Execjs.call

Author: Devin Torres

lib/execjs.ex

@@ -1,14 +1,28 @@
-defexception Execjs.RuntimeError, message: nil
+defmodule Execjs do
+  import Execjs.Escape, only: [escape: 1]
 
-defexception Execjs.RuntimeUnavailable,
-  message: "Could not find a JavaScript runtime"
+  defexception RuntimeError, message: nil
 
-defmodule Execjs do
-  def eval(string) do
+  defexception RuntimeUnavailable,
+    message: "Could not find a JavaScript runtime"
+
+  def compile(source) do
+    { pre, post } = { "(function(){\n#{source};\n", ";\n})()" }
+    fn (source) ->
+      pre <> source <> post
+    end
+  end
+
+  def call(context, thing, args) do
+    source = "return #{thing}.apply(this, #{JSON.encode!(args)})"
+    eval(context.(source))
+  end
+
+  def eval(source) do
     runtime = Execjs.Runtimes.best_available
-    program = runtime.template(escape(string))
+    program = runtime.template(escape(source))
     command = runtime.command |> System.find_executable
-    tmpfile = compile(program)
+    tmpfile = compile_to_tempfile(program)
 
     try do
       port = Port.open({ :spawn_executable, command },
@@ -34,39 +48,11 @@ defmodule Execjs do
     end
   end
 
-  defp compile(program) do
+  defp compile_to_tempfile(program) do
     hash = :erlang.phash2(:crypto.rand_bytes(8))
     filename = "execjs-#{hash}.js"
     path = Path.join(System.tmp_dir!, filename)
     File.write! path, program
     path
   end
-
-  def escape(string) do
-    iolist_to_binary(escape(string, ""))
-  end
-
-  escape_map = [
-    { ?\\, "\\\\" },
-    { ?",  "\\\"" },
-    { ?\n, "\\n"  },
-    { ?\r, "\\r"  },
-    # http://bclary.com/2004/11/07/#a-7.3
-    { "\x{2028}", "\\u2028" },
-    { "\x{2029}", "\\u2029" }
-  ]
-
-  lc { char, escaped } inlist escape_map do
-    defp escape(<< unquote(char), rest :: binary >>, acc) do
-      escape(rest, [acc, unquote(escaped)])
-    end
-  end
-
-  defp escape(<< char :: utf8, rest :: binary >>, acc) do
-    escape(rest, [acc, char])
-  end
-
-  defp escape(<<>>, acc) do
-    acc
-  end
 end

lib/execjs/escape.ex

@@ -0,0 +1,33 @@
+defmodule Execjs.Escape do
+  @compile :native
+
+  def escape(""), do: ""
+
+  def escape(string) do
+    iolist_to_binary(escape(string, ""))
+  end
+
+  escape_map = [
+    { ?\\, "\\\\" },
+    { ?",  "\\\"" },
+    { ?\n, "\\n"  },
+    { ?\r, "\\r"  },
+    # http://bclary.com/2004/11/07/#a-7.3
+    { "\x{2028}", "\\u2028" },
+    { "\x{2029}", "\\u2029" }
+  ]
+
+  lc { char, escaped } inlist escape_map do
+    defp escape(<< unquote(char), rest :: binary >>, acc) do
+      escape(rest, [acc, unquote(escaped)])
+    end
+  end
+
+  defp escape(<< char :: utf8, rest :: binary >>, acc) do
+    escape(rest, [acc, char])
+  end
+
+  defp escape(<<>>, acc) do
+    acc
+  end
+end

lib/execjs/runtimes.ex

@@ -3,22 +3,24 @@ defmodule Execjs.Runtimes do
 
   Module.register_attribute __MODULE__, :runtimes, accumulate: true
 
-  defruntime JavaScriptCore,
-    command: "/System/Library/Frameworks/JavaScriptCore.framework/Versions/A/Resources/jsc",
-    runner: "jsc_runner.js.eex"
-
   defruntime Node,
     command: "node",
     runner: "node_runner.js.eex"
 
-  def runtimes, do: @runtimes
+  defruntime JavaScriptCore,
+    command: "/System/Library/Frameworks/JavaScriptCore.framework/Versions/A/Resources/jsc",
+    runner: "jsc_runner.js.eex"
+
+  def runtimes do
+    unquote(Enum.reverse(@runtimes))
+  end
 
   def best_available do
     case :application.get_env(:execjs, :runtime) do
       { :ok, runtime } ->
         runtime
       :undefined ->
-        runtime = Enum.find(@runtimes, &(&1.available?)) || raise RuntimeUnavailable
+        runtime = Enum.find(runtimes, &(&1.available?)) || raise RuntimeUnavailable
         :application.set_env(:execjs, :runtime, runtime)
         runtime
     end

mix.exs

@@ -16,6 +16,6 @@ defmodule Execjs.Mixfile do
   # Returns the list of dependencies in the format:
   # { :foobar, "~> 0.1", git: "https://github.com/elixir-lang/foobar.git" }
   defp deps do
-    [ { :jazz, github: "meh/jazz" } ]
+    [ { :jazz, github: "meh/jazz", tag: "v0.0.1" } ]
   end
 end

mix.lock

@@ -1 +1 @@
-[ "jazz": {:git, "git://github.com/meh/jazz.git", "efac8600723bdf338a356e5671007aa54a55f327", []} ]
+[ "jazz": {:git, "git://github.com/meh/jazz.git", "5b3fd0e3efd2c8445289bdbda2f93bb0d96ad169", [{:tag, "v0.0.1"}]} ]

test/execjs_test.exs

@@ -4,14 +4,12 @@ defmodule ExecjsTest do
   test "eval" do
     # assert Execjs.eval("(function() { return 1 + 1; })();") == ["ok", 2]
 
-    IO.inspect Execjs.eval(%S""")
-(function() {
+    context = Execjs.compile(%S""")
 function addOne(n) {
   return n + 1;
 }
-
-return addOne(3);
-})();
 """
+
+    IO.inspect Execjs.call(context, "addOne", [3])
   end
 end