Add `Set#reset`

This method resets the internal state of a set after modification to
existing elements, reindexing and deduplicating them. [Feature #6589]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@60360 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 18 insertions, 0 deletions

diff --git a/lib/set.rb b/lib/set.rb
index b668738ebb..5da196d1e0 100644
--- a/lib/set.rb
+++ b/lib/set.rb
@@ -477,6 +477,19 @@ class Set
     @hash.eql?(o.instance_variable_get(:@hash))
   end
 
+  # Resets the internal state after modification to existing elements
+  # and returns self.
+  #
+  # Elements will be reindexed and deduplicated.
+  def reset
+    if @hash.respond_to?(:rehash)
+      @hash.rehash # This should perform frozenness check.
+    else
+      raise "can't modify frozen #{self.class.name}" if frozen?
+    end
+    self
+  end
+
   # Returns true if obj is a member of the set, and false otherwise.
   #
   # Used in case statements:
@@ -731,6 +744,11 @@ class SortedSet < Set
               to_a
               super
             end
+
+            def rehash
+              @keys = nil
+              super
+            end
           END
         end
         # a hack to shut up warning