From f9aa13ad81d1650ab447550502c5f54a391ae89f Mon Sep 17 00:00:00 2001
From: Danny Robson <danny@nerdcruft.net>
Date: Thu, 2 May 2019 11:03:00 +1000
Subject: [PATCH] ascii: add try_upper transform

---
 ascii.hpp | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/ascii.hpp b/ascii.hpp
index 973fc253..7f98f0c0 100644
--- a/ascii.hpp
+++ b/ascii.hpp
@@ -117,6 +117,19 @@ namespace cruft::ascii {
     }
 
 
+    ///------------------------------------------------------------------------
+    /// Convert an ASCII character into a upper case character if it is lower
+    /// case, else return it unchanged.
+    ///
+    /// If you know the character is always lower case then prefer to_upper.
+    constexpr inline
+    char
+    try_upper (char c) noexcept
+    {
+        return is_lower (c) ? to_upper (c) : c;
+    }
+
+
     ///------------------------------------------------------------------------
     /// Converts an upper case ASCII character into a lower case character.
     ///