Sean One extra point. You may need to post-process the parse to get what you want. In the 'restricted' line, if you don't have a #gen then 'gen negate' will have succeeded and will generate its own node in the parse - in your example of ' Paul' as input it will be $P. Assuming you don't want this (!), you can add ==> [:nodes| nodes second] to the definition of restricted.
I had realized this after I posted on Sunday, as well as the fact that I had put the anded elements in the wrong order, but I didn't want to generate a stream of supplementaries. HTH Peter -----Original Message----- From: Pharo-users [mailto:pharo-users-boun...@lists.pharo.org] On Behalf Of Sean P. DeNigris Sent: 09 August 2017 03:41 To: pharo-users@lists.pharo.org Subject: Re: [Pharo-users] PetitParser: Parse X as long as it's not Y Peter Kenny wrote > This seems to be what the PPAndParser is designed for. Thanks for the pointer, Peter! I finally figured it out based on your example. To get more concrete, I'm trying to parse a name, where the end of the input might be an optional middle name, followed by an optional generational (e.g. 'Paul III'). What I think the restricted line says is: "peek to make sure we don't have a #gen, then try to parse an #identifier". Interestingly the order is important. If the peek and identifier are reversed, it tries to peek after the identifier, causing an error when there is only a middle name (i.e. no more input). identifier := #letter asParser plus flatten. gen := 'Jr' asParser / 'Sr' asParser. restricted := gen negate and, identifier. parser := ((#space asParser, restricted) optional, (#space asParser, gen) optional) end. parser parse: ' Paul Jr'. parser parse: ' Paul'. parser parse: ' Jr'. This really had me baffled. Thanks again!! ----- Cheers, Sean -- View this message in context: http://forum.world.st/PetitParser-Parse-X-as-long-as-it-s-not-Y-tp4958895p49 59268.html Sent from the Pharo Smalltalk Users mailing list archive at Nabble.com.
