Backtracking when using or() and | operator.

[Charles-AntoineLaurin]

So I'm new with this library and I've come across some problems with non-terminal containing multiple production rules. The parser doesn’t seem to backtrack when it comes across an error. Here's an exemple:

S-> AB
A-> a
B-> b | bc

When given the sentence : abc it returns an error because the parser hits on B-> b and doesn't seem to backtrack when it reads c. When we switch the rule production to B-> bc | b it works but my production rules are much bigger and complicated than this example.

Is there a good way to write our production rules in order to allow backtracking?

Also, from what I've tested, it seems that the parser works Top-Down. Is it the case? And is it possible to change it to Bottom-up?

[renggli]

PetitParser is a recursive descent top-down parser. It uses the semantics of parsing expression grammars and as such it picks the first succeeding choice (ordered choice) and never backtracks.