add Enumerable#drop_while

mrbgems/mruby-enum-ext/mrblib/enum.rb

@@ -20,5 +20,25 @@ module Enumerable
     self.each {|e| n == 0 ? ary << e : n -= 1 }
     ary
   end
+
+  ##
+  # call-seq:
+  #    enum.drop_while {|arr| block }   -> array
+  #
+  # Drops elements up to, but not including, the first element for
+  # which the block returns +nil+ or +false+ and returns an array
+  # containing the remaining elements.
+  #
+  #    a = [1, 2, 3, 4, 5, 0]
+  #    a.drop_while {|i| i < 3 }   #=> [3, 4, 5, 0]
+
+  def drop_while(&block)
+    ary, state = [], false
+    self.each do |e|
+      state = true if !state and !block.call(e)
+      ary << e if state
+    end
+    ary
+  end
   
 end

mrbgems/mruby-enum-ext/test/enum.rb

@@ -8,3 +8,8 @@ assert("Enumrable#drop") do
   assert_equal a.drop(6), []
 end
 
+assert("Enumrable#drop_while") do
+  a = [1, 2, 3, 4, 5, 0]
+  assert_equal a.drop_while {|i| i < 3 }, [3, 4, 5, 0]
+end
+