pod-janet-peg

A babashka pod for calling Janet's peg/match function. Implemented using the Janet programming language.

Install

• Install Janet

• Clone the source

  git clone https://github.com/sogaiu/pod-janet-peg
  

• Build

  cd pod-janet-peg
  jpm deps
  jpm build
  

  A build subdirectory should exist and an executable named pod-janet-peg should be contained within. (On Windows it should have the usual file extension).

• Place the resulting binary on your PATH

  I tend to symlink directly to the file in the build directory from some directory on my PATH.

Demo

Run in babashka or using the babashka.pods library on the JVM.

;; the usual pod set up
(require '[babashka.pods :as pods])
(pods/load-pod "pod-janet-peg")
(require '[pod.janet.peg :as pjp])

;; ... and now the punchline
(pjp/peg-match
 "~{:main :data
    :data (choice :list :table :number :string)
    :list (group (sequence \"l\" (any :data) \"e\"))
    :table (sequence \"d\" (replace (any (sequence :string :data))
                                  ,struct)
                     \"e\")
    :number (sequence \"i\" :digits \"e\")
    :digits (replace (capture :d+)
                     ,scan-number
                     :digits)
    :string (replace (sequence :digits \":\"
                               (capture (lenprefix (backref :digits) 1)))
                     ,|$1)}"
 "li1ei2e5:threed1:ai6e3:beei7eee")

The return value should be:

[[1 2 "three" {:bee 7, :a 6}]]

What Just Happened?

The pod exposes Janet's PEG functionality.

The code above uses a mostly complete grammar for Bencoding to parse a bencoded string.

Thanks

• andrewchambers - libs and more
• bakpakin - Janet
• borkdude - babashka, pods, and more
• leafgarland - bencode grammar
• pyrmont - bencodobi

... and possibly other people I forgot including Janet gitter channel participants :)