Function on_array_open 

fn on_array_open(
    tokens: &mut TokenSlice<'_, Token>,
    array_open: &Token,
    receiver: &mut dyn EventReceiver,
    error: &mut dyn ErrorSink,
)

Parse an array

;; Array

array = array-open [ array-values ] ws-comment-newline array-close

array-values =  ws-comment-newline val ws-comment-newline array-sep array-values
array-values =/ ws-comment-newline val ws-comment-newline [ array-sep ]