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#pragma once
#include <cstdint>
#include <cstring>
#include <Containers/Pair.h>
#include <Containers/String.h>
#include <Cryptography/xxHash.h>
using namespace Death::Containers;
using namespace Death::Cryptography;
namespace nCine
{
using hash_t = std::uint32_t;
using hash64_t = std::uint64_t;
/** @brief Invalid hash value */
const hash_t NullHash = static_cast<hash_t>(~0);
/// Fowler-Noll-Vo Hash (FNV-1a)
/*!
* For more information: http://en.wikipedia.org/wiki/Fowler%E2%80%93Noll%E2%80%93Vo_hash_function
*/
template<class K>
class FNV1aHashFunc
{
public:
hash_t operator()(const K& key) const
{
const unsigned char* bytes = reinterpret_cast<const unsigned char*>(&key);
hash_t hash = static_cast<hash_t>(Seed);
for (unsigned int i = 0; i < sizeof(K); i++) {
hash = fnv1a(bytes[i], hash);
}
return hash;
}
private:
static const hash_t Prime = 0x01000193; // 16777619
static const hash_t Seed = 0x811C9DC5; // 2166136261
inline hash_t fnv1a(const unsigned char oneByte, hash_t hash = Seed) const
{
return (oneByte ^ hash) * Prime;
}
};
#ifndef DOXYGEN_GENERATING_OUTPUT
template<>
class FNV1aHashFunc<char*>
{
public:
hash_t operator()(const char*& key) const
{
const unsigned int length = (unsigned int)strlen(key);
hash_t hash = static_cast<hash_t>(Seed);
for (unsigned int i = 0; i < length; i++) {
hash = fnv1a(key[i], hash);
}
return hash;
}
private:
static const hash_t Prime = 0x01000193; // 16777619
static const hash_t Seed = 0x811C9DC5; // 2166136261
inline hash_t fnv1a(const char oneByte, hash_t hash = Seed) const
{
return (oneByte ^ hash) * Prime;
}
};
template<>
class FNV1aHashFunc<String>
{
public:
hash_t operator()(const String& string) const
{
const unsigned int length = (unsigned int)string.size();
hash_t hash = static_cast<hash_t>(Seed);
for (unsigned int i = 0; i < length; i++) {
hash = fnv1a(static_cast<hash_t>(string[i]), hash);
}
return hash;
}
private:
static const hash_t Prime = 0x01000193; // 16777619
static const hash_t Seed = 0x811C9DC5; // 2166136261
inline hash_t fnv1a(unsigned char oneByte, hash_t hash = Seed) const
{
return (oneByte ^ hash) * Prime;
}
};
template<class F, class S>
class FNV1aHashFunc<Pair<F, S>>
{
public:
hash_t operator()(const Pair<F, S>& pair) const
{
return FNV1aHashFunc<F>()(pair.first()) ^ FNV1aHashFunc<S>()(pair.second());
}
};
#endif
/// xxHash hash function (32-bit)
template<class K>
class xxHash32Func
{
public:
hash_t operator()(const K& key) const
{
return hash_t(xxHash3(reinterpret_cast<const char*>(&key), sizeof(K)));
}
};
#ifndef DOXYGEN_GENERATING_OUTPUT
template<>
class xxHash32Func<char*>
{
public:
hash64_t operator()(const char*& key) const
{
const unsigned int length = (unsigned int)strlen(key);
return hash_t(xxHash3(key, length));
}
};
template<>
class xxHash32Func<String>
{
public:
hash_t operator()(const String& string) const
{
return hash_t(xxHash3(string.data(), string.size()));
}
};
template<class F, class S>
class xxHash32Func<Pair<F, S>>
{
public:
hash_t operator()(const Pair<F, S>& pair) const
{
return xxHash32Func<F>()(pair.first()) ^ xxHash32Func<S>()(pair.second());
}
};
#endif
/// xxHash hash function (64-bit)
template<class K>
class xxHash64Func
{
public:
hash64_t operator()(const K& key) const
{
return hash64_t(xxHash3(reinterpret_cast<const char*>(&key), sizeof(K)));
}
};
#ifndef DOXYGEN_GENERATING_OUTPUT
template<>
class xxHash64Func<char*>
{
public:
hash64_t operator()(const char*& key) const
{
const unsigned int length = (unsigned int)strlen(key);
return hash64_t(xxHash3(key, length));
}
};
template<>
class xxHash64Func<String>
{
public:
hash64_t operator()(const String& string) const
{
return hash64_t(xxHash3(string.data(), string.size()));
}
};
template<class F, class S>
class xxHash64Func<Pair<F, S>>
{
public:
hash64_t operator()(const Pair<F, S>& pair) const
{
return xxHash64Func<F>()(pair.first()) ^ xxHash64Func<S>()(pair.second());
}
};
#endif
}
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