uid.h

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#pragma once
 
#include <algorithm>
#include <array>
#include <functional>
#include <sstream>
#include <string>
#include <utility>
 
#include <boost/functional/hash.hpp>
#include <boost/uuid/uuid.hpp>
#include <boost/uuid/uuid_generators.hpp>
#include <boost/uuid/uuid_io.hpp>
 
 
namespace knp::core
{
 
#if defined(_DEBUG) || defined(DEBUG)
#    define _ENABLE_PSEUDO_UID_GENERATOR 1
#endif
 
class continuously_uid_generator
{
public:
    ::boost::uuids::uuid operator()() const;
    static void reset(uint64_t initial_value = 1);
};
 
#if defined(_ENABLE_PSEUDO_UID_GENERATOR)
#    define uid_generator continuously_uid_generator
#else
#    define uid_generator ::boost::uuids::random_generator
#endif
 
 
struct UID
{
    explicit UID(bool random) : tag(random ? uid_generator()() : ::boost::uuids::nil_uuid()) {}
 
    UID() : UID(true) {}
 
    explicit UID(const ::boost::uuids::uuid &guid) : tag(guid) {}
    explicit UID(::boost::uuids::uuid &&guid) : tag(guid) {}
 
    explicit UID(const std::array<
                 boost::uuids::uuid::value_type, sizeof(boost::uuids::uuid::data) / sizeof(boost::uuids::uuid::data[0])>
                     &guid_value)
    {
        std::copy(guid_value.begin(), guid_value.end(), tag.begin());
    }
 
    UID(const UID &) = default;
 
    operator const ::boost::uuids::uuid &() const { return tag; }
 
    operator ::boost::uuids::uuid &() { return tag; }
 
    explicit operator ::std::string() const
    {
        std::stringstream ss;
        ss << tag;
        return ss.str();
    }
 
    explicit operator bool() const { return !tag.is_nil(); }
 
    bool operator<(const UID &uid) const { return uid.tag < tag; }
 
    bool operator==(const UID &uid) const { return uid.tag == tag; }
 
    bool operator!=(const UID &uid) const { return uid.tag != tag; }
 
    ::boost::uuids::uuid tag;
};
 
 
inline ::std::ostream &operator<<(std::ostream &s, const UID &uid)
{
    s << uid.tag;
    return s;
}
 
inline ::std::istream &operator>>(std::istream &s, UID &uid)
{
    s >> uid.tag;
    return s;
}
 
 
struct uid_hash
{
    auto operator()(const UID &uid) const { return boost::hash<boost::uuids::uuid>()(uid.tag); }
};
 
}  // namespace knp::core