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#pragma once

#include <util/system/defaults.h>
#include <util/generic/array_ref.h>

/* 
 * murmur2 from http://murmurhash.googlepages.com/ 
 * 
 */
namespace NMurmurPrivate { 
    Y_PURE_FUNCTION ui32 MurmurHash32(const void* key, size_t len, ui32 seed) noexcept;

    Y_PURE_FUNCTION ui64 MurmurHash64(const void* key, size_t len, ui64 seed) noexcept;

    template <unsigned N> 
    struct TMurHelper; 

#define DEF_MUR(t)                                                                         \ 
    template <>                                                                            \ 
    struct TMurHelper<t> {                                                                 \ 
        static inline ui##t MurmurHash(const void* buf, size_t len, ui##t init) noexcept { \ 
            return MurmurHash##t(buf, len, init);                                          \ 
        }                                                                                  \ 
    }; 
 
    DEF_MUR(32) 
    DEF_MUR(64) 
 
#undef DEF_MUR 
}

template <class T>
static inline T MurmurHash(const void* buf, size_t len, T init) noexcept { 
    return (T)NMurmurPrivate::TMurHelper<8 * sizeof(T)>::MurmurHash(buf, len, init); 
}

template <class T>
static inline T MurmurHash(const void* buf, size_t len) noexcept {
    return MurmurHash<T>(buf, len, (T)0);
}

//non-inline version
size_t MurmurHashSizeT(const char* buf, size_t len) noexcept;

template <typename TOut = size_t>
struct TMurmurHash {
    TOut operator()(const void* buf, size_t len) const noexcept {
        return MurmurHash<TOut>(buf, len);
    }

    template <typename ElementType>
    TOut operator()(const TArrayRef<ElementType>& data) const noexcept {
        return operator()(data.data(), data.size() * sizeof(ElementType));
    }
};