--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/yapf/autocopyptr.hpp	Sat May 27 16:12:16 2006 +0000
@@ -0,0 +1,82 @@
+/* $Id$ */
+
+#ifndef  AUTOCOPYPTR_HPP
+#define  AUTOCOPYPTR_HPP
+
+/** CAutoCopyPtrT - kind of CoW (Copy on Write) pointer.
+		It is non-invasive smart pointer (reference counter is held outside
+		of Tdata).
+		When copied, its new copy shares the same underlaying structure Tdata.
+		When dereferenced, its behavior depends on 2 factors:
+		   - whether the data is shared (used by more than one pointer)
+		   - type of access (read/write)
+		  When shared pointer is dereferenced for write, new clone of Tdata
+		is made first.
+		Can't be used for polymorphic data types (interfaces).
+*/
+template <class Tdata_>
+class CAutoCopyPtrT {
+protected:
+	typedef Tdata_ Tdata;
+
+	struct CItem	{
+		int     m_ref_cnt;  ///< reference counter
+		Tdata   m_data;     ///< custom data itself
+
+		FORCEINLINE CItem()                  : m_ref_cnt(1)                     {};
+		FORCEINLINE CItem(const Tdata& data) : m_ref_cnt(1), m_data(data)       {};
+		FORCEINLINE CItem(const CItem& src)  : m_ref_cnt(1), m_data(src.m_data) {};
+	};
+
+	mutable CItem* m_pI; ///< points to the ref-counted data
+
+public:
+	FORCEINLINE CAutoCopyPtrT() : m_pI(NULL) {};
+	FORCEINLINE CAutoCopyPtrT(const Tdata& data) : m_pI(new CItem(data)) {};
+	FORCEINLINE CAutoCopyPtrT(const CAutoCopyPtrT& src) : m_pI(src.m_pI) {if (m_pI != NULL) m_pI->m_ref_cnt++;}
+	FORCEINLINE ~CAutoCopyPtrT() {if (m_pI == NULL || (--m_pI->m_ref_cnt) > 0) return; delete m_pI; m_pI = NULL;}
+
+	/** data accessor (read only) */
+	FORCEINLINE const Tdata& GetDataRO() const {if (m_pI == NULL) m_pI = new CItem(); return m_pI->m_data;}
+	/** data accessor (read / write) */
+	FORCEINLINE Tdata& GetDataRW() {CloneIfShared(); if (m_pI == NULL) m_pI = new CItem(); return m_pI->m_data;}
+
+	/** clone data if it is shared */
+	FORCEINLINE void CloneIfShared()
+	{
+		if (m_pI != NULL && m_pI->m_ref_cnt > 1) {
+			// we share data item with somebody, clone it to become an exclusive owner
+			CItem* pNewI = new CItem(*m_pI);
+			m_pI->m_ref_cnt--;
+			m_pI = pNewI;
+		}
+	}
+
+	/** assign pointer from the other one (maintaining ref counts) */
+	FORCEINLINE void Assign(const CAutoCopyPtrT& src)
+	{
+		if (m_pI == src.m_pI) return;
+		if (m_pI != NULL && (--m_pI->m_ref_cnt) <= 0) delete m_pI;
+		m_pI = src.m_pI;
+		if (m_pI != NULL) m_pI->m_ref_cnt++;
+	}
+
+	/** dereference operator (read only) */
+	FORCEINLINE const Tdata* operator -> () const {return &GetDataRO();}
+	/** dereference operator (read / write) */
+	FORCEINLINE Tdata* operator -> () {return &GetDataRW();}
+
+	/** assignment operator */
+	FORCEINLINE CAutoCopyPtrT& operator = (const CAutoCopyPtrT& src) {Assign(src); return *this;}
+
+	/** forwarding 'lower then' operator to the underlaying items */
+	FORCEINLINE bool operator < (const CAutoCopyPtrT& other) const
+	{
+		assert(m_pI != NULL);
+		assert(other.m_pI != NULL);
+		return (m_pI->m_data) < (other.m_pI->m_data);
+	}
+};
+
+
+#endif /* AUTOCOPYPTR_HPP */