1 files changed, 73 insertions, 0 deletions
diff --git a/lib/rubygems/source/specific_file.rb b/lib/rubygems/source/specific_file.rb
new file mode 100644
index 0000000000..dde1d48a21
--- /dev/null
+++ b/lib/rubygems/source/specific_file.rb
@@ -0,0 +1,73 @@
+# frozen_string_literal: true
+
+##
+# A source representing a single .gem file.  This is used for installation of
+# local gems.
+
+class Gem::Source::SpecificFile < Gem::Source
+  ##
+  # The path to the gem for this specific file.
+
+  attr_reader :path
+
+  ##
+  # Creates a new SpecificFile for the gem in +file+
+
+  def initialize(file)
+    @uri = nil
+    @path = ::File.expand_path(file)
+
+    @package = Gem::Package.new @path
+    @spec = @package.spec
+    @name = @spec.name_tuple
+  end
+
+  ##
+  # The Gem::Specification extracted from this .gem.
+
+  attr_reader :spec
+
+  def load_specs(*a) # :nodoc:
+    [@name]
+  end
+
+  def fetch_spec(name) # :nodoc:
+    return @spec if name == @name
+    raise Gem::Exception, "Unable to find '#{name}'"
+  end
+
+  def download(spec, dir = nil) # :nodoc:
+    return @path if spec == @spec
+    raise Gem::Exception, "Unable to download '#{spec.full_name}'"
+  end
+
+  def pretty_print(q) # :nodoc:
+    q.object_group(self) do
+      q.group 2, "[SpecificFile:", "]" do
+        q.breakable
+        q.text @path
+      end
+    end
+  end
+
+  ##
+  # Orders this source against +other+.
+  #
+  # If +other+ is a SpecificFile from a different gem name +nil+ is returned.
+  #
+  # If +other+ is a SpecificFile from the same gem name the versions are
+  # compared using Gem::Version#<=>
+  #
+  # Otherwise Gem::Source#<=> is used.
+
+  def <=>(other)
+    case other
+    when Gem::Source::SpecificFile then
+      return nil if @spec.name != other.spec.name
+
+      @spec.version <=> other.spec.version
+    else
+      super
+    end
+  end
+end