From 8489103f6a13a573c14ea3bd5dcf4a966b20aa36 Mon Sep 17 00:00:00 2001
From: Vraiment <jemc44@gmail.com>
Date: Sun, 30 Jul 2017 12:03:57 -0700
Subject: [PATCH] Added Private/Utility.hh with Or for template metaprogramming

---
 CMakeLists.txt            |  1 +
 Doxyfile.in               |  3 +-
 SDL2pp/Private/Utility.hh | 70 +++++++++++++++++++++++++++++++++++++++
 3 files changed, 73 insertions(+), 1 deletion(-)
 create mode 100644 SDL2pp/Private/Utility.hh

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 51eb91e..b31df9a 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -158,6 +158,7 @@ SET(LIBRARY_HEADERS
 	SDL2pp/Texture.hh
 	SDL2pp/Wav.hh
 	SDL2pp/Window.hh
+	SDL2pp/Private/Utility.hh
 )
 
 SET(LIBRARY_EXTERNAL_HEADERS
diff --git a/Doxyfile.in b/Doxyfile.in
index 54617af..02d3b47 100644
--- a/Doxyfile.in
+++ b/Doxyfile.in
@@ -21,7 +21,8 @@ INPUT                  = "@CMAKE_CURRENT_SOURCE_DIR@/SDL2pp" \
 RECURSIVE              = YES
 
 # Exclude foreign files
-EXCLUDE                = "@CMAKE_CURRENT_SOURCE_DIR@/SDL2pp/external"
+EXCLUDE                = "@CMAKE_CURRENT_SOURCE_DIR@/SDL2pp/external" \
+                         "@CMAKE_CURRENT_SOURCE_DIR@/SDL2pp/Private"
 
 # Examples (doesn't work atm)
 EXAMPLE_PATH           = "@CMAKE_CURRENT_SOURCE_DIR@/examples"
diff --git a/SDL2pp/Private/Utility.hh b/SDL2pp/Private/Utility.hh
new file mode 100644
index 0000000..e0fb6df
--- /dev/null
+++ b/SDL2pp/Private/Utility.hh
@@ -0,0 +1,70 @@
+/*
+  libSDL2pp - C++11 bindings/wrapper for SDL2
+  Copyright (C) 2017 Vraiment <jemc44@gmail.com>
+
+  This software is provided 'as-is', without any express or implied
+  warranty.  In no event will the authors be held liable for any damages
+  arising from the use of this software.
+
+  Permission is granted to anyone to use this software for any purpose,
+  including commercial applications, and to alter it and redistribute it
+  freely, subject to the following restrictions:
+
+  1. The origin of this software must not be misrepresented; you must not
+     claim that you wrote the original software. If you use this software
+     in a product, an acknowledgment in the product documentation would be
+     appreciated but is not required.
+  2. Altered source versions must be plainly marked as such, and must not be
+     misrepresented as being the original software.
+  3. This notice may not be removed or altered from any source distribution.
+*/
+
+#ifndef SDL2PP_PRIVATE_UTILITY_HH
+#define SDL2PP_PRIVATE_UTILITY_HH
+
+#if __cplusplus > 201703L
+// No need to include utility, until C++17 there
+// is no definition for std::disjuntion before
+#include <utility>
+#endif
+
+#include <type_traits>
+
+
+namespace SDL2pp {
+/*
+ * This is code not to be used directly by users of SDL2pp.
+ */
+namespace Private {
+/*
+ * Templated class to perform an "OR" operation on any amount of types.
+ *
+ * Usage is as follows:
+ *     template <typename T,
+ *               typename = typename Or<HasFeatureOne<T>, HasFeatureTwo<T>>
+ *     void UseFeatureOneOrFeatureTwo(T t) {
+ *         // The code will be only compiled if either
+ *         // HasFeatureOne<T> or HasFeatureTwo<T> are type_true
+ *     }
+ */
+#if __cplusplus >= 201703L
+	// Use the standard definitions if they are available
+	template <typename T, typename... Tx>
+	using Or = typename std::disjunction<T, Tx...>::type;
+#else
+	template <typename...>
+	struct OrOperation : std::false_type { };
+	
+	template <typename T>
+	struct OrOperation<T> : T { };
+	
+	template <typename T, typename... Tx>
+	struct OrOperation<T, Tx...> : std::conditional<bool(T::value), T, OrOperation<Tx...>> { };
+	
+	template <typename T, typename... Tx>
+	using Or = typename OrOperation<T, Tx...>::type;
+#endif
+}
+}
+
+#endif