From: Mikko Rasa <tdb@tdb.fi>
Date: Sat, 6 Feb 2021 09:51:17 +0000 (+0200)
Subject: Move RefPtr refcount into a struct
X-Git-Url: http://git.tdb.fi/?p=libs%2Fcore.git;a=commitdiff_plain;h=74e62aabadda67d02b3eab09baa37c9d7640b794

Move RefPtr refcount into a struct

This is necessary to implement weak pointers
---

diff --git a/source/core/refptr.h b/source/core/refptr.h
index 0328340..8ab1b7c 100644
--- a/source/core/refptr.h
+++ b/source/core/refptr.h
@@ -3,6 +3,19 @@
 
 namespace Msp {
 
+struct RefCounts
+{
+	enum
+	{
+		KEEP = 1U<<(sizeof(unsigned)*8-1)
+	};
+
+	unsigned count;
+
+	RefCounts(): count(0) { }
+};
+
+
 /**
 A reference counting smart pointer.  When the last RefPtr for the data gets
 destroyed, the data is deleted as well.
@@ -13,27 +26,22 @@ class RefPtr
 	template<typename U> friend class RefPtr;
 
 private:
-	enum
-	{
-		KEEP = 1U<<(sizeof(unsigned)*8-1)
-	};
-
 	T *data;
-	unsigned *count;
+	RefCounts *counts;
 
 public:
-	RefPtr(): data(0), count(0) { }
-	RefPtr(T *d): data(d), count(data ? new unsigned(1) : 0) { }
+	RefPtr(): data(0), counts(0) { }
+	RefPtr(T *d): data(d), counts(data ? new RefCounts : 0) { incref(); }
 private:
-	RefPtr(T *d, unsigned *c): data(d), count(d ? c : 0) { incref(); }
+	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), count(p.count) { incref(); }
+	RefPtr(const RefPtr &p): data(p.data), counts(p.counts) { incref(); }
 
 	template<typename U>
-	RefPtr(const RefPtr<U> &p): data(p.data), count(p.count) { incref(); }
+	RefPtr(const RefPtr<U> &p): data(p.data), counts(p.counts) { incref(); }
 
 	~RefPtr() { decref(); }
 
@@ -41,7 +49,8 @@ public:
 	{
 		decref();
 		data = d;
-		count = (d ? new unsigned(1) : 0);
+		counts = (d ? new RefCounts : 0);
+		incref();
 		return *this;
 	}
 
@@ -57,7 +66,7 @@ private:
 	{
 		decref();
 		data = p.data;
-		count = p.count;
+		counts = p.counts;
 		incref();
 		return *this;
 	}
@@ -71,7 +80,7 @@ public:
 		T *d = data;
 		data = 0;
 		decref();
-		count = 0;
+		counts = 0;
 		return d;
 	}
 
@@ -79,8 +88,8 @@ public:
 	same data. */
 	void keep()
 	{
-		if(count)
-			*count |= KEEP;
+		if(counts)
+			counts->count |= RefCounts::KEEP;
 	}
 
 	T *get() const { return data; }
@@ -88,35 +97,35 @@ public:
 	T *operator->() const { return data; }
 	operator bool() const { return data!=0; }
 
-	unsigned refcount() const { return (data ? *count : 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.data), p.count); }
+	{ return RefPtr<T>(dynamic_cast<T *>(p.data), p.counts); }
 
 private:
 	void incref()
 	{
-		if(!count) return;
-		++*count;
+		if(!counts) return;
+		++counts->count;
 	}
 
 	void decref()
 	{
-		if(!count) return;
-		--*count;
-		if(!*count)
+		if(!counts) return;
+		--counts->count;
+		if(!counts->count)
 		{
 			delete data;
-			delete count;
+			delete counts;
 			data = 0;
-			count = 0;
+			counts = 0;
 		}
-		else if(*count==KEEP)
+		else if(counts->count==RefCounts::KEEP)
 		{
-			delete count;
+			delete counts;
 			data = 0;
-			count = 0;
+			counts = 0;
 		}
 	}
 };