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

//
// AbstractDelegate.h
//
// Library: Foundation
// Package: Events
// Module:  AbstractDelegate
//
// Implementation of the AbstractDelegate template.
//
// Copyright (c) 2006-2011, Applied Informatics Software Engineering GmbH.
// and Contributors.
//
// SPDX-License-Identifier:	BSL-1.0
//


#ifndef Foundation_AbstractDelegate_INCLUDED
#define Foundation_AbstractDelegate_INCLUDED


#include "Poco/Foundation.h"


namespace Poco
{


template <class TArgs>
class AbstractDelegate
/// Base class for Delegate and Expire.
{
public:
    AbstractDelegate() { }

    AbstractDelegate(const AbstractDelegate & /*del*/) { }

    virtual ~AbstractDelegate() { }

    virtual bool notify(const void * sender, TArgs & arguments) = 0;
    /// Invokes the delegate's callback function.
    /// Returns true if successful, or false if the delegate
    /// has been disabled or has expired.

    virtual bool equals(const AbstractDelegate & other) const = 0;
    /// Compares the AbstractDelegate with the other one for equality.

    virtual AbstractDelegate * clone() const = 0;
    /// Returns a deep copy of the AbstractDelegate.

    virtual void disable() = 0;
    /// Disables the delegate, which is done prior to removal.

    virtual const AbstractDelegate * unwrap() const
    /// Returns the unwrapped delegate. Must be overridden by decorators
    /// like Expire.
    {
        return this;
    }
};


template <>
class AbstractDelegate<void>
/// Base class for Delegate and Expire.
{
public:
    AbstractDelegate() { }

    AbstractDelegate(const AbstractDelegate &) { }

    virtual ~AbstractDelegate() { }

    virtual bool notify(const void * sender) = 0;
    /// Invokes the delegate's callback function.
    /// Returns true if successful, or false if the delegate
    /// has been disabled or has expired.

    virtual bool equals(const AbstractDelegate & other) const = 0;
    /// Compares the AbstractDelegate with the other one for equality.

    virtual AbstractDelegate * clone() const = 0;
    /// Returns a deep copy of the AbstractDelegate.

    virtual void disable() = 0;
    /// Disables the delegate, which is done prior to removal.

    virtual const AbstractDelegate * unwrap() const
    /// Returns the unwrapped delegate. Must be overridden by decorators
    /// like Expire.
    {
        return this;
    }
};


} // namespace Poco


#endif // Foundation_AbstractDelegate_INCLUDED