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/* Copyright (C) 2014 Wildfire Games.
* This file is part of 0 A.D.
*
* 0 A.D. is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 2 of the License, or
* (at your option) any later version.
*
* 0 A.D. 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with 0 A.D. If not, see <http://www.gnu.org/licenses/>.
*/
#ifndef INCLUDED_OBSERVABLE
#define INCLUDED_OBSERVABLE
/*
Wrapper around Boost.Signals to make watching objects for changes more convenient.
General usage:
Observable<int> variable_to_be_watched;
...
class Thing {
ObservableScopedConnection m_Conn;
Thing() {
m_Conn = variable_to_be_watched.RegisterObserver(OnChange);
}
void OnChange(const int& var) {
do_something_with(var);
}
}
...
variable_to_be_watched.NotifyObservers();
*/
#include <boost/bind.hpp>
#include <boost/version.hpp>
#if BOOST_VERSION >= 104000
# include <boost/signals2.hpp>
typedef boost::signals2::connection ObservableConnection;
typedef boost::signals2::scoped_connection ObservableScopedConnection;
#else
# error Atlas requires Boost 1.40 or later
#endif
template <typename T> class Observable : public T
{
public:
Observable() {}
template <typename T1>
explicit Observable(const T1& a1) : T(a1) {}
template <typename T1, typename T2>
explicit Observable(T1& a1, T2& a2) : T(a1, a2) {}
template <typename T1, typename T2>
explicit Observable(T1& a1, T2 a2) : T(a1, a2) {}
template<typename C> ObservableConnection RegisterObserver(int order, void (C::*callback) (const T&), C* obj)
{
return m_Signal.connect(order, boost::bind(std::mem_fun(callback), obj, _1));
}
ObservableConnection RegisterObserver(int order, void (*callback) (const T&))
{
return m_Signal.connect(order, callback);
}
void RemoveObserver(const ObservableConnection& conn)
{
conn.disconnect();
}
void NotifyObservers()
{
m_Signal(*this);
}
// Use when an object is changing something that it's also observing,
// because it already knows about the change and doesn't need to be notified
// again (particularly since that may cause infinite loops).
void NotifyObserversExcept(ObservableConnection& conn)
{
if (conn.blocked())
{
// conn is already blocked and won't see anything
NotifyObservers();
}
else
{
// Temporarily disable conn
boost::signals2::shared_connection_block blocker(conn);
NotifyObservers();
}
}
Observable<T>& operator=(const T& rhs)
{
*dynamic_cast<T*>(this) = rhs;
return *this;
}
private:
boost::signals2::signal<void (const T&)> m_Signal;
};
// A similar thing, but for wrapping pointers instead of objects
template <typename T> class ObservablePtr
{
public:
ObservablePtr() : m_Ptr(NULL) {}
ObservablePtr(T* p) : m_Ptr(p) {}
ObservablePtr& operator=(T* p)
{
m_Ptr = p;
return *this;
}
T* operator->()
{
return m_Ptr;
}
T* operator*()
{
return m_Ptr;
}
template<typename C> ObservableConnection RegisterObserver(int order, void (C::*callback) (T*), C* obj)
{
return m_Signal.connect(order, boost::bind(std::mem_fun(callback), obj, _1));
}
ObservableConnection RegisterObserver(int order, void (*callback) (T*))
{
return m_Signal.connect(order, callback);
}
void RemoveObserver(const ObservableConnection& conn)
{
conn.disconnect();
}
void NotifyObservers()
{
m_Signal(m_Ptr);
}
// Use when an object is changing something that it's also observing,
// because it already knows about the change and doesn't need to be notified
// again (particularly since that may cause infinite loops).
void NotifyObserversExcept(ObservableConnection& conn)
{
if (conn.blocked())
{
// conn is already blocked and won't see anything
NotifyObservers();
}
else
{
// Temporarily disable conn
boost::signals2::shared_connection_block blocker(conn);
NotifyObservers();
}
}
private:
T* m_Ptr;
boost::signals2::signal<void (T*)> m_Signal;
};
class ObservableScopedConnections
{
public:
void Add(const ObservableConnection& conn);
~ObservableScopedConnections();
private:
std::vector<ObservableConnection> m_Conns;
};
#endif // INCLUDED_OBSERVABLE
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