add constexpr containers (#187)

example/example_containers_array.cpp

@@ -0,0 +1,61 @@
+// Licensed under the MIT License <http://opensource.org/licenses/MIT>.
+// SPDX-License-Identifier: MIT
+// Copyright (c) 2019 - 2022 Daniil Goncharov <neargye@gmail.com>.
+//
+// Permission is hereby  granted, free of charge, to any  person obtaining a copy
+// of this software and associated  documentation files (the "Software"), to deal
+// in the Software  without restriction, including without  limitation the rights
+// to  use, copy,  modify, merge,  publish, distribute,  sublicense, and/or  sell
+// copies  of  the Software,  and  to  permit persons  to  whom  the Software  is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+//
+// THE SOFTWARE  IS PROVIDED "AS  IS", WITHOUT WARRANTY  OF ANY KIND,  EXPRESS OR
+// IMPLIED,  INCLUDING BUT  NOT  LIMITED TO  THE  WARRANTIES OF  MERCHANTABILITY,
+// FITNESS FOR  A PARTICULAR PURPOSE AND  NONINFRINGEMENT. IN NO EVENT  SHALL THE
+// AUTHORS  OR COPYRIGHT  HOLDERS  BE  LIABLE FOR  ANY  CLAIM,  DAMAGES OR  OTHER
+// LIABILITY, WHETHER IN AN ACTION OF  CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE  OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+
+#include <iostream>
+
+#include <magic_enum_containers.hpp>
+
+enum class Color { RED = 1, GREEN = 2, BLUE = 4 };
+
+struct RGB {
+
+  std::uint8_t r {};
+  std::uint8_t g {};
+  std::uint8_t b {};
+
+  [[nodiscard]] constexpr bool empty() { return std::equal_to{}(r, g) && std::equal_to{}(g, b) && std::equal_to{}(b, 0); }
+
+  [[nodiscard]] constexpr bool operator==(RGB rgb) const noexcept { return std::equal_to{}(r, rgb.r) && std::equal_to{}(g, rgb.g) && std::equal_to{}(b, rgb.b); }
+
+  friend std::ostream& operator<<(std::ostream& ostream, RGB rgb) {
+
+    ostream << "R=" << static_cast<std::uint32_t>(rgb.r) << " G=" << static_cast<std::uint32_t>(rgb.g) << " B=" << static_cast<std::uint32_t>(rgb.b);
+    return ostream;
+  }
+};
+
+constexpr std::uint8_t color_max = std::numeric_limits<std::uint8_t>::max();
+
+int main() {
+
+  constexpr magic_enum::containers::array<Color, RGB> color_rgb_initializer {{{{color_max, 0, 0}, {0, color_max, 0}, {0, 0, color_max}}}};
+
+  std::cout << std::get<0>(color_rgb_initializer) << std::endl; // R=255 G=0 B=0
+  std::cout << std::get<1>(color_rgb_initializer) << std::endl; // R=0 G=255 B=0
+  std::cout << std::get<2>(color_rgb_initializer) << std::endl; // R=0 G=0 B=255
+
+  std::cout << std::get<Color::RED>(color_rgb_initializer) << std::endl; // R=255 G=0 B=0
+  std::cout << std::get<Color::GREEN>(color_rgb_initializer) << std::endl; // R=0 G=255 B=0
+  std::cout << std::get<Color::BLUE>(color_rgb_initializer) << std::endl; // R=0 G=0 B=255
+
+  return 0;
+}