Int switch

sdk/lib/io/http_headers.dart

 // Copyright (c) 2013, 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.
 
 part of dart.io;
 
 class _HttpHeaders implements HttpHeaders {
   final Map<String, List<String>> _headers;
   final String protocolVersion;
 
@@ skipping 320 matching lines @@
     } else if (lowerCaseValue == 'keep-alive') {
       headers._persistentConnection = true;
     }
     headers._addValue(name, value);
   }
 
   static void _addContentType(_HttpHeaders headers, String name, value) {
     headers._set(HttpHeaders.CONTENT_TYPE, value);
   }
 
-  // TODO(ajohnsen): Change to const map, once const maps are faster.
-  static final _addMap = {
-    HttpHeaders.CONTENT_LENGTH: _addContentLength,
-    HttpHeaders.TRANSFER_ENCODING: _addTransferEncoding,
-    HttpHeaders.DATE: _addDate,
-    HttpHeaders.EXPIRES: _addExpires,
-    HttpHeaders.IF_MODIFIED_SINCE: _addIfModifiedSince,
-    HttpHeaders.HOST: _addHost,
-    HttpHeaders.CONNECTION: _addConnection,
-    HttpHeaders.CONTENT_TYPE: _addContentType
-  };
-
   // [name] must be a lower-case version of the name.
   void _add(String name, value) {
     assert(name == name.toLowerCase());

[Søren Gjesse, 2014/04/23 12:06:39]

Please add a comment on this optimization.

[Anders Johnsen, 2014/04/23 12:20:12]

Done.

-    var method = _addMap[name];
-    if (method != null) {
-      method(this, name, value);
-      return;
+    switch (name.length) {
+      case 4:
+        if (HttpHeaders.DATE == name) {
+          _addDate(this, name, value);

[Anders Johnsen, 2014/04/23 11:57:05]

Should we merge return into this line?

[Søren Gjesse, 2014/04/23 12:06:39]

Don't think so.

+          return;
+        }
+        if (HttpHeaders.HOST == name) {
+          _addHost(this, name, value);
+          return;
+        }
+        break;
+      case 7:
+        if (HttpHeaders.EXPIRES == name) {
+          _addExpires(this, name, value);
+          return;
+        }
+        break;
+      case 10:
+        if (HttpHeaders.CONNECTION == name) {
+          _addConnection(this, name, value);
+          return;
+        }
+        break;
+      case 12:
+        if (HttpHeaders.CONTENT_TYPE == name) {
+          _addContentType(this, name, value);
+          return;
+        }
+        break;
+      case 14:
+        if (HttpHeaders.CONTENT_LENGTH == name) {
+          _addContentLength(this, name, value);
+          return;
+        }
+        break;
+      case 17:
+        if (HttpHeaders.TRANSFER_ENCODING == name) {
+          _addTransferEncoding(this, name, value);
+          return;
+        }
+        if (HttpHeaders.IF_MODIFIED_SINCE == name) {
+          _addIfModifiedSince(this, name, value);
+          return;
+        }
     }
     _addValue(name, value);
   }
 
   void _addValue(String name, Object value) {
     List<String> values = _headers[name];
     if (values == null) {
       values = new List<String>();
       _headers[name] = values;
     }
@@ skipping 536 matching lines @@
   void clear() {
     throw new UnsupportedError("Cannot modify an unmodifiable map");
   }
   void forEach(void f(K key, V value)) => _map.forEach(f);
   Iterable<K> get keys => _map.keys;
   Iterable<V> get values => _map.values;
   int get length => _map.length;
   bool get isEmpty => _map.isEmpty;
   bool get isNotEmpty => _map.isNotEmpty;
 }