BString::Private class to access BString internals

headers/build/private/support/StringPrivate.h

@@ -0,0 +1 @@
+#include <../private/support/StringPrivate.h>

headers/os/support/String.h

@@ -321,9 +321,20 @@ public:
 			BString&		operator<<(float value);
 			BString&		operator<<(double value);
 
+public:
+			class Private;
+			friend class Private;
+
 private:
-	class PosVect;
-	friend class BStringRef;
+			class PosVect;
+			friend class BStringRef;
+
+			enum PrivateDataTag {
+				PRIVATE_DATA
+			};
+
+private:
+							BString(char* privateData, PrivateDataTag tag);
 
 			// Management
 			status_t		_MakeWritable();

headers/private/support/StringPrivate.h

@@ -0,0 +1,75 @@
+/*
+ * Copyright 2011, Ingo Weinhold, ingo_weinhold@gmx.de.
+ * Distributed under the terms of the MIT License.
+ */
+#ifndef _SUPPORT_BSTRING_PRIVATE_H_
+#define _SUPPORT_BSTRING_PRIVATE_H_
+
+
+#include <stdlib.h>
+
+#include <String.h>
+
+
+class BString::Private {
+public:
+	static const uint32 kPrivateDataOffset = 2 * sizeof(int32);
+
+public:
+	Private(const BString& string)
+		:
+		fString(string)
+	{
+	}
+
+	char* Data()
+	{
+		return fString.fPrivateData;
+	}
+
+	static vint32& DataRefCount(char* data)
+	{
+		return *(((int32 *)data) - 2);
+	}
+
+	vint32& DataRefCount()
+	{
+		return DataRefCount(Data());
+	}
+
+	static int32& DataLength(char* data)
+	{
+		return *(((int32*)data) - 1);
+	}
+
+	int32& DataLength()
+	{
+		return DataLength(Data());
+	}
+
+	static void IncrementDataRefCount(char* data)
+	{
+		if (data != NULL)
+			atomic_add(&DataRefCount(data), 1);
+	}
+
+	static void DecrementDataRefCount(char* data)
+	{
+		if (data != NULL) {
+			if (atomic_add(&DataRefCount(data), -1) == 1)
+				free(data - kPrivateDataOffset);
+		}
+	}
+
+	static BString StringFromData(char* data)
+	{
+		return BString(data, BString::PRIVATE_DATA);
+	}
+
+private:
+	const BString&	fString;
+};
+
+
+#endif	// _SUPPORT_BSTRING_PRIVATE_H_
+