From 523c7c7e388ac71c62ce28f41e663f83857e1e54 Mon Sep 17 00:00:00 2001
From: Danny Robson <danny@nerdcruft.net>
Date: Tue, 1 Aug 2017 13:31:47 +1000
Subject: [PATCH] iterator: add the OutputIterator "discard_iterator"

---
 iterator.hpp | 18 +++++++++++++++++-
 1 file changed, 17 insertions(+), 1 deletion(-)

diff --git a/iterator.hpp b/iterator.hpp
index c5bbde62..892ef45c 100644
--- a/iterator.hpp
+++ b/iterator.hpp
@@ -279,6 +279,22 @@ namespace util {
             data...
         );
     }
-}
+
+
+    ///////////////////////////////////////////////////////////////////////////
+    /// an output iterator that always discards any parameters on assignment.
+    ///
+    /// sometimes useful to pass to algorithms that generate useful results as
+    /// a return value, while not caring about the implicit OutputIterator
+    /// results.
+    struct discard_iterator : public std::iterator<std::output_iterator_tag, discard_iterator> {
+        template <typename T>
+        void operator= (const T&) { ; }
+
+        discard_iterator& operator++ (   ) { return *this; }
+        discard_iterator  operator++ (int) { return *this; }
+        discard_iterator& operator*  (   ) { return *this; }
+    };
+};
 
 #endif