Grammar grammaire;
Lexer
id = ('a'..'z')+;
altid = '{' id ':}';
str = '\'' (Any* - '\'') '\'';
blank = ' ' | #9 | #10 | #13;

Parser
Ignored blank;
prods = prod+;
prod = id '=' (alt Separator '|')+ ';' ;
alt = altid? atom* ;
atom = {id:} id | {str:} str ;