fixes #5: in case of include recursion the parse will throw an error

lib/hocon.ex

@@ -6,7 +6,6 @@ defmodule Hocon do
   ## Example
 
       iex(1)> conf = ~s(animal { favorite : "dog" }, key : \"\"\"${animal.favorite} is my favorite animal\"\"\")
-      "animal { favorite : \\"dog\\" }, key : \\"\\"\\"${animal.favorite} is my favorite animal\\"\\"\\""
       iex(2)> Hocon.decode(conf)
       {:ok,
       %{"animal" => %{"favorite" => "dog"}, "key" => "dog is my favorite animal"}}
@@ -46,7 +45,7 @@ defmodule Hocon do
 
       { x : 10, y : ${a.x} }
 
-  In the case we use the Hocon.FileResolver (which is the default as well):
+  In the case we use the `Hocon.FileResolver` (which is the default as well):
 
       iex> conf = ~s({ a : { include "./test/data/include-1" } })
       iex> Hocon.decode(conf, resolver: Hocon.FileResolver)

lib/hocon/parser.ex

@@ -32,7 +32,7 @@ defmodule Hocon.Parser do
       with {[], result } <- ast
                             |> contact_rule([])
                             |> parse_root(opts) do
-        Document.convert(result, opts)
+        Document.convert(result, Keyword.put(opts, :included_files, []))
       end
     end
   end
@@ -107,17 +107,30 @@ defmodule Hocon.Parser do
   # loads and parse the content of the `file`
   ##
   defp load_configuration_file(file, opts) do
-    with {:ok, conf}   <- load_contents_of_file(file, opts),
+
+    included_files = Keyword.get(opts, :included_files, [])
+
+    with :ok <- check_recursion(file, included_files),
+         {:ok, conf}   <- load_contents_of_file(file, opts),
          {:ok, ast}    <- Tokenizer.decode(conf),
          {[], result } <- ast
                           |> contact_rule([])
-                          |> parse_root(opts) do
+                          |> parse_root(Keyword.put(opts, :included_files, [file | included_files])) do
       {:ok, result}
     else
       {:error, reason} -> {:error, reason}
     end
   end
 
+  defp check_recursion(_file, []) do
+    :ok
+  end
+  defp check_recursion(file, included_files) do
+    case Enum.any?(included_files, fn included_file -> included_file == file end) do
+       true  -> throw {:error, "File " <> file <> " already included."}
+       false -> :ok
+    end
+  end
   ##
   # loads possible extension in combination with the filename
   ##

mix.exs

@@ -50,7 +50,7 @@ defmodule Hocon.MixProject do
     [main: "Hocon",
       name: "HOCON",
       extras: ["README.md"],
-      source_ref: "v#{@version}",
+      source_ref: "#{@version}",
       canonical: "http://hexdocs.pm/hocon",
       source_url: "https://github.com/zookzook/hocon"]
   end

test/data/recursion-1.conf

@@ -0,0 +1,3 @@
+{
+  b : { include "./test/data/recursion-2.conf" }
+}

test/data/recursion-2.conf

@@ -0,0 +1,3 @@
+{
+  c : { include "./test/data/recursion-1.conf" }
+}

test/parser/include_recursion_test.exs

@@ -0,0 +1,8 @@
+defmodule Parser.IncludeRecursionTest do
+  use ExUnit.Case, async: true
+
+  test "Tokenize include recursion" do
+    assert catch_throw(Hocon.decode!(~s({ a : { include "./test/data/recursion-1.conf" } }))) == {:error, "File ./test/data/recursion-1.conf already included."}
+  end
+
+end