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improve hash calc ref #3406

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This commit is contained in:
artemp 2016-04-26 15:29:27 +02:00
parent 4b3b62a40c
commit 31e8cfc659
1 changed files with 10 additions and 6 deletions
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16
include/mapnik/value_hash.hpp
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@ -26,22 +26,20 @@
// mapnik
#include <mapnik/util/variant.hpp>
#include <mapnik/value_types.hpp>
// stl
#include <functional>
#pragma GCC diagnostic push
#include <mapnik/warning_ignore.hpp>
#include <unicode/unistr.h>
#pragma GCC diagnostic pop
namespace mapnik { namespace detail {
template <class T>
inline void hash_combine(std::size_t & seed, T const& v)
inline void hash_combine(std::size_t & seed, std::size_t val)
{
std::hash<T> hasher;
seed ^= hasher(v) + 0x9e3779b9 + (seed << 6) + (seed >> 2);
seed ^= val + 0x9e3779b9 + (seed << 6) + (seed >> 2);
}
struct value_hasher
@ -56,6 +54,11 @@ struct value_hasher
return static_cast<std::size_t>(val.hashCode());
}
std::size_t operator()(value_integer val) const
{
return static_cast<std::size_t>(val);
}
template <class T>
std::size_t operator()(T const& val) const
{
@ -69,7 +72,8 @@ struct value_hasher
template <typename T>
std::size_t mapnik_hash_value(T const& val)
{
std::size_t seed = util::apply_visitor(detail::value_hasher(), val);
std::size_t seed = 0;
detail::hash_combine(seed, util::apply_visitor(detail::value_hasher(), val));
detail::hash_combine(seed, val.which());
return seed;
}