Add optimized _OneByteString.toLowerCase.

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 10 matching lines @@
 
   _HttpHeaders(this.protocolVersion,
                {int defaultPortForScheme: HttpClient.DEFAULT_HTTP_PORT})
       : _headers = new HashMap<String, List<String>>(),
         _defaultPortForScheme = defaultPortForScheme {
     if (protocolVersion == "1.0") {
       _persistentConnection = false;
     }
   }
 
-  List<String> operator[](String name) => _headers[name.toLowerCase()];
+  List<String> operator[](String name) => _headers[_toLowerCase(name)];
 
   String value(String name) {
-    name = name.toLowerCase();
+    name = _toLowerCase(name);
     List<String> values = _headers[name];
     if (values == null) return null;
     if (values.length > 1) {
       throw new HttpException("More than one value for header $name");
     }
     return values[0];
   }
 
   void add(String name, value) {
     _checkMutable();
-    _addAll(name.toLowerCase(), value);
+    _addAll(_toLowerCase(name), value);
   }
 
   void _addAll(String name, value) {
     if (value is List) {
       value.forEach((v) => _add(name, v));
     } else {
       _add(name, value);
     }
   }
 
   void set(String name, Object value) {
     _checkMutable();
-    name = name.toLowerCase();
+    name = _toLowerCase(name);
     _headers.remove(name);
     _addAll(name, value);
   }
 
   void remove(String name, Object value) {
     _checkMutable();
-    name = name.toLowerCase();
+    name = _toLowerCase(name);
     List<String> values = _headers[name];
     if (values != null) {
       int index = values.indexOf(value);
       if (index != -1) {
         values.removeRange(index, index + 1);
       }
       if (values.length == 0) _headers.remove(name);
     }
   }
 
   void removeAll(String name) {
     _checkMutable();
-    name = name.toLowerCase();
+    name = _toLowerCase(name);
     _headers.remove(name);
   }
 
   void forEach(void f(String name, List<String> values)) {
     _headers.forEach(f);
   }
 
   void noFolding(String name) {
     if (_noFoldingHeaders == null) _noFoldingHeaders = new List<String>();
     _noFoldingHeaders.add(name);
@@ skipping 233 matching lines @@
               }
             }
           }
           _set(HttpHeaders.HOST, value);
         } else {
           throw new HttpException("Unexpected type for header named $name");
         }
         break;
 
       case HttpHeaders.CONNECTION:
-        var lowerCaseValue = value.toLowerCase();
+        var lowerCaseValue = _toLowerCase(value);
         if (lowerCaseValue == 'close') {
           _persistentConnection = false;
         } else if (lowerCaseValue == 'keep-alive') {
           _persistentConnection = true;
         }
         _addValue(name, value);
         break;
 
       case HttpHeaders.CONTENT_TYPE:
         _set(HttpHeaders.CONTENT_TYPE, value);
@@ skipping 11 matching lines @@
       _headers[name] = values;
     }
     if (value is DateTime) {
       values.add(HttpDate.format(value));
     } else {
       values.add(value.toString());
     }
   }
 
   void _set(String name, String value) {
-    assert(name == name.toLowerCase());
+    assert(name == _toLowerCase(name));
     List<String> values = new List<String>();
     _headers[name] = values;
     values.add(value);
   }
 
   _checkMutable() {
     if (!_mutable) throw new HttpException("HTTP headers are not mutable");
   }
 
   _updateHostHeader() {
@@ skipping 136 matching lines @@
           continue;
         }
       }
     }
     List<String> values = _headers[HttpHeaders.COOKIE];
     if (values != null) {
       values.forEach((headerValue) => parseCookieString(headerValue));
     }
     return cookies;
   }
+
+  static String _toLowerCase(String str) {
+    int toLowerCase(int byte) {
+      final int aCode = "A".codeUnitAt(0);

[kevmoo, 2014/03/24 17:50:16]

Is this only run the first time the method is called?

Would it be better to be class-level or top-level final?

[Anders Johnsen, 2014/03/24 19:02:59]

When looking at the SSA of the VM, it's heavily inlined. But I'll consider
creating an all-static class with these constants.

[kevmoo, 2014/03/24 19:04:05]

If they are only used in http_headers, just leave 'em in this class.

[Anders Johnsen, 2014/03/24 19:05:04]

Yeah, but so far there is two places it's used (parser as well), and I just
tried to scan through, and found several other places. I should fix.

[Søren Gjesse, 2014/03/25 07:54:25]

Yes, as you have noticed we have the _CharCodes constants in http_parser.dart.
We should consolidate all of these.

+      final int zCode = "Z".codeUnitAt(0);
+      final int delta = "a".codeUnitAt(0) - aCode;
+      return (aCode <= byte && byte <= zCode) ? byte + delta : byte;
+    }
+
+    final length = str.length;
+    var result = new List(length);
+    for (int i = 0; i < length; i++) {
+      int codeUnit = str.codeUnitAt(i);
+      if (codeUnit > 127) {
+        throw new HttpException("HTTP header must be in ASCII encoding");
+      }
+      result[i] = toLowerCase(codeUnit);

[Søren Gjesse, 2014/03/25 07:54:25]

I don't see the need to a function call here (even though it most likely is
inlined).

[Anders Johnsen, 2014/03/25 13:33:40]

Pulled out and shared across all of IO.

+    }
+    return new String.fromCharCodes(result);
+  }
 }
 
 
 class _HeaderValue implements HeaderValue {
   String _value;
   _UnmodifiableMap<String, String> _parameters;
 
   _HeaderValue([String this._value = "", Map<String, String> parameters]) {
     if (parameters != null) {
       _parameters =
@@ skipping 361 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;
 }