From 3d4045f21edec899e255bcc6f62533ef90676e7e Mon Sep 17 00:00:00 2001
From: Jeremy Evans <code@jeremyevans.net>
Date: Mon, 17 Jun 2019 11:33:44 -0700
Subject: [PATCH] Implement Range#minmax

Array#minmax was previous not implemented, so calling #minmax on
array was actually calling Enumerable#minmax.  This is a simple
implementation of #minmax by just calling rb_ary_min and
rb_ary_max.

Fixes [Bug #15929]
---
 array.c                 | 21 +++++++++++++++++++++
 test/ruby/test_array.rb | 19 +++++++++++++++++++
 2 files changed, 40 insertions(+)

diff --git a/array.c b/array.c
index de2f80828a..f59d162aea 100644
--- a/array.c
+++ b/array.c
@@ -4846,6 +4846,26 @@ rb_ary_min(int argc, VALUE *argv, VALUE ary)
     return result;
 }
 
+/*
+ *  call-seq:
+ *     ary.minmax                       -> [obj, obj]
+ *     ary.minmax {| a,b | block }      -> [obj, obj]
+ *
+ *  Returns a two element array which contains the minimum and the
+ *  maximum value in the array.
+ *
+ *  Can be given an optional block to override the default comparison
+ *  method <code>a <=> b</code>.
+ */
+static VALUE
+rb_ary_minmax(VALUE ary)
+{
+    if (rb_block_given_p()) {
+        return rb_call_super(0, NULL);
+    }
+    return rb_assoc_new(rb_ary_min(0, 0, ary), rb_ary_max(0, 0, ary));
+}
+
 static int
 push_value(st_data_t key, st_data_t val, st_data_t ary)
 {
@@ -6898,6 +6918,7 @@ Init_Array(void)
 
     rb_define_method(rb_cArray, "max", rb_ary_max, -1);
     rb_define_method(rb_cArray, "min", rb_ary_min, -1);
+    rb_define_method(rb_cArray, "minmax", rb_ary_minmax, 0);
 
     rb_define_method(rb_cArray, "uniq", rb_ary_uniq, 0);
     rb_define_method(rb_cArray, "uniq!", rb_ary_uniq_bang, 0);
diff --git a/test/ruby/test_array.rb b/test/ruby/test_array.rb
index df9f08a26d..97de544b3d 100644
--- a/test/ruby/test_array.rb
+++ b/test/ruby/test_array.rb
@@ -1774,6 +1774,25 @@ def coerce(x) [x, 1] end
     assert_same(obj, [obj, 1.0].max)
   end
 
+  def test_minmax
+    assert_equal([1, 3], [1, 2, 3, 1, 2].minmax)
+    assert_equal([3, 1], [1, 2, 3, 1, 2].minmax {|a,b| b <=> a })
+    cond = ->((a, ia), (b, ib)) { (b <=> a).nonzero? or ia <=> ib }
+    assert_equal([[3, 2], [1, 3]], [1, 2, 3, 1, 2].each_with_index.minmax(&cond))
+    ary = %w(albatross dog horse)
+    assert_equal(["albatross", "horse"], ary.minmax)
+    assert_equal(["dog", "albatross"], ary.minmax {|a,b| a.length <=> b.length })
+    assert_equal([1, 3], [3,2,1].minmax)
+
+    class << (obj = Object.new)
+      def <=>(x) 1 <=> x end
+      def coerce(x) [x, 1] end
+    end
+    ary = [obj, 1.0].minmax
+    assert_same(obj, ary[0])
+    assert_equal(obj, ary[1])
+  end
+
   def test_uniq
     a = []
     b = a.uniq
-- 
2.21.0