Promise.h

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/*
 * Promise.h
 *
 * Smalltalk like class library for C++
 * Thread wrapper returning value. Header.
 *
 * Copyright (c) 2003-05 Milan Cermak
 */
/*
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */
#ifndef __PROMISE_H
#define __PROMISE_H

#include <stlib/Object.h>
#include <stlib/Array.h>
#include <stlib/String.h>
#include <stlib/GenericException.h>

#include <stlib/Callback0.h>
#include <stlib/Callback1.h>

namespace OS {

class Semaphore;
class Thread;

class Promise : public Core::Object
{
  protected:
    Callback<Object *> *_receiver;
    Array *_arguments;
    Thread *thread;

    Semaphore *sync;
    Object *_value;
    bool has_value;
    GenericException *_exception;

  public:
    Promise(Callback<Object *> *receiver);
    virtual ~Promise(void);

    /* Class-accessing protocol */
    virtual String *className(void) const;

    /* Instance creation protocol */
    static Promise *perform(Callback<Object *> *receiver, Array *args = nil);

    template <class TReceiver>
    static Promise *perform(TReceiver *receiver, Object *(TReceiver::*execFunc)(void))
    {
        Callback0<TReceiver,Object *> *callback;
        callback = new Callback0<TReceiver,Object *>(receiver, execFunc);
        return perform(callback);
    }

    template <class TReceiver>
    static Promise *perform(TReceiver *receiver, Object *(TReceiver::*execFunc)(Array *),
                            Array *args)
    {
        Callback1<TReceiver,Object*,Array*> *callback;
        callback = new Callback1<TReceiver,Object*,Array*>(receiver, execFunc);
        return perform(callback, args);
    }

    virtual void run(void);

    /* Accessing-child protocol */
    virtual void exception(GenericException *ex);
    virtual void value(Object *object);

    /* Accessing-parent protocol */
    virtual void arguments(Array *args);
    virtual bool hasValue(void);
    virtual Object *value(void);

    /* Private protocol */
    virtual void executePromise(void);
};

};

#endif /* __PROMISE_H */

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