Support both new and old style package layouts.

utils/pub/io.dart

Index: utils/pub/io.dart
diff --git a/utils/pub/io.dart b/utils/pub/io.dart
index 25e8d7fde85e7ef7c6236afdce4a0666bda86360..3d9a366264f2edfe3ca913ed3f1b4476e4695cd7 100644
--- a/utils/pub/io.dart
+++ b/utils/pub/io.dart
@@ -280,6 +280,55 @@ Future<File> createSymlink(from, 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(String name, from, to,

[nweiz, 2012/09/11 21:07:47]

Can't you infer the name from "from"?

[Bob Nystrom, 2012/09/11 21:39:01]

I could, but every callsite knew the name so I figured it was simplest just to
pass it in.

+    [bool isSelfLink = false]) {
+  // 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) {
+      if (isSelfLink) {
+        printError('Warning: Package "$name" is using a deprecated layout.');
+        printError('See http://www.dartlang.org/docs/pub-package-manager/'
+            'package-layout.html for details.');
+
+        // Do not create self-links on old style packages.
+        return new Future.immediate(to);
+      } else {
+        return createSymlink(from, to);
+      }
+    }
+
+    // It's a new style package, so symlink to the 'lib' directory. But only
+    // if the package actually *has* one. Otherwise, we won't create a
+    // symlink at all.
+    from = join(from, 'lib');
+    return dirExists(from).chain((exists) {
+      if (exists) {
+        return createSymlink(from, to);
+      } else {
+        printError('Warning: Package "$name" does not have a "lib" directory.');
+        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.
  */