pkg/shelf: change helper method on Request and Response

pkg/shelf/lib/src/message.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.message;
 
 import 'dart:async';
-import 'dart:collection';
 import 'dart:convert';
 
-// TODO(kevmoo): use UnmodifiableMapView from SDK once 1.4 ships
-import 'package:collection/wrappers.dart' as pc;
 import 'package:http_parser/http_parser.dart';
 import 'package:stack_trace/stack_trace.dart';
 
+import 'shelf_unmodifiable_map.dart';
+
 /// Represents logic shared between [Request] and [Response].
 abstract class Message {
   /// The HTTP headers.
   ///
   /// The value is immutable.
   final Map<String, String> headers;
 
   /// Extra context that can be used by for middleware and handlers.
   ///
   /// For requests, this is used to pass data to inner middleware and handlers;
@@ skipping 10 matching lines @@
   /// The streaming body of the message.
   ///
   /// This can be read via [read] or [readAsString].
   final Stream<List<int>> _body;
 
   /// Creates a new [Message].
   ///
   /// If [headers] is `null`, it is treated as empty.
   Message(this._body, {Map<String, String> headers,
         Map<String, Object> context})
-      : this.headers = _getIgnoreCaseMapView(headers),
-        this.context = new pc.UnmodifiableMapView(
-            context == null ? const {} : new Map.from(context));
+      : this.headers = new ShelfUnmodifiableMap<String>(headers,
+            ignoreKeyCase: true),
+        this.context = new ShelfUnmodifiableMap<Object>(context,
+            ignoreKeyCase: false);
 
   /// The contents of the content-length field in [headers].
   ///
   /// If not set, `null`.
   int get contentLength {
     if (_contentLengthCache != null) return _contentLengthCache;
     if (!headers.containsKey('content-length')) return null;
     _contentLengthCache = int.parse(headers['content-length']);
     return _contentLengthCache;
   }
@@ skipping 46 matching lines @@
   /// If [encoding] is passed, that's used to decode the body.
   /// Otherwise the encoding is taken from the Content-Type header. If that
   /// doesn't exist or doesn't have a "charset" parameter, UTF-8 is used.
   ///
   /// This calls [read] internally, which can only be called once.
   Future<String> readAsString([Encoding encoding]) {
     if (encoding == null) encoding = this.encoding;
     if (encoding == null) encoding = UTF8;
     return Chain.track(encoding.decodeStream(read()));
   }
+
+  /// Creates a new [Message] by copying existing values and applying specified
+  /// changes.
+  Message change({Map<String, String> headers, Map<String, Object> context});
 }
-
-/// Creates on an unmodifiable map of [headers] with case-insensitive access.
-Map<String, String> _getIgnoreCaseMapView(Map<String, String> headers) {
-  if (headers == null) return const {};
-  // TODO(kevmoo) generalize this model with a 'canonical map' to align with
-  // similiar implementation in http pkg [BaseRequest].
-  var map = new LinkedHashMap<String, String>(
-      equals: (key1, key2) => key1.toLowerCase() == key2.toLowerCase(),
-      hashCode: (key) => key.toLowerCase().hashCode);
-
-  map.addAll(headers);
-
-  return new pc.UnmodifiableMapView<String, String>(map);
-}