Support both new and old style package layouts.

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('io');
 
 #import('dart:io');
@@ skipping 261 matching lines @@
     args = ['/c', 'mklink', '/j', to, from];
   }
 
   return runProcess(command, args).transform((result) {
     // TODO(rnystrom): Check exit code and output?
     return new File(to);
   });
 }
 
 /**
+ * Creates a new symlink that creates an alias from the package [from] to [to],
+ * both of which can be a [String], [File], or [Directory]. Returns a [Future]
+ * which completes to the symlink file (i.e. [to]).
+ *
+ * Unlike [createSymlink], this has heuristics to detect if [from] is using
+ * the old or new style of package layout. If it's using the new style, then
+ * it will create a symlink to the "lib" directory contained inside that
+ * package directory. Otherwise, it just symlinks to the package directory
+ * itself.
+ */
+// TODO(rnystrom): Remove this when old style packages are no longer supported.
+// See: http://code.google.com/p/dart/issues/detail?id=4964.
+Future<File> createPackageSymlink(from, to) {
+  // If from contains any Dart files at the top level (aside from build.dart)
+  // we assume that means it's an old style package.
+  return listDir(from).chain((contents) {
+    var isOldStyle = contents.some(
+        (file) => file.endsWith('.dart') && basename(file) != 'build.dart');
+
+    if (isOldStyle) {

[nweiz, 2012/09/10 19:24:47]

Shouldn't we print some sort of deprecation warning here? At some point we're
going to break the old package layout, and we want to give people plenty of
warning.

[Bob Nystrom, 2012/09/11 19:36:59]

I don't want to warn when a dependency has the old layout because that's often
outside of the user's control.

I did add a warning (and a test for it) if the entrypoint package itself uses
the old layout.

+      return createSymlink(from, to);

[nweiz, 2012/09/10 19:24:47]

Style nit: avoid the extra indentation of the else block below.

[Bob Nystrom, 2012/09/11 19:36:59]

Done.

+    } else {
+      // It's a new style package, so symlink to the 'lib' directory. But only
+      // if the package actually *has* one. Otherwise, we won't create a
+      // symlink at all.

[nweiz, 2012/09/10 19:24:47]

It seems potentially confusing to users to just silently not create a symlink. I
can imagine a user being very puzzled because they've declared a dependency and
run "pub install" but the symlink still doesn't exist. We should probably either
print a warning or add a TODO to do so.

[Bob Nystrom, 2012/09/11 19:36:59]

Done. Prints warning.

+      from = join(from, 'lib');
+      return dirExists(from).chain((exists) {
+        if (exists) {
+          return createSymlink(from, to);
+        } else {
+          return new Future.immediate(to);
+        }
+      });
+    }
+  });
+}
+
+/**
  * Given [entry] which may be a [String], [File], or [Directory] relative to
  * the current working directory, returns its full canonicalized path.
  */
 // TODO(rnystrom): Should this be async?
 String getFullPath(entry) => new File(_getPath(entry)).fullPathSync();
 
 /**
  * Opens an input stream for a HTTP GET request to [uri], which may be a
  * [String] or [Uri].
  */
@@ skipping 259 matching lines @@
   return new Directory(entry);
 }
 
 /**
  * Gets a [Uri] for [uri], which can either already be one, or be a [String].
  */
 Uri _getUri(uri) {
   if (uri is Uri) return uri;
   return new Uri.fromString(uri);
 }