Added excerpt from mplex library for boost::optional detection.

Author: 5cript

stringify/tmp_util/fundamental/eval_if.hpp

@@ -0,0 +1,39 @@
+#ifndef MPLEX_FUNDAMENTAL_EVAL_IF_HPP_INCLUDED
+#define MPLEX_FUNDAMENTAL_EVAL_IF_HPP_INCLUDED
+
+#include "integral.hpp"
+
+namespace mplex {
+
+    template <typename Condition, typename Fallback, typename Function, typename... Parameters>
+    struct eval_if_default
+    {
+        using type = Fallback; // TODO: think about something more meaningfull here
+    };
+
+    template <typename Fallback, typename Function, typename... Parameters>
+    struct eval_if_default <true_, Fallback, Function, Parameters...>
+    {
+        using type = typename Function::template apply <Parameters...>::type;
+    };
+
+    template <typename Condition, typename Function, typename... Parameters>
+    struct eval_if
+    {
+        using type = void; // TODO: think about something more meaningfull here
+    };
+
+    template <typename Function, typename... Parameters>
+    struct eval_if <true_, Function, Parameters...>
+    {
+        using type = typename Function::template apply <Parameters...>::type;
+    };
+
+    template <typename Condition, typename Function, typename... Parameters>
+    using eval_if_t = typename eval_if <Condition, Function, Parameters...>::type;
+
+    template <typename Condition, typename Fallback, typename Function, typename... Parameters>
+    using eval_if_default_t = typename eval_if_default <Condition, Fallback, Function, Parameters...>::type;
+}
+
+#endif // MPLEX_FUNDAMENTAL_EVAL_IF_HPP_INCLUDED

stringify/tmp_util/fundamental/identity.hpp

@@ -0,0 +1,18 @@
+#ifndef IDENTITY_HPP_INCLUDED
+#define IDENTITY_HPP_INCLUDED
+
+namespace mplex {
+    template <typename T>
+    struct identity {
+        using type = T;
+    };
+
+    struct identity_functor {
+        template <typename T>
+        struct apply {
+            using type = T;
+        };
+    };
+}
+
+#endif // IDENTITY_HPP_INCLUDED

stringify/tmp_util/fundamental/integral.hpp

@@ -0,0 +1,46 @@
+#ifndef MPLEX_FUNDAMENTAL_INTEGRAL_HPP_INCLUDED
+#define MPLEX_FUNDAMENTAL_INTEGRAL_HPP_INCLUDED
+
+#include <type_traits>
+#include <cstdint>
+
+namespace mplex
+{
+    template <typename T, T Value>
+    using integral = std::integral_constant <T, Value>;
+
+#define DECLARE_INTEGRAL(TYPE) \
+    template <TYPE V> \
+    using TYPE ## _ = mplex::integral <TYPE, V>
+
+#define DECLARE_INTEGRAL_N(TYPE, NAME) \
+    template <TYPE V> \
+    using NAME ## _ = mplex::integral <TYPE, V>
+
+    DECLARE_INTEGRAL(bool);
+    DECLARE_INTEGRAL(int);
+    DECLARE_INTEGRAL(long);
+    DECLARE_INTEGRAL_N(long long, long_long);
+    DECLARE_INTEGRAL(short);
+    DECLARE_INTEGRAL(unsigned);
+
+    DECLARE_INTEGRAL_N(unsigned int, unsigned_int);
+    DECLARE_INTEGRAL_N(unsigned long, unsigned_long);
+    DECLARE_INTEGRAL_N(unsigned long long, unsigned_long_long);
+    DECLARE_INTEGRAL_N(unsigned short, unsigned_short);
+
+    DECLARE_INTEGRAL(uint8_t);
+    DECLARE_INTEGRAL(uint16_t);
+    DECLARE_INTEGRAL(uint32_t);
+    DECLARE_INTEGRAL(uint64_t);
+
+    DECLARE_INTEGRAL(int8_t);
+    DECLARE_INTEGRAL(int16_t);
+    DECLARE_INTEGRAL(int32_t);
+    DECLARE_INTEGRAL(int64_t);
+
+    using true_ = bool_ <true>;
+    using false_ = bool_ <false>;
+}
+
+#endif // MPLEX_FUNDAMENTAL_INTEGRAL_HPP_INCLUDED

stringify/tmp_util/fundamental/is_same.hpp

@@ -0,0 +1,26 @@
+#ifndef IS_SAME_HPP_INCLUDED
+#define IS_SAME_HPP_INCLUDED
+
+#include <type_traits>
+#include "integral.hpp"
+
+namespace mplex {
+    struct is_same {
+        template <typename T, typename U>
+        struct apply {
+            using type = bool_ <std::is_same<T, U>::value>;
+            constexpr static const bool value = type::value;
+        };
+    };
+
+    template <typename T>
+    struct is_type {
+        template <typename U>
+        struct apply {
+            using type = bool_ <std::is_same<T, U>::value>;
+            constexpr static const bool value = type::value;
+        };
+    };
+}
+
+#endif // IS_SAME_HPP_INCLUDED

stringify/tmp_util/fundamental/null_type.hpp

@@ -0,0 +1,8 @@
+#ifndef MPLEX_FUNDAMENTAL_NULL_TYPE_HPP_INCLUDED
+#define MPLEX_FUNDAMENTAL_NULL_TYPE_HPP_INCLUDED
+
+namespace mplex {
+    struct null_t {};
+}
+
+#endif // MPLEX_FUNDAMENTAL_NULL_TYPE_HPP_INCLUDED