Stub out the Node runtime

lib/execjs.rb

@@ -1,3 +1,7 @@
 module ExecJS
+  class Error < ::StandardError; end
+  class RuntimeError    < Error; end
+  class ProgramError    < Error; end
+
   autoload :Runtimes, "execjs/runtimes"
 end

lib/execjs/runtimes/node.js

@@ -0,0 +1,20 @@
+(function(program, execJS) { execJS(program) })(function() { #{source}
+}, function(program) {
+  var output, print = function(string) {
+    process.stdout.write('' + string);
+  };
+  try {
+    result = program();
+    if (typeof result == 'undefined' && result !== null) {
+      print('["ok"]');
+    } else {
+      try {
+        print(JSON.stringify(['ok', result]));
+      } catch (err) {
+        print('["err"]');
+      }
+    }
+  } catch (err) {
+    print(JSON.stringify(['err', '' + err]));
+  }
+});

lib/execjs/runtimes/node.rb

@@ -1,26 +1,58 @@
+require "json"
+require "tempfile"
+
 module ExecJS
   module Runtimes
-    class Node
+    module Node
+      extend self
 
-    end
+      def exec(source)
+        compile_to_tempfile(source) do |file|
+          extract_result(exec_runtime("node #{file.path}"))
         end
       end
 
-__END__
-(function(program, execJS) { execJS(program) })(function() { #{source}
-}, function(program) {
-  var result, output;
-  try {
-    result = program();
-    try {
-      output = JSON.stringify(result);
-      sys.print('ok ');
-      sys.print(output);
-    } catch (err) {
-      sys.print('err');
-    }
-  } catch (err) {
-    sys.print('err ');
-    sys.print(err);
-  }
-});
+      def eval(source)
+        if /\S/ =~ source
+          exec("return eval(#{"(#{source})".to_json})")
+        end
+      end
+
+      protected
+        def compile_to_tempfile(source)
+          tempfile = Tempfile.open("execjs")
+          tempfile.write compile(source)
+          tempfile.close
+          yield tempfile
+        ensure
+          tempfile.close!
+        end
+
+        def compile(source)
+          wrapper.sub('#{source}', source)
+        end
+
+        def wrapper
+          @wrapper ||= IO.read(File.expand_path('../node.js', __FILE__))
+        end
+
+        def exec_runtime(command)
+          output = `#{command} 2>&1`
+          if $?.success?
+            output
+          else
+            raise RuntimeError, output
+          end
+        end
+
+        def extract_result(output)
+          status, value = output.empty? ? [] : JSON.parse(output)
+          if status == "ok"
+            value
+          else
+            raise ProgramError, value
+          end
+        end
+    end
+  end
+end

readme.md

@@ -19,5 +19,5 @@ ExecJS supports these runtimes:
 A short example:
 
     require "execjs"
-    ExecJS.exec "'red yellow blue'.split('')"
+    ExecJS.eval "'red yellow blue'.split('')"
     # => ["red", "yellow", "blue"]

test/test_node_runtime.rb

@@ -0,0 +1,44 @@
+require "execjs"
+require "test/unit"
+
+class TestNodeRuntime < Test::Unit::TestCase
+  def setup
+    @runtime = ExecJS::Runtimes::Node
+  end
+
+  def test_exec
+    assert_nil @runtime.exec("1")
+    assert_nil @runtime.exec("return")
+    assert_nil @runtime.exec("return null")
+    assert_nil @runtime.exec("return function() {}")
+    assert_equal 0, @runtime.exec("return 0")
+    assert_equal true, @runtime.exec("return true")
+    assert_equal [1, 2], @runtime.exec("return [1, 2]")
+    assert_equal "hello", @runtime.exec("return 'hello'")
+    assert_equal({"a"=>1,"b"=>2}, @runtime.exec("return {a:1,b:2}"))
+  end
+
+  def test_eval
+    assert_nil @runtime.eval("")
+    assert_nil @runtime.eval(" ")
+    assert_nil @runtime.eval("null")
+    assert_nil @runtime.eval("function() {}")
+    assert_equal 0, @runtime.eval("0")
+    assert_equal true, @runtime.eval("true")
+    assert_equal [1, 2], @runtime.eval("[1, 2]")
+    assert_equal "hello", @runtime.eval("'hello'")
+    assert_equal({"a"=>1,"b"=>2}, @runtime.eval("{a:1,b:2}"))
+  end
+
+  def test_syntax_error
+    assert_raise ExecJS::RuntimeError do
+      @runtime.exec(")")
+    end
+  end
+
+  def test_thrown_exception
+    assert_raise ExecJS::ProgramError do
+      @runtime.exec("throw 'hello'")
+    end
+  end
+end