Make isEmpty a getter.

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
@@ skipping 84 matching lines @@
     // 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);
     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 (_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
         // only take a certain number of steps to solve a graph with a given
         // number of connections.
         // TODO(rnystrom): These numbers here are magic and arbitrary. Tune
         // when we have a better picture of real-world package topologies.
         _numIterations++;
         if (_numIterations > max(50, _packages.length * 5)) {
           throw new CouldNotSolveException();
@@ skipping 422 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();
+  bool get isDependedOn => !_refs.isEmpty;
 
   /** The names of all the packages that depend on this dependency. */
   Collection<String> get dependers => _refs.getKeys();
 
   /**
    * 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;
+    if (_refs.isEmpty) return null;
     return new VersionConstraint.intersect(
         _refs.getValues().map((ref) => ref.constraint));
   }
 
   /// The source of this dependency's package.
   Source get source {
      var canonical = _canonicalRef();
      if (canonical == null) return null;
      return canonical.source;
   }
 
   /// 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.
   PackageRef _canonicalRef() {
-    if (_refs.isEmpty()) return null;
+    if (_refs.isEmpty) return null;
     var refs = _refs.getValues();
     for (var ref in refs) {
       if (ref is RootSource) return ref;
     }
     return refs[0];
   }
 
   Dependency(this.name)
       : _refs = <String, PackageRef>{};
 
@@ skipping 23 matching lines @@
       }
     }
 
     _refs[package] = ref;
   }
 
   /// Returns a PackageRef whose source and description any new constraints are
   /// required to match. Returns null if there are no requirements on new
   /// constraints.
   PackageRef _requiredRef() {
-    if (_refs.isEmpty()) return null;
+    if (_refs.isEmpty) return null;
     var refs = _refs.getValues();
     var first = refs[0];
     if (refs.length == 1) {
       if (first.source is RootSource) return null;
       return first;
     }
     return refs[1];
   }
 
   /**
@@ skipping 86 matching lines @@
   final description1;
   final description2;
 
   DescriptionMismatchException(this.package, this.description1,
       this.description2);
 
   // TODO(nweiz): Dump to YAML when that's supported
   String toString() => "Package '$package' has conflicting descriptions "
     "'${JSON.stringify(description1)}' and '${JSON.stringify(description2)}'";
 }