From d6414fe112859192f953ce9e5f185971839fb495 Mon Sep 17 00:00:00 2001
From: Jun Hiroe <Jun.Hiroe@gmail.com>
Date: Fri, 25 Apr 2014 18:57:01 +0900
Subject: Add Array#keep_if

---
 mrbgems/mruby-array-ext/mrblib/array.rb | 30 ++++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)

(limited to 'mrbgems/mruby-array-ext/mrblib')

diff --git a/mrbgems/mruby-array-ext/mrblib/array.rb b/mrbgems/mruby-array-ext/mrblib/array.rb
index 67f7e51a7..9ef7eb166 100644
--- a/mrbgems/mruby-array-ext/mrblib/array.rb
+++ b/mrbgems/mruby-array-ext/mrblib/array.rb
@@ -627,4 +627,34 @@ class Array
     end
     self
   end
+
+  ##
+  #  call-seq:
+  #     ary.keep_if { |item| block } -> ary
+  #     ary.keep_if                  -> Enumerator
+  #
+  #  Deletes every element of +self+ for which the given block evaluates to
+  #  +false+.
+  #
+  #  See also Array#select!
+  #
+  #  If no block is given, an Enumerator is returned instead.
+  #
+  #     a = [1, 2, 3, 4, 5]
+  #     a.keep_if { |val| val > 3 } #=> [4, 5]
+
+  def keep_if(&block)
+    return to_enum :keep_if unless block_given?
+
+    idx = 0
+    len = self.size
+    while idx < self.size do
+      if block.call(self[idx])
+        idx += 1
+      else
+        self.delete_at(idx)
+      end
+    end
+    self
+  end
 end
-- 
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