Support removing dead packages with `pub install`.

utils/pub/entrypoint.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.
 
 #library('entrypoint');
 
 #import('io.dart');
 #import('lock_file.dart');
 #import('package.dart');
 #import('root_source.dart');
@@ skipping 125 matching lines @@
       }
       return versionSolver.solve();
     }).chain(_installDependencies);
   }
 
   /**
    * Installs all dependencies listed in [packageVersions] and writes a
    * [LockFile].
    */
   Future _installDependencies(List<PackageId> packageVersions) {
-    return Futures.wait(packageVersions.map((id) {
-      if (id.source is RootSource) return new Future.immediate(id);
-      return install(id);
-    })).chain(_saveLockFile).chain(_installSelfReference);
+    return _removeUnusedDependencies(packageVersions).chain((_) {
+      return Futures.wait(packageVersions.map((id) {
+        if (id.source is RootSource) return new Future.immediate(id);
+        return install(id);
+      }));
+    }).chain(_saveLockFile).chain(_installSelfReference);
   }
 
   /**
    * Loads the list of concrete package versions from the `pubspec.lock`, if it
    * exists. If it doesn't, this completes to an empty [LockFile].
    *
    * If there's an error reading the `pubspec.lock` file, this will print a
    * warning message and act as though the file doesn't exist.
    */
   Future<LockFile> _loadLockFile() {
@@ skipping 13 matching lines @@
 
       return true;
     });
 
     future.then((text) =>
         completer.complete(new LockFile.parse(text, cache.sources)));
     return completer.future;
   }
 
   /**
+   * Removes all dependencies that are no longer depended on from the `packages`
+   * directory. [packageIds] is a list of all packages that are still depended
+   * on.
+   */
+  Future _removeUnusedDependencies(List<PackageId> packageIds) {
+    var dependenciesToKeep = packageIds.map((id) => id.name);
+
+    return dirExists(path).chain((exists) {
+      if (exists) return listDir(path);
+      return new Future.immediate([]);
+    }).chain((existingDependencies) {
+      existingDependencies = existingDependencies.map(basename);
+      var dependenciesToRemove =
+        new List.from(setMinus(existingDependencies, dependenciesToKeep));

[Bob Nystrom, 2012/08/25 00:13:30]

Indent +2.

[nweiz, 2012/08/25 00:17:49]

Done.

+      return Futures.wait(dependenciesToRemove.map((dependency) {
+        return deleteDir(join(path, dependency));
+      }));
+    });
+  }
+
+  /**
    * Saves a list of concrete package versions to the `pubspec.lock` file.
    */
   Future _saveLockFile(List<PackageId> packageIds) {
     var lockFile = new LockFile.empty();
     for (var id in packageIds) {
       if (id.source is! RootSource) lockFile.packages[id.name] = id;
     }
 
     return writeTextFile(join(root.dir, 'pubspec.lock'), lockFile.serialize());
   }
@@ skipping 23 matching lines @@
           '$path.';
       });
     }
 
     return future.transform((_) {
       if (root.pubspec.name != null) return;
       throw '"pubspec.yaml" must contain a "name" key.';
     });
   }
 }