Support using the HEAD request in the HTTP library

runtime/bin/http_parser.dart

 // Copyright (c) 2012, 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.
 
 // Global constants.
 class _Const {
   // Bytes for "HTTP".
   static final HTTP = const [72, 84, 84, 80];
   // Bytes for "HTTP/1.".
   static final HTTP1DOT = const [72, 84, 84, 80, 47, 49, 46];
@@ skipping 130 matching lines @@
     try {
       if (_state == _State.CLOSED) {
         throw new HttpParserException("Data on closed connection");
       }
       if (_state == _State.UPGRADED) {
         throw new HttpParserException("Data on upgraded connection");
       }
       if (_state == _State.FAILURE) {
         throw new HttpParserException("Data on failed connection");
       }
-      while ((index < lastIndex) && _state != _State.FAILURE && _state != _State.UPGRADED) {
+      while ((index < lastIndex) &&
+             _state != _State.FAILURE &&
+             _state != _State.UPGRADED) {
         int byte = buffer[index];
         switch (_state) {
           case _State.START:
             if (byte == _Const.HTTP[0]) {
               // Start parsing method or HTTP version.
               _httpVersionIndex = 1;
               _state = _State.METHOD_OR_RESPONSE_HTTP_VERSION;
             } else {
               // Start parsing method.
               if (!_isTokenChar(byte)) {
                 throw new HttpParserException("Invalid request method");
               }
               _method_or_status_code.addCharCode(byte);
               _state = _State.REQUEST_LINE_METHOD;
             }
             break;
 
           case _State.METHOD_OR_RESPONSE_HTTP_VERSION:
             if (_httpVersionIndex < _Const.HTTP.length &&
                 byte == _Const.HTTP[_httpVersionIndex]) {
               // Continue parsing HTTP version.
               _httpVersionIndex++;
             } else if (_httpVersionIndex == _Const.HTTP.length &&
                        byte == _CharCode.SLASH) {
-              // HTTP/ parsed. As method is a token this cannot be a method anymore.
+              // HTTP/ parsed. As method is a token this cannot be a
+              // method anymore.
               _httpVersionIndex++;
               _state = _State.RESPONSE_HTTP_VERSION;
             } else {
               // Did not parse HTTP version. Expect method instead.
               for (int i = 0; i < _httpVersionIndex; i++) {
                 _method_or_status_code.addCharCode(_Const.HTTP[i]);
               }
-              //_method_or_status_code.addCharCode(byte);
-              _httpVersion = _HttpVersion.UNDETERMINED;
-              _state = _State.REQUEST_LINE_URI;
+              if (byte == _CharCode.SP) {
+                _state = _State.REQUEST_LINE_URI;
+              } else {
+                _method_or_status_code.addCharCode(byte);
+                _httpVersion = _HttpVersion.UNDETERMINED;
+                _state = _State.REQUEST_LINE_METHOD;
+              }
             }
             break;
 
           case _State.RESPONSE_HTTP_VERSION:
             if (_httpVersionIndex < _Const.HTTP1DOT.length) {
               // Continue parsing HTTP version.
               _expect(byte, _Const.HTTP1DOT[_httpVersionIndex]);
               _httpVersionIndex++;
             } else if (_httpVersionIndex == _Const.HTTP1DOT.length &&
                        byte == _CharCode.ONE) {
@@ skipping 512 matching lines @@
   Function dataEnd;
   Function error;
 }
 
 
 class HttpParserException implements Exception {
   const HttpParserException([String this.message = ""]);
   String toString() => "HttpParserException: $message";
   final String message;
 }