grammar:
    grammar-section+

grammar-section:
    non-terminal new-line?
    predicate new-line?
    whitespace? comment new-line?
    whitespace? new-line
    whitespace

comment:
    TERMINAL(//) NONE_OF(\r\n)*

whitespace:
    ONE_OF( \t\v\f)+

new-line:
    TERMINAL(\r) TERMINAL(\n)?
    TERMINAL(\n)

//---------------------

non-terminal:
    name-characters TERMINAL(:) whitespace? new-line productions

productions:
    production+

production:
    qualified-symbols whitespace? new-line

qualified-symbols:
    qualified-symbol+

qualified-symbol:
    whitespace symbol-name multiplicity?
    whitespace terminal    multiplicity?
    whitespace none-of     multiplicity?
    whitespace one-of      multiplicity?

multiplicity:
    ONE_OF(?+*)
    TERMINAL({) decimal-digits TERMINAL(})
    TERMINAL({) decimal-digits TERMINAL(,) decimal-digits TERMINAL(})

decimal-digits:
    ONE_OF(0123456789)+

//---------------------

symbol-name:
    name-characters

terminal:
    TERMINAL(TERMINAL() terminal-characters TERMINAL())

none-of:
    TERMINAL(NONE_OF()  terminal-characters TERMINAL())

one-of:
    TERMINAL(ONE_OF()   terminal-characters TERMINAL())

predicate:
    TERMINAL(PREDICATE()    name-characters TERMINAL())

terminal-characters:
    TERMINAL())
    NONE_OF())+

name-characters:
    ONE_OF(abcdefghijklmnopqrstuvwxyz-)+