AuROXTL/Include/auROXTL/auHashUtils.hpp

/***
    Copyright (C) 2022 J Reece Wilson (a/k/a "Reece"). All rights reserved.

    File: auHashUtils.hpp
    Date: 2022-3-23
    Author: Reece
***/
#pragma once

#include "auFNV1Utils.hpp"
#include "auMemoryModel.hpp"
#include "auString.hpp"
#include "auUTF8StringView.hpp"

#define _AU_HASH_UTILS_HAS_STD

#if 1 || defined(AURORA_COMPILER_CLANG) && !defined(AURORA_BUG_DOES_CLANG_SUPPORT_64_BIT_CONSTEXPR_YET)
    #define _AU_HASH_RETARD_COMPILER
    #define _AH_HAS_RETARD_CONSTEXPR
#else
    #define _AH_HAS_RETARD_CONSTEXPR constexpr
#endif

template <class T>
struct AuHasHashCode
{
    template <class C> static constexpr AuTrueType  Test(decltype(&C::HashCode));
    template <class C> static constexpr AuFalseType Test(...);
    using type = decltype(Test<T>(0));
};

template <class T>
constexpr inline bool AuHasHashCode_v = AuHasHashCode<T>::type::value;

namespace AuHash
{
    template <class Key>
    struct hash
    {
    #if defined(_AU_HASH_UTILS_HAS_STD)
        AuConditional_t<AuHasHashCode_v<Key>, AuUInt8, std::hash<Key>> trashHasher;
    #endif

        AuUInt operator()(const Key &ref) const
        {
            if constexpr (AuHasHashCode_v<Key>)
            {
                return ref.HashCode();
            }
        #if defined(_AU_HASH_UTILS_HAS_STD)
            else
            {
                return trashHasher(ref);
            }
        #endif
        }
    };

#if defined(_AU_WANT_GOOGLE_HASHES)
    // Thomas Wang, Integer Hash Functions: https://web.archive.org/web/20061201032901/http://www.concentric.net/%7ETtwang/tech/inthash.htm
    // Updated version under V8:            V8/v9-11/src/utils/utils.h
    //
    // I'm sure Google's tweaks and subsequence implementations have justification grounded in reality more so than the initial publishing of a 1999ish article by some dude at HP
    // Real world experience > 1999 HP guy > whatever the fuck the stl is doing (i think ms just uses fnv1s for everything)
    //
    // Preserving original function names for ease of xref. unseeded vs implied seeded doesnt mean anything. see: ComputeLongHash comment.
    inline _AH_HAS_RETARD_CONSTEXPR AuUInt32 ComputeUnseededHash(AuUInt32 key)
    {
        AuUInt32 hash = key;
        hash = ~hash + (hash << 15);  // hash = (hash << 15) - hash - 1;
        hash = hash ^ (hash >> 12);
        hash = hash + (hash << 2);
        hash = hash ^ (hash >> 4);
        hash = hash * 2057;  // hash = (hash + (hash << 3)) + (hash << 11);
        hash = hash ^ (hash >> 16);
        return hash;
    }

    // ComputeLongHash(base::double_to_uint64(AsNumber()));     ( pre-maglev V8 wasn't u64 optimizated. )
    // ComputeLongHash(static_cast<uint64_t>(digit(0)));        ( most js wont touch >31bit ints. )
    inline _AH_HAS_RETARD_CONSTEXPR AuUInt64 ComputeLongHash(AuUInt64 key)//   ( i'm sure this function's fine for all ranges. )
    {
        AuUInt64 hash = key;
        hash = ~hash + (hash << 18);     // hash = (hash << 18) - hash - 1;
        hash = hash ^ (hash >> 31);
        hash = hash * 21;                // hash = (hash + (hash << 2)) + (hash << 4);
        hash = hash ^ (hash >> 11);      //  key = key ^ (key >>> 28); ?
        hash = hash + (hash << 6);       //  key = key + (key << 31); ?
        hash = hash ^ (hash >> 22);      //  ???????????
        return hash;
    }
#else
    // nvm lost respect for google
    // maybe the above hashing algorithms could squeeze out a few more cycles on some architectures, but i doubt it.

    inline _AH_HAS_RETARD_CONSTEXPR AuUInt32 ComputeUnseededHash(AuUInt32 key)
    {
        #if defined(_AU_HASH_RETARD_COMPILER)
            return AuFnv1aRuntime(&key, sizeof(key));
        #else
            return AuFnv1a64Runtime<sizeof(AuUInt32)>(&key);
        #endif
    }

    inline _AH_HAS_RETARD_CONSTEXPR AuUInt64 ComputeLongHash(AuUInt64 key)
    {
        #if defined(_AU_HASH_RETARD_COMPILER)
            return AuFnv1aRuntime(&key, sizeof(key));
        #else
            return AuFnv1a64Runtime<sizeof(AuUInt64)>(&key);
        #endif
    }
#endif

#if defined(_AU_HASH_RETARD_COMPILER)
    #define _HASH_INT(type)                                               \
        template <>                                                       \
        struct hash<type>                                                 \
        {                                                                 \
            _AH_HAS_RETARD_CONSTEXPR AuUInt operator ()(const type b) const \
            {                                                             \
                return AuFnv1aRuntime<sizeof(b)>(&b);                     \
            }                                                             \
        };
#else
    #define _HASH_INT(type)                                               \
        template <>                                                       \
        struct hash<type>                                                 \
        {                                                                 \
            _AH_HAS_RETARD_CONSTEXPR AuUInt operator ()(const type b) const \
            {                                                             \
                return AuFnv1aRuntime<sizeof(b)>(&b);                     \
            }                                                             \
        };
#endif

#if defined(AURORA_IS_32BIT) 

#define _HASH_INT32BIT(type)                                          \
    template <>                                                       \
    struct hash<type>                                                 \
    {                                                                 \
        _AH_HAS_RETARD_CONSTEXPR AuUInt operator ()(const type intValue) const \
        {                                                             \
            return ComputeUnseededHash(AuUInt32(intValue));           \
        }                                                             \
    };

#else

#define _HASH_INT32BIT(type)                                          \
    template <>                                                       \
    struct hash<type>                                                 \
    {                                                                 \
        _AH_HAS_RETARD_CONSTEXPR AuUInt operator ()(const type intValue) const \
        {                                                             \
            return ComputeLongHash(AuUInt64(intValue));               \
        }                                                             \
    };

#endif

#if defined(AURORA_IS_32BIT) 

#define _HASH_INT64BIT(type)                                          \
    template <>                                                       \
    struct hash<type>                                                 \
    {                                                                 \
        _AH_HAS_RETARD_CONSTEXPR AuUInt operator ()(const type intValue) const \
        {                                                             \
            return AuUInt32(ComputeLongHash(AuUInt64(intValue)) & 0xFFFFFFFF); \
        }                                                             \
    };

#else

#define _HASH_INT64BIT(type)                                          \
    template <>                                                       \
    struct hash<type>                                                 \
    {                                                                 \
        _AH_HAS_RETARD_CONSTEXPR AuUInt operator ()(const type intValue) const \
        {                                                             \
            return ComputeLongHash(AuUInt64(intValue));               \
        }                                                             \
    };

#endif

#if 0
    _HASH_INT32BIT(bool);
    _HASH_INT32BIT(char);
    _HASH_INT32BIT(signed char);
    _HASH_INT32BIT(unsigned char);
    _HASH_INT32BIT(char8_t);
    _HASH_INT32BIT(char16_t);
    _HASH_INT32BIT(char32_t);
    _HASH_INT32BIT(wchar_t);
    _HASH_INT32BIT(short);
    _HASH_INT32BIT(unsigned short);
    _HASH_INT32BIT(int);
    _HASH_INT32BIT(unsigned int);
    _HASH_INT64BIT(long); // I know, I don't care.
    _HASH_INT64BIT(long long);
    _HASH_INT64BIT(unsigned long);
    _HASH_INT64BIT(unsigned long long);
#else
    _HASH_INT(bool);
    _HASH_INT(char);
    _HASH_INT(signed char);
    _HASH_INT(unsigned char);
    _HASH_INT(char8_t);
    _HASH_INT(char16_t);
    _HASH_INT(char32_t);
    _HASH_INT(wchar_t);
    _HASH_INT(short);
    _HASH_INT(unsigned short);
    _HASH_INT(int);
    _HASH_INT(unsigned int);
    _HASH_INT(long); // I know, I don't care.
    _HASH_INT(long long);
    _HASH_INT(unsigned long);
    _HASH_INT(unsigned long long);
#endif
    _HASH_INT(float);
    _HASH_INT(double);
    _HASH_INT(long double);
    _HASH_INT(std::nullptr_t);

#undef _HASH_INT
#undef _HASH_INT32BIT
#undef _HASH_INT64BIT

    template <class T>
    struct hash<T *>
    {
        _AH_HAS_RETARD_CONSTEXPR AuUInt operator ()(T *ptr) const
        {
        #if defined(AURORA_IS_32BIT)
            return ComputeUnseededHash(AuUInt(ptr));
        #else
            return ComputeLongHash(AuUInt(ptr));
        #endif
        }
    };

    template <class T>
    struct less
    {
        bool operator()(const T &lhs, const T &rhs) const
        {
            if constexpr (AuHasHashCode_v<T>)
            {
                return lhs.HashCode() < rhs.HashCode();
            }
            else
            {
                return lhs < rhs;
            }
        }
    };

    template <class T>
    struct equal
    {
        bool operator()(const T &lhs, const T &rhs) const
        {
            return lhs == rhs;
        }
    };

    template <>
    struct equal<std::string>
    {
        using is_transparent = void;

        bool operator()(std::string_view lhs, std::string_view rhs) const
        {
            return lhs == rhs;
        }
    };

    template <>
    struct equal<AuRONString>
    {
        using is_transparent = void;

        bool operator()(std::string_view lhs, std::string_view rhs) const
        {
            return lhs == rhs;
        }
    };

    template <>
    struct equal<std::basic_string<char, std::char_traits<char>, Aurora::Memory::StringAllocator<char>>>
    {
        using is_transparent = void;

        bool operator()(std::string_view lhs, std::string_view rhs) const
        {
            return lhs == rhs;
        }
    };
}

template <class T, AU_TEMPLATE_ENABLE_WHEN(AuHasHashCode_v<T>)>
inline AuUInt AuHashCode(const T &ref)
{
    return ref.HashCode();
}

template <class T, AU_TEMPLATE_ENABLE_WHEN(!AuHasHashCode_v<T>)>
inline AuUInt AuHashCode(const T &ref)
{
    return AuHash::hash<T>()(ref);
}

#include <auROXTL/auTuple.hpp>

namespace AuHash
{
    template <typename T, typename Z>
    struct hash<AuPair<T, Z>>
    {
        AuUInt operator ()(const AuPair<T, Z> &pair) const
        {
            return AuHashCode(pair.first) ^
                AuHashCode(pair.second);
        }
    };

    template <class ...Ts>
    struct hash<AuTuple<Ts...>>
    {
        AuUInt operator ()(const AuTuple<Ts...> &tuple) const
        {
            AuUInt uHashCode {};
            AuTupleForEach(tuple, [&](auto & a /*c++14 poggurs*/)
            {
                uHashCode ^= AuHashCode(a);
            });
            return uHashCode;
        }
    };

    // container bug in msvc?
#if 0
    template <>
    struct hash<std::string_view>
    {
        size_t operator()(std::string_view txt) const
        {
            return AuFnv1aRuntime(txt.data(), txt.size());
        }
    };
#endif

    template <>
    struct hash<std::string>
    {
        using is_transparent = void;
        using transparent_key_equal = equal<std::string>;

        size_t operator()(std::string_view txt) const
        {
            return hash<std::string_view>{}(txt);
        }
    };

    template <>
    struct hash<std::basic_string<char, std::char_traits<char>, Aurora::Memory::StringAllocator<char>>>
    {
        using is_transparent = void;
        using transparent_key_equal = equal<std::basic_string<char, std::char_traits<char>, Aurora::Memory::StringAllocator<char>>>;

        size_t operator()(std::string_view txt) const
        {
            return hash<std::string_view>{}(txt);
        }
    };

    template <>
    struct less<std::string>
    {
        using is_transparent = void;

        bool operator()(std::string_view lhs, std::string_view rhs) const
        {
        #if 0
            return AuFnv1aRuntime(lhs.data(), lhs.size()) < AuFnv1aRuntime(rhs.data(), rhs.size());
        #else
            return hash<std::string_view>{}(lhs) < hash<std::string_view>{}(rhs);
        #endif
        }
    };

    template <>
    struct less<std::basic_string<char, std::char_traits<char>, Aurora::Memory::StringAllocator<char>>>
    {
        using is_transparent = void;

        bool operator()(std::string_view lhs, std::string_view rhs) const
        {
        #if 0
            return AuFnv1aRuntime(lhs.data(), lhs.size()) < AuFnv1aRuntime(rhs.data(), rhs.size());
        #else
            return hash<std::string_view>{}(lhs) < hash<std::string_view>{}(rhs);
        #endif
        }
    };

    template <>
    struct less<std::string_view>
    {
        bool operator()(std::string_view lhs, std::string_view rhs) const
        {
        #if 0
            return AuFnv1aRuntime(lhs.data(), lhs.size()) < AuFnv1aRuntime(rhs.data(), rhs.size());
        #else
            return hash<std::string_view>{}(lhs) < hash<std::string_view>{}(rhs);
        #endif
        }
    };

    template <>
    struct less<AuRONString>
    {
        bool operator()(AuRONString lhs, AuRONString rhs) const
        {
        #if 0
            return AuFnv1aRuntime(lhs.data(), lhs.size()) < AuFnv1aRuntime(rhs.data(), rhs.size());
        #else
            return hash<std::string_view>{}(lhs) < hash<std::string_view>{}(rhs);
        #endif
        }
    };

    template <>
    struct less<const char *>
    {
        bool operator()(const char *lhs, const char *rhs) const
        {
        #if 0
            return AuFnv1aRuntime(lhs, strlen(lhs)) < AuFnv1aRuntime(rhs, strlen(rhs));
        #else
            return hash<std::string_view>{}(lhs) < hash<std::string_view>{}(rhs);
        #endif
        }
    };
}

template <class T>
struct AuEnableHashCodeOnData
{
    AuUInt HashCode() const
    {
    #if defined(AURORA_IS_32BIT)
        return AuFnv1a64Runtime<sizeof(T)>(AuStaticCast<AuAddConst_t<T>>(this));
    #else
        return AuFnv1a64Runtime<sizeof(T)>(AuStaticCast<AuAddConst_t<T>>(this));
    #endif
    }
};

#if defined(_AU_HASH_RETARD_COMPILER)
    #undef _AU_HASH_RETARD_COMPILER
    #undef _AH_HAS_RETARD_CONSTEXPR
#endif

namespace AuHash
{
    template <class T>
    struct hash<AuSPtr<T>>
    {
        AuUInt operator ()(const AuSPtr<T> &ptr) const
        {
        #if defined(AURORA_IS_32BIT)
            return ComputeUnseededHash(AuUInt(ptr.get()));
        #else
            return ComputeLongHash(AuUInt(ptr.get()));
        #endif
        }
    };
}