From 861f8bdfa9fe06eda6cf1257658a1aff03ee47df Mon Sep 17 00:00:00 2001
From: "Yukihiro \"Matz\" Matsumoto" <matz@ruby.or.jp>
Date: Mon, 2 Oct 2023 00:15:01 +0900
Subject: [PATCH] mruby-enumerator: add Enumerator#size

If the original object responds to `size` method, `Enumerator#size` calls
that method, otherwise return `nil`. CRuby returns the exact size for
more cases (e.g. Enumerable::Lazy#size), but mruby has more limitations.
---
 mrbgems/mruby-enumerator/mrblib/enumerator.rb | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/mrbgems/mruby-enumerator/mrblib/enumerator.rb b/mrbgems/mruby-enumerator/mrblib/enumerator.rb
index eaad43cd1..faaabf18a 100644
--- a/mrbgems/mruby-enumerator/mrblib/enumerator.rb
+++ b/mrbgems/mruby-enumerator/mrblib/enumerator.rb
@@ -238,6 +238,14 @@ class Enumerator
     end
   end
 
+  def size
+    if @size
+      @size
+    elsif @obj.respond_to?(:size)
+      @obj.size
+    end
+  end
+
   ##
   # call-seq:
   #   enum.each { |elm| block }                    -> obj