From 24d0454d6d05fc3b2c6a952a9d48574199b85815 Mon Sep 17 00:00:00 2001
From: Joshua Peek <josh@joshpeek.com>
Date: Mon, 11 Apr 2016 21:49:10 -0700
Subject: [PATCH] Check arity to support existing runtime classes

---
 lib/execjs/runtime.rb | 24 +++++++++++++++++++-----
 1 file changed, 19 insertions(+), 5 deletions(-)

diff --git a/lib/execjs/runtime.rb b/lib/execjs/runtime.rb
index ed06857..eba424c 100644
--- a/lib/execjs/runtime.rb
+++ b/lib/execjs/runtime.rb
@@ -31,17 +31,31 @@ module ExecJS
     end
 
     def exec(source, options = {})
-      context = context_class.new(self)
-      context.exec(source, options)
+      context = compile("", options)
+
+      if context.method(:exec).arity == 1
+        context.exec(source)
+      else
+        context.exec(source, options)
+      end
     end
 
     def eval(source, options = {})
-      context = context_class.new(self)
-      context.eval(source, options)
+      context = compile("", options)
+
+      if context.method(:eval).arity == 1
+        context.eval(source)
+      else
+        context.eval(source, options)
+      end
     end
 
     def compile(source, options = {})
-      context_class.new(self, source, options)
+      if context_class.instance_method(:initialize).arity == 2
+        context_class.new(self, source)
+      else
+        context_class.new(self, source, options)
+      end
     end
 
     def deprecated?