Initial support for duktape

Gemfile

@@ -3,6 +3,7 @@ source 'https://rubygems.org'
 gemspec
 
 group :test do
+  gem 'duktape'
   gem 'therubyracer', platform: :mri
   gem 'therubyrhino', ">=1.73.3", platform: :jruby
 end

lib/execjs/duktape_runtime.rb

@@ -0,0 +1,67 @@
+require "execjs/runtime"
+require "json"
+
+module ExecJS
+  class DuktapeRuntime < Runtime
+    class Context < Runtime::Context
+      def initialize(runtime, source = "")
+        @ctx = Duktape::Context.new
+
+        # Disable CJS
+        exec("module = exports = require = undefined")
+        exec(source)
+      end
+
+      def exec(source, options = {})
+        source = encode(source)
+
+        js = <<-JS
+          (function(program, execJS) { return execJS(program); })(function() { #{source}
+          }, function(program) {
+            try {
+              return JSON.stringify(['ok', program()]);
+            } catch (err) {
+              return JSON.stringify(['err', '' + err]);
+            }
+          });
+        JS
+
+        if json = @ctx.eval_string(js, '(execjs)')
+          status, value = ::JSON.parse(json, create_additions: false)
+          if status == "ok"
+            value
+          elsif value =~ /SyntaxError:/
+            raise RuntimeError, value
+          else
+            raise ProgramError, value
+          end
+        end
+      rescue Duktape::ContextError => e
+        raise RuntimeError, e.message
+      end
+
+      def eval(source, options = {})
+        source = encode(source)
+
+        if /\S/ =~ source
+          exec("return eval(#{::JSON.generate("(#{source})", quirks_mode: true)})")
+        end
+      end
+
+      def call(identifier, *args)
+        eval "#{identifier}.apply(this, #{::JSON.generate(args)})"
+      end
+    end
+
+    def name
+      "Duktape"
+    end
+
+    def available?
+      require "duktape"
+      true
+    rescue LoadError
+      false
+    end
+  end
+end

lib/execjs/runtimes.rb

@@ -1,5 +1,6 @@
 require "execjs/module"
 require "execjs/disabled_runtime"
+require "execjs/duktape_runtime"
 require "execjs/external_runtime"
 require "execjs/johnson_runtime"
 require "execjs/mustang_runtime"
@@ -10,6 +11,8 @@ module ExecJS
   module Runtimes
     Disabled = DisabledRuntime.new
 
+    Duktape = DuktapeRuntime.new
+
     RubyRacer = RubyRacerRuntime.new
 
     RubyRhino = RubyRhinoRuntime.new
@@ -78,6 +81,7 @@ module ExecJS
       @runtimes ||= [
         RubyRacer,
         RubyRhino,
+        Duktape,
         Johnson,
         Mustang,
         Node,

test/test_execjs.rb

@@ -171,6 +171,9 @@ class TestExecJS < Test
   end
 
   def test_coffeescript
+    # Skip coffeescript on Duktape for now
+    skip if ExecJS.runtime.is_a?(ExecJS::DuktapeRuntime)
+
     assert source = File.read(File.expand_path("../fixtures/coffee-script.js", __FILE__))
     context = ExecJS.compile(source)
     assert_equal 64, context.call("CoffeeScript.eval", "((x) -> x * x)(8)")