1 files changed, 47 insertions, 0 deletions
diff --git a/lib/rubygems/resolver/source_set.rb b/lib/rubygems/resolver/source_set.rb
new file mode 100644
index 0000000000..074b473edc
--- /dev/null
+++ b/lib/rubygems/resolver/source_set.rb
@@ -0,0 +1,47 @@
+# frozen_string_literal: true
+
+##
+# The SourceSet chooses the best available method to query a remote index.
+#
+# Kind off like BestSet but filters the sources for gems
+
+class Gem::Resolver::SourceSet < Gem::Resolver::Set
+  ##
+  # Creates a SourceSet for the given +sources+ or Gem::sources if none are
+  # specified.  +sources+ must be a Gem::SourceList.
+
+  def initialize
+    super()
+
+    @links = {}
+    @sets  = {}
+  end
+
+  def find_all(req) # :nodoc:
+    if set = get_set(req.dependency.name)
+      set.find_all req
+    else
+      []
+    end
+  end
+
+  # potentially no-op
+  def prefetch(reqs) # :nodoc:
+    reqs.each do |req|
+      if set = get_set(req.dependency.name)
+        set.prefetch reqs
+      end
+    end
+  end
+
+  def add_source_gem(name, source)
+    @links[name] = source
+  end
+
+  private
+
+  def get_set(name)
+    link = @links[name]
+    @sets[link] ||= Gem::Source.new(link).dependency_resolver_set(@prerelease) if link
+  end
+end