Improve the performance of isWithin().

test/posix_test.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 path.test.posix_test;
 
 import 'package:test/test.dart';
 import 'package:path/path.dart' as path;
 
 import 'utils.dart';
@@ skipping 401 matching lines @@
     test('simple cases', () {
       expect(context.isWithin('foo/bar', 'foo/bar'), isFalse);
       expect(context.isWithin('foo/bar', 'foo/bar/baz'), isTrue);
       expect(context.isWithin('foo/bar', 'foo/baz'), isFalse);
       expect(context.isWithin('foo/bar', '../path/foo/bar/baz'), isTrue);
       expect(context.isWithin('/', '/foo/bar'), isTrue);
       expect(context.isWithin('baz', '/root/path/baz/bang'), isTrue);
       expect(context.isWithin('baz', '/root/path/bang/baz'), isFalse);
     });
 
+    test('complex cases', () {
+      expect(context.isWithin('foo/./bar', 'foo/bar/baz'), isTrue);
+      expect(context.isWithin('foo//bar', 'foo/bar/baz'), isTrue);
+      expect(context.isWithin('foo/qux/../bar', 'foo/bar/baz'), isTrue);
+      expect(context.isWithin('foo/bar', 'foo/bar/baz/../..'), isFalse);
+      expect(context.isWithin('foo/bar', 'foo/bar///'), isFalse);
+      expect(context.isWithin('foo/.bar', 'foo/.bar/baz'), isTrue);
+      expect(context.isWithin('foo/./bar', 'foo/.bar/baz'), isFalse);
+      expect(context.isWithin('foo/..bar', 'foo/..bar/baz'), isTrue);
+    });
+
     test('from a relative root', () {
       var r = new path.Context(style: path.Style.posix, current: 'foo/bar');
       expect(r.isWithin('.', 'a/b/c'), isTrue);
       expect(r.isWithin('.', '../a/b/c'), isFalse);
       expect(r.isWithin('.', '../../a/foo/b/c'), isFalse);
       expect(r.isWithin('/', '/baz/bang'), isTrue);
       expect(r.isWithin('.', '/baz/bang'), isFalse);
     });
   });
 
@@ skipping 97 matching lines @@
 
     test('with a root-relative URI', () {
       expect(context.prettyUri('/a/b'), '/a/b');
     });
 
     test('with a Uri object', () {
       expect(context.prettyUri(Uri.parse('a/b')), 'a/b');
     });
   });
 }