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// RUN: %clang_cc1 -std=c++11 -fsyntax-only -verify %s
// This is a collection of various template metafunctions involving
// variadic templates, which are meant to exercise common use cases.
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...> struct tuple { };
template<int ...> struct int_tuple { };
template<typename T, typename U> struct pair { };
namespace Count {
template<typename Head, typename ...Tail>
struct count {
static const unsigned value = 1 + count<Tail...>::value;
};
template<typename T>
struct count<T> {
static const unsigned value = 1;
};
int check1[count<int>::value == 1? 1 : -1];
int check2[count<float, double>::value == 2? 1 : -1];
int check3[count<char, signed char, unsigned char>::value == 3? 1 : -1];
}
namespace CountWithPackExpansion {
template<typename ...> struct count;
template<typename Head, typename ...Tail>
struct count<Head, Tail...> {
static const unsigned value = 1 + count<Tail...>::value;
};
template<>
struct count<> {
static const unsigned value = 0;
};
int check0[count<>::value == 0? 1 : -1];
int check1[count<int>::value == 1? 1 : -1];
int check2[count<float, double>::value == 2? 1 : -1];
int check3[count<char, signed char, unsigned char>::value == 3? 1 : -1];
}
namespace Replace {
// Simple metafunction that replaces the template arguments of
// template template parameters with 'int'.
template<typename T>
struct EverythingToInt;
template<template<typename ...> class TT, typename T1, typename T2>
struct EverythingToInt<TT<T1, T2> > {
typedef TT<int, int> type;
};
int check0[is_same<EverythingToInt<tuple<double, float>>::type,
tuple<int, int>>::value? 1 : -1];
}
namespace Math {
template<int ...Values>
struct double_values {
typedef int_tuple<Values*2 ...> type;
};
int check0[is_same<double_values<1, 2, -3>::type,
int_tuple<2, 4, -6>>::value? 1 : -1];
template<int ...Values>
struct square {
typedef int_tuple<(Values*Values)...> type;
};
int check1[is_same<square<1, 2, -3>::type,
int_tuple<1, 4, 9>>::value? 1 : -1];
template<typename IntTuple> struct square_tuple;
template<int ...Values>
struct square_tuple<int_tuple<Values...>> {
typedef int_tuple<(Values*Values)...> type;
};
int check2[is_same<square_tuple<int_tuple<1, 2, -3> >::type,
int_tuple<1, 4, 9>>::value? 1 : -1];
template<int ...Values> struct sum;
template<int First, int ...Rest>
struct sum<First, Rest...> {
static const int value = First + sum<Rest...>::value;
};
template<>
struct sum<> {
static const int value = 0;
};
int check3[sum<1, 2, 3, 4, 5>::value == 15? 1 : -1];
template<int ... Values>
struct lazy_sum {
int operator()() {
return sum<Values...>::value;
}
};
void f() {
lazy_sum<1, 2, 3, 4, 5>()();
}
}
namespace ListMath {
template<typename T, T ... V> struct add;
template<typename T, T i, T ... V>
struct add<T, i, V...> {
static const T value = i + add<T, V...>::value;
};
template<typename T>
struct add<T> {
static const T value = T();
};
template<typename T, T ... V>
struct List {
struct sum {
static const T value = add<T, V...>::value;
};
};
template<int ... V>
struct ListI : public List<int, V...> {
};
int check0[ListI<1, 2, 3>::sum::value == 6? 1 : -1];
}
namespace Indices {
template<unsigned I, unsigned N, typename IntTuple>
struct build_indices_impl;
template<unsigned I, unsigned N, int ...Indices>
struct build_indices_impl<I, N, int_tuple<Indices...> >
: build_indices_impl<I+1, N, int_tuple<Indices..., I> > {
};
template<unsigned N, int ...Indices>
struct build_indices_impl<N, N, int_tuple<Indices...> > {
typedef int_tuple<Indices...> type;
};
template<unsigned N>
struct build_indices : build_indices_impl<0, N, int_tuple<> > { };
int check0[is_same<build_indices<5>::type,
int_tuple<0, 1, 2, 3, 4>>::value? 1 : -1];
}
namespace TemplateTemplateApply {
template<typename T, template<class> class ...Meta>
struct apply_each {
typedef tuple<typename Meta<T>::type...> type;
};
template<typename T>
struct add_reference {
typedef T& type;
};
template<typename T>
struct add_pointer {
typedef T* type;
};
template<typename T>
struct add_const {
typedef const T type;
};
int check0[is_same<apply_each<int,
add_reference, add_pointer, add_const>::type,
tuple<int&, int*, int const>>::value? 1 : -1];
template<typename T, template<class> class ...Meta>
struct apply_each_indirect {
typedef typename apply_each<T, Meta...>::type type;
};
int check1[is_same<apply_each_indirect<int, add_reference, add_pointer,
add_const>::type,
tuple<int&, int*, int const>>::value? 1 : -1];
template<typename T, typename ...Meta>
struct apply_each_nested {
typedef typename apply_each<T, Meta::template apply...>::type type;
};
struct add_reference_meta {
template<typename T>
struct apply {
typedef T& type;
};
};
struct add_pointer_meta {
template<typename T>
struct apply {
typedef T* type;
};
};
struct add_const_meta {
template<typename T>
struct apply {
typedef const T type;
};
};
int check2[is_same<apply_each_nested<int, add_reference_meta,
add_pointer_meta, add_const_meta>::type,
tuple<int&, int*, int const>>::value? 1 : -1];
}
namespace FunctionTypes {
template<typename FunctionType>
struct Arity;
template<typename R, typename ...Types>
struct Arity<R(Types...)> {
static const unsigned value = sizeof...(Types);
};
template<typename R, typename ...Types>
struct Arity<R(Types......)> {
static const unsigned value = sizeof...(Types);
};
template<typename R, typename T1, typename T2, typename T3, typename T4>
struct Arity<R(T1, T2, T3, T4)>; // expected-note{{template is declared here}}
int check0[Arity<int()>::value == 0? 1 : -1];
int check1[Arity<int(float, double)>::value == 2? 1 : -1];
int check2[Arity<int(float...)>::value == 1? 1 : -1];
int check3[Arity<int(float, double, long double...)>::value == 3? 1 : -1];
Arity<int(float, double, long double, char)> check4; // expected-error{{implicit instantiation of undefined template 'FunctionTypes::Arity<int (float, double, long double, char)>'}}
}
namespace SuperReplace {
template<typename T>
struct replace_with_int {
typedef int type;
};
template<template<typename ...> class TT, typename ...Types>
struct replace_with_int<TT<Types...>> {
typedef TT<typename replace_with_int<Types>::type...> type;
};
int check0[is_same<replace_with_int<pair<tuple<float, double, short>,
pair<char, unsigned char>>>::type,
pair<tuple<int, int, int>, pair<int, int>>>::value? 1 : -1];
}
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