Make VersionSolver source- and description-aware.

utils/pub/source.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('source');
 
 #import('package.dart');
 #import('pubspec.dart');
 #import('version.dart');
 
@@ skipping 14 matching lines @@
    * Whether this source's packages should be cached in Pub's global cache
    * directory.
    *
    * A source should be cached if it requires network access to retrieve
    * packages. It doesn't need to be cached if all packages are available
    * locally.
    */
   abstract bool get shouldCache();
 
   /**
-   * Get the list of all versions that exist for package [name].
+   * Get the list of all versions that exist for the package described by
+   * [description].
    *
    * Note that this does *not* require the packages to be installed, which is
    * the point. This is used during version resolution to determine which
    * package versions are available to be installed (or already installed).
    */
-  Future<List<Version>> getVersions(String name) {
+  Future<List<Version>> getVersions(description) {
     // TODO(rnystrom): Do something better here.
     throw "Source $name doesn't support versioning.";
   }
 
   /**
-   * Loads the (possibly remote) pubspec for the desired [version] of the named
-   * [package]. This will be called for packages that have not yet been
-   * installed during the version resolution process.
+   * Loads the (possibly remote) pubspec for the package version identified by
+   * [id]. This will be called for packages that have not yet been installed
+   * during the version resolution process.
    */
-  Future<Pubspec> describe(String package, Version version) {
+  Future<Pubspec> describe(PackageId id) {
     // TODO(rnystrom): Figure out how non-default sources should handle this.
     throw "Source $name doesn't support versioning.";
   }
 
   /**
    * Installs the package identified by [id] to [path]. Returns a [Future] that
    * completes when the installation was finished. The [Future] should resolve
    * to true if the package was found in the source and false if it wasn't. For
    * all other error conditions, it should complete with an exception.
    *
    * [path] is guaranteed not to exist, and its parent directory is guaranteed
    * to exist.
    */
   abstract Future<bool> install(PackageId id, String path);
 
   /**
    * Returns the directory in the system cache that the package identified by
    * [id] should be installed to. [parent] is this source's subdirectory in the
    * system cache directory.
    *
    * This doesn't need to be implemented if [shouldCache] is false.
    */
   String systemCacheDirectory(PackageId id, String parent) =>
-    join(parent, packageName(id));
+    join(parent, packageName(id.description));
 
   /**
    * When a [Pubspec] is parsed, it reads in the description for each
    * dependency. It is up to the dependency's [Source] to determine how that
    * should be interpreted. This will be called during parsing to validate that
    * the given [description] is well-formed according to this source. It should
    * return if the description is valid, or throw a [FormatException] if not.
    */
   void validateDescription(description) {}
 
   /**
-   * Returns a human-friendly name for the package identified by [id]. This
-   * method should be light-weight. It doesn't need to validate that the given
-   * package exists.
+   * Returns a human-friendly name for the package described by [description].
+   * This method should be light-weight. It doesn't need to validate that the
+   * given package exists.
    *
    * The package name should be lower-case and suitable for use in a filename.
    * It may contain forward slashes.
    */
-  String packageName(PackageId id) => id.description;
+  String packageName(description) => description;
+
+  /**
+   * Returns whether or not [description1] describes the same package as
+   * [description2] for this source. This method should be light-weight. It
+   * doesn't need to validate that either package exists.
+   *
+   * By default, this assumes both descriptions are strings and compares them
+   * for equality.
+   */
+  bool descriptionsEqual(description1, description2) =>
+    description1 == description2;
 }