From af9338ad9c782b1753e1e73aa46eb48b99291bc4 Mon Sep 17 00:00:00 2001
From: Jacques Wagener <jacques@dilectum.co.za>
Date: Wed, 26 Sep 2018 16:06:36 +0200
Subject: [PATCH 1/3] Add Access-Control-Allow-Origin: * to all vyper-server
 requests.

---
 bin/vyper-serve | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)
 mode change 100644 => 100755 bin/vyper-serve

diff --git a/bin/vyper-serve b/bin/vyper-serve
old mode 100644
new mode 100755
index f81f850773..55caad597a
--- a/bin/vyper-serve
+++ b/bin/vyper-serve
@@ -1,4 +1,4 @@
-#!/usr/bin/env python3.6
+#!/usr/bin/env python3
 
 import argparse
 import sys
@@ -34,10 +34,17 @@ class VyperRequestHandler(BaseHTTPRequestHandler):
         self.end_headers()
         return
 
-    def do_GET(self):
+    def send_cors_all(self):
+        self.send_header("Access-Control-Allow-Origin", "*")
+
+    def do_OPTIONS(self):
+        self.send_cors_all()
+        self.end_headers()
 
+    def do_GET(self):
         if self.path == '/':
             self.send_response(200)
+            self.send_cors_all()
             self.end_headers()
             self.wfile.write(b'Vyper Compiler.\n')
         else:
@@ -56,6 +63,7 @@ class VyperRequestHandler(BaseHTTPRequestHandler):
 
             self.send_response(status_code)
             self.send_header("Content-type", "application/json")
+            self.send_cors_all()
             self.end_headers()
             self.wfile.write(json.dumps(response).encode())
 

From 1f7c487765c0309b852142d4e04a5556bbe56d86 Mon Sep 17 00:00:00 2001
From: Jacques Wagener <jacques@dilectum.co.za>
Date: Wed, 26 Sep 2018 16:11:49 +0200
Subject: [PATCH 2/3] Add version to default vyper-serve page.

---
 bin/vyper-serve | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/bin/vyper-serve b/bin/vyper-serve
index 55caad597a..ed6550eb6c 100755
--- a/bin/vyper-serve
+++ b/bin/vyper-serve
@@ -46,7 +46,7 @@ class VyperRequestHandler(BaseHTTPRequestHandler):
             self.send_response(200)
             self.send_cors_all()
             self.end_headers()
-            self.wfile.write(b'Vyper Compiler.\n')
+            self.wfile.write('Vyper Compiler. Version: {} \n'.format(vyper.__version__).encode())
         else:
             self.send_404()
 

From ea97ef09ed59a0623f0240ea061a56b108f19fc3 Mon Sep 17 00:00:00 2001
From: Jacques Wagener <jacques@dilectum.co.za>
Date: Thu, 27 Sep 2018 13:33:08 +0200
Subject: [PATCH 3/3] Addadditiona Access-Control header.

---
 bin/vyper-serve   | 1 +
 vyper/compiler.py | 2 +-
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/bin/vyper-serve b/bin/vyper-serve
index ed6550eb6c..9413a67975 100755
--- a/bin/vyper-serve
+++ b/bin/vyper-serve
@@ -36,6 +36,7 @@ class VyperRequestHandler(BaseHTTPRequestHandler):
 
     def send_cors_all(self):
         self.send_header("Access-Control-Allow-Origin", "*")
+        self.send_header("Access-Control-Allow-Headers", "X-Requested-With, Content-type")
 
     def do_OPTIONS(self):
         self.send_cors_all()
diff --git a/vyper/compiler.py b/vyper/compiler.py
index 0d3ac7fdfd..e33eda4051 100644
--- a/vyper/compiler.py
+++ b/vyper/compiler.py
@@ -27,7 +27,7 @@ def gas_estimate(origcode, *args, **kwargs):
 
     # Extract the stuff inside the LLL bracket
     if code.value == 'seq':
-        if code.args[-1].value == 'return':
+        if len(code.args) > 0 and code.args[-1].value == 'return':
             code = code.args[-1].args[1].args[0]
 
     assert code.value == 'seq'