X-Git-Url: http://git.tdb.fi/?p=libs%2Fcore.git;a=blobdiff_plain;f=source%2Fcore%2Frefptr.h;h=79401dce5be40094a9f55212c0c3fb4abd8f7dc9;hp=28666ea816380e0547205a1f6d83b14da0e13016;hb=HEAD;hpb=be8ea216d23bf36bdfb2d3e302638782575fc136

diff --git a/source/core/refptr.h b/source/core/refptr.h
index 28666ea..1a164c1 100644
--- a/source/core/refptr.h
+++ b/source/core/refptr.h
@@ -10,11 +10,13 @@ struct RefCounts
 		KEEP = 1U<<(sizeof(unsigned)*8-1)
 	};
 
-	unsigned count;
-
-	RefCounts(): count(0) { }
+	unsigned count = 0;
+	unsigned weak_count = 0;
 };
 
+template<typename T>
+class WeakPtr;
+
 
 /**
 A reference counting smart pointer.  When the last RefPtr for the data gets
@@ -24,16 +26,17 @@ template<typename T>
 class RefPtr
 {
 	template<typename U> friend class RefPtr;
+	template<typename U> friend class WeakPtr;
 
 private:
-	T *data;
-	RefCounts *counts;
+	T *data = nullptr;
+	RefCounts *counts = nullptr;
 
 public:
-	RefPtr(): data(0), counts(0) { }
-	RefPtr(T *d): data(d), counts(data ? new RefCounts : 0) { incref(); }
+	RefPtr() = default;
+	RefPtr(T *d): data(d), counts(data ? new RefCounts : nullptr) { incref(); }
 private:
-	RefPtr(T *d, RefCounts *c): data(d), counts(d ? c : 0) { incref(); }
+	RefPtr(T *d, RefCounts *c): data(d), counts(d ? c : nullptr) { incref(); }
 
 public:
 	/* Must have this or the compiler will generate a default copy-c'tor despite
@@ -43,6 +46,9 @@ public:
 	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 : nullptr) { incref(); }
+
 	~RefPtr() { decref(); }
 
 	RefPtr &operator=(T *);
@@ -53,6 +59,9 @@ public:
 	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> &);
@@ -70,7 +79,7 @@ public:
 	T *get() const { return data; }
 	T &operator*() const { return *data; }
 	T *operator->() const { return data; }
-	operator bool() const { return data!=0; }
+	explicit operator bool() const { return data; }
 
 	unsigned refcount() const { return (data ? counts->count : 0); }
 
@@ -84,12 +93,54 @@ private:
 };
 
 
+template<typename T>
+class WeakPtr
+{
+	template<typename U> friend class RefPtr;
+	template<typename U> friend class WeakPtr;
+
+private:
+	T *data = nullptr;
+	RefCounts *counts = nullptr;
+
+public:
+	WeakPtr() = default;
+private:
+	WeakPtr(T *d, RefCounts *c): data(d), counts(d ? c : nullptr) { incref(); }
+
+public:
+	WeakPtr(const WeakPtr &p): data(p.get()), counts(data ? p.counts : nullptr) { incref(); }
+
+	template<typename U>
+	WeakPtr(const WeakPtr<U> &p): data(p.get()), counts(data ? p.counts : nullptr) { 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:
+	template<typename U>
+	WeakPtr &assign(const WeakPtr<U> &);
+
+	T *get() const { return (counts && counts->count ? data : nullptr); }
+	void incref() { if(counts) ++counts->weak_count; }
+	void decref();
+};
+
+
 template<typename T>
 RefPtr<T> &RefPtr<T>::operator=(T *d)
 {
 	decref();
 	data = d;
-	counts = (d ? new RefCounts : 0);
+	counts = (d ? new RefCounts : nullptr);
 	incref();
 	return *this;
 }
@@ -98,6 +149,9 @@ template<typename T>
 template<typename U>
 RefPtr<T> &RefPtr<T>::assign(const RefPtr<U> &p)
 {
+	if(static_cast<const void *>(&p)==this)
+		return *this;
+
 	decref();
 	data = p.data;
 	counts = p.counts;
@@ -109,9 +163,9 @@ template<typename T>
 T *RefPtr<T>::release()
 {
 	T *d = data;
-	data = 0;
+	data = nullptr;
 	decref();
-	counts = 0;
+	counts = nullptr;
 	return d;
 }
 
@@ -123,15 +177,45 @@ void RefPtr<T>::decref()
 	if(!counts->count)
 	{
 		delete data;
-		delete counts;
-		data = 0;
-		counts = 0;
+		data = nullptr;
 	}
 	else if(counts->count==RefCounts::KEEP)
+		data = nullptr;
+	else
+		return;
+
+	if(!counts->weak_count)
+	{
+		delete counts;
+		counts = nullptr;
+	}
+}
+
+
+template<typename T>
+template<typename U>
+WeakPtr<T> &WeakPtr<T>::assign(const WeakPtr<U> &p)
+{
+	if(&p==this)
+		return *this;
+
+	decref();
+	data = p.get();
+	counts = (data ? p.counts : nullptr);
+	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;
+		data = nullptr;
+		counts = nullptr;
 	}
 }