Share a body across all versions of a message.

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 'dart:convert';
 
 import 'package:http_parser/http_parser.dart';
@@ skipping 192 matching lines @@
   ///     print(request.url);        // => dir/file.html
   ///
   ///     request = request.change(path: "dir");
   ///     print(request.handlerPath); // => /static/dir/
   ///     print(request.url);        // => file.html
   Request change({Map<String, String> headers, Map<String, Object> context,
       String path, body}) {
     headers = updateMap(this.headers, headers);
     context = updateMap(this.context, context);
 
-    if (body == null) body = this.read();
+    if (body == null) body = getBody(this);
 
     var handlerPath = this.handlerPath;
     if (path != null) handlerPath += path;
 
     return new Request._(this.method, this.requestedUri,
         protocolVersion: this.protocolVersion,
         headers: headers,
         handlerPath: handlerPath,
         body: body,
         context: context,
@@ skipping 122 matching lines @@
     return handlerPath;
   } else if (url != null) {
     if (url.path.isEmpty) return requestedUri.path;
 
     var index = requestedUri.path.indexOf(url.path);
     return requestedUri.path.substring(0, index);
   } else {
     return '/';
   }
 }