Add new methods `Module#{>,>=,<=>}`; ref #4174

mrbgems/mruby-class-ext/mrblib/module.rb

@@ -35,4 +35,55 @@ class Module
     end
   end
 
+  ##
+  # call-seq:
+  #  mod > other   ->  true, false, or nil
+  #
+  # Returns true if `mod` is an ancestor of `other`. Returns
+  # <code>nil</code> if there's no relationship between the two.
+  # (Think of the relationship in terms of the class definition:
+  # "class A < B" implies "B > A".)
+  #
+  def >(other)
+    if self.equal?(other)
+      false
+    else
+      self >= other
+    end
+  end
+
+  ##
+  # call-seq:
+  #   mod >= other   ->  true, false, or nil
+  #
+  # Returns true if `mod` is an ancestor of `other`, or the
+  # two modules are the same. Returns
+  # <code>nil</code> if there's no relationship between the two.
+  # (Think of the relationship in terms of the class definition:
+  # "class A < B" implies "B > A".)
+  #
+  def >=(other)
+    raise TypeError, 'compared with non class/module' unless other.is_a?(Module)
+    return other < self
+  end
+
+  ##
+  # call-seq:
+  #    module <=> other_module   -> -1, 0, +1, or nil
+  #
+  # Comparison---Returns -1, 0, +1 or nil depending on whether `module`
+  # includes `other_module`, they are the same, or if `module` is included by
+  # `other_module`.
+  #
+  # Returns `nil` if `module` has no relationship with `other_module`, if
+  # `other_module` is not a module, or if the two values are incomparable.
+  #
+  def <=>(other)
+    return 0 if self.equal?(other)
+    return nil unless other.is_a?(Module)
+    cmp = self < other
+    return -1 if cmp
+    return 1 unless cmp.nil?
+    return nil
+  end
 end