ident: member interface

For representing full identifiers of system and member.

Signed-off-by: Yonah <contrib@gensokyo.uk>

ident/member.go

@@ -23,6 +23,8 @@ type M struct {
 	System S
 }
 
+func (*M) ident() {}
+
 const (
 	// SizeMember is the size of the binary representation of [M].
 	SizeMember = SizeSystem * 2
@@ -30,6 +32,9 @@ const (
 	EncodedSizeMember = SizeMember / 3 * 4
 )
 
+// EncodedSize returns the number of bytes appended by Encode.
+func (*M) EncodedSize() int { return EncodedSizeMember }
+
 // Encode appends the canonical string representation of mid to dst and returns
 // the extended buffer.
 func (mid *M) Encode(dst []byte) []byte {