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