Added thirdparty: boost library

thirdparty/include/boost/spirit/home/x3/support/unused.hpp

@@ -0,0 +1,61 @@
+/*=============================================================================
+    Copyright (c) 2001-2014 Joel de Guzman
+    Copyright (c) 2001-2011 Hartmut Kaiser
+
+    Distributed under the Boost Software License, Version 1.0. (See accompanying
+    file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+==============================================================================*/
+#if !defined(BOOST_SPIRIT_X3_UNUSED_APRIL_16_2006_0616PM)
+#define BOOST_SPIRIT_X3_UNUSED_APRIL_16_2006_0616PM
+
+#include <iosfwd>
+
+///////////////////////////////////////////////////////////////////////////////
+namespace boost { namespace spirit { namespace x3
+{
+    struct unused_type
+    {
+        unused_type() = default;
+
+        template <typename T>
+        unused_type(T const&)
+        {
+        }
+
+        template <typename T>
+        unused_type const&
+        operator=(T const&) const
+        {
+            return *this;
+        }
+
+        template <typename T>
+        unused_type&
+        operator=(T const&)
+        {
+            return *this;
+        }
+
+        // unused_type can also masquerade as an empty context (see context.hpp)
+
+        template <typename ID>
+        unused_type get(ID) const
+        {
+            return {};
+        }
+
+        friend std::ostream& operator<<(std::ostream& out, unused_type const&)
+        {
+            return out;
+        }
+
+        friend std::istream& operator>>(std::istream& in, unused_type&)
+        {
+            return in;
+        }
+    };
+
+    constexpr auto unused = unused_type{};
+}}}
+
+#endif