nerdcruft/libcruft-util
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point: make distance metrics constexpr

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This commit is contained in:
Danny Robson 2015-09-15 21:06:43 +10:00
parent 95e5fc5834
commit 21b51a5011
2 changed files with 13 additions and 9 deletions
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8
point.hpp
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@ -45,16 +45,16 @@ namespace util {
// distance operators // distance operators
template <size_t S, typename T, typename U> template <size_t S, typename T, typename U>
typename std::common_type<T,U>::type distance (point<S,T>, point<S,U>); constexpr typename std::common_type<T,U>::type distance (point<S,T>, point<S,U>);
template <size_t S, typename T, typename U> template <size_t S, typename T, typename U>
typename std::common_type<T,U>::type distance2 (point<S,T>, point<S,U>); constexpr typename std::common_type<T,U>::type distance2 (point<S,T>, point<S,U>);
template <size_t S, typename T, typename U> template <size_t S, typename T, typename U>
typename std::common_type<T,U>::type manhattan (point<S,T>, point<S,U>); constexpr typename std::common_type<T,U>::type manhattan (point<S,T>, point<S,U>);
template <size_t S, typename T, typename U> template <size_t S, typename T, typename U>
typename std::common_type<T,U>::type chebyshev (point<S,T>, point<S,U>); constexpr typename std::common_type<T,U>::type chebyshev (point<S,T>, point<S,U>);
// iostream operators // iostream operators
template <size_t S, typename T> template <size_t S, typename T>

14
point.ipp
View File

@ -48,16 +48,20 @@ namespace util {
//------------------------------------------------------------------------- //-------------------------------------------------------------------------
template <size_t S, typename T, typename U> template <size_t S, typename T, typename U>
typename std::common_type<T,U>::type constexpr typename std::common_type<T,U>::type
distance (point<S,T> a, point<S,U> b) distance (point<S,T> a, point<S,U> b)
{ {
using type_t = typename std::common_type<T,U>::type;
static_assert (std::is_floating_point<type_t>::value,
"sqrt likely requires fractional types");
return std::sqrt (distance2 (a, b)); return std::sqrt (distance2 (a, b));
} }
//------------------------------------------------------------------------- //-------------------------------------------------------------------------
template <size_t S, typename T, typename U> template <size_t S, typename T, typename U>
typename std::common_type<T,U>::type constexpr typename std::common_type<T,U>::type
distance2 (point<S,T> a, point<S,U> b) distance2 (point<S,T> a, point<S,U> b)
{ {
typename std::common_type<T,U>::type sum {0}; typename std::common_type<T,U>::type sum {0};
@ -71,13 +75,13 @@ namespace util {
//------------------------------------------------------------------------- //-------------------------------------------------------------------------
template <size_t S, typename T, typename U> template <size_t S, typename T, typename U>
typename std::common_type<T,U>::type constexpr typename std::common_type<T,U>::type
manhattan (point<S,T> a, point<S,U> b) manhattan (point<S,T> a, point<S,U> b)
{ {
typename std::common_type<T,U>::type sum {0}; typename std::common_type<T,U>::type sum {0};
for (size_t i = 0; i < S; ++i) for (size_t i = 0; i < S; ++i)
sum += std::abs (a.data[i] - b.data[i]); sum += util::abs (a.data[i] - b.data[i]);
return sum; return sum;
} }
@ -85,7 +89,7 @@ namespace util {
//------------------------------------------------------------------------- //-------------------------------------------------------------------------
template <size_t S, typename T, typename U> template <size_t S, typename T, typename U>
typename std::common_type<T,U>::type constexpr typename std::common_type<T,U>::type
chebyshev(point<S,T> a, point<S,U> b) chebyshev(point<S,T> a, point<S,U> b)
{ {
return util::max (abs (a - b)); return util::max (abs (a - b));