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/*
Copyright (C) 2009 Paul Davis
This program 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.
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 General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#ifndef __pbd_closure_h__
#define __pbd_closure_h__
#include <glib.h>
/**
* Here we implement thread-safe but lifetime-unsafe closures (aka "functor"), which
* wrap an object and one of its methods, plus zero-or-more arguments, in a convenient,
* ready to use package.
*
* These differ from sigc::slot<> in that they are totally non-invasive with
* respect to the objects referenced by the closure. There is no requirement
* that the object be derived from any particular base class, and nothing
* will be done to the object during the creation of the closure, or its deletion,
* or at any time other than when the object's method is invoked via
* Closure::operator(). As a result, the closure can be constructed and deleted without
* concerns for thread safety. If the object method is thread-safe, then the closure
* can also be invoked in a thread safe fashion.
*
* However, this also means that the closure is not safe against lifetime
* management issues - if the referenced object is deleted before the closure,
* and then closure is invoked via operator(), the results are undefined (but
* will almost certainly be bad). This class should therefore be used only
* where you can guarantee that the referred-to object will outlive the
* life of the closure.
*/
namespace PBD {
struct ClosureBaseImpl {
ClosureBaseImpl() { g_atomic_int_set (&_ref, 0); }
ClosureBaseImpl* ref() { g_atomic_int_inc (&_ref); return this; }
void unref() { if (g_atomic_int_dec_and_test (&_ref)) delete this; }
virtual void operator() () = 0;
protected:
virtual ~ClosureBaseImpl() { }
private:
gint _ref;
};
struct Closure {
Closure () : impl (0) {}
Closure (ClosureBaseImpl* i) : impl (i->ref()) {}
Closure (const Closure& other) : impl (other.impl ? other.impl->ref() : 0) {}
Closure& operator= (const Closure& other) {
if (&other == this) {
return *this;
}
if (impl) {
impl->unref();
}
if (other.impl) {
impl = other.impl->ref();
} else {
impl = 0;
}
return *this;
}
virtual ~Closure () { if (impl) { impl->unref(); } }
/* will crash if impl is unset */
void operator() () const { (*impl)(); }
protected:
ClosureBaseImpl* impl;
};
template<typename T>
struct ClosureImpl0 : public ClosureBaseImpl {
ClosureImpl0 (T& obj, void (T::*m)())
: object (obj), method (m) {}
void operator() () { (object.*method)(); }
private:
T& object;
void (T::*method)();
};
template<typename T, typename A1>
struct ClosureImpl1 : public ClosureBaseImpl
{
ClosureImpl1 (T& obj, void (T::*m)(A1), A1 arg)
: object (obj), method (m), arg1 (arg) {}
void operator() () { (object.*method) (arg1); }
private:
T& object;
void (T::*method)(A1);
A1 arg1;
};
template<typename T, typename A1, typename A2>
struct ClosureImpl2 : public ClosureBaseImpl
{
ClosureImpl2 (T& obj, void (T::*m)( A1, A2), A1 arga, A2 argb)
: object (obj), method (m), arg1 (arga), arg2 (argb) {}
void operator() () { (object.*method) (arg1, arg2); }
private:
T& object;
void (T::*method)(A1, A2);
A1 arg1;
A2 arg2;
};
template<typename T, typename A1, typename A2, typename A3>
struct ClosureImpl3 : public ClosureBaseImpl
{
ClosureImpl3 (T& obj, void (T::*m)( A1, A2, A3), A1 arga, A2 argb, A3 argc)
: object (obj), method (m), arg1 (arga), arg2 (argb), arg3 (argc) {}
void operator() () { (object.*method) (arg1, arg2, arg3); }
private:
T& object;
void (T::*method)(A1, A2, A3);
A1 arg1;
A2 arg2;
A3 arg3;
};
template<typename T>
Closure closure (T& t, void (T::*m)()) {return Closure (new ClosureImpl0<T> (t,m)); }
template<typename T, typename A>
Closure closure (T& t, void (T::*m)(A), A a) { return Closure (new ClosureImpl1<T,A>(t,m,a)); }
template<typename T, typename A1, typename A2>
Closure closure (T& t, void (T::*m)(A1,A2), A1 a1, A2 a2) { return Closure (new ClosureImpl2<T,A1,A2>(t,m, a1, a2)); }
template<typename T, typename A1, typename A2, typename A3>
Closure closure (T& t, void (T::*m)(A1, A2, A3), A1 a1, A2 a2, A3 a3) { return Closure (new ClosureImpl3<T,A1,A2,A3>(t,m , a1, a2, a3)); }
/*--- CALL TIME CLOSURES : these accept arguments at run time */
template<typename A>
struct CTClosureBaseImpl : ClosureBaseImpl {
CTClosureBaseImpl() {}
virtual void operator() () { operator() (A()); }
virtual void operator() (A arg) = 0;
protected:
virtual ~CTClosureBaseImpl() { }
};
template<typename A>
struct CTClosure : public Closure {
CTClosure() {}
CTClosure (CTClosureBaseImpl<A>* i) : Closure (i) {}
CTClosure (const CTClosure& other) : Closure (other) {}
/* will crash if impl is unset */
void operator() (A arg) const { (*(dynamic_cast<CTClosureBaseImpl<A>*> (impl))) (arg); }
};
template<typename T, typename A>
struct CTClosureImpl1 : public CTClosureBaseImpl<A>
{
CTClosureImpl1 (T& obj, void (T::*m)(A))
: object (obj), method (m) {}
void operator() (A call_time_arg) { (object.*method) (call_time_arg); }
private:
T& object;
void (T::*method)(A);
};
/* functor wraps a method that takes 1 arg provided at call-time */
template<typename T, typename A>
CTClosure<A> closure (T& t, void (T::*m)(A)) { return CTClosure<A> (new CTClosureImpl1<T,A>(t,m)); }
}
#endif /* __pbd_closure_h__ */
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