* 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

ChangeLog

@@ -1,3 +1,7 @@
+Sun May 30 22:18:49 2010  Marc-Andre Lafortune  <ruby-core@marc-andre.ca>
+
+	* lib/set.rb (keep_if, select!): New methods [ruby-core:29749]
+
 Sun May 30 21:51:59 2010  Yusuke Endoh  <mame@tsg.ne.jp>
 
 	* test/rake/test_application.rb: update a test because of r28089.

NEWS

@@ -373,6 +373,11 @@ with all sufficient information, see the ChangeLog file.
     * Readline.completion_proc= accepts nil.
       nil means to use default completion proc.
 
+* set
+  * new methods:
+    * Set#keep_if
+    * Set#select!
+
 * time
   * incompatible changes:
     * Time.parse raises ArgumentError when no date information.

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