Viewing file:  variadic-lambda.C (1.79 KB) -rw-r--r--
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// { dg-do compile { target c++11 } }
struct int_placeholder;
template<typename T>
struct do_replace
{
typedef T type;
};
template<>
struct do_replace<int_placeholder>
{
typedef int type;
};
template<typename T> struct lambdalike
{
typedef T type;
};
template<template<typename...> class TT, typename... Args>
struct lambdalike<TT<Args...> > {
typedef TT<typename do_replace<Args>::type...> 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... Elements> struct tuple;
template<typename T1, typename T2> struct pair;
static_assert(is_same<lambdalike<tuple<float, int_placeholder, double>>::type,
tuple<float, int, double>>::value,
"MPL lambda-like replacement on tuple");
static_assert(is_same<lambdalike<pair<float, int_placeholder>>::type,
pair<float, int>>::value,
"MPL lambda-like replacement on pair");
struct _1 {};
template<typename Arg0, typename Lambda>
struct eval
{
typedef Lambda type;
};
template<typename Arg0>
struct eval<Arg0, _1>
{
typedef Arg0 type;
};
template<typename Arg0, template<typename...> class T, typename... Pack>
struct eval<Arg0, T<Pack...> >
{
typedef T< typename eval<Arg0, Pack>::type... > type;
};
static_assert(is_same<eval<int, tuple<float, _1, double>>::type,
tuple<float, int, double>>::value, "eval tuple");
static_assert(is_same<eval<int, pair<_1, double>>::type,
pair<int, double>>::value, "eval pair");
static_assert(is_same<eval<int,
tuple<pair<_1, _1>, pair<float, float>,
pair<double, _1>>>::type,
tuple<pair<int, int>, pair<float, float>, pair<double, int>>>::value,
"recursive eval");
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