Open-Harbor/osrm-backend
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases 3 Wiki Activity

add a hash combine implementation that has some minor performance guarantees

Browse Source
This commit is contained in:
Dennis Luxen 2014-06-25 18:50:46 +02:00
parent 31fbf99109
commit 2b2ed50721
1 changed files with 29 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

30
Util/StdHashExtensions.h
View File

@ -32,13 +32,41 @@ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#include <functional>
// this is largely inspired by boost's hash combine
template<typename T>
inline void hash_combine(std::size_t &seed, const T& val)
{
seed ^= std::hash<T>()(val) + 0x9e3779b9 + (seed << 6) + (seed >> 2);
}
template<typename T>
inline void hash_val(std::size_t &seed, const T& val)
{
hash_combine(seed, val);
}
template<typename T, typename ... Types>
inline void hash_val(std::size_t &seed, const T& val, const Types& ... args)
{
hash_combine(seed, val);
hash_val(seed, args ...);
}
template<typename ... Types>
inline std::size_t hash_val( const Types&... args)
{
std::size_t seed = 0;
hash_val(seed, args...);
return seed;
}
namespace std
{
template <> struct hash<std::pair<NodeID, NodeID>>
{
size_t operator()(const std::pair<NodeID, NodeID> &pair) const
{
return std::hash<int>()(pair.first) ^ std::hash<int>()(pair.second);
return hash_val(pair.first, pair.second);
}
};
}