1 files changed, 43 insertions, 0 deletions
diff --git a/lib/bundler/resolver/strategy.rb b/lib/bundler/resolver/strategy.rb
new file mode 100644
index 0000000000..7519d38968
--- /dev/null
+++ b/lib/bundler/resolver/strategy.rb
@@ -0,0 +1,43 @@
+# frozen_string_literal: true
+
+module Bundler
+  class Resolver
+    class Strategy
+      def initialize(source)
+        @source = source
+        @package_priority_cache = {}
+      end
+
+      def next_package_and_version(unsatisfied)
+        package, range = next_term_to_try_from(unsatisfied)
+
+        [package, most_preferred_version_of(package, range).first]
+      end
+
+      private
+
+      def next_term_to_try_from(unsatisfied)
+        unsatisfied.min_by do |package, range|
+          @package_priority_cache[[package, range]] ||= begin
+            matching_versions = @source.versions_for(package, range)
+            higher_versions = @source.versions_for(package, range.upper_invert)
+
+            [matching_versions.count <= 1 ? 0 : 1, higher_versions.count]
+          end
+        end
+      end
+
+      def most_preferred_version_of(package, range)
+        versions = @source.versions_for(package, range)
+
+        # Conditional avoids (among other things) calling
+        # sort_versions_by_preferred with the root package
+        if versions.size > 1
+          @source.sort_versions_by_preferred(package, versions)
+        else
+          versions
+        end
+      end
+    end
+  end
+end