Add Set#intersect? and #disjoint?.

* lib/set.rb (Set#intersect?, Set#disjoint?): Add new methods for
  testing if two sets have any element in common.
  [ruby-core:45641] [Feature #6588] Based on the code by marcandre.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@42253 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 17 insertions, 0 deletions

diff --git a/lib/set.rb b/lib/set.rb
index 47fcc3efc7..aec22ef4fe 100644
--- a/lib/set.rb
+++ b/lib/set.rb
@@ -231,6 +231,23 @@ class Set
   end
   alias < proper_subset?
 
+  # Returns true if the set and the given set have at least one
+  # element in common.
+  def intersect?(set)
+    set.is_a?(Set) or raise ArgumentError, "value must be a set"
+    if size < set.size
+      any? { |o| set.include?(o) }
+    else
+      set.any? { |o| include?(o) }
+    end
+  end
+
+  # Returns true if the set and the given set have no element in
+  # common.  This method is the opposite of +intersect?+.
+  def disjoint?(set)
+    !intersect?(set)
+  end
+
   # Calls the given block once for each element in the set, passing
   # the element as parameter.  Returns an enumerator if no block is
   # given.