| // RUN: %clang_cc1 -std=c++11 -fsyntax-only -verify %s |
| // expected-no-diagnostics |
| |
| // Example bind implementation from the variadic templates proposal, |
| // ISO C++ committee document number N2080. |
| |
| // Helper type traits |
| template<typename T> |
| struct add_reference { |
| typedef T &type; |
| }; |
| |
| template<typename T> |
| struct add_reference<T&> { |
| typedef T &type; |
| }; |
| |
| template<typename T> |
| struct add_const_reference { |
| typedef T const &type; |
| }; |
| |
| template<typename T> |
| struct add_const_reference<T&> { |
| typedef T &type; |
| }; |
| |
| template<typename T, typename U> |
| struct is_same { |
| static const bool value = false; |
| }; |
| |
| template<typename T> |
| struct is_same<T, T> { |
| static const bool value = true; |
| }; |
| |
| template<typename T> |
| class reference_wrapper { |
| T *ptr; |
| |
| public: |
| reference_wrapper(T& t) : ptr(&t) { } |
| operator T&() const { return *ptr; } |
| }; |
| |
| template<typename T> reference_wrapper<T> ref(T& t) { |
| return reference_wrapper<T>(t); |
| } |
| template<typename T> reference_wrapper<const T> cref(const T& t) { |
| return reference_wrapper<const T>(t); |
| } |
| |
| template<typename... Values> class tuple; |
| |
| // Basis case: zero-length tuple |
| template<> class tuple<> { }; |
| |
| template<typename Head, typename... Tail> |
| class tuple<Head, Tail...> : private tuple<Tail...> { |
| typedef tuple<Tail...> inherited; |
| |
| public: |
| tuple() { } |
| // implicit copy-constructor is okay |
| |
| // Construct tuple from separate arguments. |
| tuple(typename add_const_reference<Head>::type v, |
| typename add_const_reference<Tail>::type... vtail) |
| : m_head(v), inherited(vtail...) { } |
| |
| // Construct tuple from another tuple. |
| template<typename... VValues> tuple(const tuple<VValues...>& other) |
| : m_head(other.head()), inherited(other.tail()) { } |
| |
| template<typename... VValues> tuple& |
| operator=(const tuple<VValues...>& other) { |
| m_head = other.head(); |
| tail() = other.tail(); |
| return *this; |
| } |
| |
| typename add_reference<Head>::type head() { return m_head; } |
| typename add_reference<const Head>::type head() const { return m_head; } |
| inherited& tail() { return *this; } |
| const inherited& tail() const { return *this; } |
| |
| protected: |
| Head m_head; |
| }; |
| |
| // Creation functions |
| template<typename T> |
| struct make_tuple_result { |
| typedef T type; |
| }; |
| |
| template<typename T> |
| struct make_tuple_result<reference_wrapper<T> > { |
| typedef T& type; |
| }; |
| |
| template<typename... Values> |
| tuple<typename make_tuple_result<Values>::type...> |
| make_tuple(const Values&... values) { |
| return tuple<typename make_tuple_result<Values>::type...>(values...); |
| } |
| |
| template<typename... Values> |
| tuple<Values&...> tie(Values&... values) { |
| return tuple<Values&...>(values...); |
| } |
| |
| // Helper classes |
| template<typename Tuple> struct tuple_size; |
| |
| template<typename... Values> struct tuple_size<tuple<Values...> > { |
| static const int value = sizeof...(Values); |
| }; |
| |
| template<int I, typename Tuple> struct tuple_element; |
| |
| template<int I, typename Head, typename... Tail> |
| struct tuple_element<I, tuple<Head, Tail...> > { |
| typedef typename tuple_element<I-1, tuple<Tail...> >::type type; |
| }; |
| |
| template<typename Head, typename... Tail> |
| struct tuple_element<0, tuple<Head, Tail...> > { |
| typedef Head type; |
| }; |
| |
| // Element access |
| template<int I, typename Tuple> class get_impl; |
| template<int I, typename Head, typename... Values> |
| class get_impl<I, tuple<Head, Values...> > { |
| typedef typename tuple_element<I-1, tuple<Values...> >::type Element; |
| typedef typename add_reference<Element>::type RJ; |
| typedef typename add_const_reference<Element>::type PJ; |
| typedef get_impl<I-1, tuple<Values...> > Next; |
| public: |
| static RJ get(tuple<Head, Values...>& t) { return Next::get(t.tail()); } |
| static PJ get(const tuple<Head, Values...>& t) { return Next::get(t.tail()); } |
| }; |
| |
| template<typename Head, typename... Values> |
| class get_impl<0, tuple<Head, Values...> > { |
| typedef typename add_reference<Head>::type RJ; |
| typedef typename add_const_reference<Head>::type PJ; |
| public: |
| static RJ get(tuple<Head, Values...>& t) { return t.head(); } |
| static PJ get(const tuple<Head, Values...>& t) { return t.head(); } |
| }; |
| |
| template<int I, typename... Values> typename add_reference< |
| typename tuple_element<I, tuple<Values...> >::type >::type |
| get(tuple<Values...>& t) { |
| return get_impl<I, tuple<Values...> >::get(t); |
| } |
| |
| template<int I, typename... Values> typename add_const_reference< |
| typename tuple_element<I, tuple<Values...> >::type >::type |
| get(const tuple<Values...>& t) { |
| return get_impl<I, tuple<Values...> >::get(t); |
| } |
| |
| // Relational operators |
| inline bool operator==(const tuple<>&, const tuple<>&) { return true; } |
| |
| template<typename T, typename... TTail, typename U, typename... UTail> |
| bool operator==(const tuple<T, TTail...>& t, const tuple<U, UTail...>& u) { |
| return t.head() == u.head() && t.tail() == u.tail(); |
| } |
| |
| template<typename... TValues, typename... UValues> |
| bool operator!=(const tuple<TValues...>& t, const tuple<UValues...>& u) { |
| return !(t == u); |
| } |
| |
| inline bool operator<(const tuple<>&, const tuple<>&) { return false; } |
| |
| template<typename T, typename... TTail, typename U, typename... UTail> |
| bool operator<(const tuple<T, TTail...>& t, const tuple<U, UTail...>& u) { |
| return (t.head() < u.head() || (!(t.head() < u.head()) && t.tail() < u.tail())); |
| } |
| |
| template<typename... TValues, typename... UValues> |
| bool operator>(const tuple<TValues...>& t, const tuple<UValues...>& u) { |
| return u < t; |
| } |
| |
| template<typename... TValues, typename... UValues> |
| bool operator<=(const tuple<TValues...>& t, const tuple<UValues...>& u) { |
| return !(u < t); |
| } |
| |
| template<typename... TValues, typename... UValues> |
| bool operator>=(const tuple<TValues...>& t, const tuple<UValues...>& u) { |
| return !(t < u); |
| } |
| |
| // make_indices helper |
| template<int...> struct int_tuple {}; |
| // make_indexes impl is a helper for make_indexes |
| template<int I, typename IntTuple, typename... Types> struct make_indexes_impl; |
| |
| template<int I, int... Indexes, typename T, typename... Types> |
| struct make_indexes_impl<I, int_tuple<Indexes...>, T, Types...> { |
| typedef typename make_indexes_impl<I+1, int_tuple<Indexes..., I>, Types...>::type type; |
| }; |
| |
| template<int I, int... Indexes> |
| struct make_indexes_impl<I, int_tuple<Indexes...> > { |
| typedef int_tuple<Indexes...> type; |
| }; |
| |
| template<typename... Types> |
| struct make_indexes : make_indexes_impl<0, int_tuple<>, Types...> { |
| }; |
| |
| // Bind |
| template<typename T> struct is_bind_expression { |
| static const bool value = false; |
| }; |
| |
| template<typename T> struct is_placeholder { |
| static const int value = 0; |
| }; |
| |
| |
| template<typename F, typename... BoundArgs> class bound_functor { |
| typedef typename make_indexes<BoundArgs...>::type indexes; |
| public: |
| typedef typename F::result_type result_type; |
| explicit bound_functor(const F& f, const BoundArgs&... bound_args) |
| : f(f), bound_args(bound_args...) { } template<typename... Args> |
| typename F::result_type operator()(Args&... args); |
| private: F f; |
| tuple<BoundArgs...> bound_args; |
| }; |
| |
| template<typename F, typename... BoundArgs> |
| inline bound_functor<F, BoundArgs...> bind(const F& f, const BoundArgs&... bound_args) { |
| return bound_functor<F, BoundArgs...>(f, bound_args...); |
| } |
| |
| template<typename F, typename ...BoundArgs> |
| struct is_bind_expression<bound_functor<F, BoundArgs...> > { |
| static const bool value = true; |
| }; |
| |
| // enable_if helper |
| template<bool Cond, typename T = void> |
| struct enable_if; |
| |
| template<typename T> |
| struct enable_if<true, T> { |
| typedef T type; |
| }; |
| |
| template<typename T> |
| struct enable_if<false, T> { }; |
| |
| // safe_tuple_element helper |
| template<int I, typename Tuple, typename = void> |
| struct safe_tuple_element { }; |
| |
| template<int I, typename... Values> |
| struct safe_tuple_element<I, tuple<Values...>, |
| typename enable_if<(I >= 0 && I < tuple_size<tuple<Values...> >::value)>::type> { |
| typedef typename tuple_element<I, tuple<Values...> >::type type; |
| }; |
| |
| // mu |
| template<typename Bound, typename... Args> |
| inline typename safe_tuple_element<is_placeholder<Bound>::value -1, |
| tuple<Args...> >::type |
| mu(Bound& bound_arg, const tuple<Args&...>& args) { |
| return get<is_placeholder<Bound>::value-1>(args); |
| } |
| |
| template<typename T, typename... Args> |
| inline T& mu(reference_wrapper<T>& bound_arg, const tuple<Args&...>&) { |
| return bound_arg.get(); |
| } |
| |
| template<typename F, int... Indexes, typename... Args> |
| inline typename F::result_type |
| unwrap_and_forward(F& f, int_tuple<Indexes...>, const tuple<Args&...>& args) { |
| return f(get<Indexes>(args)...); |
| } |
| |
| template<typename Bound, typename... Args> |
| inline typename enable_if<is_bind_expression<Bound>::value, |
| typename Bound::result_type>::type |
| mu(Bound& bound_arg, const tuple<Args&...>& args) { |
| typedef typename make_indexes<Args...>::type Indexes; |
| return unwrap_and_forward(bound_arg, Indexes(), args); |
| } |
| |
| template<typename T> |
| struct is_reference_wrapper { |
| static const bool value = false; |
| }; |
| |
| template<typename T> |
| struct is_reference_wrapper<reference_wrapper<T>> { |
| static const bool value = true; |
| }; |
| |
| template<typename Bound, typename... Args> |
| inline typename enable_if<(!is_bind_expression<Bound>::value |
| && !is_placeholder<Bound>::value |
| && !is_reference_wrapper<Bound>::value), |
| Bound&>::type |
| mu(Bound& bound_arg, const tuple<Args&...>&) { |
| return bound_arg; |
| } |
| |
| template<typename F, typename... BoundArgs, int... Indexes, typename... Args> |
| typename F::result_type apply_functor(F& f, tuple<BoundArgs...>& bound_args, |
| int_tuple<Indexes...>, |
| const tuple<Args&...>& args) { |
| return f(mu(get<Indexes>(bound_args), args)...); |
| } |
| |
| template<typename F, typename... BoundArgs> |
| template<typename... Args> |
| typename F::result_type bound_functor<F, BoundArgs...>::operator()(Args&... args) { |
| return apply_functor(f, bound_args, indexes(), tie(args...)); |
| } |
| |
| template<int N> struct placeholder { }; |
| template<int N> |
| struct is_placeholder<placeholder<N>> { |
| static const int value = N; |
| }; |
| |
| template<typename T> |
| struct plus { |
| typedef T result_type; |
| |
| T operator()(T x, T y) { return x + y; } |
| }; |
| |
| placeholder<1> _1; |
| |
| // Test bind |
| void test_bind() { |
| int x = 17; |
| int y = 25; |
| bind(plus<int>(), x, _1)(y); |
| } |
