Get rid of RootSource.

utils/pub/version_solver.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.
 
 /// Attempts to resolve a set of version constraints for a package dependency
 /// graph and select an appropriate set of best specific versions for all
 /// dependent packages. It works iteratively and tries to reach a stable
 /// solution where the constraints of all dependencies are met. If it fails to
 /// reach a solution after a certain number of iterations, it assumes the
 /// dependency graph is unstable and reports and error.
@@ skipping 25 matching lines @@
 library version_solver;
 
 import 'dart:async';
 import 'dart:collection' show Queue;
 import 'dart:json' as json;
 import 'dart:math';
 import 'lock_file.dart';
 import 'log.dart' as log;
 import 'package.dart';
 import 'pubspec.dart';
-import 'root_source.dart';
 import 'source.dart';
 import 'source_registry.dart';
 import 'utils.dart';
 import 'version.dart';
 
 /// Attempts to select the best concrete versions for all of the transitive
 /// dependencies of [root] taking into account all of the [VersionConstraint]s
 /// that those dependencies place on each other and the requirements imposed by
 /// [lockFile]. If successful, completes to a [Map] that maps package names to
 /// the selected version for that package. If it fails, the future will complete
@@ skipping 27 matching lines @@
   void useLatestVersion(String package) {
     // TODO(nweiz): How do we want to detect and handle unknown dependencies
     // here?
     getDependency(package).useLatestVersion = true;
     lockFile.packages.remove(package);
   }
 
   Future<List<PackageId>> solve() {
     // Kick off the work by adding the root package at its concrete version to
     // the dependency graph.
-    var ref = new PackageRef(
-        _root.name, new RootSource(_root), _root.version, _root.name);
+    var ref = new PackageRef.root(_root);
     enqueue(new AddConstraint('(entrypoint)', ref));
     _pubspecs.cache(ref.atVersion(_root.version), _root.pubspec);
 
     Future processNextWorkItem(_) {
       while (true) {
         // Stop if we are done.
         if (_work.isEmpty) return new Future.immediate(buildResults());
 
         // If we appear to be stuck in a loop, then we probably have an unstable
         // graph, bail. We guess this based on a rough heuristic that it should
@@ skipping 129 matching lines @@
 
   /// The source of the package whose version is changing.
   final Source source;
 
   /// The description identifying the package whose version is changing.
   final description;
 
   /// The new selected version.
   final Version version;
 
-  ChangeVersion(this.package, this.source, this.description, this.version) {
-    if (source == null) throw "null source";
-  }
+  ChangeVersion(this.package, this.source, this.description, this.version);
 
   Future process(VersionSolver solver) {
     log.fine("Changing $package to version $version.");
 
     var dependency = solver.getDependency(package);
     var oldVersion = dependency.version;
     solver.setVersion(package, version);
 
     // The dependencies between the old and new version may be different. Walk
     // them both and update any constraints that differ between the two.
@@ skipping 264 matching lines @@
   }
 
   /// The description of this dependency's package.
   get description {
      var canonical = _canonicalRef();
      if (canonical == null) return null;
      return canonical.description;
   }
 
   /// Return the PackageRef that has the canonical source and description for
-  /// this package. If any dependency requires that this package come from a
-  /// [RootSource], that will be used; otherwise, it will be the source and
-  /// description that all dependencies agree upon.
+  /// this package. If any dependency is on the root package, that will be used;
+  /// otherwise, it will be the source and description that all dependencies
+  /// agree upon.
   PackageRef _canonicalRef() {
     if (_refs.isEmpty) return null;
     var refs = _refs.values;
     for (var ref in refs) {
-      if (ref is RootSource) return ref;
+      if (ref.isRoot) return ref;
     }
     return refs.first;
   }
 
   Dependency(this.name)
       : _refs = <String, PackageRef>{};
 
   Dependency._clone(Dependency other)
       : name = other.name,
         version = other.version,
@@ skipping 25 matching lines @@
 
   /// Returns the name of a package whose constraint source and description
   /// all other constraints must match. Returns null if there are no
   /// requirements on new constraints.
   String _requiredDepender() {
     if (_refs.isEmpty) return null;
 
     var dependers = _refs.keys.toList();
     if (dependers.length == 1) {
       var depender = dependers[0];
-      if (_refs[depender].source is RootSource) return null;
+      if (_refs[depender].isRoot) return null;
       return depender;
     }
 
     return dependers[1];
   }
 
   /// Removes the constraint from [package] onto this.
   PackageRef removeConstraint(String package) => _refs.remove(package);
 }
 
@@ skipping 105 matching lines @@
 
   String toString() {
     // TODO(nweiz): Dump descriptions to YAML when that's supported.
     return "Incompatible dependencies on '$package':\n"
         "- '$depender1' depends on it with description "
         "${json.stringify(description1)}\n"
         "- '$depender2' depends on it with description "
         "${json.stringify(description2)}";
   }
 }