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hashed_string: internal changes

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This commit is contained in:
Michele Caini
2024-06-03 14:44:31 +02:00
parent 69864955af
commit 126f3caba0
1 changed files with 14 additions and 10 deletions
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24
src/entt/core/hashed_string.hpp
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@@ -12,16 +12,19 @@ namespace entt {
namespace internal {
template<typename = id_type>
inline constexpr auto offset = 2166136261;
struct fnv_1a_params;
template<>
inline constexpr auto offset<std::uint64_t> = 14695981039346656037ull;
template<typename = id_type>
inline constexpr auto prime = 16777619;
struct fnv_1a_params<std::uint32_t> {
static constexpr auto offset = 2166136261;
static constexpr auto prime = 16777619;
};
template<>
inline constexpr auto prime<std::uint64_t> = 1099511628211ull;
struct fnv_1a_params<std::uint64_t> {
static constexpr auto offset = 14695981039346656037ull;
static constexpr auto prime = 1099511628211ull;
};
template<typename Char>
struct basic_hashed_string {
@@ -55,6 +58,7 @@ struct basic_hashed_string {
template<typename Char>
class basic_hashed_string: internal::basic_hashed_string<Char> {
using base_type = internal::basic_hashed_string<Char>;
using params = internal::fnv_1a_params<>;
struct const_wrapper {
// non-explicit constructor on purpose
@@ -66,10 +70,10 @@ class basic_hashed_string: internal::basic_hashed_string<Char> {
// Fowler–Noll–Vo hash function v. 1a - the good
[[nodiscard]] static constexpr auto helper(const Char *str) noexcept {
base_type base{str, 0u, internal::offset<>};
base_type base{str, 0u, params::offset};
for(; str[base.length]; ++base.length) {
base.hash = (base.hash ^ static_cast<id_type>(str[base.length])) * internal::prime<>;
base.hash = (base.hash ^ static_cast<id_type>(str[base.length])) * params::prime;
}
return base;
@@ -77,10 +81,10 @@ class basic_hashed_string: internal::basic_hashed_string<Char> {
// Fowler–Noll–Vo hash function v. 1a - the good
[[nodiscard]] static constexpr auto helper(const Char *str, const std::size_t len) noexcept {
base_type base{str, len, internal::offset<>};
base_type base{str, len, params::offset};
for(size_type pos{}; pos < len; ++pos) {
base.hash = (base.hash ^ static_cast<id_type>(str[pos])) * internal::prime<>;
base.hash = (base.hash ^ static_cast<id_type>(str[pos])) * params::prime;
}
return base;