* lib/set.rb (keep_if, select!): New methods [ruby-core:29749]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@28096 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 25 insertions, 0 deletions

diff --git a/lib/set.rb b/lib/set.rb
index 0835f8a4ca..5e4e0878bd 100644
--- a/lib/set.rb
+++ b/lib/set.rb
@@ -266,6 +266,14 @@ class Set
     self
   end
 
+  # Deletes every element of the set for which block evaluates to
+  # false, and returns self.
+  def keep_if
+    block_given? or return enum_for(__method__)
+    to_a.each { |o| @hash.delete(o) unless yield(o) }
+    self
+  end
+
   # Replaces the elements with ones returned by collect().
   def collect!
     block_given? or return enum_for(__method__)
@@ -284,6 +292,15 @@ class Set
     size == n ? nil : self
   end
 
+  # Equivalent to Set#keep_if, but returns nil if no changes were
+  # made.
+  def select!
+    block_given? or return enum_for(__method__)
+    n = size
+    keep_if { |o| yield(o) }
+    size == n ? nil : self
+  end
+
   # Merges the elements of the given enumerable object to the set and
   # returns self.
   def merge(enum)
@@ -563,6 +580,14 @@ class SortedSet < Set
 	    self
 	  end
 
+	  def keep_if
+	    block_given? or return enum_for(__method__)
+	    n = @hash.size
+	    super
+	    @keys = nil if @hash.size != n
+	    self
+	  end
+
 	  def merge(enum)
 	    @keys = nil
 	    super