ClickHouse/base/poco/Foundation/include/Poco/AutoPtr.h

//
// AutoPtr.h
//
// Library: Foundation
// Package: Core
// Module:  AutoPtr
//
// Definition of the AutoPtr template class.
//
// Copyright (c) 2004-2006, Applied Informatics Software Engineering GmbH.
// and Contributors.
//
// SPDX-License-Identifier:	BSL-1.0
//


#ifndef Foundation_AutoPtr_INCLUDED
#define Foundation_AutoPtr_INCLUDED


#include <algorithm>
#include "Poco/Exception.h"
#include "Poco/Foundation.h"


namespace Poco
{


template <class C>
class AutoPtr
/// AutoPtr is a "smart" pointer for classes implementing
/// reference counting based garbage collection.
/// To be usable with the AutoPtr template, a class must
/// implement the following behaviour:
/// A class must maintain a reference count.
/// The constructors of the object initialize the reference
/// count to one.
/// The class must implement a public duplicate() method:
///     void duplicate();
/// that increments the reference count by one.
/// The class must implement a public release() method:
///     void release()
/// that decrements the reference count by one, and,
/// if the reference count reaches zero, deletes the
/// object.
///
/// AutoPtr works in the following way:
/// If an AutoPtr is assigned an ordinary pointer to
/// an object (via the constructor or the assignment operator),
/// it takes ownership of the object and the object's reference
/// count remains unchanged.
/// If the AutoPtr is assigned another AutoPtr, the
/// object's reference count is incremented by one by
/// calling duplicate() on its object.
/// The destructor of AutoPtr calls release() on its
/// object.
/// AutoPtr supports dereferencing with both the ->
/// and the * operator. An attempt to dereference a null
/// AutoPtr results in a NullPointerException being thrown.
/// AutoPtr also implements all relational operators.
/// Note that AutoPtr allows casting of its encapsulated data types.
{
public:
    AutoPtr() : _ptr(0) { }

    AutoPtr(C * ptr) : _ptr(ptr) { }

    AutoPtr(C * ptr, bool shared) : _ptr(ptr)
    {
        if (shared && _ptr)
            _ptr->duplicate();
    }

    AutoPtr(const AutoPtr & ptr) : _ptr(ptr._ptr)
    {
        if (_ptr)
            _ptr->duplicate(); // NOLINT
    }

    template <class Other>
    AutoPtr(const AutoPtr<Other> & ptr) : _ptr(const_cast<Other *>(ptr.get()))
    {
        if (_ptr)
            _ptr->duplicate();
    }

    ~AutoPtr()
    {
        if (_ptr)
            _ptr->release(); // NOLINT
    }

    AutoPtr & assign(C * ptr)
    {
        if (_ptr != ptr)
        {
            if (_ptr)
                _ptr->release();
            _ptr = ptr;
        }
        return *this;
    }

    AutoPtr & assign(C * ptr, bool shared)
    {
        if (_ptr != ptr)
        {
            if (_ptr)
                _ptr->release();
            _ptr = ptr;
            if (shared && _ptr)
                _ptr->duplicate();
        }
        return *this;
    }

    AutoPtr & assign(const AutoPtr & ptr)
    {
        if (&ptr != this)
        {
            if (_ptr)
                _ptr->release();
            _ptr = ptr._ptr;
            if (_ptr)
                _ptr->duplicate(); // NOLINT
        }
        return *this;
    }

    template <class Other>
    AutoPtr & assign(const AutoPtr<Other> & ptr)
    {
        if (ptr.get() != _ptr)
        {
            if (_ptr)
                _ptr->release();
            _ptr = const_cast<Other *>(ptr.get());
            if (_ptr)
                _ptr->duplicate();
        }
        return *this;
    }

    void reset()
    {
        if (_ptr)
        {
            _ptr->release();
            _ptr = 0;
        }
    }

    void reset(C * ptr) { assign(ptr); }

    void reset(C * ptr, bool shared) { assign(ptr, shared); }

    void reset(const AutoPtr & ptr) { assign(ptr); }

    template <class Other>
    void reset(const AutoPtr<Other> & ptr)
    {
        assign<Other>(ptr);
    }

    AutoPtr & operator=(C * ptr) { return assign(ptr); }

    AutoPtr & operator=(const AutoPtr & ptr) { return assign(ptr); }

    template <class Other>
    AutoPtr & operator=(const AutoPtr<Other> & ptr)
    {
        return assign<Other>(ptr);
    }

    void swap(AutoPtr & ptr) { std::swap(_ptr, ptr._ptr); }

    template <class Other>
    AutoPtr<Other> cast() const
    /// Casts the AutoPtr via a dynamic cast to the given type.
    /// Returns an AutoPtr containing NULL if the cast fails.
    /// Example: (assume class Sub: public Super)
    ///    AutoPtr<Super> super(new Sub());
    ///    AutoPtr<Sub> sub = super.cast<Sub>();
    ///    poco_assert (sub.get());
    {
        Other * pOther = dynamic_cast<Other *>(_ptr);
        return AutoPtr<Other>(pOther, true);
    }

    template <class Other>
    AutoPtr<Other> unsafeCast() const
    /// Casts the AutoPtr via a static cast to the given type.
    /// Example: (assume class Sub: public Super)
    ///    AutoPtr<Super> super(new Sub());
    ///    AutoPtr<Sub> sub = super.unsafeCast<Sub>();
    ///    poco_assert (sub.get());
    {
        Other * pOther = static_cast<Other *>(_ptr);
        return AutoPtr<Other>(pOther, true);
    }

    C * operator->()
    {
        if (_ptr)
            return _ptr; // NOLINT
        else
            throw NullPointerException();
    }

    const C * operator->() const
    {
        if (_ptr)
            return _ptr;
        else
            throw NullPointerException();
    }

    C & operator*()
    {
        if (_ptr)
            return *_ptr; // NOLINT
        else
            throw NullPointerException();
    }

    const C & operator*() const
    {
        if (_ptr)
            return *_ptr;
        else
            throw NullPointerException();
    }

    C * get() { return _ptr; }

    const C * get() const { return _ptr; }

    operator C *()
    {
        return _ptr; // NOLINT
    }

    operator const C *() const { return _ptr; }

    bool operator!() const { return _ptr == 0; }

    bool isNull() const { return _ptr == 0; }

    C * duplicate()
    {
        if (_ptr)
            _ptr->duplicate();
        return _ptr;
    }

    bool operator==(const AutoPtr & ptr) const { return _ptr == ptr._ptr; }

    bool operator==(const C * ptr) const { return _ptr == ptr; }

    bool operator==(C * ptr) const { return _ptr == ptr; }

    bool operator!=(const AutoPtr & ptr) const { return _ptr != ptr._ptr; }

    bool operator!=(const C * ptr) const { return _ptr != ptr; }

    bool operator!=(C * ptr) const { return _ptr != ptr; }

    bool operator<(const AutoPtr & ptr) const { return _ptr < ptr._ptr; }

    bool operator<(const C * ptr) const { return _ptr < ptr; }

    bool operator<(C * ptr) const { return _ptr < ptr; }

    bool operator<=(const AutoPtr & ptr) const { return _ptr <= ptr._ptr; }

    bool operator<=(const C * ptr) const { return _ptr <= ptr; }

    bool operator<=(C * ptr) const { return _ptr <= ptr; }

    bool operator>(const AutoPtr & ptr) const { return _ptr > ptr._ptr; }

    bool operator>(const C * ptr) const { return _ptr > ptr; }

    bool operator>(C * ptr) const { return _ptr > ptr; }

    bool operator>=(const AutoPtr & ptr) const { return _ptr >= ptr._ptr; }

    bool operator>=(const C * ptr) const { return _ptr >= ptr; }

    bool operator>=(C * ptr) const { return _ptr >= ptr; }

private:
    C * _ptr;
};


template <class C>
inline void swap(AutoPtr<C> & p1, AutoPtr<C> & p2)
{
    p1.swap(p2);
}


} // namespace Poco


#endif // Foundation_AutoPtr_INCLUDED