cpp: add sbuffer::clear() and vrefbuffer::clear()

cpp/msgpack/sbuffer.h

@@ -77,6 +77,10 @@ static inline char* msgpack_sbuffer_release(msgpack_sbuffer* sbuf)
 	return tmp;
 }
 
+static inline void msgpack_sbuffer_clear(msgpack_sbuffer* sbuf)
+{
+	sbuf->size = 0;
+}
 
 #ifdef __cplusplus
 }

cpp/msgpack/sbuffer.hpp

@@ -72,6 +72,11 @@ public:
 		return msgpack_sbuffer_release(this);
 	}
 
+	void clear()
+	{
+		msgpack_sbuffer_clear(this);
+	}
+
 private:
 	void expand_buffer(size_t len)
 	{

cpp/msgpack/vrefbuffer.h

@@ -80,6 +80,9 @@ int msgpack_vrefbuffer_append_ref(msgpack_vrefbuffer* vbuf,
 
 int msgpack_vrefbuffer_migrate(msgpack_vrefbuffer* vbuf, msgpack_vrefbuffer* to);
 
+void msgpack_vrefbuffer_clear(msgpack_vrefbuffer* vref);
+
+
 int msgpack_vrefbuffer_write(void* data, const char* buf, unsigned int len)
 {
 	msgpack_vrefbuffer* vbuf = (msgpack_vrefbuffer*)data;

cpp/msgpack/vrefbuffer.hpp

@@ -78,6 +78,11 @@ public:
 		}
 	}
 
+	void clear()
+	{
+		msgpack_vrefbuffer_clear(this);
+	}
+
 private:
 	typedef msgpack_vrefbuffer base;