1 files changed, 47 insertions, 0 deletions
diff --git a/mrbgems/mruby-enum-ext/mrblib/enum.rb b/mrbgems/mruby-enum-ext/mrblib/enum.rb
index f250d39f1..90f321596 100644
--- a/mrbgems/mruby-enum-ext/mrblib/enum.rb
+++ b/mrbgems/mruby-enum-ext/mrblib/enum.rb
@@ -161,4 +161,51 @@ module Enumerable
     h
   end
 
+  ##
+  # call-seq:
+  #    enum.sort_by { |obj| block }   -> array
+  #
+  # Sorts <i>enum</i> using a set of keys generated by mapping the
+  # values in <i>enum</i> through the given block.
+  def sort_by(&block)
+    ary = []
+    orig = [] 
+    self.each_with_index{|e, i|
+      orig.push(e)
+      ary.push([block.call(e), i])
+    }
+    if ary.size > 1
+      __sort_sub__(ary, ::Array.new(ary.size), 0, 0, ary.size - 1) do |a,b|
+        a <=> b
+      end
+    end
+    ary.collect{|e,i| orig[i]}
+  end
+
+  NONE = Object.new
+  ##
+  # call-seq:
+  #    enum.first       ->  obj or nil
+  #    enum.first(n)    ->  an_array
+  #
+  # Returns the first element, or the first +n+ elements, of the enumerable.
+  # If the enumerable is empty, the first form returns <code>nil</code>, and the
+  # second form returns an empty array.
+  def first(n=NONE)
+    if n == NONE
+      self.each do |e|
+        return e
+      end
+      return nil
+    else
+      a = []
+      i = 0
+      self.each do |e|
+        break if n<=i
+        a.push e
+        i += 1
+      end
+      a
+    end
+  end
 end