shell_hash.h

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#pragma once
 
#include <cstdint>
#include <string>
 
namespace bs {
    struct shell_hash {
        static constexpr std::uint64_t FNV_OFFSET = 1469598103934665603ull;
        static constexpr std::uint64_t FNV_PRIME = 1099511628211ull;
 
 
        std::uint64_t operator()(const std::string &sString) const noexcept {
            std::uint64_t nHash = FNV_OFFSET;
            for (const unsigned char cChar: sString) {
                nHash ^= cChar;
                nHash *= FNV_PRIME;
            }
            return nHash;
        }
    };
 
    struct shell_hash_view {
        static constexpr std::uint64_t FNV_OFFSET = 1469598103934665603ull;
        static constexpr std::uint64_t FNV_PRIME = 1099511628211ull;
 
 
        std::uint64_t operator()(const std::string_view &sString) const noexcept {
            std::uint64_t nHash = FNV_OFFSET;
            for (const unsigned char cChar: sString) {
                nHash ^= cChar;
                nHash *= FNV_PRIME;
            }
            return nHash;
        }
    };
 
}