Refactor pkg/path.

pkg/path/lib/src/style/windows.dart

+// Copyright (c) 2013, 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.style.windows;
+
+import '../parsed_path.dart';
+import '../style.dart';
+
+/// The style for Windows paths.
+class WindowsStyle extends Style {
+  WindowsStyle();
+
+  final name = 'windows';
+  final separator = '\\';
+  final separatorPattern = new RegExp(r'[/\\]');
+  final needsSeparatorPattern = new RegExp(r'[^/\\]$');
+  final rootPattern = new RegExp(r'^(\\\\[^\\]+\\[^\\/]+|[a-zA-Z]:[/\\])');
+  final relativeRootPattern = new RegExp(r"^[/\\](?![/\\])");
+
+  String pathFromUri(Uri uri) {
+    if (uri.scheme != '' && uri.scheme != 'file') {
+      throw new ArgumentError("Uri $uri must have scheme 'file:'.");
+    }
+
+    var path = uri.path;
+    if (uri.host == '') {
+      // Drive-letter paths look like "file:///C:/path/to/file". The
+      // replaceFirst removes the extra initial slash.
+      if (path.startsWith('/')) path = path.replaceFirst("/", "");
+    } else {
+      // Network paths look like "file://hostname/path/to/file".
+      path = '\\\\${uri.host}$path';
+    }
+    return Uri.decodeComponent(path.replaceAll("/", "\\"));
+  }
+
+  Uri absolutePathToUri(String path) {
+    var parsed = new ParsedPath.parse(path, this);
+    if (parsed.root.startsWith(r'\\')) {
+      // Network paths become "file://server/share/path/to/file".
+
+      // The root is of the form "\\server\share". We want "server" to be the
+      // URI host, and "share" to be the first element of the path.
+      var rootParts = parsed.root.split('\\').where((part) => part != '');
+      parsed.parts.insert(0, rootParts.last);
+
+      if (parsed.hasTrailingSeparator) {
+        // If the path has a trailing slash, add a single empty component so the
+        // URI has a trailing slash as well.
+        parsed.parts.add("");
+      }
+
+      return new Uri(scheme: 'file', host: rootParts.first,
+          pathSegments: parsed.parts);
+    } else {
+      // Drive-letter paths become "file:///C:/path/to/file".
+
+      // If the path is a bare root (e.g. "C:\"), [parsed.parts] will currently
+      // be empty. We add an empty component so the URL constructor produces
+      // "file:///C:/", with a trailing slash. We also add an empty component if
+      // the URL otherwise has a trailing slash.
+      if (parsed.parts.length == 0 || parsed.hasTrailingSeparator) {
+        parsed.parts.add("");
+      }
+
+      // Get rid of the trailing "\" in "C:\" because the URI constructor will
+      // add a separator on its own.
+      parsed.parts.insert(0, parsed.root.replaceAll(separatorPattern, ""));
+
+      return new Uri(scheme: 'file', pathSegments: parsed.parts);
+    }
+  }
+}