ident: member interface

For representing full identifiers of system and member.

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

ident/system.go

@@ -31,6 +31,8 @@ type S struct {
 	ID uint64
 }
 
+func (*S) ident() {}
+
 const (
 	// SizeSystem is the size of the binary representation of [S].
 	SizeSystem = 24
@@ -38,6 +40,9 @@ const (
 	EncodedSizeSystem = SizeSystem / 3 * 4
 )
 
+// EncodedSize returns the number of bytes appended by Encode.
+func (*S) EncodedSize() int { return EncodedSizeSystem }
+
 // Encode appends the canonical string representation of sid to dst and returns
 // the extended buffer.
 func (sid *S) Encode(dst []byte) []byte {