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niha/split_at.cpp

Created September 7, 2010 16:43
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split_at.cpp
#include <cstdio>
template <typename... seq>
struct array;
template <typename ary>
struct head;
template <typename first, typename... rest>
struct head<array<first, rest...>> {
typedef first type;
};
template <typename lhs, typename rhs>
struct append;
template <typename... lhs, typename... rhs>
struct append<array<lhs...>, array<rhs...>> {
typedef array<lhs..., rhs...> type;
};
template <typename ary, int n>
struct split_at;
template <typename ary>
struct split_at<ary, 0> {
typedef array<> front;
typedef ary back;
};
template <typename head, typename... tail>
struct split_at<array<head, tail...>, 1> {
typedef array<head> front;
typedef array<tail...> back;
};
template <typename... seq, int n>
struct split_at<array<seq...>, n> {
static const int lhs_len = n / 2;
static const int rhs_len = n - lhs_len;
typedef split_at<array<seq...>, lhs_len> lhs;
typedef typename lhs::front lhs_front;
typedef typename lhs::back lhs_back;
typedef split_at<lhs_back, rhs_len> rhs;
typedef typename rhs::front rhs_front;
typedef typename rhs::back rhs_back;
typedef typename append<lhs_front, rhs_front>::type front;
typedef rhs_back back;
};
template <typename T, int size>
struct fill;
template <typename T>
struct fill<T, 0> {
typedef array<> type;
};
template <typename T>
struct fill<T, 1> {
typedef array<T> type;
};
template <typename T, int size>
struct fill {
static const int lhs_size = size / 2;
static const int rhs_size = size - lhs_size;
typedef typename fill<T, lhs_size>::type lhs;
typedef typename fill<T, rhs_size>::type rhs;
typedef typename append<lhs, rhs>::type type;
};
typedef
typename fill<int, 1024>::type
tmp;
typedef
typename append<tmp, array<double>>::type
tmp_;
typedef
typename split_at<tm_, 1024>::back
tmp__;
typedef
typename head<tmp__>::type
should_double;
int main(){
should_double d = 1.0;
printf("%lf\n", d);
return 0;
}
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