completion_handler.h

/***************************************************************************
 *  include/stxxl/bits/io/completion_handler.h
 *
 *  Loki-style completion handler (functors)
 *
 *  Part of the STXXL. See http://stxxl.sourceforge.net
 *
 *  Copyright (C) 2003 Roman Dementiev <[email protected]>
 *
 *  Distributed under the Boost Software License, Version 1.0.
 *  (See accompanying file LICENSE_1_0.txt or copy at
 *  http://www.boost.org/LICENSE_1_0.txt)
 **************************************************************************/

#ifndef STXXL_COMPLETION_HANDLER_HEADER
#define STXXL_COMPLETION_HANDLER_HEADER

#include <memory>

#include <stxxl/bits/namespace.h>


__STXXL_BEGIN_NAMESPACE

class request;

class completion_handler_impl
{
public:
    virtual void operator () (request *) = 0;
    virtual completion_handler_impl * clone() const = 0;
    virtual ~completion_handler_impl() { }
};


class completion_handler
{
public:
    completion_handler() : sp_impl_(0) { }
    completion_handler(const completion_handler & obj) : sp_impl_(obj.sp_impl_.get()->clone()) { }
    completion_handler & operator = (const completion_handler & obj)
    {
        completion_handler copy(obj);
        completion_handler_impl * p = sp_impl_.release();
        sp_impl_.reset(copy.sp_impl_.release());
        copy.sp_impl_.reset(p);
        return *this;
    }
    void operator () (request * req)
    {
        (*sp_impl_)(req);
    }
    template <typename handler_type>
    completion_handler(const handler_type & handler__);

private:
    std::auto_ptr<completion_handler_impl> sp_impl_;
};

template <typename handler_type>
class completion_handler1 : public completion_handler_impl
{
private:
    handler_type handler_;

public:
    completion_handler1(const handler_type & handler__) : handler_(handler__) { }
    completion_handler1 * clone() const
    {
        return new completion_handler1(*this);
    }
    void operator () (request * req)
    {
        handler_(req);
    }
};

template <typename handler_type>
completion_handler::completion_handler(const handler_type & handler__) :
    sp_impl_(new completion_handler1<handler_type>(handler__))
{ }

__STXXL_END_NAMESPACE

#endif // !STXXL_COMPLETION_HANDLER_HEADER