Matthew Flatt wrote at 08/01/2011 08:40 PM:
At Mon, 01 Aug 2011 18:13:11 -0600, Jon Rafkind wrote:
How do I deal with partial lexemes when using the color:text colorer? It
seems that if my lexer cannot produce a valid token then it will throw
an error and the color thread will keep calling `get-token' in a busy loop.
Speaking generally of parsing for editors here, not of the DrRacket
syntax-colorer specifically...
You can have the notion of an "error" token, and, if all other rules for
matching a token fail, have a final rule (or rules) that consume your
error token. You can color the error token bright red boldface or
similar. Like I think Matthew said, you probably want to recover, not
abort.
For your error token, you should try to consume a chunk of input such
that the following text is likely to be a valid token that was likely
intended. This is more art than science, and depends very much on the
language. For your first attempt, you might try to just consume one
character followed by any non-whitespace-or-punctuation. You can also
be smarter about things like unterminated string literals and other
patterns of characters (e.g., "#" in Racket).
--
http://www.neilvandyke.org/
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