ydb/util/generic/guid.h

#pragma once

#include "fwd.h"

#include <util/str_stl.h>

/**
 * UUID generation
 *
 * NOTE: It is not a real GUID (RFC 4122), as described in
 * https://en.wikipedia.org/wiki/Universally_unique_identifier
 * https://en.wikipedia.org/wiki/Globally_unique_identifier
 *
 * See https://clubs.at.yandex-team.ru/stackoverflow/10238/10240
 * and https://st.yandex-team.ru/IGNIETFERRO-768 for details.
 */
struct TGUID {
    ui32 dw[4] = {};

    constexpr bool IsEmpty() const noexcept {
        return (dw[0] | dw[1] | dw[2] | dw[3]) == 0;
    }

    constexpr explicit operator bool() const noexcept {
        return !IsEmpty();
    }

    // xxxx-xxxx-xxxx-xxxx
    TString AsGuidString() const;

    /**
     * RFC4122 GUID, which described in
     * https://en.wikipedia.org/wiki/Universally_unique_identifier
     * xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx
     **/
    TString AsUuidString() const;

    static TGUID Create();

    /**
     * Generate time based UUID version 1 RFC4122 GUID
     * https://datatracker.ietf.org/doc/html/rfc4122#section-4.1
     **/
    static TGUID CreateTimebased();
};

constexpr bool operator==(const TGUID& a, const TGUID& b) noexcept {
    return a.dw[0] == b.dw[0] && a.dw[1] == b.dw[1] && a.dw[2] == b.dw[2] && a.dw[3] == b.dw[3];
}

constexpr bool operator!=(const TGUID& a, const TGUID& b) noexcept {
    return !(a == b);
}

struct TGUIDHash {
    constexpr int operator()(const TGUID& a) const noexcept {
        return a.dw[0] + a.dw[1] + a.dw[2] + a.dw[3];
    }
};

template <>
struct THash<TGUID> {
    constexpr size_t operator()(const TGUID& g) const noexcept {
        return (unsigned int)TGUIDHash()(g);
    }
};

void CreateGuid(TGUID* res);
TString GetGuidAsString(const TGUID& g);
TString CreateGuidAsString();
TGUID GetGuid(TStringBuf s);
bool GetGuid(TStringBuf s, TGUID& result);

/**
 * Functions for correct parsing RFC4122 GUID, which described in
 * https://en.wikipedia.org/wiki/Universally_unique_identifier
 **/
TGUID GetUuid(TStringBuf s);
bool GetUuid(TStringBuf s, TGUID& result);