Normalize UriData.parse result.

sdk/lib/internal/internal.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.
 
 library dart._internal;
 
 import 'dart:collection';
 
 import 'dart:core' hide Symbol;
 import 'dart:core' as core;
@@ skipping 51 matching lines @@
 }
 
 /// Marks a function as an external implementation ("native" in the Dart VM).
 ///
 /// Provides a backend-specific String that can be used to identify the
 /// function's implementation.
 class ExternalName {
   final String name;
   const ExternalName(this.name);
 }
+
+// Shared hex-parsing utilities.
+
+/// Parses a single hex-digit as code unit.
+///
+/// Returns a negative value if the character is not a valid hex-digit.
+int hexDigitValue(int char) {
+  assert(char >= 0 && char <= 0xFFFF);
+  const int digit0 = 0x30;
+  const int a = 0x61;
+  const int f = 0x66;
+  int digit = char ^ digit0;
+  if (digit <= 9) return digit;
+  int letter = (char | 0x20);
+  if (a <= letter && letter <= f) return letter - (a - 10);
+  return -1;
+}
+
+/// Parses two hex digits in a string.
+///
+/// Returns a negative value if either digit isn't valid.
+int parseHexByte(String source, int index) {
+  assert(index + 2 <= source.length);
+  int digit1 = hexDigitValue(source.codeUnitAt(index));
+  int digit2 = hexDigitValue(source.codeUnitAt(index + 1));
+  return digit1 * 16 + digit2 - (digit2 & 256);
+}