fix readme to new api

untests/enum_examples.cpp

@@ -0,0 +1,53 @@
+/*******************************************************************************
+ * This file is part of the "https://github.com/blackmatov/enum.hpp"
+ * For conditions of distribution and use, see copyright notice in LICENSE.md
+ * Copyright (C) 2019, by Matvey Cherevko (blackmatov@gmail.com)
+ ******************************************************************************/
+
+#define CATCH_CONFIG_FAST_COMPILE
+#include <catch2/catch.hpp>
+
+#include <enum.hpp/enum.hpp>
+
+#include <string>
+#include <iostream>
+
+namespace
+{
+    ENUM_HPP_CLASS_DECL(color, unsigned,
+        (red = 0xFF0000)
+        (green = 0x00FF00)
+        (blue = 0x0000FF)
+        (white = red | green | blue))
+}
+
+TEST_CASE("examples") {
+    SECTION("traits_using") {
+        // size
+        STATIC_REQUIRE(color_traits::size == 4);
+
+        // to_underlying
+        STATIC_REQUIRE(color_traits::to_underlying(color::white) == 0xFFFFFF);
+
+        // to_string
+        STATIC_REQUIRE(color_traits::to_string(color::red) == "red");
+        STATIC_REQUIRE(color_traits::to_string(color(42)) == std::nullopt);
+
+        // from_string
+        STATIC_REQUIRE(color_traits::from_string("green") == color::green);
+        STATIC_REQUIRE(color_traits::from_string("error") == std::nullopt);
+
+        // to_index
+        STATIC_REQUIRE(color_traits::to_index(color::blue) == 2u);
+        STATIC_REQUIRE(color_traits::to_index(color(42)) == std::nullopt);
+
+        // from_index
+        STATIC_REQUIRE(color_traits::from_index(2) == color::blue);
+        STATIC_REQUIRE(color_traits::from_index(42) == std::nullopt);
+
+        // names
+        for ( auto n : color_traits::names ) {
+            std::cout << n << ",";
+        }
+    }
+}