Comment on desambiguation at lexing

lexer.mll

@@ -8,9 +8,10 @@ let id = [ 'a'-'z' '_' '0'-'9' ] ['a'-'z' 'A'-'Z' '_' '0'-'9']*
 rule token = parse
     | [ ' ' '\t' ] { token lexbuf }
     | '\n' { token lexbuf }
-    | '.'(id as s)"<=" { UPDATE (s) }
-    | '.'(id as s)":=" { FUPD(s) }
-    | '.'(id as s) { SELECT (s) }
+    (* The several meanings of "." are disambiguated at lexing *)
+    | '.' (id as s) ' '* "<=" { UPDATE (s) }
+    | '.' (id as s) ' '* ":=" { FUPD(s) }
+    | '.' (id as s) { SELECT (s) }
     | '[' { LBRACK }
     | ']' { RBRACK }
     | ':' { COLUMN }