-/* $Id$
-
-This file is part of libmspcore
-Copyright © 2006-2007 Mikko Rasa, Mikkosoft Productions
-Distributed under the LGPL
-*/
#ifndef MSP_CORE_REFPTR_H_
#define MSP_CORE_REFPTR_H_
namespace Msp {
+struct RefCounts
+{
+ enum
+ {
+ KEEP = 1U<<(sizeof(unsigned)*8-1)
+ };
+
+ unsigned count;
+ unsigned weak_count;
+
+ RefCounts(): count(0), weak_count(0) { }
+};
+
+template<typename T>
+class WeakPtr;
+
+
+/**
+A reference counting smart pointer. When the last RefPtr for the data gets
+destroyed, the data is deleted as well.
+*/
template<typename T>
class RefPtr
{
+ template<typename U> friend class RefPtr;
+ template<typename U> friend class WeakPtr;
+
+private:
+ T *data;
+ RefCounts *counts;
+
public:
- RefPtr(): data(0), count(0) { }
- RefPtr(T *d): data(d), count(0) { if(data) count=new unsigned(1); }
- RefPtr(const RefPtr &p): data(p.data), count(p.count) { incref(); }
+ RefPtr(): data(0), counts(0) { }
+ RefPtr(T *d): data(d), counts(data ? new RefCounts : 0) { incref(); }
+private:
+ RefPtr(T *d, RefCounts *c): data(d), counts(d ? c : 0) { incref(); }
+
+public:
+ /* Must have this or the compiler will generate a default copy-c'tor despite
+ the template version */
+ RefPtr(const RefPtr &p): data(p.data), counts(p.counts) { incref(); }
+
+ template<typename U>
+ RefPtr(const RefPtr<U> &p): data(p.data), counts(p.counts) { incref(); }
+
+ template<typename U>
+ RefPtr(const WeakPtr<U> &p): data(p.get()), counts(data ? p.counts : 0) { incref(); }
+
~RefPtr() { decref(); }
- RefPtr &operator=(const RefPtr &p)
- {
- decref();
- data=p.data;
- count=p.count;
- incref();
- return *this;
- }
+ RefPtr &operator=(T *);
+
+ // Likewise for the assignment operator
+ RefPtr &operator=(const RefPtr &p) { return assign(p); }
- T *get() const { return data; }
- T &operator*() const { return *data; }
+ template<typename U>
+ RefPtr &operator=(const RefPtr<U> &p) { return assign(p); }
+
+ template<typename U>
+ RefPtr &operator=(const WeakPtr<U> &p) { return assign(RefPtr(p)); }
+
+private:
+ template<typename U>
+ RefPtr &assign(const RefPtr<U> &);
+
+public:
+ /** Makes the RefPtr release its reference of the data without deleting it.
+ Note that if there are other RefPtrs left with the same data, it might
+ still get deleted automatically. */
+ T *release();
+
+ /** Marks the data to not be deleted. This affects all RefPtrs with the
+ same data. */
+ void keep() { if(counts) counts->count |= RefCounts::KEEP; }
+
+ T *get() const { return data; }
+ T &operator*() const { return *data; }
T *operator->() const { return data; }
operator bool() const { return data!=0; }
+ unsigned refcount() const { return (data ? counts->count : 0); }
+
template<typename U>
- static RefPtr<T> cast_dynamic(const RefPtr<U> &p) { return RefPtr<T>(dynamic_cast<T *>(p.get()), p.count); }
+ static RefPtr<T> cast_dynamic(const RefPtr<U> &p)
+ { return RefPtr<T>(dynamic_cast<T *>(p.data), p.counts); }
+
+private:
+ void incref() { if(counts) ++counts->count; }
+ void decref();
+};
+
+
+template<typename T>
+class WeakPtr
+{
template<typename U> friend class RefPtr;
+ template<typename U> friend class WeakPtr;
+
+private:
+ T *data;
+ RefCounts *counts;
+
+public:
+ WeakPtr(): data(0), counts(0) { }
+private:
+ WeakPtr(T *d, RefCounts *c): data(d), counts(d ? c : 0) { incref(); }
+
+public:
+ WeakPtr(const WeakPtr &p): data(p.get()), counts(data ? p.counts : 0) { incref(); }
+
+ template<typename U>
+ WeakPtr(const WeakPtr<U> &p): data(p.get()), counts(data ? p.counts : 0) { incref(); }
+
+ template<typename U>
+ WeakPtr(const RefPtr<U> &p): data(p.data), counts(p.counts) { incref(); }
+
+ WeakPtr &operator=(const WeakPtr &p) { return assign(p); }
+
+ template<typename U>
+ WeakPtr &operator=(const WeakPtr<U> &p) { return assign(p); }
+
+ template<typename U>
+ WeakPtr &operator=(const RefPtr<U> &p) { return assign(WeakPtr(p)); }
+
private:
- T *data;
- unsigned *count;
+ template<typename U>
+ WeakPtr &assign(const WeakPtr<U> &);
+
+ T *get() const { return (counts && counts->count ? data : 0); }
+ void incref() { if(counts) ++counts->weak_count; }
+ void decref();
+};
- RefPtr(T *d, unsigned *c): data(d), count(c) { incref(); }
- void incref()
+template<typename T>
+RefPtr<T> &RefPtr<T>::operator=(T *d)
+{
+ decref();
+ data = d;
+ counts = (d ? new RefCounts : 0);
+ incref();
+ return *this;
+}
+
+template<typename T>
+template<typename U>
+RefPtr<T> &RefPtr<T>::assign(const RefPtr<U> &p)
+{
+ decref();
+ data = p.data;
+ counts = p.counts;
+ incref();
+ return *this;
+}
+
+template<typename T>
+T *RefPtr<T>::release()
+{
+ T *d = data;
+ data = 0;
+ decref();
+ counts = 0;
+ return d;
+}
+
+template<typename T>
+void RefPtr<T>::decref()
+{
+ if(!counts) return;
+ --counts->count;
+ if(!counts->count)
{
- if(!count) return;
- ++*count;
+ delete data;
+ data = 0;
}
+ else if(counts->count==RefCounts::KEEP)
+ data = 0;
+ else
+ return;
- void decref()
+ if(!counts->weak_count)
{
- if(!count) return;
- --*count;
- if(!*count)
- {
- delete data;
- delete count;
- data=0;
- count=0;
- }
+ delete counts;
+ counts = 0;
}
-};
+}
+
+
+template<typename T>
+template<typename U>
+WeakPtr<T> &WeakPtr<T>::assign(const WeakPtr<U> &p)
+{
+ decref();
+ data = p.get();
+ counts = (data ? p.counts : 0);
+ incref();
+ return *this;
+}
+
+template<typename T>
+void WeakPtr<T>::decref()
+{
+ if(!counts) return;
+ --counts->weak_count;
+ if(!counts->weak_count && (!counts->count || counts->count==RefCounts::KEEP))
+ {
+ delete counts;
+ data = 0;
+ counts = 0;
+ }
+}
} // namespace Msp
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