Add FileSystemEntity.absolutePath and .isAbsolute properties.

BUG=
R=sgjesse@google.com

Review URL: https://codereview.chromium.org//23468027

git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge/dart@27467 260f80e4-7a28-3924-810f-c04153c831b5

sdk/lib/io/directory.dart

@@ -108,6 +108,15 @@ abstract class Directory implements FileSystemEntity {
    */
   Directory renameSync(String newPath);
 
+  /**
+   * Returns a [Directory] instance whose path is the absolute path to [this].
+   *
+   * The absolute path is computed by prefixing
+   * a relative path with the current working directory, and returning
+   * an absolute path unchanged.
+   */
+  Directory get absolute;
+
   /**
    * Lists the sub-directories and files of this [Directory].
    * Optionally recurses into sub-directories.

sdk/lib/io/directory_impl.dart

@@ -74,6 +74,8 @@ class _Directory extends FileSystemEntity implements Directory {
     return (result == 1);
   }
 
+  Directory get absolute => new Directory(_absolutePath);
+
   Future<FileStat> stat() => FileStat.stat(path);
 
   FileStat statSync() => FileStat.statSync(path);

sdk/lib/io/file.dart

@@ -98,6 +98,15 @@ abstract class File implements FileSystemEntity {
    */
   int lengthSync();
 
+  /**
+   * Returns a [File] instance whose path is the absolute path to [this].
+   *
+   * The absolute path is computed by prefixing
+   * a relative path with the current working directory, and returning
+   * an absolute path unchanged.
+   */
+  File get absolute;
+
   /**
    * Get the last-modified time of the file. Returns a
    * [:Future<DateTime>:] that completes with a [DateTime] object for the

sdk/lib/io/file_impl.dart

@@ -267,6 +267,8 @@ class _File extends FileSystemEntity implements File {
     return result;
   }
 
+  File get absolute => new File(_absolutePath);
+
   Future<FileStat> stat() => FileStat.stat(path);
 
   FileStat statSync() => FileStat.statSync(path);

sdk/lib/io/file_system_entity.dart

@@ -343,6 +343,45 @@ abstract class FileSystemEntity {
     });
   }
 
+  static final RegExp _absoluteWindowsPathPattern =
+      new RegExp(r'^(\\\\|[a-zA-Z]:[/\\])');
+
+  /**
+   * Returns a [bool] indicating whether this object's path is absolute.
+   *
+   * On Windows, a path is absolute if it starts with \\ or a drive letter
+   * between a and z (upper or lower case) followed by :\ or :/.
+   * On non-Windows, a path is absolute if it starts with /.
+   */
+  bool get isAbsolute {
+    if (Platform.isWindows) {
+      return path.startsWith(_absoluteWindowsPathPattern);
+    } else {
+      return path.startsWith('/');
+    }
+  }
+
+  /**
+   * Returns a [FileSystemEntity] whose path is the absolute path to [this].
+   * The type of the returned instance is the type of [this].
+   *
+   * The absolute path is computed by prefixing
+   * a relative path with the current working directory, and returning
+   * an absolute path unchanged.
+   */
+  FileSystemEntity get absolute;
+
+  String get _absolutePath {
+    if (isAbsolute) return path;
+    String current = Directory.current.path;
+    if (current.endsWith('/') ||
+        (Platform.isWindows && current.endsWith('\\'))) {
+      return '$current$path';
+    } else {
+      return '$current${Platform.pathSeparator}$path';
+    }
+  }
+
 
   /**
    * Synchronously checks whether two paths refer to the same object in the

sdk/lib/io/link.dart

@@ -84,6 +84,15 @@ abstract class Link implements FileSystemEntity {
    */
   Link renameSync(String newPath);
 
+  /**
+   * Returns a [Link] instance whose path is the absolute path to [this].
+   *
+   * The absolute path is computed by prefixing
+   * a relative path with the current working directory, and returning
+   * an absolute path unchanged.
+   */
+  Link get absolute;
+
   /**
    * Gets the target of the link. Returns a future that completes with
    * the path to the target.
@@ -127,6 +136,8 @@ class _Link extends FileSystemEntity implements Link {
 
   bool existsSync() => FileSystemEntity.isLinkSync(path);
 
+  Link get absolute => new Link(_absolutePath);
+
   Future<FileStat> stat() => FileStat.stat(path);
 
   FileStat statSync() => FileStat.statSync(path);

tests/standalone/io/file_absolute_path_test.dart

@@ -0,0 +1,66 @@
+// 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.
+//
+// Dart test program for testing FileSystemEntity.absolute
+
+import "package:expect/expect.dart";
+import 'dart:io';
+
+main() {
+  if (Platform.isWindows) {
+    testWindows();
+    try {
+      Directory.current = 'C:\\';
+    } catch (e) {
+      return;
+    }
+    testWindows();
+  } else {
+    testPosix();
+    Directory.current = '.';
+    testPosix();
+    Directory.current = '/';
+    testPosix();
+
+  }
+}
+
+testWindows() {
+  String current = Directory.current.path;
+  for (String relative in ['abd', '..', '.', 'efg/hij', 'abc/']) {
+    if (current.endsWith('\\')) {
+      Expect.equals(new File(relative).absolute.path, '$current$relative');
+    } else {
+      Expect.equals(new File(relative).absolute.path, '$current\\$relative');
+    }
+    Expect.isTrue(new File(relative).absolute.isAbsolute);
+  }
+  for (String absolute in ['c:/abd', 'D:\\rf', '\\\\a_share\\folder',
+                           '\\\\?\\c:\\prefixed\path\\']) {
+    Expect.isTrue(new File(absolute).absolute.path == absolute);
+    Expect.isTrue(new File(absolute).absolute.isAbsolute);
+  }
+}
+
+testPosix() {
+  String current = Directory.current.path;
+  print(Directory.current.path);
+  for (String relative in ['abd', '..', '.', 'efg/hij', 'abc/']) {
+    if (current.endsWith('/')) {
+      Expect.equals(new File(relative).absolute.path, '$current$relative');
+    } else {
+      Expect.equals(new File(relative).absolute.path, '$current/$relative');
+    }
+    Expect.isTrue(new File(relative).absolute.isAbsolute);
+    Expect.equals(new Directory(relative).absolute.path,
+                  new Link(relative).absolute.path);
+    Expect.isTrue(new File(relative).absolute is File);
+    Expect.isTrue(new Directory(relative).absolute is Directory);
+    Expect.isTrue(new Link(relative).absolute is Link);
+  }
+  for (String absolute in ['/abd', '/', '/./..\\', '/efg/hij', '/abc/']) {
+    Expect.equals(new File(absolute).absolute.path, absolute);
+    Expect.isTrue(new File(absolute).absolute.isAbsolute);
+  }
+}