UnionMatcher doesn't add possible matches when throwing on ambiguity

[hugoduncan]

When the UnionMatcher throws due to ambiguous match, the possible matches are not added to the exception, which makes it harder than necessary to debug parsers for this case.

[cgrand]

Hugo how is the error message in the brand new Parsley v0.9.0 -- not great I expect.

On Thu, May 31, 2012 at 6:31 PM, Hugo Duncan < [email protected]

wrote:

When the UnionMatcher throws due to ambiguous match, the possible matches are not added to the exception, which makes it harder than necessary to debug parsers for this case.

---

Reply to this email directly or view it on GitHub: https://github.com/cgrand/parsley/issues/3

Professional: http://cgrand.net/ (fr) On Clojure: http://clj-me.cgrand.net/ (en)

[hugoduncan]

Looks like I get:

nth not supported on this type: Boolean

(def ambiguous-parser
  (parser
   :expr #{#"Abc" #"Ade"}))
(clojure.pprint/pprint (ambiguous-parser "A"))

Edit: Not sure what I was testing above...

[hugoduncan]

0.9.0 reports the matcher functions that give ambiguous matches - is this what you intended?

I was expecting to see something like (pr-str (filter identity (map #(% s eof) matchers)))

[cgrand]

I reverted my modification and push a 0.9.1 out of the door (I should never commit in a hurry, even if I have to get off the train :-))

I don't know how to make the message more informative without more widespread changes: a successful matcher returns: the number of characters matched and the (usually) numerical id of the original matcher which are not that helpful when you have two conflicting regexes. Am I overlooking something there?