/* -*- mode: c++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */

/*

 Copyright (C) 2005, 2006 StatPro Italia srl

 This file is part of QuantLib, a free-software/open-source library

 for financial quantitative analysts and developers - http://quantlib.org/

 QuantLib is free software: you can redistribute it and/or modify it

 under the terms of the QuantLib license.  You should have received a

 copy of the license along with this program; if not, please email

 <quantlib-dev@lists.sf.net>. The license is also available online at

 <http://quantlib.org/license.shtml>.

 This program 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 license for more details.

*/

/*! \file observablevalue.hpp

    \brief observable and assignable proxy to concrete value

*/

#ifndef quantlib_observable_value_hpp

#define quantlib_observable_value_hpp

#include <ql/patterns/observable.hpp>

namespace QuantLib {

    //! %observable and assignable proxy to concrete value

    /*! Observers can be registered with instances of this class so

        that they are notified when a different value is assigned to

        such instances. Client code can copy the contained value or

        pass it to functions via implicit conversion.

        \note it is not possible to call non-const method on the

              returned value. This is by design, as this possibility

              would necessarily bypass the notification code; client

              code should modify the value via re-assignment instead.

    */

    template <class T>

    class ObservableValue { // NOLINT(cppcoreguidelines-special-member-functions)

      public:

        ObservableValue();

        ObservableValue(T&&);

        ObservableValue(const T&);

        ObservableValue(const ObservableValue<T>&);

        ~ObservableValue() = default;

        //! \name controlled assignment

        //@{

        ObservableValue<T>& operator=(T&&);

        ObservableValue<T>& operator=(const T&);

        ObservableValue<T>& operator=(const ObservableValue<T>&);

        //@}

        //! implicit conversion

        operator T() const;

        operator ext::shared_ptr<Observable>() const;

        //! explicit inspector

        const T& value() const;

      private:

        T value_;

        ext::shared_ptr<Observable> observable_;

    };

    // template definition

    template <class T>

    ObservableValue<T>::ObservableValue()

    : value_(), observable_(new Observable) {}

    template <class T>

    ObservableValue<T>::ObservableValue(T&& t)

    : value_(std::move(t)), observable_(new Observable) {}

    template <class T>

    ObservableValue<T>::ObservableValue(const T& t)

    : value_(t), observable_(new Observable) {}

    template <class T>

    ObservableValue<T>::ObservableValue(const ObservableValue<T>& t)

    : value_(t.value_), observable_(new Observable) {}

    template <class T>

    ObservableValue<T>& ObservableValue<T>::operator=(T&& t) {

        value_ = std::move(t);

        observable_->notifyObservers();

        return *this;

    }

    template <class T>

    ObservableValue<T>& ObservableValue<T>::operator=(const T& t) {

        value_ = t;

        observable_->notifyObservers();

        return *this;

    }

    template <class T>

    ObservableValue<T>&

    ObservableValue<T>::operator=(const ObservableValue<T>& t) { // NOLINT(bugprone-unhandled-self-assignment)

        value_ = t.value_;

        observable_->notifyObservers();

        return *this;

    }

    template <class T>

    ObservableValue<T>::operator T() const {

        return value_;

    }

    template <class T>

    ObservableValue<T>::operator ext::shared_ptr<Observable>() const {

        return observable_;

    }

    template <class T>

    const T& ObservableValue<T>::value() const {

        return value_;

    }

}

#endif