tgSubject.h

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/*
 * Copyright © 2012, United States Government, as represented by the
 * Administrator of the National Aeronautics and Space Administration.
 * All rights reserved.
 * 
 * The NASA Tensegrity Robotics Toolkit (NTRT) v1 platform is licensed
 * under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * http://www.apache.org/licenses/LICENSE-2.0.
 * 
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
 * either express or implied. See the License for the specific language
 * governing permissions and limitations under the License.
*/

#ifndef TG_SUBJECT_H
#define TG_SUBJECT_H

// This application
#include "tgObserver.h"
// The C++ standard library
#include <vector>

template <typename T>
class tgSubject
{
public:

    tgSubject() { }

    virtual ~tgSubject() { }

    void attach(tgObserver<T>* pObserver);
    
    void notifyStep(double dt);
    
    void notifySetup();

    void notifyTeardown();
    
private:

     std::vector<tgObserver<T> * > m_observers;
};

template <typename Subject>
void tgSubject<Subject>::attach(tgObserver<Subject>* pObserver)
{
    if (pObserver) { m_observers.push_back(pObserver); 
        pObserver->onAttach(static_cast<Subject&>(*this));}
}

template <typename Subject>
void tgSubject<Subject>::notifyStep(double dt)
{
    if (dt > 0)
    {
        const std::size_t n = m_observers.size();
    for (std::size_t i = 0; i < n; ++i) 
    {
        tgObserver<Subject>* const pObserver = m_observers[i];
        if (pObserver) { pObserver->onStep(static_cast<Subject&>(*this), dt); }
    }
    }
}

template <typename Subject>
void tgSubject<Subject>::notifySetup()
{
        const std::size_t n = m_observers.size();
    for (std::size_t i = 0; i < n; ++i) 
    {
        tgObserver<Subject>* const pObserver = m_observers[i];
        if (pObserver) { pObserver->onSetup(static_cast<Subject&>(*this)); }
    }
}

template <typename Subject> 
void tgSubject<Subject>::notifyTeardown()
{
        const std::size_t n = m_observers.size();
    for (std::size_t i = 0; i < n; ++i) 
    {
        tgObserver<Subject>* const pObserver = m_observers[i];
        if (pObserver) { pObserver->onTeardown(static_cast<Subject&>(*this)); }
    }
}
#endif  // TG_SUBJECT_H