Get codebase ready for actually supporting versioning.

utils/pub/entrypoint.dart

Index: utils/pub/entrypoint.dart
diff --git a/utils/pub/packages_dir.dart b/utils/pub/entrypoint.dart
similarity index 62%
rename from utils/pub/packages_dir.dart
rename to utils/pub/entrypoint.dart
index 04f8bd9a8208210a5cc7f6779988e309c722fd08..bf064dfb2b746cb137b8ead6ef371d32ff2cc1c8 100644
--- a/utils/pub/packages_dir.dart
+++ b/utils/pub/entrypoint.dart
@@ -3,17 +3,21 @@
 // BSD-style license that can be found in the LICENSE file.
 
 /**
- * The "packages" directory for an application or library.
+ * Pub operates over a directed graph of dependencies that starts at a root
+ * "entrypoint" package. This is typically the package where the current

[nweiz, 2012/05/18 21:16:01]

I'd make it more explicit that an entrypoint could be an application or a
library.

[Bob Nystrom, 2012/05/18 22:13:04]

Done.

+ * working directory is located. An entrypoint knows the [root] package it is
+ * associated with and is responsible for building the "packages" directory

[nweiz, 2012/05/18 21:16:01]

s/building/managing/

[Bob Nystrom, 2012/05/18 22:13:04]

Done.

+ * for it.
  *
- * This directory contains symlinks to all packages used by an app. These links
+ * That directory contains symlinks to all packages used by an app. These links
  * point either to the [SystemCache] or to some other location on the local
  * filesystem.
  */
-class PackagesDir {
+class Entrypoint {
   /**
-   * The package containing this directory.
+   * The root package this entrypoint is associated with.
    */
-  final Package owner;
+  final Package root;
 
   /**
    * The system-wide cache which caches packages that need to be fetched over
@@ -32,15 +36,14 @@ class PackagesDir {
    */
   final Map<PackageId, Future<Package>> _pendingInstalls;
 
-  PackagesDir(this.owner, this.cache)
+  Entrypoint(this.root, this.cache)
   : _loadedPackages  = new Map<PackageId, Package>(),
     _pendingInstalls = new Map<PackageId, Future<Package>>();
 
   /**
-   * Returns the path to the "packages" directory.
+   * The path to this "packages" directory.
    */
-  // TODO(rnystrom): Make this path configurable.

[nweiz, 2012/05/18 21:16:01]

This TODO should probably come back now, right?

[Bob Nystrom, 2012/05/18 22:13:04]

Done.

-  String get path() => join(owner.dir, 'packages');
+  String get path() => join(root.dir, 'packages');
 
   /**
    * Ensures that the package identified by [id] is installed to the directory,
@@ -76,8 +79,7 @@ class PackagesDir {
         return id.source.install(id, packageDir).transform((found) {
           if (found) return null;
           // TODO(nweiz): More robust error-handling.
-          throw 'Package ${id.fullName} not found in source '
-            '"${id.source.name}".';
+          throw 'Package ${id.name} not found in source "${id.source.name}".';
         });
       }
     }).chain((_) => Package.load(packageDir, cache.sources));
@@ -90,30 +92,35 @@ class PackagesDir {
   }
 
   /**
-   * Installs the package identified by [id] and all its transitive
-   * dependencies.
+   * Installs all of the packages referred to by [packages] and their transitive
+   * dependencies. References are resolved using [entrypoint].
    */
-  Future<Package> installTransitively(PackageId id) {
+  Future installTransitively(Package entrypoint,

[nweiz, 2012/05/18 21:16:01]

Taking "Package entrypoint" here seems weird for a couple reasons. First, isn't
it always going to be identical to this.root? Second, "entrypoint" is a
confusing name for a package when it's also the name of this class.

Given that we're starting to think of installing dependencies as a holistic
action that involves resolving the whole dependency tree, it might make sense to
remove this method entirely and just move its contents into
#installDependencies.

[Bob Nystrom, 2012/05/18 22:13:04]

Yeah, that's just stale code from before this refactoring.
Ditto here.
Good call. Done.

+      List<PackageRef> packages) {
     var seen = new Set<PackageId>();
-    Future<Package> helper(id) {
-      if (seen.contains(id)) return new Future.immediate(null);
-      seen.add(id);
-
-      return install(id).chain((package) {
-        return Futures.wait(package.dependencies.map(helper)).
-          transform((_) => package);
-      });
+
+    Future helper(List<PackageRef> packages) {
+      return Futures.wait(packages.map((ref) {
+        return entrypoint.resolve(ref).chain((id) {
+          if (seen.contains(id)) return new Future.immediate(null);
+          seen.add(id);
+
+          return install(id).chain((package) {
+            return helper(package.dependencies);
+          });
+        });
+      }));
     }
 
-    return helper(id);
+    return helper(packages);
   }
 
   /**
-   * Installs all dependencies of [owner] to the "packages" directory. Returns a
-   * [Future] that completes when all dependencies are installed.
+   * Installs all dependencies of the [root] package to its "packages"
+   * directory. Returns a [Future] that completes when all dependencies are
+   * installed.
    */
   Future installDependencies() {
-    return Futures.wait(owner.dependencies.map(installTransitively)).
-      transform((_) => null);
+    return installTransitively(root, root.dependencies);
   }
 }