Revert "remove external libraries from main branch"protocol-modeling

This reverts commit 0558244645611f314f47e0fa427f7323ce253eaf.

1 files changed, 69 insertions, 0 deletions

diff --git a/include/lib/modernjson/detail/json_ref.hpp b/include/lib/modernjson/detail/json_ref.hpp
new file mode 100644
index 0000000..c44aa66
--- /dev/null
+++ b/include/lib/modernjson/detail/json_ref.hpp
@@ -0,0 +1,69 @@
+#pragma once
+
+#include <initializer_list>
+#include <utility>
+
+#include <lib/modernjson/detail/meta/type_traits.hpp>
+
+namespace nlohmann
+{
+namespace detail
+{
+template<typename BasicJsonType>
+class json_ref
+{
+  public:
+    using value_type = BasicJsonType;
+
+    json_ref(value_type&& value)
+        : owned_value(std::move(value)), value_ref(&owned_value), is_rvalue(true)
+    {}
+
+    json_ref(const value_type& value)
+        : value_ref(const_cast<value_type*>(&value)), is_rvalue(false)
+    {}
+
+    json_ref(std::initializer_list<json_ref> init)
+        : owned_value(init), value_ref(&owned_value), is_rvalue(true)
+    {}
+
+    template <
+        class... Args,
+        enable_if_t<std::is_constructible<value_type, Args...>::value, int> = 0 >
+    json_ref(Args && ... args)
+        : owned_value(std::forward<Args>(args)...), value_ref(&owned_value),
+          is_rvalue(true) {}
+
+    // class should be movable only
+    json_ref(json_ref&&) = default;
+    json_ref(const json_ref&) = delete;
+    json_ref& operator=(const json_ref&) = delete;
+    json_ref& operator=(json_ref&&) = delete;
+    ~json_ref() = default;
+
+    value_type moved_or_copied() const
+    {
+        if (is_rvalue)
+        {
+            return std::move(*value_ref);
+        }
+        return *value_ref;
+    }
+
+    value_type const& operator*() const
+    {
+        return *static_cast<value_type const*>(value_ref);
+    }
+
+    value_type const* operator->() const
+    {
+        return static_cast<value_type const*>(value_ref);
+    }
+
+  private:
+    mutable value_type owned_value = nullptr;
+    value_type* value_ref = nullptr;
+    const bool is_rvalue;
+};
+}  // namespace detail
+}  // namespace nlohmann