feat: add streams

include/sp/common/VarInt.h

@@ -7,12 +7,14 @@
 
 #include <cstddef>
 #include <cstdint>
-#include <ostream>
+#include <functional>
 
 namespace sp {
 
 class DataBuffer;
 
+using ReadFunc = std::function<void(std::uint8_t&)>;
+
 /**
  * \class VarInt
  * \brief Variable-length format such that smaller numbers use fewer bytes.
@@ -57,6 +59,7 @@ class VarInt {
 	 */
 	friend DataBuffer& operator>>(DataBuffer& in, VarInt& var);
 
+	void Read(const ReadFunc& read);
 };
 
 }  // namespace sp