pkg/shelf: include the original `onHijack` callback for Request.change

pkg/shelf/lib/src/request.dart

 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library shelf.request;
 
 import 'dart:async';
 
 import 'package:http_parser/http_parser.dart';
 
@@ skipping 98 matching lines @@
   /// sending a response or notifying the user of an error if a
   /// [HijackException] is caught.
   ///
   /// An adapter can check whether a request was hijacked using [canHijack],
   /// which will be `false` for a hijacked request. The adapter may throw an
   /// error if a [HijackException] is received for a non-hijacked request, or if
   /// no [HijackException] is received for a hijacked request.
   ///
   /// See also [hijack].
   // TODO(kevmoo) finish documenting the rest of the arguments.
-  Request(this.method, Uri requestedUri, {String protocolVersion,
+  Request(String method, Uri requestedUri, {String protocolVersion,
+      Map<String, String> headers, Uri url, String scriptName,
+      Stream<List<int>> body, Map<String, Object> context,
+      OnHijackCallback onHijack})
+        : this._(method, requestedUri, protocolVersion: protocolVersion,
+            headers: headers, url: url, scriptName: scriptName,
+            body: body, context: context,
+            onHijack: onHijack == null ? null : new _OnHijack(onHijack));
+
+  /// This constructor has the same signature as [new Request] except that
+  /// accepts [onHijack] as [_OnHijack].
+  ///
+  /// Any [Request] created by calling [change] will pass [_onHijack] from the
+  /// source [Request] to ensure that [hijack] can only be called once, even
+  /// from a changed [Request].
+  Request._(this.method, Uri requestedUri, {String protocolVersion,
     Map<String, String> headers, Uri url, String scriptName,
     Stream<List<int>> body, Map<String, Object> context,
-    OnHijackCallback onHijack})
+    _OnHijack onHijack})
       : this.requestedUri = requestedUri,
         this.protocolVersion = protocolVersion == null ?
             '1.1' : protocolVersion,
         this.url = _computeUrl(requestedUri, url, scriptName),
         this.scriptName = _computeScriptName(requestedUri, url, scriptName),
-        this._onHijack = onHijack == null ? null : new _OnHijack(onHijack),
+        this._onHijack = onHijack,
         super(body == null ? new Stream.fromIterable([]) : body,
             headers: headers, context: context) {
     if (method.isEmpty) throw new ArgumentError('method cannot be empty.');
 
     if (!requestedUri.isAbsolute) {
       throw new ArgumentError('requstedUri must be an absolute URI.');
     }
 
     // TODO(kevmoo) if defined, check that scriptName is a fully-encoded, valid
     // path component
@@ skipping 48 matching lines @@
         url = new Uri(path: path, query: this.url.query);
       } else {
         throw new ArgumentError('If scriptName is provided without url, it must'
             ' be a prefix of the existing url path.');
       }
     }
 
     if (url == null) url = this.url;
     if (scriptName == null) scriptName = this.scriptName;
 
-    return new Request(this.method, this.requestedUri,
+    return new Request._(this.method, this.requestedUri,
         protocolVersion: this.protocolVersion, headers: headers, url: url,
-        scriptName: scriptName, body: this.read(), context: context);
+        scriptName: scriptName, body: this.read(), context: context,
+        onHijack: _onHijack);
   }
 
   /// Takes control of the underlying request socket.
   ///
   /// Synchronously, this throws a [HijackException] that indicates to the
   /// adapter that it shouldn't emit a response itself. Asynchronously,
   /// [callback] is called with a [Stream<List<int>>] and
   /// [StreamSink<List<int>>], respectively, that provide access to the
   /// underlying request socket.
   ///
@@ skipping 69 matching lines @@
     return '';
   }
 
   if (url != null && scriptName != null) {
     return scriptName;
   }
 
   throw new ArgumentError(
       'url and scriptName must both be null or both be set.');
 }