IVGCVSW-4519 Remove Boost Variant and apply_visitor variant

  * add mapbox/variant third party package

Signed-off-by: James Ward <james.ward@arm.com>
Change-Id: I181302780edd9dace40f158a11327316a12ce69a

1 files changed, 43 insertions, 0 deletions

diff --git a/third-party/mapbox/variant_visitor.hpp b/third-party/mapbox/variant_visitor.hpp
new file mode 100644
index 0000000000..54ddba0e1c
--- /dev/null
+++ b/third-party/mapbox/variant_visitor.hpp
@@ -0,0 +1,43 @@
+#ifndef MAPBOX_UTIL_VARIANT_VISITOR_HPP
+#define MAPBOX_UTIL_VARIANT_VISITOR_HPP
+
+#include <utility>
+
+namespace mapbox {
+namespace util {
+
+template <typename... Fns>
+struct visitor;
+
+template <typename Fn>
+struct visitor<Fn> : Fn
+{
+    using Fn::operator();
+
+    template<typename T>
+    visitor(T&& fn) : Fn(std::forward<T>(fn)) {}    
+};
+
+template <typename Fn, typename... Fns>
+struct visitor<Fn, Fns...> : Fn, visitor<Fns...>
+{
+    using Fn::operator();
+    using visitor<Fns...>::operator();
+
+    template<typename T, typename... Ts>
+    visitor(T&& fn, Ts&&... fns)
+        : Fn(std::forward<T>(fn))
+        , visitor<Fns...>(std::forward<Ts>(fns)...) {}
+};
+
+template <typename... Fns>
+visitor<typename std::decay<Fns>::type...> make_visitor(Fns&&... fns)
+{
+    return visitor<typename std::decay<Fns>::type...>
+        (std::forward<Fns>(fns)...);
+}
+    
+} // namespace util
+} // namespace mapbox
+
+#endif // MAPBOX_UTIL_VARIANT_VISITOR_HPP