun::_Target)
+#else
+            nullptr
+#endif
+        };
+        return &__policy_;
+    }
+};
+
+// Used to choose between perfect forwarding or pass-by-value. Pass-by-value is
+// faster for types that can be passed in registers.
+template <typename _Tp>
+using __fast_forward =
+    typename conditional<is_scalar<_Tp>::value, _Tp, _Tp&&>::type;
+
+// __policy_invoker calls an instance of __alloc_func held in __policy_storage.
+
+template <class _Fp> struct __policy_invoker;
+
+template <class _Rp, class... _ArgTypes>
+struct __policy_invoker<_Rp(_ArgTypes...)>
+{
+    typedef _Rp (*__Call)(const __policy_storage*,
+                          __fast_forward<_ArgTypes>...);
+
+    __Call __call_;
+
+    // Creates an invoker that throws bad_function_call.
+    _LIBCPP_INLINE_VISIBILITY
+    __policy_invoker() : __call_(&__call_empty) {}
+
+    // Creates an invoker that calls the given instance of __func.
+    template <typename _Fun>
+    _LIBCPP_INLINE_VISIBILITY static __policy_invoker __create()
+    {
+        return __policy_invoker(&__call_impl<_Fun>);
+    }
+
+  private:
+    _LIBCPP_INLINE_VISIBILITY
+    explicit __policy_invoker(__Call __c) : __call_(__c) {}
+
+    static _Rp __call_empty(const __policy_storage*,
+                            __fast_forward<_ArgTypes>...)
+    {
+        __throw_bad_function_call();
+    }
+
+    template <typename _Fun>
+    static _Rp __call_impl(const __policy_storage* __buf,
+                           __fast_forward<_ArgTypes>... __args)
+    {
+        _Fun* __f = reinterpret_cast<_Fun*>(__use_small_storage<_Fun>::value
+                                                ? &__buf->__small
+                                                : __buf->__large);
+        return (*__f)(_VSTD::forward<_ArgTypes>(__args)...);
+    }
+};
+
+// __policy_func uses a __policy and __policy_invoker to create a type-erased,
+// copyable functor.
+
+template <class _Fp> class __policy_func;
+
+template <class _Rp, class... _ArgTypes> class __policy_func<_Rp(_ArgTypes...)>
+{
+    // Inline storage for small objects.
+    __policy_storage __buf_;
+
+    // Calls the value stored in __buf_. This could technically be part of
+    // policy, but storing it here eliminates a level of indirection inside
+    // operator().
+    typedef __function::__policy_invoker<_Rp(_ArgTypes...)> __invoker;
+    __invoker __invoker_;
+
+    // The policy that describes how to move / copy / destroy __buf_. Never
+    // null, even if the function is empty.
+    const __policy* __policy_;
+
+  public:
+    _LIBCPP_INLINE_VISIBILITY
+    __policy_func() : __policy_(__policy::__create_empty()) {}
+
+    template <class _Fp, class _Alloc>
+    _LIBCPP_INLINE_VISIBILITY __policy_func(_Fp&& __f, const _Alloc& __a)
+        : __policy_(__policy::__create_empty())
+    {
+        typedef __alloc_func<_Fp, _Alloc, _Rp(_ArgTypes...)> _Fun;
+        typedef allocator_traits<_Alloc> __alloc_traits;
+        typedef typename __rebind_alloc_helper<__alloc_traits, _Fun>::type
+            _FunAlloc;
+
+        if (__function::__not_null(__f))
+        {
+            __invoker_ = __invoker::template __create<_Fun>();
+            __policy_ = __policy::__create<_Fun>();
+
+            _FunAlloc __af(__a);
+            if (__use_small_storage<_Fun>())
+            {
+                ::new ((void*)&__buf_.__small)
+                    _Fun(_VSTD::move(__f), _Alloc(__af));
+            }
+            else
+            {
+                typedef __allocator_destructor<_FunAlloc> _Dp;
+                unique_ptr<_Fun, _Dp> __hold(__af.allocate(1), _Dp(__af, 1));
+                ::new ((void*)__hold.get())
+                    _Fun(_VSTD::move(__f), _Alloc(__af));
+                __buf_.__large = __hold.release();
+            }
+        }
+    }
+
+    template <class _Fp, class = typename enable_if<!is_same<typename decay<_Fp>::type, __policy_func>::value>::type>
+    _LIBCPP_INLINE_VISIBILITY explicit __policy_func(_Fp&& __f)
+        : __policy_(__policy::__create_empty()) {
+      typedef __default_alloc_func<_Fp, _Rp(_ArgTypes...)> _Fun;
+
+      if (__function::__not_null(__f)) {
+        __invoker_ = __invoker::template __create<_Fun>();
+        __policy_ = __policy::__create<_Fun>();
+        if (__use_small_storage<_Fun>()) {
+          ::new ((void*)&__buf_.__small) _Fun(_VSTD::move(__f));
+        } else {
+          __builtin_new_allocator::__holder_t __hold =
+              __builtin_new_allocator::__allocate_type<_Fun>(1);
+          __buf_.__large = ::new ((void*)__hold.get()) _Fun(_VSTD::move(__f));
+          (void)__hold.release();
+        }
+      }
+    }
+
+    _LIBCPP_INLINE_VISIBILITY
+    __policy_func(const __policy_func& __f)
+        : __buf_(__f.__buf_), __invoker_(__f.__invoker_),
+          __policy_(__f.__policy_)
+    {
+        if (__policy_->__clone)
+            __buf_.__large = __policy_->__clone(__f.__buf_.__large);
+    }
+
+    _LIBCPP_INLINE_VISIBILITY
+    __policy_func(__policy_func&& __f)
+        : __buf_(__f.__buf_), __invoker_(__f.__invoker_),
+          __policy_(__f.__policy_)
+    {
+        if (__policy_->__destroy)
+        {
+            __f.__policy_ = __policy::__create_empty();
+            __f.__invoker_ = __invoker();
+        }
+    }
+
+    _LIBCPP_INLINE_VISIBILITY
+    ~__policy_func()
+    {
+        if (__policy_->__destroy)
+            __policy_->__destroy(__buf_.__large);
+    }
+
+    _LIBCPP_INLINE_VISIBILITY
+    __policy_func& operator=(__policy_func&& __f)
+    {
+        *this = nullptr;
+        __buf_ = __f.__buf_;
+        __invoker_ = __f.__invoker_;
+        __policy_ = __f.__policy_;
+        __f.__policy_ = __policy::__create_empty();
+        __f.__invoker_ = __invoker();
+        return *this;
+    }
+
+    _LIBCPP_INLINE_VISIBILITY
+    __policy_func& operator=(nullptr_t)
+    {
+        const __policy* __p = __policy_;
+        __policy_ = __policy::__create_empty();
+        __invoker_ = __invoker();
+        if (__p->__destroy)
+            __p->__destroy(__buf_.__large);
+        return *this;
+    }
+
+    _LIBCPP_INLINE_VISIBILITY
+    _Rp operator()(_ArgTypes&&... __args) const
+    {
+        return __invoker_.__call_(_VSTD::addressof(__buf_),
+                                  _VSTD::forward<_ArgTypes>(__args)...);
+    }
+
+    _LIBCPP_INLINE_VISIBILITY
+    void swap(__policy_func& __f)
+    {
+        _VSTD::swap(__invoker_, __f.__invoker_);
+        _VSTD::swap(__policy_, __f.__policy_);
+        _VSTD::swap(__buf_, __f.__buf_);
+    }
+
+    _LIBCPP_INLINE_VISIBILITY
+    explicit operator bool() const _NOEXCEPT
+    {
+        return !__policy_->__is_null;
+    }
+
+#ifndef _LIBCPP_NO_RTTI
+    _LIBCPP_INLINE_VISIBILITY
+    const std::type_info& target_type() const _NOEXCEPT
+    {
+        return *__policy_->__type_info;
+    }
+
+    template <typename _Tp>
+    _LIBCPP_INLINE_VISIBILITY const _Tp* target() const _NOEXCEPT
+    {
+        if (__policy_->__is_null || typeid(_Tp) != *__policy_->__type_info)
+            return nullptr;
+        if (__policy_->__clone) // Out of line storage.
+            return reinterpret_cast<const _Tp*>(__buf_.__large);
+        else
+            return reinterpret_cast<const _Tp*>(&__buf_.__small);
+    }
+#endif // _LIBCPP_NO_RTTI
+};
+
+#if defined(_LIBCPP_HAS_BLOCKS_RUNTIME) && !defined(_LIBCPP_HAS_OBJC_ARC)
+
+extern "C" void *_Block_copy(const void *);
+extern "C" void _Block_release(const void *);
+
+template<class _Rp1, class ..._ArgTypes1, class _Alloc, class _Rp, class ..._ArgTypes>
+class __func<_Rp1(^)(_ArgTypes1...), _Alloc, _Rp(_ArgTypes...)>
+    : public  __base<_Rp(_ArgTypes...)>
+{
+    typedef _Rp1(^__block_type)(_ArgTypes1...);
+    __block_type __f_;
+
+public:
+    _LIBCPP_INLINE_VISIBILITY
+    explicit __func(__block_type const& __f)
+        : __f_(reinterpret_cast<__block_type>(__f ? _Block_copy(__f) : nullptr))
+    { }
+
+    // [TODO] add && to save on a retain
+
+    _LIBCPP_INLINE_VISIBILITY
+    explicit __func(__block_type __f, const _Alloc& /* unused */)
+        : __f_(reinterpret_cast<__block_type>(__f ? _Block_copy(__f) : nullptr))
+    { }
+
+    virtual __base<_Rp(_ArgTypes...)>* __clone() const {
+        _LIBCPP_ASSERT(false,
+            "Block pointers are just pointers, so they should always fit into "
+            "std::function's small buffer optimization. This function should "
+            "never be invoked.");
+        return nullptr;
+    }
+
+    virtual void __clone(__base<_Rp(_ArgTypes...)>* __p) const {
+        ::new ((void*)__p) __func(__f_);
+    }
+
+    virtual void destroy() _NOEXCEPT {
+        if (__f_)
+            _Block_release(__f_);
+        __f_ = 0;
+    }
+
+    virtual void destroy_deallocate() _NOEXCEPT {
+        _LIBCPP_ASSERT(false,
+            "Block pointers are just pointers, so they should always fit into "
+            "std::function's small buffer optimization. This function should "
+            "never be invoked.");
+    }
+
+    virtual _Rp operator()(_ArgTypes&& ... __arg) {
+        return _VSTD::__invoke(__f_, _VSTD::forward<_ArgTypes>(__arg)...);
+    }
+
+#ifndef _LIBCPP_NO_RTTI
+    virtual const void* target(type_info const& __ti) const _NOEXCEPT {
+        if (__ti == typeid(__func::__block_type))
+            return &__f_;
+        return (const void*)nullptr;
+    }
+
+    virtual const std::type_info& target_type() const _NOEXCEPT {
+        return typeid(__func::__block_type);
+    }
+#endif // _LIBCPP_NO_RTTI
+};
+
+#endif // _LIBCPP_HAS_EXTENSION_BLOCKS && !_LIBCPP_HAS_OBJC_ARC
+
+}  // __function
+
+template<class _Rp, class ..._ArgTypes>
+class _LIBCPP_TEMPLATE_VIS function<_Rp(_ArgTypes...)>
+#if _LIBCPP_STD_VER <= 17 || !defined(_LIBCPP_ABI_NO_BINDER_BASES)
+    : public __function::__maybe_derive_from_unary_function<_Rp(_ArgTypes...)>,
+      public __function::__maybe_derive_from_binary_function<_Rp(_ArgTypes...)>
+#endif
+{
+#ifndef _LIBCPP_ABI_OPTIMIZED_FUNCTION
+    typedef __function::__value_func<_Rp(_ArgTypes...)> __func;
+#else
+    typedef __function::__policy_func<_Rp(_ArgTypes...)> __func;
+#endif
+
+    __func __f_;
+
+    template <class _Fp, bool = _And<
+        _IsNotSame<__uncvref_t<_Fp>, function>,
+        __invokable<_Fp, _ArgTypes...>
+    >::value>
+    struct __callable;
+    template <class _Fp>
+        struct __callable<_Fp, true>
+        {
+            static const bool value = is_void<_Rp>::value ||
+                __is_core_convertible<typename __invoke_of<_Fp, _ArgTypes...>::type,
+                                      _Rp>::value;
+        };
+    template <class _Fp>
+        struct __callable<_Fp, false>
+        {
+            static const bool value = false;
+        };
+
+  template <class _Fp>
+  using _EnableIfLValueCallable = typename enable_if<__callable<_Fp&>::value>::type;
+public:
+    typedef _Rp result_type;
+
+    // construct/copy/destroy:
+    _LIBCPP_INLINE_VISIBILITY
+    function() _NOEXCEPT { }
+    _LIBCPP_INLINE_VISIBILITY
+    function(nullptr_t) _NOEXCEPT {}
+    function(const function&);
+    function(function&&) _NOEXCEPT;
+    template<class _Fp, class = _EnableIfLValueCallable<_Fp>>
+    function(_Fp);
+
+#if _LIBCPP_STD_VER <= 14
+    template<class _Alloc>
+      _LIBCPP_INLINE_VISIBILITY
+      function(allocator_arg_t, const _Alloc&) _NOEXCEPT {}
+    template<class _Alloc>
+      _LIBCPP_INLINE_VISIBILITY
+      function(allocator_arg_t, const _Alloc&, nullptr_t) _NOEXCEPT {}
+    template<class _Alloc>
+      function(allocator_arg_t, const _Alloc&, const function&);
+    template<class _Alloc>
+      function(allocator_arg_t, const _Alloc&, function&&);
+    template<class _Fp, class _Alloc, class = _EnableIfLValueCallable<_Fp>>
+      function(allocator_arg_t, const _Alloc& __a, _Fp __f);
+#endif
+
+    function& operator=(const function&);
+    function& operator=(function&&) _NOEXCEPT;
+    function& operator=(nullptr_t) _NOEXCEPT;
+    template<class _Fp, class = _EnableIfLValueCallable<typename decay<_Fp>::type>>
+    function& operator=(_Fp&&);
+
+    ~function();
+
+    // function modifiers:
+    void swap(function&) _NOEXCEPT;
+
+#if _LIBCPP_STD_VER <= 14
+    template<class _Fp, class _Alloc>
+      _LIBCPP_INLINE_VISIBILITY
+      void assign(_Fp&& __f, const _Alloc& __a)
+        {function(allocator_arg, __a, _VSTD::forward<_Fp>(__f)).swap(*this);}
+#endif
+
+    // function capacity:
+    _LIBCPP_INLINE_VISIBILITY
+    explicit operator bool() const _NOEXCEPT {
+      return static_cast<bool>(__f_);
+    }
+
+    // deleted overloads close possible hole in the type system
+    template<class _R2, class... _ArgTypes2>
+      bool operator==(const function<_R2(_ArgTypes2...)>&) const = delete;
+    template<class _R2, class... _ArgTypes2>
+      bool operator!=(const function<_R2(_ArgTypes2...)>&) const = delete;
+public:
+    // function invocation:
+    _Rp operator()(_ArgTypes...) const;
+
+#ifndef _LIBCPP_NO_RTTI
+    // function target access:
+    const std::type_info& target_type() const _NOEXCEPT;
+    template <typename _Tp> _Tp* target() _NOEXCEPT;
+    template <typename _Tp> const _Tp* target() const _NOEXCEPT;
+#endif // _LIBCPP_NO_RTTI
+};
+
+#ifndef _LIBCPP_HAS_NO_DEDUCTION_GUIDES
+template<class _Rp, class ..._Ap>
+function(_Rp(*)(_Ap...)) -> function<_Rp(_Ap...)>;
+
+template<class _Fp>
+struct __strip_signature;
+
+template<class _Rp, class _Gp, class ..._Ap>
+struct __strip_signature<_Rp (_Gp::*) (_Ap...)> { using type = _Rp(_Ap...); };
+template<class _Rp, class _Gp, class ..._Ap>
+struct __strip_signature<_Rp (_Gp::*) (_Ap...) const> { using type = _Rp(_Ap...); };
+template<class _Rp, class _Gp, class ..._Ap>
+struct __strip_signature<_Rp (_Gp::*) (_Ap...) volatile> { using type = _Rp(_Ap...); };
+template<class _Rp, class _Gp, class ..._Ap>
+struct __strip_signature<_Rp (_Gp::*) (_Ap...) const volatile> { using type = _Rp(_Ap...); };
+
+template<class _Rp, class _Gp, class ..._Ap>
+struct __strip_signature<_Rp (_Gp::*) (_Ap...) &> { using type = _Rp(_Ap...); };
+template<class _Rp, class _Gp, class ..._Ap>
+struct __strip_signature<_Rp (_Gp::*) (_Ap...) const &> { using type = _Rp(_Ap...); };
+template<class _Rp, class _Gp, class ..._Ap>
+struct __strip_signature<_Rp (_Gp::*) (_Ap...) volatile &> { using type = _Rp(_Ap...); };
+template<class _Rp, class _Gp, class ..._Ap>
+struct __strip_signature<_Rp (_Gp::*) (_Ap...) const volatile &> { using type = _Rp(_Ap...); };
+
+template<class _Rp, class _Gp, class ..._Ap>
+struct __strip_signature<_Rp (_Gp::*) (_Ap...) noexcept> { using type = _Rp(_Ap...); };
+template<class _Rp, class _Gp, class ..._Ap>
+struct __strip_signature<_Rp (_Gp::*) (_Ap...) const noexcept> { using type = _Rp(_Ap...); };
+template<class _Rp, class _Gp, class ..._Ap>
+struct __strip_signature<_Rp (_Gp::*) (_Ap...) volatile noexcept> { using type = _Rp(_Ap...); };
+template<class _Rp, class _Gp, class ..._Ap>
+struct __strip_signature<_Rp (_Gp::*) (_Ap...) const volatile noexcept> { using type = _Rp(_Ap...); };
+
+template<class _Rp, class _Gp, class ..._Ap>
+struct __strip_signature<_Rp (_Gp::*) (_Ap...) & noexcept> { using type = _Rp(_Ap...); };
+template<class _Rp, class _Gp, class ..._Ap>
+struct __strip_signature<_Rp (_Gp::*) (_Ap...) const & noexcept> { using type = _Rp(_Ap...); };
+template<class _Rp, class _Gp, class ..._Ap>
+struct __strip_signature<_Rp (_Gp::*) (_Ap...) volatile & noexcept> { using type = _Rp(_Ap...); };
+template<class _Rp, class _Gp, class ..._Ap>
+struct __strip_signature<_Rp (_Gp::*) (_Ap...) const volatile & noexcept> { using type = _Rp(_Ap...); };
+
+template<class _Fp, class _Stripped = typename __strip_signature<decltype(&_Fp::operator())>::type>
+function(_Fp) -> function<_Stripped>;
+#endif // !_LIBCPP_HAS_NO_DEDUCTION_GUIDES
+
+template<class _Rp, class ..._ArgTypes>
+function<_Rp(_ArgTypes...)>::function(const function& __f) : __f_(__f.__f_) {}
+
+#if _LIBCPP_STD_VER <= 14
+template<class _Rp, class ..._ArgTypes>
+template <class _Alloc>
+function<_Rp(_ArgTypes...)>::function(allocator_arg_t, const _Alloc&,
+                                     const function& __f) : __f_(__f.__f_) {}
+#endif
+
+template <class _Rp, class... _ArgTypes>
+function<_Rp(_ArgTypes...)>::function(function&& __f) _NOEXCEPT
+    : __f_(_VSTD::move(__f.__f_)) {}
+
+#if _LIBCPP_STD_VER <= 14
+template<class _Rp, class ..._ArgTypes>
+template <class _Alloc>
+function<_Rp(_ArgTypes...)>::function(allocator_arg_t, const _Alloc&,
+                                      function&& __f)
+    : __f_(_VSTD::move(__f.__f_)) {}
+#endif
+
+template <class _Rp, class... _ArgTypes>
+template <class _Fp, class>
+function<_Rp(_ArgTypes...)>::function(_Fp __f) : __f_(_VSTD::move(__f)) {}
+
+#if _LIBCPP_STD_VER <= 14
+template <class _Rp, class... _ArgTypes>
+template <class _Fp, class _Alloc, class>
+function<_Rp(_ArgTypes...)>::function(allocator_arg_t, const _Alloc& __a,
+                                      _Fp __f)
+    : __f_(_VSTD::move(__f), __a) {}
+#endif
+
+template<class _Rp, class ..._ArgTypes>
+function<_Rp(_ArgTypes...)>&
+function<_Rp(_ArgTypes...)>::operator=(const function& __f)
+{
+    function(__f).swap(*this);
+    return *this;
+}
+
+template<class _Rp, class ..._ArgTypes>
+function<_Rp(_ArgTypes...)>&
+function<_Rp(_ArgTypes...)>::operator=(function&& __f) _NOEXCEPT
+{
+    __f_ = _VSTD::move(__f.__f_);
+    return *this;
+}
+
+template<class _Rp, class ..._ArgTypes>
+function<_Rp(_ArgTypes...)>&
+function<_Rp(_ArgTypes...)>::operator=(nullptr_t) _NOEXCEPT
+{
+    __f_ = nullptr;
+    return *this;
+}
+
+template<class _Rp, class ..._ArgTypes>
+template <class _Fp, class>
+function<_Rp(_ArgTypes...)>&
+function<_Rp(_ArgTypes...)>::operator=(_Fp&& __f)
+{
+    function(_VSTD::forward<_Fp>(__f)).swap(*this);
+    return *this;
+}
+
+template<class _Rp, class ..._ArgTypes>
+function<_Rp(_ArgTypes...)>::~function() {}
+
+template<class _Rp, class ..._ArgTypes>
+void
+function<_Rp(_ArgTypes...)>::swap(function& __f) _NOEXCEPT
+{
+    __f_.swap(__f.__f_);
+}
+
+template<class _Rp, class ..._ArgTypes>
+_Rp
+function<_Rp(_ArgTypes...)>::operator()(_ArgTypes... __arg) const
+{
+    return __f_(_VSTD::forward<_ArgTypes>(__arg)...);
+}
+
+#ifndef _LIBCPP_NO_RTTI
+
+template<class _Rp, class ..._ArgTypes>
+const std::type_info&
+function<_Rp(_ArgTypes...)>::target_type() const _NOEXCEPT
+{
+    return __f_.target_type();
+}
+
+template<class _Rp, class ..._ArgTypes>
+template <typename _Tp>
+_Tp*
+function<_Rp(_ArgTypes...)>::target() _NOEXCEPT
+{
+    return (_Tp*)(__f_.template target<_Tp>());
+}
+
+template<class _Rp, class ..._ArgTypes>
+template <typename _Tp>
+const _Tp*
+function<_Rp(_ArgTypes...)>::target() const _NOEXCEPT
+{
+    return __f_.template target<_Tp>();
+}
+
+#endif // _LIBCPP_NO_RTTI
+
+template <class _Rp, class... _ArgTypes>
+inline _LIBCPP_INLINE_VISIBILITY
+bool
+operator==(const function<_Rp(_ArgTypes...)>& __f, nullptr_t) _NOEXCEPT {return !__f;}
+
+template <class _Rp, class... _ArgTypes>
+inline _LIBCPP_INLINE_VISIBILITY
+bool
+operator==(nullptr_t, const function<_Rp(_ArgTypes...)>& __f) _NOEXCEPT {return !__f;}
+
+template <class _Rp, class... _ArgTypes>
+inline _LIBCPP_INLINE_VISIBILITY
+bool
+operator!=(const function<_Rp(_ArgTypes...)>& __f, nullptr_t) _NOEXCEPT {return (bool)__f;}
+
+template <class _Rp, class... _ArgTypes>
+inline _LIBCPP_INLINE_VISIBILITY
+bool
+operator!=(nullptr_t, const function<_Rp(_ArgTypes...)>& __f) _NOEXCEPT {return (bool)__f;}
+
+template <class _Rp, class... _ArgTypes>
+inline _LIBCPP_INLINE_VISIBILITY
+void
+swap(function<_Rp(_ArgTypes...)>& __x, function<_Rp(_ArgTypes...)>& __y) _NOEXCEPT
+{return __x.swap(__y);}
+
+#else // _LIBCPP_CXX03_LANG
+
+namespace __function {
+
+template<class _Fp> class __base;
+
+template<class _Rp>
+class __base<_Rp()>
+{
+    __base(const __base&);
+    __base& operator=(const __base&);
+public:
+    __base() {}
+    virtual ~__base() {}
+    virtual __base* __clone() const = 0;
+    virtual void __clone(__base*) const = 0;
+    virtual void destroy() = 0;
+    virtual void destroy_deallocate() = 0;
+    virtual _Rp operator()() = 0;
+#ifndef _LIBCPP_NO_RTTI
+    virtual const void* target(const type_info&) const = 0;
+    virtual const std::type_info& target_type() const = 0;
+#endif // _LIBCPP_NO_RTTI
+};
+
+template<class _Rp, class _A0>
+class __base<_Rp(_A0)>
+{
+    __base(const __base&);
+    __base& operator=(const __base&);
+public:
+    __base() {}
+    virtual ~__base() {}
+    virtual __base* __clone() const = 0;
+    virtual void __clone(__base*) const = 0;
+    virtual void destroy() = 0;
+    virtual void destroy_deallocate() = 0;
+    virtual _Rp operator()(_A0) = 0;
+#ifndef _LIBCPP_NO_RTTI
+    virtual const void* target(const type_info&) const = 0;
+    virtual const std::type_info& target_type() const = 0;
+#endif // _LIBCPP_NO_RTTI
+};
+
+template<class _Rp, class _A0, class _A1>
+class __base<_Rp(_A0, _A1)>
+{
+    __base(const __base&);
+    __base& operator=(const __base&);
+public:
+    __base() {}
+    virtual ~__base() {}
+    virtual __base* __clone() const = 0;
+    virtual void __clone(__base*) const = 0;
+    virtual void destroy() = 0;
+    virtual void destroy_deallocate() = 0;
+    virtual _Rp operator()(_A0, _A1) = 0;
+#ifndef _LIBCPP_NO_RTTI
+    virtual const void* target(const type_info&) const = 0;
+    virtual const std::type_info& target_type() const = 0;
+#endif // _LIBCPP_NO_RTTI
+};
+
+template<class _Rp, class _A0, class _A1, class _A2>
+class __base<_Rp(_A0, _A1, _A2)>
+{
+    __base(const __base&);
+    __base& operator=(const __base&);
+public:
+    __base() {}
+    virtual ~__base() {}
+    virtual __base* __clone() const = 0;
+    virtual void __clone(__base*) const = 0;
+    virtual void destroy() = 0;
+    virtual void destroy_deallocate() = 0;
+    virtual _Rp operator()(_A0, _A1, _A2) = 0;
+#ifndef _LIBCPP_NO_RTTI
+    virtual const void* target(const type_info&) const = 0;
+    virtual const std::type_info& target_type() const = 0;
+#endif // _LIBCPP_NO_RTTI
+};
+
+template<class _FD, class _Alloc, class _FB> class __func;
+
+template<class _Fp, class _Alloc, class _Rp>
+class __func<_Fp, _Alloc, _Rp()>
+    : public  __base<_Rp()>
+{
+    __compressed_pair<_Fp, _Alloc> __f_;
+public:
+    explicit __func(_Fp __f) : __f_(_VSTD::move(__f), __default_init_tag()) {}
+    explicit __func(_Fp __f, _Alloc __a) : __f_(_VSTD::move(__f), _VSTD::move(__a)) {}
+    virtual __base<_Rp()>* __clone() const;
+    virtual void __clone(__base<_Rp()>*) const;
+    virtual void destroy();
+    virtual void destroy_deallocate();
+    virtual _Rp operator()();
+#ifndef _LIBCPP_NO_RTTI
+    virtual const void* target(const type_info&) const;
+    virtual const std::type_info& target_type() const;
+#endif // _LIBCPP_NO_RTTI
+};
+
+template<class _Fp, class _Alloc, class _Rp>
+__base<_Rp()>*
+__func<_Fp, _Alloc, _Rp()>::__clone() const
+{
+    typedef allocator_traits<_Alloc> __alloc_traits;
+    typedef typename __rebind_alloc_helper<__alloc_traits, __func>::type _Ap;
+    _Ap __a(__f_.second());
+    typedef __allocator_destructor<_Ap> _Dp;
+    unique_ptr<__func, _Dp> __hold(__a.allocate(1), _Dp(__a, 1));
+    ::new ((void*)__hold.get()) __func(__f_.first(), _Alloc(__a));
+    return __hold.release();
+}
+
+template<class _Fp, class _Alloc, class _Rp>
+void
+__func<_Fp, _Alloc, _Rp()>::__clone(__base<_Rp()>* __p) const
+{
+    ::new ((void*)__p) __func(__f_.first(), __f_.second());
+}
+
+template<class _Fp, class _Alloc, class _Rp>
+void
+__func<_Fp, _Alloc, _Rp()>::destroy()
+{
+    __f_.~__compressed_pair<_Fp, _Alloc>();
+}
+
+template<class _Fp, class _Alloc, class _Rp>
+void
+__func<_Fp, _Alloc, _Rp()>::destroy_deallocate()
+{
+    typedef allocator_traits<_Alloc> __alloc_traits;
+    typedef typename __rebind_alloc_helper<__alloc_traits, __func>::type _Ap;
+    _Ap __a(__f_.second());
+    __f_.~__compressed_pair<_Fp, _Alloc>();
+    __a.deallocate(this, 1);
+}
+
+template<class _Fp, class _Alloc, class _Rp>
+_Rp
+__func<_Fp, _Alloc, _Rp()>::operator()()
+{
+    typedef __invoke_void_return_wrapper<_Rp> _Invoker;
+    return _Invoker::__call(__f_.first());
+}
+
+#ifndef _LIBCPP_NO_RTTI
+
+template<class _Fp, class _Alloc, class _Rp>
+const void*
+__func<_Fp, _Alloc, _Rp()>::target(const type_info& __ti) const
+{
+    if (__ti == typeid(_Fp))
+        return &__f_.first();
+    return (const void*)0;
+}
+
+template<class _Fp, class _Alloc, class _Rp>
+const std::type_info&
+__func<_Fp, _Alloc, _Rp()>::target_type() const
+{
+    return typeid(_Fp);
+}
+
+#endif // _LIBCPP_NO_RTTI
+
+template<class _Fp, class _Alloc, class _Rp, class _A0>
+class __func<_Fp, _Alloc, _Rp(_A0)>
+    : public  __base<_Rp(_A0)>
+{
+    __compressed_pair<_Fp, _Alloc> __f_;
+public:
+    _LIBCPP_INLINE_VISIBILITY explicit __func(_Fp __f) : __f_(_VSTD::move(__f), __default_init_tag()) {}
+    _LIBCPP_INLINE_VISIBILITY explicit __func(_Fp __f, _Alloc __a)
+        : __f_(_VSTD::move(__f), _VSTD::move(__a)) {}
+    virtual __base<_Rp(_A0)>* __clone() const;
+    virtual void __clone(__base<_Rp(_A0)>*) const;
+    virtual void destroy();
+    virtual void destroy_deallocate();
+    virtual _Rp operator()(_A0);
+#ifndef _LIBCPP_NO_RTTI
+    virtual const void* target(const type_info&) const;
+    virtual const std::type_info& target_type() const;
+#endif // _LIBCPP_NO_RTTI
+};
+
+template<class _Fp, class _Alloc, class _Rp, class _A0>
+__base<_Rp(_A0)>*
+__func<_Fp, _Alloc, _Rp(_A0)>::__clone() const
+{
+    typedef allocator_traits<_Alloc> __alloc_traits;
+    typedef typename __rebind_alloc_helper<__alloc_traits, __func>::type _Ap;
+    _Ap __a(__f_.second());
+    typedef __allocator_destructor<_Ap> _Dp;
+    unique_ptr<__func, _Dp> __hold(__a.allocate(1), _Dp(__a, 1));
+    ::new ((void*)__hold.get()) __func(__f_.first(), _Alloc(__a));
+    return __hold.release();
+}
+
+template<class _Fp, class _Alloc, class _Rp, class _A0>
+void
+__func<_Fp, _Alloc, _Rp(_A0)>::__clone(__base<_Rp(_A0)>* __p) const
+{
+    ::new ((void*)__p) __func(__f_.first(), __f_.second());
+}
+
+template<class _Fp, class _Alloc, class _Rp, class _A0>
+void
+__func<_Fp, _Alloc, _Rp(_A0)>::destroy()
+{
+    __f_.~__compressed_pair<_Fp, _Alloc>();
+}
+
+template<class _Fp, class _Alloc, class _Rp, class _A0>
+void
+__func<_Fp, _Alloc, _Rp(_A0)>::destroy_deallocate()
+{
+    typedef allocator_traits<_Alloc> __alloc_traits;
+    typedef typename __rebind_alloc_helper<__alloc_traits, __func>::type _Ap;
+    _Ap __a(__f_.second());
+    __f_.~__compressed_pair<_Fp, _Alloc>();
+    __a.deallocate(this, 1);
+}
+
+template<class _Fp, class _Alloc, class _Rp, class _A0>
+_Rp
+__func<_Fp, _Alloc, _Rp(_A0)>::operator()(_A0 __a0)
+{
+    typedef __invoke_void_return_wrapper<_Rp> _Invoker;
+    return _Invoker::__call(__f_.first(), __a0);
+}
+
+#ifndef _LIBCPP_NO_RTTI
+
+template<class _Fp, class _Alloc, class _Rp, class _A0>
+const void*
+__func<_Fp, _Alloc, _Rp(_A0)>::target(const type_info& __ti) const
+{
+    if (__ti == typeid(_Fp))
+        return &__f_.first();
+    return (const void*)0;
+}
+
+template<class _Fp, class _Alloc, class _Rp, class _A0>
+const std::type_info&
+__func<_Fp, _Alloc, _Rp(_A0)>::target_type() const
+{
+    return typeid(_Fp);
+}
+
+#endif // _LIBCPP_NO_RTTI
+
+template<class _Fp, class _Alloc, class _Rp, class _A0, class _A1>
+class __func<_Fp, _Alloc, _Rp(_A0, _A1)>
+    : public  __base<_Rp(_A0, _A1)>
+{
+    __compressed_pair<_Fp, _Alloc> __f_;
+public:
+    _LIBCPP_INLINE_VISIBILITY explicit __func(_Fp __f) : __f_(_VSTD::move(__f), __default_init_tag()) {}
+    _LIBCPP_INLINE_VISIBILITY explicit __func(_Fp __f, _Alloc __a)
+        : __f_(_VSTD::move(__f), _VSTD::move(__a)) {}
+    virtual __base<_Rp(_A0, _A1)>* __clone() const;
+    virtual void __clone(__base<_Rp(_A0, _A1)>*) const;
+    virtual void destroy();
+    virtual void destroy_deallocate();
+    virtual _Rp operator()(_A0, _A1);
+#ifndef _LIBCPP_NO_RTTI
+    virtual const void* target(const type_info&) const;
+    virtual const std::type_info& target_type() const;
+#endif // _LIBCPP_NO_RTTI
+};
+
+template<class _Fp, class _Alloc, class _Rp, class _A0, class _A1>
+__base<_Rp(_A0, _A1)>*
+__func<_Fp, _Alloc, _Rp(_A0, _A1)>::__clone() const
+{
+    typedef allocator_traits<_Alloc> __alloc_traits;
+    typedef typename __rebind_alloc_helper<__alloc_traits, __func>::type _Ap;
+    _Ap __a(__f_.second());
+    typedef __allocator_destructor<_Ap> _Dp;
+    unique_ptr<__func, _Dp> __hold(__a.allocate(1), _Dp(__a, 1));
+    ::new ((void*)__hold.get()) __func(__f_.first(), _Alloc(__a));
+    return __hold.release();
+}
+
+template<class _Fp, class _Alloc, class _Rp, class _A0, class _A1>
+void
+__func<_Fp, _Alloc, _Rp(_A0, _A1)>::__clone(__base<_Rp(_A0, _A1)>* __p) const
+{
+    ::new ((void*)__p) __func(__f_.first(), __f_.second());
+}
+
+template<class _Fp, class _Alloc, class _Rp, class _A0, class _A1>
+void
+__func<_Fp, _Alloc, _Rp(_A0, _A1)>::destroy()
+{
+    __f_.~__compressed_pair<_Fp, _Alloc>();
+}
+
+template<class _Fp, class _Alloc, class _Rp, class _A0, class _A1>
+void
+__func<_Fp, _Alloc, _Rp(_A0, _A1)>::destroy_deallocate()
+{
+    typedef allocator_traits<_Alloc> __alloc_traits;
+    typedef typename __rebind_alloc_helper<__alloc_traits, __func>::type _Ap;
+    _Ap __a(__f_.second());
+    __f_.~__compressed_pair<_Fp, _Alloc>();
+    __a.deallocate(this, 1);
+}
+
+template<class _Fp, class _Alloc, class _Rp, class _A0, class _A1>
+_Rp
+__func<_Fp, _Alloc, _Rp(_A0, _A1)>::operator()(_A0 __a0, _A1 __a1)
+{
+    typedef __invoke_void_return_wrapper<_Rp> _Invoker;
+    return _Invoker::__call(__f_.first(), __a0, __a1);
+}
+
+#ifndef _LIBCPP_NO_RTTI
+
+template<class _Fp, class _Alloc, class _Rp, class _A0, class _A1>
+const void*
+__func<_Fp, _Alloc, _Rp(_A0, _A1)>::target(const type_info& __ti) const
+{
+    if (__ti == typeid(_Fp))
+        return &__f_.first();
+    return (const void*)0;
+}
+
+template<class _Fp, class _Alloc, class _Rp, class _A0, class _A1>
+const std::type_info&
+__func<_Fp, _Alloc, _Rp(_A0, _A1)>::target_type() const
+{
+    return typeid(_Fp);
+}
+
+#endif // _LIBCPP_NO_RTTI
+
+template<class _Fp, class _Alloc, class _Rp, class _A0, class _A1, class _A2>
+class __func<_Fp, _Alloc, _Rp(_A0, _A1, _A2)>
+    : public  __base<_Rp(_A0, _A1, _A2)>
+{
+    __compressed_pair<_Fp, _Alloc> __f_;
+public:
+    _LIBCPP_INLINE_VISIBILITY explicit __func(_Fp __f) : __f_(_VSTD::move(__f), __default_init_tag()) {}
+    _LIBCPP_INLINE_VISIBILITY explicit __func(_Fp __f, _Alloc __a)
+        : __f_(_VSTD::move(__f), _VSTD::move(__a)) {}
+    virtual __base<_Rp(_A0, _A1, _A2)>* __clone() const;
+    virtual void __clone(__base<_Rp(_A0, _A1, _A2)>*) const;
+    virtual void destroy();
+    virtual void destroy_deallocate();
+    virtual _Rp operator()(_A0, _A1, _A2);
+#ifndef _LIBCPP_NO_RTTI
+    virtual const void* target(const type_info&) const;
+    virtual const std::type_info& target_type() const;
+#endif // _LIBCPP_NO_RTTI
+};
+
+template<class _Fp, class _Alloc, class _Rp, class _A0, class _A1, class _A2>
+__base<_Rp(_A0, _A1, _A2)>*
+__func<_Fp, _Alloc, _Rp(_A0, _A1, _A2)>::__clone() const
+{
+    typedef allocator_traits<_Alloc> __alloc_traits;
+    typedef typename __rebind_alloc_helper<__alloc_traits, __func>::type _Ap;
+    _Ap __a(__f_.second());
+    typedef __allocator_destructor<_Ap> _Dp;
+    unique_ptr<__func, _Dp> __hold(__a.allocate(1), _Dp(__a, 1));
+    ::new ((void*)__hold.get()) __func(__f_.first(), _Alloc(__a));
+    return __hold.release();
+}
+
+template<class _Fp, class _Alloc, class _Rp, class _A0, class _A1, class _A2>
+void
+__func<_Fp, _Alloc, _Rp(_A0, _A1, _A2)>::__clone(__base<_Rp(_A0, _A1, _A2)>* __p) const
+{
+    ::new ((void*)__p) __func(__f_.first(), __f_.second());
+}
+
+template<class _Fp, class _Alloc, class _Rp, class _A0, class _A1, class _A2>
+void
+__func<_Fp, _Alloc, _Rp(_A0, _A1, _A2)>::destroy()
+{
+    __f_.~__compressed_pair<_Fp, _Alloc>();
+}
+
+template<class _Fp, class _Alloc, class _Rp, class _A0, class _A1, class _A2>
+void
+__func<_Fp, _Alloc, _Rp(_A0, _A1, _A2)>::destroy_deallocate()
+{
+    typedef allocator_traits<_Alloc> __alloc_traits;
+    typedef typename __rebind_alloc_helper<__alloc_traits, __func>::type _Ap;
+    _Ap __a(__f_.second());
+    __f_.~__compressed_pair<_Fp, _Alloc>();
+    __a.deallocate(this, 1);
+}
+
+template<class _Fp, class _Alloc, class _Rp, class _A0, class _A1, class _A2>
+_Rp
+__func<_Fp, _Alloc, _Rp(_A0, _A1, _A2)>::operator()(_A0 __a0, _A1 __a1, _A2 __a2)
+{
+    typedef __invoke_void_return_wrapper<_Rp> _Invoker;
+    return _Invoker::__call(__f_.first(), __a0, __a1, __a2);
+}
+
+#ifndef _LIBCPP_NO_RTTI
+
+template<class _Fp, class _Alloc, class _Rp, class _A0, class _A1, class _A2>
+const void*
+__func<_Fp, _Alloc, _Rp(_A0, _A1, _A2)>::target(const type_info& __ti) const
+{
+    if (__ti == typeid(_Fp))
+        return &__f_.first();
+    return (const void*)0;
+}
+
+template<class _Fp, class _Alloc, class _Rp, class _A0, class _A1, class _A2>
+const std::type_info&
+__func<_Fp, _Alloc, _Rp(_A0, _A1, _A2)>::target_type() const
+{
+    return typeid(_Fp);
+}
+
+#endif // _LIBCPP_NO_RTTI
+
+}  // __function
+
+template<class _Rp>
+class _LIBCPP_TEMPLATE_VIS function<_Rp()>
+{
+    typedef __function::__base<_Rp()> __base;
+    aligned_storage<3*sizeof(void*)>::type __buf_;
+    __base* __f_;
+
+public:
+    typedef _Rp result_type;
+
+    // 20.7.16.2.1, construct/copy/destroy:
+    _LIBCPP_INLINE_VISIBILITY explicit function() : __f_(0) {}
+    _LIBCPP_INLINE_VISIBILITY function(nullptr_t) : __f_(0) {}
+    function(const function&);
+    template<class _Fp>
+      function(_Fp,
+               typename enable_if<!is_integral<_Fp>::value>::type* = 0);
+
+    template<class _Alloc>
+      _LIBCPP_INLINE_VISIBILITY
+      function(allocator_arg_t, const _Alloc&) : __f_(0) {}
+    template<class _Alloc>
+      _LIBCPP_INLINE_VISIBILITY
+      function(allocator_arg_t, const _Alloc&, nullptr_t) : __f_(0) {}
+    template<class _Alloc>
+      function(allocator_arg_t, const _Alloc&, const function&);
+    template<class _Fp, class _Alloc>
+      function(allocator_arg_t, const _Alloc& __a, _Fp __f,
+               typename enable_if<!is_integral<_Fp>::value>::type* = 0);
+
+    function& operator=(const function&);
+    function& operator=(nullptr_t);
+    template<class _Fp>
+      typename enable_if
+      <
+        !is_integral<_Fp>::value,
+        function&
+      >::type
+      operator=(_Fp);
+
+    ~function();
+
+    // 20.7.16.2.2, function modifiers:
+    void swap(function&);
+    template<class _Fp, class _Alloc>
+      _LIBCPP_INLINE_VISIBILITY
+      void assign(_Fp __f, const _Alloc& __a)
+        {function(allocator_arg, __a, __f).swap(*this);}
+
+    // 20.7.16.2.3, function capacity:
+    _LIBCPP_INLINE_VISIBILITY explicit operator bool() const {return __f_;}
+
+private:
+    // deleted overloads close possible hole in the type system
+    template<class _R2>
+      bool operator==(const function<_R2()>&) const;// = delete;
+    template<class _R2>
+      bool operator!=(const function<_R2()>&) const;// = delete;
+public:
+    // 20.7.16.2.4, function invocation:
+    _Rp operator()() const;
+
+#ifndef _LIBCPP_NO_RTTI
+    // 20.7.16.2.5, function target access:
+    const std::type_info& target_type() const;
+    template <typename _Tp> _Tp* target();
+    template <typename _Tp> const _Tp* target() const;
+#endif // _LIBCPP_NO_RTTI
+};
+
+template<class _Rp>
+function<_Rp()>::function(const function& __f)
+{
+    if (__f.__f_ == 0)
+        __f_ = 0;
+    else if (__f.__f_ == (const __base*)&__f.__buf_)
+    {
+        __f_ = (__base*)&__buf_;
+        __f.__f_->__clone(__f_);
+    }
+    else
+        __f_ = __f.__f_->__clone();
+}
+
+template<class _Rp>
+template<class _Alloc>
+function<_Rp()>::function(allocator_arg_t, const _Alloc&, const function& __f)
+{
+    if (__f.__f_ == 0)
+        __f_ = 0;
+    else if (__f.__f_ == (const __base*)&__f.__buf_)
+    {
+        __f_ = (__base*)&__buf_;
+        __f.__f_->__clone(__f_);
+    }
+    else
+        __f_ = __f.__f_->__clone();
+}
+
+template<class _Rp>
+template <class _Fp>
+function<_Rp()>::function(_Fp __f,
+                                     typename enable_if<!is_integral<_Fp>::value>::type*)
+    : __f_(0)
+{
+    if (__function::__not_null(__f))
+    {
+        typedef __function::__func<_Fp, allocator<_Fp>, _Rp()> _FF;
+        if (sizeof(_FF) <= sizeof(__buf_))
+        {
+            __f_ = (__base*)&__buf_;
+            ::new ((void*)__f_) _FF(__f);
+        }
+        else
+        {
+            typedef allocator<_FF> _Ap;
+            _Ap __a;
+            typedef __allocator_destructor<_Ap> _Dp;
+            unique_ptr<__base, _Dp> __hold(__a.allocate(1), _Dp(__a, 1));
+            ::new ((void*)__hold.get()) _FF(__f, allocator<_Fp>(__a));
+            __f_ = __hold.release();
+        }
+    }
+}
+
+template<class _Rp>
+template <class _Fp, class _Alloc>
+function<_Rp()>::function(allocator_arg_t, const _Alloc& __a0, _Fp __f,
+                                     typename enable_if<!is_integral<_Fp>::value>::type*)
+    : __f_(0)
+{
+    typedef allocator_traits<_Alloc> __alloc_traits;
+    if (__function::__not_null(__f))
+    {
+        typedef __function::__func<_Fp, _Alloc, _Rp()> _FF;
+        if (sizeof(_FF) <= sizeof(__buf_))
+        {
+            __f_ = (__base*)&__buf_;
+            ::new ((void*)__f_) _FF(__f, __a0);
+        }
+        else
+        {
+            typedef typename __rebind_alloc_helper<__alloc_traits, _FF>::type _Ap;
+            _Ap __a(__a0);
+            typedef __allocator_destructor<_Ap> _Dp;
+            unique_ptr<__base, _Dp> __hold(__a.allocate(1), _Dp(__a, 1));
+            ::new ((void*)__hold.get()) _FF(__f, _Alloc(__a));
+            __f_ = __hold.release();
+        }
+    }
+}
+
+template<class _Rp>
+function<_Rp()>&
+function<_Rp()>::operator=(const function& __f)
+{
+    if (__f)
+        function(__f).swap(*this);
+    else
+        *this = nullptr;
+    return *this;
+}
+
+template<class _Rp>
+function<_Rp()>&
+function<_Rp()>::operator=(nullptr_t)
+{
+    __base* __t = __f_;
+    __f_ = 0;
+    if (__t == (__base*)&__buf_)
+        __t->destroy();
+    else if (__t)
+        __t->destroy_deallocate();
+    return *this;
+}
+
+template<class _Rp>
+template <class _Fp>
+typename enable_if
+<
+    !is_integral<_Fp>::value,
+    function<_Rp()>&
+>::type
+function<_Rp()>::operator=(_Fp __f)
+{
+    function(_VSTD::move(__f)).swap(*this);
+    return *this;
+}
+
+template<class _Rp>
+function<_Rp()>::~function()
+{
+    if (__f_ == (__base*)&__buf_)
+        __f_->destroy();
+    else if (__f_)
+        __f_->destroy_deallocate();
+}
+
+template<class _Rp>
+void
+function<_Rp()>::swap(function& __f)
+{
+    if (_VSTD::addressof(__f) == this)
+      return;
+    if (__f_ == (__base*)&__buf_ && __f.__f_ == (__base*)&__f.__buf_)
+    {
+        typename aligned_storage<sizeof(__buf_)>::type __tempbuf;
+        __base* __t = (__base*)&__tempbuf;
+        __f_->__clone(__t);
+        __f_->destroy();
+        __f_ = 0;
+        __f.__f_->__clone((__base*)&__buf_);
+        __f.__f_->destroy();
+        __f.__f_ = 0;
+        __f_ = (__base*)&__buf_;
+        __t->__clone((__base*)&__f.__buf_);
+        __t->destroy();
+        __f.__f_ = (__base*)&__f.__buf_;
+    }
+    else if (__f_ == (__base*)&__buf_)
+    {
+        __f_->__clone((__base*)&__f.__buf_);
+        __f_->destroy();
+        __f_ = __f.__f_;
+        __f.__f_ = (__base*)&__f.__buf_;
+    }
+    else if (__f.__f_ == (__base*)&__f.__buf_)
+    {
+        __f.__f_->__clone((__base*)&__buf_);
+        __f.__f_->destroy();
+        __f.__f_ = __f_;
+        __f_ = (__base*)&__buf_;
+    }
+    else
+        _VSTD::swap(__f_, __f.__f_);
+}
+
+template<class _Rp>
+_Rp
+function<_Rp()>::operator()() const
+{
+    if (__f_ == 0)
+        __throw_bad_function_call();
+    return (*__f_)();
+}
+
+#ifndef _LIBCPP_NO_RTTI
+
+template<class _Rp>
+const std::type_info&
+function<_Rp()>::target_type() const
+{
+    if (__f_ == 0)
+        return typeid(void);
+    return __f_->target_type();
+}
+
+template<class _Rp>
+template <typename _Tp>
+_Tp*
+function<_Rp()>::target()
+{
+    if (__f_ == 0)
+        return (_Tp*)0;
+    return (_Tp*) const_cast<void *>(__f_->target(typeid(_Tp)));
+}
+
+template<class _Rp>
+template <typename _Tp>
+const _Tp*
+function<_Rp()>::target() const
+{
+    if (__f_ == 0)
+        return (const _Tp*)0;
+    return (const _Tp*)__f_->target(typeid(_Tp));
+}
+
+#endif // _LIBCPP_NO_RTTI
+
+template<class _Rp, class _A0>
+class _LIBCPP_TEMPLATE_VIS function<_Rp(_A0)>
+    : public unary_function<_A0, _Rp>
+{
+    typedef __function::__base<_Rp(_A0)> __base;
+    aligned_storage<3*sizeof(void*)>::type __buf_;
+    __base* __f_;
+
+public:
+    typedef _Rp result_type;
+
+    // 20.7.16.2.1, construct/copy/destroy:
+    _LIBCPP_INLINE_VISIBILITY explicit function() : __f_(0) {}
+    _LIBCPP_INLINE_VISIBILITY function(nullptr_t) : __f_(0) {}
+    function(const function&);
+    template<class _Fp>
+      function(_Fp,
+               typename enable_if<!is_integral<_Fp>::value>::type* = 0);
+
+    template<class _Alloc>
+      _LIBCPP_INLINE_VISIBILITY
+      function(allocator_arg_t, const _Alloc&) : __f_(0) {}
+    template<class _Alloc>
+      _LIBCPP_INLINE_VISIBILITY
+      function(allocator_arg_t, const _Alloc&, nullptr_t) : __f_(0) {}
+    template<class _Alloc>
+      function(allocator_arg_t, const _Alloc&, const function&);
+    template<class _Fp, class _Alloc>
+      function(allocator_arg_t, const _Alloc& __a, _Fp __f,
+               typename enable_if<!is_integral<_Fp>::value>::type* = 0);
+
+    function& operator=(const function&);
+    function& operator=(nullptr_t);
+    template<class _Fp>
+      typename enable_if
+      <
+        !is_integral<_Fp>::value,
+        function&
+      >::type
+      operator=(_Fp);
+
+    ~function();
+
+    // 20.7.16.2.2, function modifiers:
+    void swap(function&);
+    template<class _Fp, class _Alloc>
+      _LIBCPP_INLINE_VISIBILITY
+      void assign(_Fp __f, const _Alloc& __a)
+        {function(allocator_arg, __a, __f).swap(*this);}
+
+    // 20.7.16.2.3, function capacity:
+    _LIBCPP_INLINE_VISIBILITY explicit operator bool() const {return __f_;}
+
+private:
+    // deleted overloads close possible hole in the type system
+    template<class _R2, class _B0>
+      bool operator==(const function<_R2(_B0)>&) const;// = delete;
+    template<class _R2, class _B0>
+      bool operator!=(const function<_R2(_B0)>&) const;// = delete;
+public:
+    // 20.7.16.2.4, function invocation:
+    _Rp operator()(_A0) const;
+
+#ifndef _LIBCPP_NO_RTTI
+    // 20.7.16.2.5, function target access:
+    const std::type_info& target_type() const;
+    template <typename _Tp> _Tp* target();
+    template <typename _Tp> const _Tp* target() const;
+#endif // _LIBCPP_NO_RTTI
+};
+
+template<class _Rp, class _A0>
+function<_Rp(_A0)>::function(const function& __f)
+{
+    if (__f.__f_ == 0)
+        __f_ = 0;
+    else if (__f.__f_ == (const __base*)&__f.__buf_)
+    {
+        __f_ = (__base*)&__buf_;
+        __f.__f_->__clone(__f_);
+    }
+    else
+        __f_ = __f.__f_->__clone();
+}
+
+template<class _Rp, class _A0>
+template<class _Alloc>
+function<_Rp(_A0)>::function(allocator_arg_t, const _Alloc&, const function& __f)
+{
+    if (__f.__f_ == 0)
+        __f_ = 0;
+    else if (__f.__f_ == (const __base*)&__f.__buf_)
+    {
+        __f_ = (__base*)&__buf_;
+        __f.__f_->__clone(__f_);
+    }
+    else
+        __f_ = __f.__f_->__clone();
+}
+
+template<class _Rp, class _A0>
+template <class _Fp>
+function<_Rp(_A0)>::function(_Fp __f,
+                                     typename enable_if<!is_integral<_Fp>::value>::type*)
+    : __f_(0)
+{
+    if (__function::__not_null(__f))
+    {
+        typedef __function::__func<_Fp, allocator<_Fp>, _Rp(_A0)> _FF;
+        if (sizeof(_FF) <= sizeof(__buf_))
+        {
+            __f_ = (__base*)&__buf_;
+            ::new ((void*)__f_) _FF(__f);
+        }
+        else
+        {
+            typedef allocator<_FF> _Ap;
+            _Ap __a;
+            typedef __allocator_destructor<_Ap> _Dp;
+            unique_ptr<__base, _Dp> __hold(__a.allocate(1), _Dp(__a, 1));
+            ::new ((void*)__hold.get()) _FF(__f, allocator<_Fp>(__a));
+            __f_ = __hold.release();
+        }
+    }
+}
+
+template<class _Rp, class _A0>
+template <class _Fp, class _Alloc>
+function<_Rp(_A0)>::function(allocator_arg_t, const _Alloc& __a0, _Fp __f,
+                                     typename enable_if<!is_integral<_Fp>::value>::type*)
+    : __f_(0)
+{
+    typedef allocator_traits<_Alloc> __alloc_traits;
+    if (__function::__not_null(__f))
+    {
+        typedef __function::__func<_Fp, _Alloc, _Rp(_A0)> _FF;
+        if (sizeof(_FF) <= sizeof(__buf_))
+        {
+            __f_ = (__base*)&__buf_;
+            ::new ((void*)__f_) _FF(__f, __a0);
+        }
+        else
+        {
+            typedef typename __rebind_alloc_helper<__alloc_traits, _FF>::type _Ap;
+            _Ap __a(__a0);
+            typedef __allocator_destructor<_Ap> _Dp;
+            unique_ptr<__base, _Dp> __hold(__a.allocate(1), _Dp(__a, 1));
+            ::new ((void*)__hold.get()) _FF(__f, _Alloc(__a));
+            __f_ = __hold.release();
+        }
+    }
+}
+
+template<class _Rp, class _A0>
+function<_Rp(_A0)>&
+function<_Rp(_A0)>::operator=(const function& __f)
+{
+    if (__f)
+        function(__f).swap(*this);
+    else
+        *this = nullptr;
+    return *this;
+}
+
+template<class _Rp, class _A0>
+function<_Rp(_A0)>&
+function<_Rp(_A0)>::operator=(nullptr_t)
+{
+    __base* __t = __f_;
+    __f_ = 0;
+    if (__t == (__base*)&__buf_)
+        __t->destroy();
+    else if (__t)
+        __t->destroy_deallocate();
+    return *this;
+}
+
+template<class _Rp, class _A0>
+template <class _Fp>
+typename enable_if
+<
+    !is_integral<_Fp>::value,
+    function<_Rp(_A0)>&
+>::type
+function<_Rp(_A0)>::operator=(_Fp __f)
+{
+    function(_VSTD::move(__f)).swap(*this);
+    return *this;
+}
+
+template<class _Rp, class _A0>
+function<_Rp(_A0)>::~function()
+{
+    if (__f_ == (__base*)&__buf_)
+        __f_->destroy();
+    else if (__f_)
+        __f_->destroy_deallocate();
+}
+
+template<class _Rp, class _A0>
+void
+function<_Rp(_A0)>::swap(function& __f)
+{
+    if (_VSTD::addressof(__f) == this)
+      return;
+    if (__f_ == (__base*)&__buf_ && __f.__f_ == (__base*)&__f.__buf_)
+    {
+        typename aligned_storage<sizeof(__buf_)>::type __tempbuf;
+        __base* __t = (__base*)&__tempbuf;
+        __f_->__clone(__t);
+        __f_->destroy();
+        __f_ = 0;
+        __f.__f_->__clone((__base*)&__buf_);
+        __f.__f_->destroy();
+        __f.__f_ = 0;
+        __f_ = (__base*)&__buf_;
+        __t->__clone((__base*)&__f.__buf_);
+        __t->destroy();
+        __f.__f_ = (__base*)&__f.__buf_;
+    }
+    else if (__f_ == (__base*)&__buf_)
+    {
+        __f_->__clone((__base*)&__f.__buf_);
+        __f_->destroy();
+        __f_ = __f.__f_;
+        __f.__f_ = (__base*)&__f.__buf_;
+    }
+    else if (__f.__f_ == (__base*)&__f.__buf_)
+    {
+        __f.__f_->__clone((__base*)&__buf_);
+        __f.__f_->destroy();
+        __f.__f_ = __f_;
+        __f_ = (__base*)&__buf_;
+    }
+    else
+        _VSTD::swap(__f_, __f.__f_);
+}
+
+template<class _Rp, class _A0>
+_Rp
+function<_Rp(_A0)>::operator()(_A0 __a0) const
+{
+    if (__f_ == 0)
+        __throw_bad_function_call();
+    return (*__f_)(__a0);
+}
+
+#ifndef _LIBCPP_NO_RTTI
+
+template<class _Rp, class _A0>
+const std::type_info&
+function<_Rp(_A0)>::target_type() const
+{
+    if (__f_ == 0)
+        return typeid(void);
+    return __f_->target_type();
+}
+
+template<class _Rp, class _A0>
+template <typename _Tp>
+_Tp*
+function<_Rp(_A0)>::target()
+{
+    if (__f_ == 0)
+        return (_Tp*)0;
+    return (_Tp*) const_cast<void *>(__f_->target(typeid(_Tp)));
+}
+
+template<class _Rp, class _A0>
+template <typename _Tp>
+const _Tp*
+function<_Rp(_A0)>::target() const
+{
+    if (__f_ == 0)
+        return (const _Tp*)0;
+    return (const _Tp*)__f_->target(typeid(_Tp));
+}
+
+#endif // _LIBCPP_NO_RTTI
+
+template<class _Rp, class _A0, class _A1>
+class _LIBCPP_TEMPLATE_VIS function<_Rp(_A0, _A1)>
+    : public binary_function<_A0, _A1, _Rp>
+{
+    typedef __function::__base<_Rp(_A0, _A1)> __base;
+    aligned_storage<3*sizeof(void*)>::type __buf_;
+    __base* __f_;
+
+public:
+    typedef _Rp result_type;
+
+    // 20.7.16.2.1, construct/copy/destroy:
+    _LIBCPP_INLINE_VISIBILITY explicit function() : __f_(0) {}
+    _LIBCPP_INLINE_VISIBILITY function(nullptr_t) : __f_(0) {}
+    function(const function&);
+    template<class _Fp>
+      function(_Fp,
+               typename enable_if<!is_integral<_Fp>::value>::type* = 0);
+
+    template<class _Alloc>
+      _LIBCPP_INLINE_VISIBILITY
+      function(allocator_arg_t, const _Alloc&) : __f_(0) {}
+    template<class _Alloc>
+      _LIBCPP_INLINE_VISIBILITY
+      function(allocator_arg_t, const _Alloc&, nullptr_t) : __f_(0) {}
+    template<class _Alloc>
+      function(allocator_arg_t, const _Alloc&, const function&);
+    template<class _Fp, class _Alloc>
+      function(allocator_arg_t, const _Alloc& __a, _Fp __f,
+               typename enable_if<!is_integral<_Fp>::value>::type* = 0);
+
+    function& operator=(const function&);
+    function& operator=(nullptr_t);
+    template<class _Fp>
+      typename enable_if
+      <
+        !is_integral<_Fp>::value,
+        function&
+      >::type
+      operator=(_Fp);
+
+    ~function();
+
+    // 20.7.16.2.2, function modifiers:
+    void swap(function&);
+    template<class _Fp, class _Alloc>
+      _LIBCPP_INLINE_VISIBILITY
+      void assign(_Fp __f, const _Alloc& __a)
+        {function(allocator_arg, __a, __f).swap(*this);}
+
+    // 20.7.16.2.3, function capacity:
+    _LIBCPP_INLINE_VISIBILITY explicit operator bool() const {return __f_;}
+
+private:
+    // deleted overloads close possible hole in the type system
+    template<class _R2, class _B0, class _B1>
+      bool operator==(const function<_R2(_B0, _B1)>&) const;// = delete;
+    template<class _R2, class _B0, class _B1>
+      bool operator!=(const function<_R2(_B0, _B1)>&) const;// = delete;
+public:
+    // 20.7.16.2.4, function invocation:
+    _Rp operator()(_A0, _A1) const;
+
+#ifndef _LIBCPP_NO_RTTI
+    // 20.7.16.2.5, function target access:
+    const std::type_info& target_type() const;
+    template <typename _Tp> _Tp* target();
+    template <typename _Tp> const _Tp* target() const;
+#endif // _LIBCPP_NO_RTTI
+};
+
+template<class _Rp, class _A0, class _A1>
+function<_Rp(_A0, _A1)>::function(const function& __f)
+{
+    if (__f.__f_ == 0)
+        __f_ = 0;
+    else if (__f.__f_ == (const __base*)&__f.__buf_)
+    {
+        __f_ = (__base*)&__buf_;
+        __f.__f_->__clone(__f_);
+    }
+    else
+        __f_ = __f.__f_->__clone();
+}
+
+template<class _Rp, class _A0, class _A1>
+template<class _Alloc>
+function<_Rp(_A0, _A1)>::function(allocator_arg_t, const _Alloc&, const function& __f)
+{
+    if (__f.__f_ == 0)
+        __f_ = 0;
+    else if (__f.__f_ == (const __base*)&__f.__buf_)
+    {
+        __f_ = (__base*)&__buf_;
+        __f.__f_->__clone(__f_);
+    }
+    else
+        __f_ = __f.__f_->__clone();
+}
+
+template<class _Rp, class _A0, class _A1>
+template <class _Fp>
+function<_Rp(_A0, _A1)>::function(_Fp __f,
+                                 typename enable_if<!is_integral<_Fp>::value>::type*)
+    : __f_(0)
+{
+    if (__function::__not_null(__f))
+    {
+        typedef __function::__func<_Fp, allocator<_Fp>, _Rp(_A0, _A1)> _FF;
+        if (sizeof(_FF) <= sizeof(__buf_))
+        {
+            __f_ = (__base*)&__buf_;
+            ::new ((void*)__f_) _FF(__f);
+        }
+        else
+        {
+            typedef allocator<_FF> _Ap;
+            _Ap __a;
+            typedef __allocator_destructor<_Ap> _Dp;
+            unique_ptr<__base, _Dp> __hold(__a.allocate(1), _Dp(__a, 1));
+            ::new ((void*)__hold.get()) _FF(__f, allocator<_Fp>(__a));
+            __f_ = __hold.release();
+        }
+    }
+}
+
+template<class _Rp, class _A0, class _A1>
+template <class _Fp, class _Alloc>
+function<_Rp(_A0, _A1)>::function(allocator_arg_t, const _Alloc& __a0, _Fp __f,
+                                 typename enable_if<!is_integral<_Fp>::value>::type*)
+    : __f_(0)
+{
+    typedef allocator_traits<_Alloc> __alloc_traits;
+    if (__function::__not_null(__f))
+    {
+        typedef __function::__func<_Fp, _Alloc, _Rp(_A0, _A1)> _FF;
+        if (sizeof(_FF) <= sizeof(__buf_))
+        {
+            __f_ = (__base*)&__buf_;
+            ::new ((void*)__f_) _FF(__f, __a0);
+        }
+        else
+        {
+            typedef typename __rebind_alloc_helper<__alloc_traits, _FF>::type _Ap;
+            _Ap __a(__a0);
+            typedef __allocator_destructor<_Ap> _Dp;
+            unique_ptr<__base, _Dp> __hold(__a.allocate(1), _Dp(__a, 1));
+            ::new ((void*)__hold.get()) _FF(__f, _Alloc(__a));
+            __f_ = __hold.release();
+        }
+    }
+}
+
+template<class _Rp, class _A0, class _A1>
+function<_Rp(_A0, _A1)>&
+function<_Rp(_A0, _A1)>::operator=(const function& __f)
+{
+    if (__f)
+        function(__f).swap(*this);
+    else
+        *this = nullptr;
+    return *this;
+}
+
+template<class _Rp, class _A0, class _A1>
+function<_Rp(_A0, _A1)>&
+function<_Rp(_A0, _A1)>::operator=(nullptr_t)
+{
+    __base* __t = __f_;
+    __f_ = 0;
+    if (__t == (__base*)&__buf_)
+        __t->destroy();
+    else if (__t)
+        __t->destroy_deallocate();
+    return *this;
+}
+
+template<class _Rp, class _A0, class _A1>
+template <class _Fp>
+typename enable_if
+<
+    !is_integral<_Fp>::value,
+    function<_Rp(_A0, _A1)>&
+>::type
+function<_Rp(_A0, _A1)>::operator=(_Fp __f)
+{
+    function(_VSTD::move(__f)).swap(*this);
+    return *this;
+}
+
+template<class _Rp, class _A0, class _A1>
+function<_Rp(_A0, _A1)>::~function()
+{
+    if (__f_ == (__base*)&__buf_)
+        __f_->destroy();
+    else if (__f_)
+        __f_->destroy_deallocate();
+}
+
+template<class _Rp, class _A0, class _A1>
+void
+function<_Rp(_A0, _A1)>::swap(function& __f)
+{
+    if (_VSTD::addressof(__f) == this)
+      return;
+    if (__f_ == (__base*)&__buf_ && __f.__f_ == (__base*)&__f.__buf_)
+    {
+        typename aligned_storage<sizeof(__buf_)>::type __tempbuf;
+        __base* __t = (__base*)&__tempbuf;
+        __f_->__clone(__t);
+        __f_->destroy();
+        __f_ = 0;
+        __f.__f_->__clone((__base*)&__buf_);
+        __f.__f_->destroy();
+        __f.__f_ = 0;
+        __f_ = (__base*)&__buf_;
+        __t->__clone((__base*)&__f.__buf_);
+        __t->destroy();
+        __f.__f_ = (__base*)&__f.__buf_;
+    }
+    else if (__f_ == (__base*)&__buf_)
+    {
+        __f_->__clone((__base*)&__f.__buf_);
+        __f_->destroy();
+        __f_ = __f.__f_;
+        __f.__f_ = (__base*)&__f.__buf_;
+    }
+    else if (__f.__f_ == (__base*)&__f.__buf_)
+    {
+        __f.__f_->__clone((__base*)&__buf_);
+        __f.__f_->destroy();
+        __f.__f_ = __f_;
+        __f_ = (__base*)&__buf_;
+    }
+    else
+        _VSTD::swap(__f_, __f.__f_);
+}
+
+template<class _Rp, class _A0, class _A1>
+_Rp
+function<_Rp(_A0, _A1)>::operator()(_A0 __a0, _A1 __a1) const
+{
+    if (__f_ == 0)
+        __throw_bad_function_call();
+    return (*__f_)(__a0, __a1);
+}
+
+#ifndef _LIBCPP_NO_RTTI
+
+template<class _Rp, class _A0, class _A1>
+const std::type_info&
+function<_Rp(_A0, _A1)>::target_type() const
+{
+    if (__f_ == 0)
+        return typeid(void);
+    return __f_->target_type();
+}
+
+template<class _Rp, class _A0, class _A1>
+template <typename _Tp>
+_Tp*
+function<_Rp(_A0, _A1)>::target()
+{
+    if (__f_ == 0)
+        return (_Tp*)0;
+    return (_Tp*) const_cast<void *>(__f_->target(typeid(_Tp)));
+}
+
+template<class _Rp, class _A0, class _A1>
+template <typename _Tp>
+const _Tp*
+function<_Rp(_A0, _A1)>::target() const
+{
+    if (__f_ == 0)
+        return (const _Tp*)0;
+    return (const _Tp*)__f_->target(typeid(_Tp));
+}
+
+#endif // _LIBCPP_NO_RTTI
+
+template<class _Rp, class _A0, class _A1, class _A2>
+class _LIBCPP_TEMPLATE_VIS function<_Rp(_A0, _A1, _A2)>
+{
+    typedef __function::__base<_Rp(_A0, _A1, _A2)> __base;
+    aligned_storage<3*sizeof(void*)>::type __buf_;
+    __base* __f_;
+
+public:
+    typedef _Rp result_type;
+
+    // 20.7.16.2.1, construct/copy/destroy:
+    _LIBCPP_INLINE_VISIBILITY explicit function() : __f_(0) {}
+    _LIBCPP_INLINE_VISIBILITY function(nullptr_t) : __f_(0) {}
+    function(const function&);
+    template<class _Fp>
+      function(_Fp,
+               typename enable_if<!is_integral<_Fp>::value>::type* = 0);
+
+    template<class _Alloc>
+      _LIBCPP_INLINE_VISIBILITY
+      function(allocator_arg_t, const _Alloc&) : __f_(0) {}
+    template<class _Alloc>
+      _LIBCPP_INLINE_VISIBILITY
+      function(allocator_arg_t, const _Alloc&, nullptr_t) : __f_(0) {}
+    template<class _Alloc>
+      function(allocator_arg_t, const _Alloc&, const function&);
+    template<class _Fp, class _Alloc>
+      function(allocator_arg_t, const _Alloc& __a, _Fp __f,
+               typename enable_if<!is_integral<_Fp>::value>::type* = 0);
+
+    function& operator=(const function&);
+    function& operator=(nullptr_t);
+    template<class _Fp>
+      typename enable_if
+      <
+        !is_integral<_Fp>::value,
+        function&
+      >::type
+      operator=(_Fp);
+
+    ~function();
+
+    // 20.7.16.2.2, function modifiers:
+    void swap(function&);
+    template<class _Fp, class _Alloc>
+      _LIBCPP_INLINE_VISIBILITY
+      void assign(_Fp __f, const _Alloc& __a)
+        {function(allocator_arg, __a, __f).swap(*this);}
+
+    // 20.7.16.2.3, function capacity:
+    _LIBCPP_INLINE_VISIBILITY explicit operator bool() const {return __f_;}
+
+private:
+    // deleted overloads close possible hole in the type system
+    template<class _R2, class _B0, class _B1, class _B2>
+      bool operator==(const function<_R2(_B0, _B1, _B2)>&) const;// = delete;
+    template<class _R2, class _B0, class _B1, class _B2>
+      bool operator!=(const function<_R2(_B0, _B1, _B2)>&) const;// = delete;
+public:
+    // 20.7.16.2.4, function invocation:
+    _Rp operator()(_A0, _A1, _A2) const;
+
+#ifndef _LIBCPP_NO_RTTI
+    // 20.7.16.2.5, function target access:
+    const std::type_info& target_type() const;
+    template <typename _Tp> _Tp* target();
+    template <typename _Tp> const _Tp* target() const;
+#endif // _LIBCPP_NO_RTTI
+};
+
+template<class _Rp, class _A0, class _A1, class _A2>
+function<_Rp(_A0, _A1, _A2)>::function(const function& __f)
+{
+    if (__f.__f_ == 0)
+        __f_ = 0;
+    else if (__f.__f_ == (const __base*)&__f.__buf_)
+    {
+        __f_ = (__base*)&__buf_;
+        __f.__f_->__clone(__f_);
+    }
+    else
+        __f_ = __f.__f_->__clone();
+}
+
+template<class _Rp, class _A0, class _A1, class _A2>
+template<class _Alloc>
+function<_Rp(_A0, _A1, _A2)>::function(allocator_arg_t, const _Alloc&,
+                                      const function& __f)
+{
+    if (__f.__f_ == 0)
+        __f_ = 0;
+    else if (__f.__f_ == (const __base*)&__f.__buf_)
+    {
+        __f_ = (__base*)&__buf_;
+        __f.__f_->__clone(__f_);
+    }
+    else
+        __f_ = __f.__f_->__clone();
+}
+
+template<class _Rp, class _A0, class _A1, class _A2>
+template <class _Fp>
+function<_Rp(_A0, _A1, _A2)>::function(_Fp __f,
+                                     typename enable_if<!is_integral<_Fp>::value>::type*)
+    : __f_(0)
+{
+    if (__function::__not_null(__f))
+    {
+        typedef __function::__func<_Fp, allocator<_Fp>, _Rp(_A0, _A1, _A2)> _FF;
+        if (sizeof(_FF) <= sizeof(__buf_))
+        {
+            __f_ = (__base*)&__buf_;
+            ::new ((void*)__f_) _FF(__f);
+        }
+        else
+        {
+            typedef allocator<_FF> _Ap;
+            _Ap __a;
+            typedef __allocator_destructor<_Ap> _Dp;
+            unique_ptr<__base, _Dp> __hold(__a.allocate(1), _Dp(__a, 1));
+            ::new ((void*)__hold.get()) _FF(__f, allocator<_Fp>(__a));
+            __f_ = __hold.release();
+        }
+    }
+}
+
+template<class _Rp, class _A0, class _A1, class _A2>
+template <class _Fp, class _Alloc>
+function<_Rp(_A0, _A1, _A2)>::function(allocator_arg_t, const _Alloc& __a0, _Fp __f,
+                                     typename enable_if<!is_integral<_Fp>::value>::type*)
+    : __f_(0)
+{
+    typedef allocator_traits<_Alloc> __alloc_traits;
+    if (__function::__not_null(__f))
+    {
+        typedef __function::__func<_Fp, _Alloc, _Rp(_A0, _A1, _A2)> _FF;
+        if (sizeof(_FF) <= sizeof(__buf_))
+        {
+            __f_ = (__base*)&__buf_;
+            ::new ((void*)__f_) _FF(__f, __a0);
+        }
+        else
+        {
+            typedef typename __rebind_alloc_helper<__alloc_traits, _FF>::type _Ap;
+            _Ap __a(__a0);
+            typedef __allocator_destructor<_Ap> _Dp;
+            unique_ptr<__base, _Dp> __hold(__a.allocate(1), _Dp(__a, 1));
+            ::new ((void*)__hold.get()) _FF(__f, _Alloc(__a));
+            __f_ = __hold.release();
+        }
+    }
+}
+
+template<class _Rp, class _A0, class _A1, class _A2>
+function<_Rp(_A0, _A1, _A2)>&
+function<_Rp(_A0, _A1, _A2)>::operator=(const function& __f)
+{
+    if (__f)
+        function(__f).swap(*this);
+    else
+        *this = nullptr;
+    return *this;
+}
+
+template<class _Rp, class _A0, class _A1, class _A2>
+function<_Rp(_A0, _A1, _A2)>&
+function<_Rp(_A0, _A1, _A2)>::operator=(nullptr_t)
+{
+    __base* __t = __f_;
+    __f_ = 0;
+    if (__t == (__base*)&__buf_)
+        __t->destroy();
+    else if (__t)
+        __t->destroy_deallocate();
+    return *this;
+}
+
+template<class _Rp, class _A0, class _A1, class _A2>
+template <class _Fp>
+typename enable_if
+<
+    !is_integral<_Fp>::value,
+    function<_Rp(_A0, _A1, _A2)>&
+>::type
+function<_Rp(_A0, _A1, _A2)>::operator=(_Fp __f)
+{
+    function(_VSTD::move(__f)).swap(*this);
+    return *this;
+}
+
+template<class _Rp, class _A0, class _A1, class _A2>
+function<_Rp(_A0, _A1, _A2)>::~function()
+{
+    if (__f_ == (__base*)&__buf_)
+        __f_->destroy();
+    else if (__f_)
+        __f_->destroy_deallocate();
+}
+
+template<class _Rp, class _A0, class _A1, class _A2>
+void
+function<_Rp(_A0, _A1, _A2)>::swap(function& __f)
+{
+    if (_VSTD::addressof(__f) == this)
+      return;
+    if (__f_ == (__base*)&__buf_ && __f.__f_ == (__base*)&__f.__buf_)
+    {
+        typename aligned_storage<sizeof(__buf_)>::type __tempbuf;
+        __base* __t = (__base*)&__tempbuf;
+        __f_->__clone(__t);
+        __f_->destroy();
+        __f_ = 0;
+        __f.__f_->__clone((__base*)&__buf_);
+        __f.__f_->destroy();
+        __f.__f_ = 0;
+        __f_ = (__base*)&__buf_;
+        __t->__clone((__base*)&__f.__buf_);
+        __t->destroy();
+        __f.__f_ = (__base*)&__f.__buf_;
+    }
+    else if (__f_ == (__base*)&__buf_)
+    {
+        __f_->__clone((__base*)&__f.__buf_);
+        __f_->destroy();
+        __f_ = __f.__f_;
+        __f.__f_ = (__base*)&__f.__buf_;
+    }
+    else if (__f.__f_ == (__base*)&__f.__buf_)
+    {
+        __f.__f_->__clone((__base*)&__buf_);
+        __f.__f_->destroy();
+        __f.__f_ = __f_;
+        __f_ = (__base*)&__buf_;
+    }
+    else
+        _VSTD::swap(__f_, __f.__f_);
+}
+
+template<class _Rp, class _A0, class _A1, class _A2>
+_Rp
+function<_Rp(_A0, _A1, _A2)>::operator()(_A0 __a0, _A1 __a1, _A2 __a2) const
+{
+    if (__f_ == 0)
+        __throw_bad_function_call();
+    return (*__f_)(__a0, __a1, __a2);
+}
+
+#ifndef _LIBCPP_NO_RTTI
+
+template<class _Rp, class _A0, class _A1, class _A2>
+const std::type_info&
+function<_Rp(_A0, _A1, _A2)>::target_type() const
+{
+    if (__f_ == 0)
+        return typeid(void);
+    return __f_->target_type();
+}
+
+template<class _Rp, class _A0, class _A1, class _A2>
+template <typename _Tp>
+_Tp*
+function<_Rp(_A0, _A1, _A2)>::target()
+{
+    if (__f_ == 0)
+        return (_Tp*)0;
+    return (_Tp*) const_cast<void *>(__f_->target(typeid(_Tp)));
+}
+
+template<class _Rp, class _A0, class _A1, class _A2>
+template <typename _Tp>
+const _Tp*
+function<_Rp(_A0, _A1, _A2)>::target() const
+{
+    if (__f_ == 0)
+        return (const _Tp*)0;
+    return (const _Tp*)__f_->target(typeid(_Tp));
+}
+
+#endif // _LIBCPP_NO_RTTI
+
+template <class _Fp>
+inline _LIBCPP_INLINE_VISIBILITY
+bool
+operator==(const function<_Fp>& __f, nullptr_t) {return !__f;}
+
+template <class _Fp>
+inline _LIBCPP_INLINE_VISIBILITY
+bool
+operator==(nullptr_t, const function<_Fp>& __f) {return !__f;}
+
+template <class _Fp>
+inline _LIBCPP_INLINE_VISIBILITY
+bool
+operator!=(const function<_Fp>& __f, nullptr_t) {return (bool)__f;}
+
+template <class _Fp>
+inline _LIBCPP_INLINE_VISIBILITY
+bool
+operator!=(nullptr_t, const function<_Fp>& __f) {return (bool)__f;}
+
+template <class _Fp>
+inline _LIBCPP_INLINE_VISIBILITY
+void
+swap(function<_Fp>& __x, function<_Fp>& __y)
+{return __x.swap(__y);}
+
+#endif
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // _LIBCPP___FUNCTIONAL_FUNCTION_H