Short-circuit Uri._uriEncode for components that don't need encoding.

sdk/lib/core/uri.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.core;
 
 /**
  * A parsed URI, such as a URL.
  *
  * **See also:**
@@ skipping 2233 matching lines @@
   static const int _UPPER_CASE_F = 0x46;
   static const int _UPPER_CASE_Z = 0x5A;
   static const int _LEFT_BRACKET = 0x5B;
   static const int _BACKSLASH = 0x5C;
   static const int _RIGHT_BRACKET = 0x5D;
   static const int _LOWER_CASE_A = 0x61;
   static const int _LOWER_CASE_F = 0x66;
   static const int _LOWER_CASE_Z = 0x7A;
   static const int _BAR = 0x7C;
 
+  // Matches a String that _uriEncodes to itself regardless of the kind of
+  // component.  This corresponds to [_unreservedTable].
+  static final RegExp _needsNoEncoding = new RegExp(r'^[\-\.0-9A-Z_a-z~]*$');

[Ivan Posva, 2015/11/04 05:11:50]

Please refrain from using RegExp in core library code. They are extremely
expensive to generate and should be avoided at all cost. Also they do not
necessarily execute fast depending on the execution platform or OS. Measuring on
a desktop gives you bad information in that matter.

+
   /**
    * This is the internal implementation of JavaScript's encodeURI function.
    * It encodes all characters in the string [text] except for those
    * that appear in [canonicalTable], and returns the escaped string.
    */
   static String _uriEncode(List<int> canonicalTable,
                            String text,
                            {Encoding encoding: UTF8,
                             bool spaceToPlus: false}) {
+    if (_needsNoEncoding.hasMatch(text)) return text;

[Lasse Reichstein Nielsen, 2015/11/03 07:08:19]

This should be a regexp that matches canonicalTable. This function handles
encoding for all possible tables.

[Lasse Reichstein Nielsen, 2015/11/03 07:12:08]

Ah, finally realized that the only characters used are the ones that are not
encoded by any encoding table.

[Lasse Reichstein Nielsen, 2015/11/04 08:32:41]

Only do this if encoding is UTF8, LATIN1 or ASCII (or even only if it's UTF8
since that's the common case). 
Otherwise we don't know that an "A" is encoded as 0x41. I doubt we'll have
EBCDIC encoding (letters are above 128), but to be fair, we should allow for it.

It's too late to remove the encoding argument (if we want to reuse the function,
at least, there is only one call that actually passed the encoding).

If the optional parameters cause extra code, just make them non-optional. We can
call with ..., UTF8, false) in the places where the parameter is not passed.

+
     byteToHex(byte, buffer) {
       const String hex = '0123456789ABCDEF';
       buffer.writeCharCode(hex.codeUnitAt(byte >> 4));
       buffer.writeCharCode(hex.codeUnitAt(byte & 0x0f));
     }
 
     // Encode the string into bytes then generate an ASCII only string
     // by percent encoding selected bytes.
     StringBuffer result = new StringBuffer();
     var bytes = encoding.encode(text);
@@ skipping 331 matching lines @@
       0xafff,   // 0x30 - 0x3f  1111111111110101
                 //              @ABCDEFGHIJKLMNO
       0xffff,   // 0x40 - 0x4f  1111111111111111
                 //              PQRSTUVWXYZ    _
       0x87ff,   // 0x50 - 0x5f  1111111111100001
                 //               abcdefghijklmno
       0xfffe,   // 0x60 - 0x6f  0111111111111111
                 //              pqrstuvwxyz   ~
       0x47ff];  // 0x70 - 0x7f  1111111111100010
 }