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/** \file
* Inkscape::Lifecycle - automatic object lifecycle management
*
* Copyright 2008 MenTaLguY <mental@rydia.net>
*
* 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.
*
* See the file COPYING for details.
*
*/
#ifndef SEEN_INKSCAPE_LIFECYCLE_H
#define SEEN_INKSCAPE_LIFECYCLE_H
#include <glib/gtypes.h>
#include <glib/gatomic.h>
namespace Inkscape {
namespace Lifecycle {
class BaseManagedPtr;
// Abstract base class for managed objects
class AbstractManaged {
public:
AbstractManaged() {}
virtual ~AbstractManaged() {}
protected:
virtual void managedAddReference() const=0;
virtual void managedRemoveReference() const=0;
friend class BaseManagedPtr;
private:
AbstractManaged(AbstractManaged &); // no copy
void operator=(AbstractManaged &); // no assign
};
// Base class for managed pointers; not intended for direct use
class BaseManagedPtr {
protected:
BaseManagedPtr() : ptr(NULL) {}
BaseManagedPtr(AbstractManaged const *managed) : ptr(NULL) {
set(managed);
}
BaseManagedPtr(BaseManagedPtr const &other) : ptr(NULL) {
set(other.ptr);
}
AbstractManaged const *get() const { return ptr; }
void set(AbstractManaged const *managed) {
if (managed) {
ptr->managedAddReference();
}
if (ptr) {
ptr->managedRemoveReference();
}
ptr = managed;
}
private:
AbstractManaged const *ptr;
};
// Type-safe managed pointer
template <typename T>
class ManagedPtr : public BaseManagedPtr {
public:
ManagedPtr() : BaseManagedPtr() {}
ManagedPtr(T *managed) : BaseManagedPtr(managed) {}
ManagedPtr(ManagedPtr const &other) : BaseManagedPtr(other) {}
operator T *() const { return get_recast(); }
T &operator*() const { return *get_recast(); }
T *operator->() const { return get_recast(); }
ManagedPtr &operator=(T *managed) {
set(managed);
return *this;
}
ManagedPtr &operator=(ManagedPtr const &other) {
set(other.get());
return *this;
}
private:
T *get_recast() const {
return const_cast<T *>(static_cast<T const *>(get()));
}
};
// Wrapper for a simple pointer emulating the ManagedPtr interface
template <typename T>
class DumbPtr {
public:
DumbPtr() : ptr(NULL) {}
DumbPtr(T *p) : ptr(p) {}
DumbPtr(DumbPtr const &other) : ptr(other.ptr) {}
operator T *() const { return ptr; }
T &operator*() const { return *ptr; }
T *operator->() const { return ptr; }
DumbPtr &operator=(T *p) {
ptr = p;
return *this;
}
DumbPtr &operator=(DumbPtr const &other) {
ptr = other.ptr;
return *this;
}
private:
T *ptr;
};
// Dummy implementation of AbstractManaged to ease migration
class DummyManaged : public virtual AbstractManaged {
protected:
virtual void managedAddReference() const {}
virtual void managedRemoveReference() const {}
};
// Straightforward refcounting implementation of AbstractManaged
class SimpleManaged : public virtual AbstractManaged {
protected:
SimpleManaged() : refcount(0) {}
virtual ~SimpleManaged() {}
virtual void managedAddReference() const {
g_atomic_int_inc(&refcount);
}
virtual void managedRemoveReference() const {
if (g_atomic_int_dec_and_test(&refcount)) {
const_cast<SimpleManaged *>(this)->managedDispose();
}
}
virtual void managedDispose() {
delete this;
}
private:
mutable volatile gint refcount;
};
}
}
#endif
/*
Local Variables:
mode:c++
c-file-style:"stroustrup"
c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))
indent-tabs-mode:nil
fill-column:99
End:
*/
// vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:encoding=utf-8:textwidth=99 :
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