I am trying to implement a parser. I want to parse a string that has the following format: [Screenshot 2021-10-28 at 23.45.01] I did the following: sample = empty() |> ascii_string([?A..?Z, ?0..?9], 2) |> ascii_string([0..127], 4) |> ascii_string([0..127], 4) |> ignore(str…

Using nimble_parsec I tend to prefer using a helper module for combinators rather than inline. I also tend to create semantic functions because sooner or later debugging a nimble_parsec combinator - and providing reasonable messages back to a user on parse errors - becomes a challenge. Example pars…

EDIT: I misread the protocol version part which is not hex … taking another stab I think in this simple case a binary decomposition will be more straight forward: case some_string do <<version::binary-6, count::binary-4, "$">> -> version = String.to_integer(version, 16) count = String.to…

OK, revised version. Not sure its any more “beautiful” than your version but may be food for thought: case some_string do <<h1::integer-8, h2::integer-8, version::binary-4, count::binary-4, "$">> when (h1 in ?A..?Z or h1 in ?0..?9) and (h2 in ?A..?Z or h2 in ?0..?9)-> header = List.to_…

Thnx for the reply @kip The reason I chose for nimble_parsec is because, down the line, there are many more commands that I have to implement where some have variable byte lenghts for some of the paramters and I don’t want to type those all out. I’d rather use nimble_parse for that. Here is an exa…

Noting BTW that you can use binary pattern matching to parse variable length content. This article has a really good example for parsing PNG files.

Thnx a lot @kip ! :heart: You’ve thought me so much with this one example.

@kip One last question: There are several commands in this protocol that I need to parse. They all have a different starting string that identifies them. Which of the following paths would you suggest I use: a) Using binary pattern matching then routing into a nimble_parsec parser ... defpars…

Given you’re heading down the nimble_parsec route I would stay in that domain and do something like: defparsec :parse, choice([ string("+ACK:GTHBD") |> parsec(:parse_ack), string("+SACK:GTHBD") |> parsec(:parse_sack) ]) end

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dunyakirkali October 30, 2021, 8:20am 7

Thnx a lot @kip !

You’ve thought me so much with this one example.