From 22d57105eb814de6117c7d819711a90a8129a56c Mon Sep 17 00:00:00 2001
From: "Yukihiro \"Matz\" Matsumoto" <matz@ruby-lang.org>
Date: Sat, 22 Mar 2014 16:55:47 +0900
Subject: add Enumerable#min_by as well; ref #1912

---
 mrbgems/mruby-enum-ext/mrblib/enum.rb | 34 ++++++++++++++++++++++++++++++++++
 mrbgems/mruby-enum-ext/test/enum.rb   |  4 ++++
 2 files changed, 38 insertions(+)

(limited to 'mrbgems/mruby-enum-ext')

diff --git a/mrbgems/mruby-enum-ext/mrblib/enum.rb b/mrbgems/mruby-enum-ext/mrblib/enum.rb
index aea2f83c7..1849ff4cd 100644
--- a/mrbgems/mruby-enum-ext/mrblib/enum.rb
+++ b/mrbgems/mruby-enum-ext/mrblib/enum.rb
@@ -301,4 +301,38 @@ module Enumerable
     end
     max
   end
+
+  ##
+  # call-seq:
+  #    enum.min_by {|obj| block }      -> obj
+  #    enum.min_by                     -> an_enumerator
+  #
+  # Returns the object in <i>enum</i> that gives the minimum
+  # value from the given block.
+  #
+  # If no block is given, an enumerator is returned instead.
+  #
+  #    %w[albatross dog horse].min_by {|x| x.length }   #=> "dog"
+
+  def min_by(&block)
+    return to_enum :min_by unless block_given?
+
+    first = true
+    min = nil
+    min_cmp = nil
+
+    self.each do |*val|
+      if first
+        min = val.__svalue
+        min_cmp = block.call(*val)
+        first = false
+      else
+        if (cmp = block.call(*val)) < min_cmp
+          min = val.__svalue
+          min_cmp = cmp
+        end
+      end
+    end
+    min
+  end
 end
diff --git a/mrbgems/mruby-enum-ext/test/enum.rb b/mrbgems/mruby-enum-ext/test/enum.rb
index bca1fc4f6..ba0851582 100644
--- a/mrbgems/mruby-enum-ext/test/enum.rb
+++ b/mrbgems/mruby-enum-ext/test/enum.rb
@@ -80,3 +80,7 @@ end
 assert("Enumerable#max_by") do
   assert_equal "albatross", %w[albatross dog horse].max_by { |x| x.length }
 end
+
+assert("Enumerable#min_by") do
+  assert_equal "dog", %w[albatross dog horse].min_by { |x| x.length }
+end
-- 
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