exercism-solutions/cpp/grains/grains.cpp

56 lines
989 B
C++

#include "grains.h"
#include <limits>
#include <stdexcept>
namespace grains {
using namespace std;
namespace {
static const index_t number_of_squares = 64;
template <typename T>
struct total_as_max
{
static inline T total()
{
return numeric_limits<T>::max();
}
};
template <typename T>
struct total_by_shift
{
static inline T total()
{
return T(1) << number_of_squares - 1;
}
};
static_assert(number_of_squares <= numeric_limits<ulong_t>::digits,
"grains::ulong_t is too small for grains::total");
typedef conditional<number_of_squares == numeric_limits<ulong_t>::digits,
total_as_max<ulong_t>,
total_by_shift<ulong_t>>::type total_policy_t;
}
ulong_t square(index_t index)
{
if (index < 1 || index > number_of_squares)
throw domain_error("invalid square number");
return ulong_t(1) << (index - 1);
}
ulong_t total()
{
return total_policy_t::total();
}
}