futureFunction.h

/* Copyright (c) 2013-2014, Stefan.Eilemann@epfl.ch
 *
 * This library is free software; you can redistribute it and/or modify it under
 * the terms of the GNU Lesser General Public License version 2.1 as published
 * by the Free Software Foundation.
 *
 * This library is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
 * FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License for more
 * details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this library; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */

#ifndef LUNCHBOX_FUTUREFUNCTION_H
#define LUNCHBOX_FUTUREFUNCTION_H

#include <lunchbox/future.h> // base class
#include <boost/function/function0.hpp>

namespace lunchbox
{
class FutureTrue : public FutureImpl< bool >
{
protected:
    bool wait( const uint32_t ) final { return true; }
    bool isReady() const final { return true; }
};

template< class T > class FutureFunction : public FutureImpl< T >
{
public:
    typedef boost::function< T() > Func; 

    explicit FutureFunction( const Func& func ) : func_( func ) {}

protected:
    virtual ~FutureFunction() { wait( 0 ); }

    T wait( const uint32_t ) final
    {
        if( !func_.empty( ))
        {
            result_ = func_();
            func_.clear();
        }
        return result_;
    }

    bool isReady() const final { return func_.empty(); }

    Func func_;
    T result_;
};

}
#endif //LUNCHBOX_FUTURE_H