Add torrent-viewer script (#644) [skip ci]

examples/README.md

@@ -334,3 +334,14 @@ $ examples/image_viewer.clj
 ```
 
 See [image_viewer.clj](image_viewer.clj).
+
+### Torrent viewer
+
+Shows the content of a torrent file. Note that pieces' content is hidden.
+
+Example usage:
+``` shell
+$ examples/torrent-viewer.clj file.torrent
+```
+
+See [torrent-viewer.clj](torrent-viewer.clj).

examples/torrent-viewer.clj

@@ -0,0 +1,19 @@
+#!/usr/bin/env bb
+
+(require '[clojure.java.io :as io])
+(require '[bencode.core :refer [read-bencode]])
+(require '[clojure.walk :refer [prewalk]])
+(require '[clojure.pprint :refer [pprint]])
+(import 'java.io.PushbackInputStream)
+
+(defn bytes->strings [coll]
+  (prewalk #(if (bytes? %) (String. % "UTF-8") %) coll))
+
+(defn read-torrent [src]
+  (with-open [in (io/input-stream (io/file src))]
+    (-> in PushbackInputStream. read-bencode bytes->strings)))
+
+(when-let [src (first *command-line-args*)]
+  (-> (read-torrent src)
+      (assoc-in ["info" "pieces"] "...") ; binary data
+      pprint))