Mercurial > hg > CbC > CbC_gcc
view gcc/testsuite/g++.dg/cpp0x/variadic-bind.C @ 131:84e7813d76e9
gcc-8.2
author | mir3636 |
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date | Thu, 25 Oct 2018 07:37:49 +0900 |
parents | 04ced10e8804 |
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// { dg-do run { target c++11 } } // A basic implementation of TR1's bind using variadic teplates // Contributed by Douglas Gregor <doug.gregor@gmail.com> #include <cassert> // Trivial reference_wrapper template<typename T> struct reference_wrapper { reference_wrapper(T& x) : ptr(&x) { } operator T&() const { return *ptr; } T& get() const { return *ptr; } T* ptr; }; template<typename T> reference_wrapper<T> ref(T& x) { return x; } template<typename T> reference_wrapper<const T> cref(const T& x) { return x; } // Simple type-traits we'll need template<typename T> struct add_reference { typedef T& type; }; template<typename T> struct add_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; }; // For creating the constructor parameters of tuple<> template<typename T> struct add_const_reference { typedef const T& type; }; template<typename T> struct add_const_reference<T&> { typedef T& type; }; // 6.1.3 Class template tuple: Needed for bind() implementation template<typename... Values> class 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 tuple(typename add_const_reference<Head>::type v, typename add_const_reference<Tail>::type... vtail) : m_head(v), inherited(vtail...) { } 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; }; template<typename T> struct make_tuple_result { typedef T type; }; template<typename T> struct make_tuple_result<reference_wrapper<T> > { typedef T& type; }; // 6.1.3.2 Tuple creation functions struct ignore_t { template<typename T> ignore_t& operator=(const T&) { return *this; } } ignore; 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...); } // 6.1.3.3 Tuple helper classes template<typename Tuple> struct tuple_size; template<> struct tuple_size<tuple<> > { static const __SIZE_TYPE__ value = 0; }; template<typename Head, typename... Tail> struct tuple_size<tuple<Head, Tail...> > { static const __SIZE_TYPE__ value = 1 + tuple_size<tuple<Tail...> >::value; }; 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; }; // 6.1.3.4 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); } // 6.1.3.5 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); } // enable_if, the breakfast of champions template<bool Cond, typename Type = void> struct enable_if { typedef Type type; }; template<typename Type> struct enable_if<false, Type> { }; // 3.6 Function object binders // 3.6.1 Class template is_bind_expression template<typename T> struct is_bind_expression { static const bool value = false; }; // 3.6.2 Class template is_placeholder template<typename T> struct is_placeholder { static const int value = 0; }; // 3.6.3 Function template bind template<int I> struct placeholder {} ; template<int N> struct int_c { }; // A tuple of integer values 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; }; // make_indexes takes a variable-length number of N types and // generates an int_tuple that contains <0, 1, 2, ..., N-1>. These can // be used as indexes for tuple's get or tuple_element operation. template<typename... Types> struct make_indexes : make_indexes_impl<0, int_tuple<>, Types...> { }; // Get the Ith tuple element, but only if I is in bounds. 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 maps a bound argument to an actual argument, given a tuple of // the arguments passed to the function object returned by bind(). // Return the stored reference from reference_wrapper template<typename T, typename... Args> inline T& mu(reference_wrapper<T>& bound_arg, const tuple<Args&...>&) { return bound_arg.get(); } // Unwrap a tuple into separate arguments and forward to the function // object f. 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)...); } // Evaluate the inner bind expression 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); } // Retrieve the Ith argument from args 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); } // Return the stored value. 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> 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) { return apply_functor(f, bound_args, indexes(), tie(args...)); } private: F f; tuple<BoundArgs...> bound_args; }; template<typename F, typename... BoundArgs> struct is_bind_expression<bound_functor<F, BoundArgs...> > { static const bool value = true; }; 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...); } // 3.6.4 Placeholders template<int I> struct is_placeholder<placeholder<I> > { static const int value = I; }; placeholder<1> _1; placeholder<2> _2; placeholder<3> _3; placeholder<4> _4; placeholder<5> _5; placeholder<6> _6; placeholder<7> _7; placeholder<8> _8; placeholder<9> _9; // Test code template<typename T> struct plus { typedef T result_type; T operator()(T x, T y) { return x + y; } }; template<typename T> struct multiplies { typedef T result_type; T operator()(T x, T y) { return x * y; } }; template<typename T> struct negate { typedef T result_type; T operator()(T x) { return -x; } }; int main() { int seventeen = 17; int forty_two = 42; assert(bind(plus<int>(), _1, _2)(seventeen, forty_two) == 59); assert(bind(plus<int>(), _1, _1)(seventeen, forty_two) == 34); assert(bind(plus<int>(), _2, _1)(seventeen, forty_two) == 59); assert(bind(plus<int>(), 5, _1)(seventeen, forty_two) == 22); assert(bind(plus<int>(), ref(seventeen), _2)(seventeen, forty_two) == 59); assert(bind(plus<int>(), bind(multiplies<int>(), 3, _1), _2)(seventeen, forty_two) == 93); return 0; }