First pass at build dependency graph for barback.

pkg/pathos/lib/path.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.
 
 /// A comprehensive, cross-platform path manipulation library.
 ///
 /// ## Installing ##
 ///
 /// Use [pub][] to install this package. Add the following to your
 /// `pubspec.yaml` file.
@@ skipping 185 matching lines @@
 ///     path.relative('/root/other.dart',
 ///         from: '/root/path'); // -> '../other.dart'
 ///
 /// Since there is no relative path from one drive letter to another on Windows,
 /// this will return an absolute path in that case.
 ///
 ///     path.relative(r'D:\other', from: r'C:\home'); // -> 'D:\other'
 String relative(String path, {String from}) =>
     _builder.relative(path, from: from);
 
+/// Returns whether or not [path] is nested somewhere within [dir].
+///
+///     path.isWithin('a/b/c.dart', 'a/b') // -> true
+///     path.isWithin('a/b/c.dart', 'd/b') // -> false
+bool isWithin(String path, String dir) => _builder.isWithin(path, dir);
+
 /// Removes a trailing extension from the last part of [path].
 ///
 ///     withoutExtension('path/to/foo.dart'); // -> 'path/to/foo'
 String withoutExtension(String path) => _builder.withoutExtension(path);
 
 /// Validates that there are no non-null arguments following a null one and
 /// throws an appropriate [ArgumentError] on failure.
 _validateArgList(String method, List<String> args) {
   for (var i = 1; i < args.length; i++) {
     // Ignore nulls hanging off the end.
@@ skipping 126 matching lines @@
   /// Returns `true` if [path] is an absolute path and `false` if it is a
   /// relative path. On POSIX systems, absolute paths start with a `/` (forward
   /// slash). On Windows, an absolute path starts with `\\`, or a drive letter
   /// followed by `:/` or `:\`.
   bool isAbsolute(String path) => _parse(path).isAbsolute;
 
   /// Returns `true` if [path] is a relative path and `false` if it is absolute.
   /// On POSIX systems, absolute paths start with a `/` (forward slash). On
   /// Windows, an absolute path starts with `\\`, or a drive letter followed by
   /// `:/` or `:\`.
-  bool isRelative(String path) => !isAbsolute(path);
+  bool isRelative(String path) => !this.isAbsolute(path);
+
+  /// Returns whether or not [path] is nested somewhere within [dir].
+  ///
+  ///     path.isWithin('a/b/c.dart', 'a/b') // -> true
+  ///     path.isWithin('a/b/c.dart', 'd/b') // -> false
+  bool isWithin(String path, String dir) {
+    var relative = this.relative(path, from: dir);
+    return !this.isAbsolute(relative) && this.split(relative)[0] != '..';
+  }
 
   /// Joins the given path parts into a single path. Example:
   ///
   ///     builder.join('path', 'to', 'foo'); // -> 'path/to/foo'
   ///
   /// If any part ends in a path separator, then a redundant separator will not
   /// be added:
   ///
   ///     builder.join('path/', 'to', 'foo'); // -> 'path/to/foo
   ///
@@ skipping 390 matching lines @@
     // If there is no dot, or it's the first character, like '.bashrc', it
     // doesn't count.
     if (lastDot <= 0) return [file, ''];
 
     return [file.substring(0, lastDot), file.substring(lastDot)];
   }
 
   _ParsedPath clone() => new _ParsedPath(
       style, root, new List.from(parts), new List.from(separators));
 }