Add support for pub install.

utils/pub/io.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.
 
 /**
  * Helper functionality to make working with IO easier.
  */
 #library('pub_io');
 
 #import('dart:io');
@@ skipping 32 matching lines @@
 
 /**
  * Gets the basename, the file name without any leading directory path, for
  * [file], which can either be a [String], [File], or [Directory].
  */
 String basename(file) {
   return fs.basename(_getPath(file));
 }
 
 /**
+ * Gets the the leading directory path for [file], which can either be a
+ * [String], [File], or [Directory].
+ */
+String dirname(file) {
+  return fs.dirname(_getPath(file));
+}
+
+/**
+ * Asynchronously determines if [path], which can be a [String] file path, a
+ * [File], or a [Directory] exists on the file system. Returns a [Future] that
+ * completes with the result.
+ */
+Future<bool> exists(path) {
+  path = _getPath(path);
+  return fileExists(path).chain((exists) {
+    if (exists) return new Future.immediate(true);
+    return dirExists(path);
+  });

[Bob Nystrom, 2012/05/03 00:15:49]

I hate to suggest this, but ideally you could kick off fileExists and dirExists
in parallel, right?

[nweiz, 2012/05/04 01:03:43]

Done.

+}
+
+/**
  * Asynchronously determines if [file], which can be a [String] file path or a
  * [File], exists on the file system. Returns a [Future] that completes with
  * the result.
  */
 Future<bool> fileExists(file) {
+  // Currently File#exists will not detect the existence of symlinks. Issue 2765

[Bob Nystrom, 2012/05/03 00:15:49]

Make this a TODO so it's greppable.

[nweiz, 2012/05/04 01:03:43]

Done.

+  return runProcess('stat', [_getPath(file)]).
+    transform((result) => result.exitCode == 0);
+
+  // Real code:
+  /*
   final completer = new Completer<bool>();
 
   file = new File(_getPath(file));
   file.onError = (error) => completer.completeException(error);
   file.exists((exists) => completer.complete(exists));
 
   return completer.future;
+  */
 }
 
 /**
  * Reads the contents of the text file [file], which can either be a [String] or
  * a [File].
  */
 Future<String> readTextFile(file) {
   file = new File(_getPath(file));
   final completer = new Completer<String>();
   file.onError = (error) => completer.completeException(error);
@@ skipping 28 matching lines @@
 Future<Directory> createDir(dir) {
   final completer = new Completer<Directory>();
   dir = _getDirectory(dir);
   dir.onError = (error) => completer.completeException(error);
   dir.create(() => completer.complete(dir));
 
   return completer.future;
 }
 
 /**
+ * Ensures that [dir] exists and is a directory. If it doesn't exist, creates
+ * it. Returns a [Future] that completes once the directory is created.
+ */
+Future<Directory> ensureDir(dir) {
+  var completer = new Completer<Directory>();
+  var future = createDir(dir);
+  future.handleException((error) {
+    if (error is! DirectoryIOException) return false;
+    if (error.osError.errorCode != 17) return false;
+
+    // Error 17 means the directory already exists.

[Bob Nystrom, 2012/05/03 00:15:49]

Move comment above preceding line.

[nweiz, 2012/05/04 01:03:43]

Done.

+    completer.complete(_getDirectory(dir));
+    return true;
+  });
+  future.then(completer.complete);
+  return completer.future;
+}
+
+/**
+ * Ensures that [path] and all its parent directories exist. If they don't
+ * exist, creates them. Returns a [Future] that completes once all the
+ * directories are created.
+ */
+Future<Directory> ensureNestedDir(path) {

[Bob Nystrom, 2012/05/03 00:15:49]

Is there any reason someone would prefer ensureDir over ensureNestedDir? If not,
and I can't think why they would, why not just make ensureDir implicitly handle
nesting?

[nweiz, 2012/05/04 01:03:43]

Done.

+  if (path == '.') return new Future.immediate(new Directory('.'));
+
+  path = _getPath(path);
+  return dirExists(path).chain((exists) {
+    if (exists) return new Future.immediate(new Directory(path));
+    return ensureNestedDir(dirname(path));
+  }).chain((_) => ensureDir(path));
+}
+
+/**
  * Creates a temp directory whose name will be based on [dir] with a unique
  * suffix appended to it. Returns a [Future] that completes when the directory
  * is created.
  */
 Future<Directory> createTempDir(dir) {
   final completer = new Completer<Directory>();
   dir = _getDirectory(dir);
   dir.onError = (error) => completer.completeException(error);
   dir.createTemp(() => completer.complete(dir));
 
@@ skipping 195 matching lines @@
 }
 
 /**
  * Gets a [Directory] for [entry], which can either already be one, or be a
  * [String].
  */
 Directory _getDirectory(entry) {
   if (entry is Directory) return entry;
   return new Directory(entry);
 }