InstanceId.h

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/*
 * Copyright (C) 1996-2018 The Squid Software Foundation and contributors
 *
 * Squid software is distributed under GPLv2+ license and includes
 * contributions from numerous individuals and organizations.
 * Please see the COPYING and CONTRIBUTORS files for details.
 */

#ifndef SQUID_BASE_INSTANCE_ID_H
#define SQUID_BASE_INSTANCE_ID_H

#include <iosfwd>

template <class Class>
class InstanceId
{
public:
    typedef unsigned int Value; 

    InstanceId() {change();}

    operator Value() const { return value; }
    bool operator ==(const InstanceId &o) const { return value == o.value; }
    bool operator !=(const InstanceId &o) const { return !(*this == o); }
    void change();

    std::ostream &print(std::ostream &) const;

    const char * prefix() const;

public:
    Value value = 0; 

private:
    InstanceId(const InstanceId &); 
    InstanceId& operator=(const InstanceId &); 
};

#define InstanceIdDefinitions(Class, pfx) \
    template<> const char * \
    InstanceId<Class>::prefix() const { \
        return pfx; \
    } \
    template<> std::ostream & \
    InstanceId<Class>::print(std::ostream &os) const { \
        return os << pfx << value; \
    } \
    template<> void \
    InstanceId<Class>::change() { \
        static InstanceId<Class>::Value Last = 0; \
        value = ++Last ? Last : ++Last; \
    }

template <class Class>
inline
std::ostream &operator <<(std::ostream &os, const InstanceId<Class> &id)
{
    return id.print(os);
}

#endif /* SQUID_BASE_INSTANCE_ID_H */