merkeldag: change SetPrefix param to a pointer and reset the prefix on nil

License: MIT
Signed-off-by: Kevin Atkinson <k@kevina.org>

node.go

@@ -53,10 +53,17 @@ func PrefixForCidVersion(version int) (cid.Prefix, error) {
 	}
 }
 
-func (n *ProtoNode) SetPrefix(prefix cid.Prefix) {
-	n.Prefix = prefix
-	n.encoded = nil
-	n.cached = nil
+// SetPrefix sets the prefix if it is non nil, if prefix is nil then
+// it resets it the default value
+func (n *ProtoNode) SetPrefix(prefix *cid.Prefix) {
+	if prefix == nil {
+		n.Prefix = v0CidPrefix
+	} else {
+		n.Prefix = *prefix
+		n.Prefix.Codec = cid.DagProtobuf
+		n.encoded = nil
+		n.cached = nil
+	}
 }
 
 type LinkSlice []*node.Link
@@ -287,7 +294,7 @@ func (n *ProtoNode) Cid() *cid.Cid {
 	}
 
 	if n.Prefix.Codec == 0 {
-		n.Prefix = v0CidPrefix
+		n.SetPrefix(nil)
 	}
 
 	c, err := n.Prefix.Sum(n.RawData())