From efa55eb5b3d3a4942789bdf397c3a6d6226475d4 Mon Sep 17 00:00:00 2001
From: Daniel Friesel <daniel.friesel@uos.de>
Date: Mon, 7 Sep 2020 12:57:22 +0200
Subject: Revert "remove external libraries from main branch"

This reverts commit 0558244645611f314f47e0fa427f7323ce253eaf.
---
 include/lib/modernjson/detail/meta/detected.hpp | 56 +++++++++++++++++++++++++
 1 file changed, 56 insertions(+)
 create mode 100644 include/lib/modernjson/detail/meta/detected.hpp

(limited to 'include/lib/modernjson/detail/meta/detected.hpp')

diff --git a/include/lib/modernjson/detail/meta/detected.hpp b/include/lib/modernjson/detail/meta/detected.hpp
new file mode 100644
index 0000000..8fb318a
--- /dev/null
+++ b/include/lib/modernjson/detail/meta/detected.hpp
@@ -0,0 +1,56 @@
+#pragma once
+
+#include <type_traits>
+
+#include <lib/modernjson/detail/meta/void_t.hpp>
+
+// http://en.cppreference.com/w/cpp/experimental/is_detected
+namespace nlohmann
+{
+namespace detail
+{
+struct nonesuch
+{
+    nonesuch() = delete;
+    ~nonesuch() = delete;
+    nonesuch(nonesuch const&) = delete;
+    void operator=(nonesuch const&) = delete;
+};
+
+template <class Default,
+          class AlwaysVoid,
+          template <class...> class Op,
+          class... Args>
+struct detector
+{
+    using value_t = std::false_type;
+    using type = Default;
+};
+
+template <class Default, template <class...> class Op, class... Args>
+struct detector<Default, void_t<Op<Args...>>, Op, Args...>
+{
+    using value_t = std::true_type;
+    using type = Op<Args...>;
+};
+
+template <template <class...> class Op, class... Args>
+using is_detected = typename detector<nonesuch, void, Op, Args...>::value_t;
+
+template <template <class...> class Op, class... Args>
+using detected_t = typename detector<nonesuch, void, Op, Args...>::type;
+
+template <class Default, template <class...> class Op, class... Args>
+using detected_or = detector<Default, void, Op, Args...>;
+
+template <class Default, template <class...> class Op, class... Args>
+using detected_or_t = typename detected_or<Default, Op, Args...>::type;
+
+template <class Expected, template <class...> class Op, class... Args>
+using is_detected_exact = std::is_same<Expected, detected_t<Op, Args...>>;
+
+template <class To, template <class...> class Op, class... Args>
+using is_detected_convertible =
+    std::is_convertible<detected_t<Op, Args...>, To>;
+}  // namespace detail
+}  // namespace nlohmann
-- 
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