proper method of rendering template files contained in jars

src/clj_jtwig/core.clj

@@ -1,6 +1,7 @@
 (ns clj-jtwig.core
   "wrapper functions for working with JTwig from clojure"
   (:import (com.lyncode.jtwig JtwigTemplate JtwigContext JtwigModelMap)
+           (com.lyncode.jtwig.resource ClasspathJtwigResource)
            (com.lyncode.jtwig.tree.api Content)
            (java.io File FileNotFoundException ByteArrayOutputStream)
            (java.net URL))
@@ -56,9 +57,15 @@
        (.compile)))
 
 (defn- compile-template-file [^File file]
-  (->> file
-       (new JtwigTemplate)
-       (.compile)))
+  (if (inside-jar? file)
+    (->> (.getPath file)
+         (get-jar-resource-filename)
+         (new ClasspathJtwigResource)
+         (new JtwigTemplate)
+         (.compile))
+    (->> file
+         (new JtwigTemplate)
+         (.compile))))
 
 (defn- newer? [^File file other-timestamp]
   (let [file-last-modified (get-file-last-modified file)]

src/clj_jtwig/utils.clj

@@ -9,6 +9,12 @@
       ; the path of a file inside a jar looks something like "jar:file:/path/to/file.jar!/path/inside/jar/to/file"
       (.contains "jar!")))
 
+(defn get-jar-resource-filename [^String resource-filename]
+  (let [pos (.indexOf resource-filename "jar!")]
+    (if-not (= -1 pos)
+      (subs resource-filename (+ pos 5))
+      resource-filename)))
+
 (defn exists? [^File file]
   (if (inside-jar? file)
     ;; TODO: can't use File.exists() for this