From: Mikko Rasa <tdb@tdb.fi>
Date: Fri, 8 Oct 2010 19:54:28 +0000 (+0000)
Subject: RefPtr:
X-Git-Url: http://git.tdb.fi/?a=commitdiff_plain;h=de795c6fa9ea4d10431692a673be989a502ac475;p=libs%2Fcore.git

RefPtr:
Add templated copy-ctor and copy-assignment
Add assignment from a plain pointer for efficiency
Add keep() method to prevent deletion of data
Fix a potential leak in cast_dynamic
Style updates
---

diff --git a/source/core/refptr.h b/source/core/refptr.h
index dd07256..ddada0b 100644
--- a/source/core/refptr.h
+++ b/source/core/refptr.h
@@ -1,7 +1,7 @@
 /* $Id$
 
 This file is part of libmspcore
-Copyright © 2006-2007 Mikko Rasa, Mikkosoft Productions
+Copyright © 2006-2007, 2010 Mikko Rasa, Mikkosoft Productions
 Distributed under the LGPL
 */
 
@@ -17,18 +17,35 @@ destroyed, the data is deleted as well.
 template<typename T>
 class RefPtr
 {
+private:
+	enum
+	{
+		KEEP = 1U<<(sizeof(unsigned)*8-1)
+	};
+
 public:
 	RefPtr(): data(0), count(0) { }
-	RefPtr(T *d): data(d), count(0) { if(data) count=new unsigned(1); }
+	RefPtr(T *d): data(d), count(data ? new unsigned(1) : 0) { }
+
+	// Must have this or the compiler will generate a default copy-c'tor
 	RefPtr(const RefPtr &p): data(p.data), count(p.count) { incref(); }
-	RefPtr &operator=(const RefPtr &p)
+
+	template<typename U>
+	RefPtr(const RefPtr<U> &p): data(p.data), count(p.count) { incref(); }
+
+	RefPtr &operator=(T *d)
 	{
 		decref();
-		data=p.data;
-		count=p.count;
-		incref();
+		data = d;
+		count = (d ? new unsigned(1) : 0);
 		return *this;
 	}
+
+	// Likewise for the assignment operator
+	RefPtr &operator=(const RefPtr &p) { return assign(p); }
+
+	template<typename U>
+	RefPtr &operator=(const RefPtr<U> &p) { return assign(p); }
 	
 	~RefPtr() { decref(); }
 
@@ -39,34 +56,56 @@ public:
 	*/
 	T *release()
 	{
-		T *d=data;
-		data=0;
+		T *d = data;
+		data = 0;
 		decref();
-		count=0;
+		count = 0;
 		return d;
 	}
 
-	T *get() const        { return data; }
-	T &operator*() const  { return *data; }
+	/**
+	Marks the data to not be deleted.  This affects all RefPtrs with the same
+	data.
+	*/
+	void keep()
+	{
+		if(count)
+			*count |= KEEP;
+	}
+
+	T *get() const { return data; }
+	T &operator*() const { return *data; }
 	T *operator->() const { return data; }
 	operator bool() const { return data!=0; }
 
 	template<typename U>
-	static RefPtr<T> cast_dynamic(const RefPtr<U> &p)  { return RefPtr<T>(dynamic_cast<T *>(p.data), p.count); }
+	static RefPtr<T> cast_dynamic(const RefPtr<U> &p)
+	{ return RefPtr<T>(dynamic_cast<T *>(p.data), p.count); }
+
 	template<typename U> friend class RefPtr;
 private:
-	T        *data;
+	T *data;
 	unsigned *count;
 
-	RefPtr(T *d, unsigned *c): data(d), count(c) { incref(); }
+	RefPtr(T *d, unsigned *c): data(d), count(d ? c : 0) { incref(); }
 
-	void  incref()
+	template<typename U>
+	RefPtr &assign(const RefPtr<U> &p)
+	{
+		decref();
+		data = p.data;
+		count = p.count;
+		incref();
+		return *this;
+	}
+
+	void incref()
 	{
 		if(!count) return;
 		++*count;
 	}
 
-	void  decref()
+	void decref()
 	{
 		if(!count) return;
 		--*count;
@@ -74,8 +113,14 @@ private:
 		{
 			delete data;
 			delete count;
-			data=0;
-			count=0;
+			data = 0;
+			count = 0;
+		}
+		else if(*count==KEEP)
+		{
+			delete count;
+			data = 0;
+			count = 0;
 		}
 	}
 };