Make Map.keys/values Iterables.

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 484 matching lines @@
 
   /// Whether this dependency should always select the latest version.
   bool useLatestVersion = false;
 
   /// Gets whether or not any other packages are currently depending on this
   /// one. If `false`, then it means this package is not part of the dependency
   /// graph and should be omitted.
   bool get isDependedOn => !_refs.isEmpty;
 
   /// The names of all the packages that depend on this dependency.
-  Collection<String> get dependers => _refs.keys;
+  Iterable<String> get dependers => _refs.keys;
 
   /// Gets the overall constraint that all packages are placing on this one.
   /// If no packages have a constraint on this one (which can happen when this
   /// package is in the process of being added to the graph), returns `null`.
   VersionConstraint get constraint {
     if (_refs.isEmpty) return null;
     return new VersionConstraint.intersection(
         _refs.values.mappedBy((ref) => ref.constraint));
   }
 
@@ skipping 14 matching lines @@
   /// 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.
   PackageRef _canonicalRef() {
     if (_refs.isEmpty) return null;
     var refs = _refs.values;
     for (var ref in refs) {
       if (ref is RootSource) return ref;
     }
-    return refs[0];
+    return refs.first;
   }
 
   Dependency(this.name)
       : _refs = <String, PackageRef>{};
 
   Dependency._clone(Dependency other)
       : name = other.name,
         version = other.version,
         _refs = new Map<String, PackageRef>.from(other._refs);
 
@@ skipping 20 matching lines @@
 
     _refs[package] = ref;
   }
 
   /// 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;
+    var dependers = _refs.keys.toList();
     if (dependers.length == 1) {
       var depender = dependers[0];
       if (_refs[depender].source is RootSource) return null;
       return depender;
     }
 
     return dependers[1];
   }
 
   /// Removes the constraint from [package] onto this.
@@ skipping 108 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)}";
   }
 }