Skip to content

%fallback

Jump to bottom
ksherlock edited this page Dec 19, 2015 · 2 revisions

The %fallback directive

The %fallback directive allows for context sensitive terminals. If a terminal cannot be parsed, it will try again as it's fallback before throwing an error.

Consider a language where keywords are not reserved -- IF IF THEN THEN might be a legal (and confusing) statement.

%fallback ID IF THEN
stmt ::= IF expr THEN stmt.
stmt ::= ID. // function call
expr ::= ID.
Clone this wiki locally