Create angel.dart

lib/angel.dart

@@ -0,0 +1,22 @@
+import 'package:angel_framework/angel_framework.dart';
+import 'user_agent.dart';
+
+/// Injects a [UserAgent] into requests.
+/// 
+/// If [strict] is `true`, then an invalid
+/// `User-Agent` header will throw a `400 Bad Request`.
+RequestMiddleware parseUserAgent({bool strict: true}) {
+  return (req, res) async {
+    try {
+      req.inject(UserAgent, parse(req.headers.value('User-Agent')));
+    } catch (e) {
+      if (e is UserAgentException && strict) {
+        throw new AngelHttpException.BadRequest(message: 'Invalid user agent.');
+      } else {
+        rethrow;
+      }
+    }
+    
+    return true;
+  };
+}