Improve parsing of query string

sdk/lib/io/http_utils.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.
 
 part of dart.io;
 
 class _HttpUtils {
   static String decodeUrlEncodedString(String urlEncoded) {
     // First check the string for any encoding.
     int index = 0;
@@ skipping 35 matching lines @@
       } else {
         bytes.add(urlEncoded.codeUnitAt(i));
       }
     }
     return decodeUtf8(bytes);
   }
 
   static Map<String, String> splitQueryString(String queryString) {
     Map<String, String> result = new Map<String, String>();
     int currentPosition = 0;
-    while (currentPosition < queryString.length) {
-      int position = queryString.indexOf("=", currentPosition);
-      if (position == -1) {
-        break;
+    int length = queryString.length;
+
+    while (currentPosition < length) {
+
+      // Find the first equals character between current position and
+      // the provided end.
+      int indexOfEquals(int end) {
+        int index = currentPosition;
+        while (index < end) {
+          if (queryString.codeUnitAt(index) == _CharCode.EQUAL) return index;
+          index++;
+        }
+        return -1;
       }
-      String name = queryString.substring(currentPosition, position);
-      currentPosition = position + 1;
-      position = queryString.indexOf("&", currentPosition);
+
+      // Find the next separator (either & or ;), see
+      // http://www.w3.org/TR/REC-html40/appendix/notes.html#ampersands-in-uris
+      // relating the ; separator. If no separator is found returns
+      // the length of the query string.
+      int indexOfSeparator() {
+        int end = length;
+        int index = currentPosition;
+        while (index < end) {
+          int codeUnit = queryString.codeUnitAt(index);
+          if (codeUnit == _CharCode.AMPERSAND ||
+              codeUnit == _CharCode.SEMI_COLON) {
+            return index;
+          }
+          index++;
+        }
+        return end;
+      }
+
+      int seppos = indexOfSeparator();
+      int equalspos = indexOfEquals(seppos);
+      String name;
       String value;
-      if (position == -1) {
-        value = queryString.substring(currentPosition);
-        currentPosition = queryString.length;
+      if (equalspos == -1) {
+        name = queryString.substring(currentPosition, seppos);
+        value = '';
       } else {
-        value = queryString.substring(currentPosition, position);
-        currentPosition = position + 1;
+        name = queryString.substring(currentPosition, equalspos);
+        value = queryString.substring(equalspos + 1, seppos);
       }
+      currentPosition = seppos + 1;  // This also works when seppos == length.
+      if (name == '') continue;
       result[_HttpUtils.decodeUrlEncodedString(name)] =
         _HttpUtils.decodeUrlEncodedString(value);
     }
     return result;
   }
 
   // From RFC 2616 section "3.3.1 Full Date"
   // HTTP-date    = rfc1123-date | rfc850-date | asctime-date
   // rfc1123-date = wkday "," SP date1 SP time SP "GMT"
   // rfc850-date  = weekday "," SP date2 SP time SP "GMT"
@@ skipping 307 matching lines @@
     while ((amp = input.indexOf('&', offset)) >= 0) {
       buffer.write(input.substring(offset, amp));
       int end = input.indexOf(';', amp);
       parse(amp, end);
       offset = end + 1;
     }
     buffer.write(input.substring(offset));
     return buffer.toString();
   }
 }