Add boost.shared_ptr workaround.

git-svn-id: https://assimp.svn.sourceforge.net/svnroot/assimp/trunk@631 67173fc5-114c-0410-ac8e-9d2fd5bffc1f

code/BoostWorkaround/boost/shared_ptr.hpp

@@ -0,0 +1,160 @@
+
+#ifndef INCLUDED_AI_BOOST_SHARED_PTR
+#define INCLUDED_AI_BOOST_SHARED_PTR
+
+#ifndef BOOST_SCOPED_PTR_HPP_INCLUDED
+
+#include <assert.h>
+
+// ------------------------------
+// Internal stub
+namespace boost {
+	namespace detail {
+		class controller {
+
+		public:
+
+			controller()
+				: cnt()
+			{}
+
+			template <typename T>
+			controller(T* ptr)
+				: cnt(1)
+			{}
+		
+		public:
+
+			template <typename T>
+			controller* decref(T* pt) {
+				if (--cnt <= 0) {
+					delete this;
+					delete pt;
+				}
+				return NULL;
+			}
+		
+			controller* incref() {
+				++cnt;
+				return this;
+			}
+
+		private:
+			long cnt;
+		};
+
+		struct empty {};
+		
+		template <typename DEST, typename SRC>
+		struct is_convertible_stub {
+			
+			struct yes {char s[1];};
+			struct no  {char s[2];};
+
+			static yes foo(DEST*);
+			static no  foo(...);
+
+			enum {result = sizeof foo((SRC*)0) == sizeof yes};	
+		};
+
+		template <bool> struct enable_if {};
+		template <> struct enable_if<true> {
+			typedef empty result;
+		};
+
+		template <typename DEST, typename SRC>
+		struct is_convertible : public enable_if<is_convertible_stub<DEST,SRC>::result > {
+		};
+	}
+
+// ------------------------------
+// Small replacement for boost::shared_ptr, not threadsafe because no
+// atomic reference counter is in use.
+// ------------------------------
+template <class T>
+class shared_ptr
+{
+	friend class shared_ptr;
+public:
+
+	// provide a default construtctor
+	shared_ptr()
+		: ptr()
+		, ctr(new detail::controller())
+	{
+	}
+
+	// construction from an existing object of type T
+	shared_ptr(T* _ptr)
+		: ptr(_ptr)
+		, ctr(new detail::controller(ptr))
+	{
+	}
+
+	shared_ptr(const shared_ptr& o)
+		: ptr(o.ptr)
+		, ctr(o.ctr->incref())
+	{
+	}
+
+	template <typename Y>
+	shared_ptr(const shared_ptr<Y>& o,typename detail::is_convertible<T,Y>::result = detail::empty())
+		: ptr(o.ptr)
+		, ctr(o.ctr->incref())
+	{
+	}
+
+	// automatic destruction of the wrapped object when all
+	// references are freed.
+	~shared_ptr()	{
+		ctr = ctr->decref(ptr);
+	}
+
+	// pointer access
+	inline operator T*()	{
+		return ptr;
+	}
+
+	inline T* operator-> ()	{
+		return ptr;
+	}
+
+	// standard semantics
+	inline T* get()	{
+		return ptr;
+	}
+
+	inline void reset (T* t = 0)	{
+		ctr = ctr->decref(ptr);
+		ptr = t;
+		if(ptr) {
+			ctr = new detail::controller(ptr);
+		}
+	}
+
+	void swap(shared_ptr & b)	{
+		std::swap(ptr, b.ptr);
+		std::swap(ctr, b.ctr);
+	}
+
+private:
+
+	// encapsulated object pointer
+	T* ptr;
+
+	// control block
+	detail::controller* ctr;
+};
+
+template<class T>
+inline void swap(shared_ptr<T> & a, shared_ptr<T> & b)
+{
+	a.swap(b);
+}
+
+} // end of namespace boost
+
+#else
+#	error "shared_ptr.h was already included"
+#endif
+#endif // INCLUDED_AI_BOOST_SCOPED_PTR