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// RUN: %clang_cc1 -std=c++0x -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 { };
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 Multiply {
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];
}
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];
}
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