From f237af03d7e39f2ab65627f7e3e44451f124ca63 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jon=20B=C3=B6rjesson?= <jon@spuun.se>
Date: Thu, 10 Oct 2024 12:17:10 +0200
Subject: [PATCH] Add `Iterator(T).empty` (#15039)

---
 spec/std/iterator_spec.cr |  7 +++++++
 src/iterator.cr           | 13 +++++++++++++
 2 files changed, 20 insertions(+)

diff --git a/spec/std/iterator_spec.cr b/spec/std/iterator_spec.cr
index a07b8bedb191..b7f000a871cb 100644
--- a/spec/std/iterator_spec.cr
+++ b/spec/std/iterator_spec.cr
@@ -33,6 +33,13 @@ private class MockIterator
 end
 
 describe Iterator do
+  describe "Iterator.empty" do
+    it "creates empty iterator" do
+      iter = Iterator(String).empty
+      iter.next.should be_a(Iterator::Stop)
+    end
+  end
+
   describe "Iterator.of" do
     it "creates singleton" do
       iter = Iterator.of(42)
diff --git a/src/iterator.cr b/src/iterator.cr
index a46c813b36b3..6a1513ef2130 100644
--- a/src/iterator.cr
+++ b/src/iterator.cr
@@ -144,6 +144,19 @@ module Iterator(T)
     Stop::INSTANCE
   end
 
+  # Returns an empty iterator.
+  def self.empty
+    EmptyIterator(T).new
+  end
+
+  private struct EmptyIterator(T)
+    include Iterator(T)
+
+    def next
+      stop
+    end
+  end
+
   def self.of(element : T)
     SingletonIterator(T).new(element)
   end