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/*
* Copyright © 2013 Canonical Ltd.
*
* This program is free software: you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License version 3,
* as published by the Free Software Foundation.
*
* 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
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
* Authored by: Thomas Voß <thomas.voss@canonical.com>
*/
#ifndef CORE_PROPERTY_H_
#define CORE_PROPERTY_H_
#include <core/signal.h>
#include <iostream>
namespace core
{
/**
* @brief A very simple, templated class that allows for uniform declaration of get-able/set-able/observable members.
* @tparam The type of the value contained within the property.
*/
template<typename T>
class Property
{
public:
/**
* @brief ValueType refers to the type of the contained value.
*/
typedef T ValueType;
/**
* @brief Property creates a new instance of property and initializes the contained value.
* @param t The initial value, defaults to Property<T>::default_value().
*/
inline explicit Property(const T& t = T{}) : value{t}
{
}
/**
* @brief Copy c'tor, only copies the contained value, not the changed signal and its connections.
* @param rhs
*/
inline Property(const Property<T>& rhs) : value{rhs.value}
{
}
inline virtual ~Property() = default;
/**
* @brief Assignment operator, only assigns to the contained value.
* @param rhs The right-hand-side, raw value to assign to this property.
*/
inline Property& operator=(const T& rhs)
{
set(rhs);
return *this;
}
/**
* @brief Assignment operator, only assigns to the contained value, not the changed signal and its connections.
* @param rhs The right-hand-side property to assign from.
*/
inline Property& operator=(const Property<T>& rhs)
{
set(rhs.value);
return *this;
}
/**
* @brief Explicit casting operator to the contained value type.
* @return A non-mutable reference to the contained value.
*/
inline operator const T&() const
{
return get();
}
/**
* @brief Provides access to a pointer to the contained value.
*/
inline const T* operator->() const
{
return &get();
}
/**
* @brief operator == checks if the value of a property and a raw value are equal.
* @param lhs Non-mutable reference to a property.
* @param rhs Non-mutable reference to a raw value.
* @return True iff the value contained in lhs equals rhs.
*/
friend inline bool operator==(const Property<T>& lhs, const T& rhs)
{
return lhs.get() == rhs;
}
/**
* @brief operator == checks if the value of two properties are equal.
* @param lhs Non-mutable reference to a property.
* @param rhs Non-mutable reference to a property.
* @return True iff the value contained in lhs equals the value contained in rhs.
*/
friend inline bool operator==(const Property<T>& lhs, const Property<T>& rhs)
{
return lhs.get() == rhs.get();
}
/**
* @brief Set the contained value to the provided value. Notify observers of the change.
* @param [in] new_value The new value to assign to this property.
* @post get() == new_value;
*/
inline virtual void set(const T& new_value)
{
if (value != new_value)
{
value = new_value;
signal_changed(value);
}
}
/**
* @brief Access the value contained within this property.
* @return A non-mutable reference to the property value.
*/
inline virtual const T& get() const
{
return value;
}
/**
* @brief Access to the changed signal, allows observers to subscribe to change notifications.
* @return A non-mutable reference to the changed signal.
*/
inline const Signal<T>& changed() const
{
return signal_changed;
}
/**
* @brief Provides in-place update facilities.
*
* The provided update_functor is applied to the contained value. If the update functor
* returns true, indicating that the value has been changed, the changed signal is emitted.
*
* @param update_functor The update function to be applied to the contained value.
* @return true iff application of the update functor has been successful.
*/
inline virtual bool update(const std::function<bool(T& t)>& update_functor)
{
if (update_functor(mutable_get()))
{
signal_changed(value);
return true;
}
return false;
}
protected:
inline T& mutable_get() const
{
return value;
}
private:
mutable T value;
Signal<T> signal_changed;
};
}
#endif // CORE_PROPERTY_H_
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