Implement decode!/2 (#18)

lib/lua.ex

@@ -252,7 +252,17 @@ defmodule Lua do
     {encoded, wrap(state)}
   rescue
     ArgumentError ->
-      reraise Lua.RuntimeException, "Failed to encode value", __STACKTRACE__
+      reraise Lua.RuntimeException, "Failed to encode #{inspect(value)}", __STACKTRACE__
+  end
+
+  @doc """
+  Decodes a Lua value from its internal form
+  """
+  def decode!(%__MODULE__{} = lua, value) do
+    :luerl_new.decode(value, lua.state)
+  rescue
+    ArgumentError ->
+      reraise Lua.RuntimeException, "Failed to decode #{inspect(value)}", __STACKTRACE__
   end
 
   @doc """

mix.exs

@@ -2,7 +2,7 @@ defmodule Lua.MixProject do
   use Mix.Project
 
   @url "https://github.com/tv-labs/lua"
-  @version "0.0.8"
+  @version "0.0.9"
 
   def project do
     [

test/lua_test.exs

@@ -222,24 +222,36 @@ defmodule LuaTest do
     end
   end
 
-  describe "encode!/1" do
+  describe "encode!/1 and decode!/1" do
     test "it can encode values into their internal representation" do
       lua = Lua.new()
 
       assert {"hello", lua} = Lua.encode!(lua, "hello")
+      assert "hello" = Lua.decode!(lua, "hello")
       assert {"hello", lua} = Lua.encode!(lua, :hello)
       assert {5, lua} = Lua.encode!(lua, 5)
-      assert {{:tref, _}, lua} = Lua.encode!(lua, %{a: 1, b: 2})
-      assert {{:tref, _}, _lua} = Lua.encode!(lua, [1, 2, 3, 4])
+      assert 5 = Lua.decode!(lua, 5)
+      assert {{:tref, _} = ref, lua} = Lua.encode!(lua, %{a: 1, b: 2})
+      assert [{"a", 1}, {"b", 2}] = Lua.decode!(lua, ref)
+      assert {{:tref, _} = ref, lua} = Lua.encode!(lua, [1, 2])
+      assert [{1, 1}, {2, 2}] = Lua.decode!(lua, ref)
     end
 
     test "it raises for values that cannot be encoded" do
-      error = "Lua runtime error: Failed to encode value"
+      error = "Lua runtime error: Failed to encode {:foo, :bar}"
 
       assert_raise Lua.RuntimeException, error, fn ->
         Lua.encode!(Lua.new(), {:foo, :bar})
       end
     end
+
+    test "it raises for values that cannot be decoded" do
+      error = "Lua runtime error: Failed to decode :hello"
+
+      assert_raise Lua.RuntimeException, error, fn ->
+        Lua.decode!(Lua.new(), :hello)
+      end
+    end
   end
 
   describe "error messages" do