Cleanup URI and use String.replaceRange.

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 735 matching lines @@
     if (argumentError) {
       throw new ArgumentError("Illegal drive letter " +
                               new String.fromCharCode(charCode));
     } else {
       throw new UnsupportedError("Illegal drive letter " +
                               new String.fromCharCode(charCode));
     }
   }
 
   static _makeFileUri(String path) {
-    String sep = "/";
-  if (path.startsWith(sep)) {
+    const String sep = "/";
+    if (path.startsWith(sep)) {
       // Absolute file:// URI.
       return new Uri(scheme: "file", pathSegments: path.split(sep));
     } else {
       // Relative URI.
       return new Uri(pathSegments: path.split(sep));
     }
   }
 
   static _makeWindowsFileUrl(String path) {
-    if (path.startsWith("\\\\?\\")) {
-      if (path.startsWith("\\\\?\\UNC\\")) {
-        path = "\\${path.substring(7)}";
+    if (path.startsWith(r"\\?\")) {
+      if (path.startsWith(r"UNC\", 4)) {
+        path = path.replaceRange(0, 7, r'\');
       } else {
         path = path.substring(4);
         if (path.length < 3 ||
             path.codeUnitAt(1) != _COLON ||
             path.codeUnitAt(2) != _BACKSLASH) {
           throw new ArgumentError(
-              "Windows paths with \\\\?\\ prefix must be absolute");
+              r"Windows paths with \\?\ prefix must be absolute");
         }
       }
     } else {
-      path = path.replaceAll("/", "\\");
+      path = path.replaceAll("/", r'\');
     }
-    String sep = "\\";
-    if (path.length > 1 && path[1] == ":") {
+    const String sep = r'\';
+    if (path.length > 1 && path.codeUnitAt(1) == _COLON) {
       _checkWindowsDriveLetter(path.codeUnitAt(0), true);
       if (path.length == 2 || path.codeUnitAt(2) != _BACKSLASH) {
         throw new ArgumentError(
             "Windows paths with drive letter must be absolute");
       }
       // Absolute file://C:/ URI.
       var pathSegments = path.split(sep);
       _checkWindowsPathReservedCharacters(pathSegments, true, 1);
       return new Uri(scheme: "file", pathSegments: pathSegments);
     }
 
-    if (path.length > 0 && path[0] == sep) {
-      if (path.length > 1 && path[1] == sep) {
+    if (path.startsWith(sep)) {
+      if (path.startsWith(sep, 1)) {
         // Absolute file:// URI with host.
-        int pathStart = path.indexOf("\\", 2);
+        int pathStart = path.indexOf(r'\', 2);
         String hostPart =
-            pathStart == -1 ? path.substring(2) : path.substring(2, pathStart);
+            (pathStart < 0) ? path.substring(2) : path.substring(2, pathStart);
         String pathPart =
-            pathStart == -1 ? "" : path.substring(pathStart + 1);
+            (pathStart < 0) ? "" : path.substring(pathStart + 1);
         var pathSegments = pathPart.split(sep);
         _checkWindowsPathReservedCharacters(pathSegments, true);
         return new Uri(
             scheme: "file", host: hostPart, pathSegments: pathSegments);
       } else {
         // Absolute file:// URI.
         var pathSegments = path.split(sep);
         _checkWindowsPathReservedCharacters(pathSegments, true);
         return new Uri(scheme: "file", pathSegments: pathSegments);
       }
@@ skipping 567 matching lines @@
       // If we see a "." or ".." segment in base, stop here and let
       // _removeDotSegments handle it.
       if ((delta == 2 || delta == 3) &&
           base.codeUnitAt(newEnd + 1) == _DOT &&
           (delta == 2 || base.codeUnitAt(newEnd + 2) == _DOT)) {
         break;
       }
       baseEnd = newEnd;
       backCount--;
     }
-    return base.substring(0, baseEnd + 1) +
-           reference.substring(refStart - 3 * backCount);
+    return base.replaceRange(baseEnd + 1, null,
+                             reference.substring(refStart - 3 * backCount));
   }
 
   bool _hasDotSegments(String path) {
     if (path.length > 0 && path.codeUnitAt(0) == _DOT) return true;
     int index = path.indexOf("/.");
     return index != -1;
   }
 
   String _removeDotSegments(String path) {
     if (!_hasDotSegments(path)) return path;
@@ skipping 996 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
 }