105 lines
4.0 KiB
C++
105 lines
4.0 KiB
C++
// Licensed under the MIT License <http://opensource.org/licenses/MIT>.
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// SPDX-License-Identifier: MIT
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// Copyright (c) 2019 - 2022 Daniil Goncharov <neargye@gmail.com>.
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// Copyright (c) 2020 - 2022 Bela Schaum <schaumb@gmail.com>.
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//
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// Permission is hereby granted, free of charge, to any person obtaining a copy
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// of this software and associated documentation files (the "Software"), to deal
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// in the Software without restriction, including without limitation the rights
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// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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// copies of the Software, and to permit persons to whom the Software is
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// furnished to do so, subject to the following conditions:
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//
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// The above copyright notice and this permission notice shall be included in all
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// copies or substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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// SOFTWARE.
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#include <iostream>
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#define MAGIC_ENUM_ENABLE_HASH
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#include <magic_enum_switch.hpp>
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enum class Color { RED, BLUE, GREEN };
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template <Color C>
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constexpr std::string_view DoWork() {
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return "default";
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}
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template <>
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constexpr std::string_view DoWork<Color::GREEN>() {
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return "override";
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}
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// Helper type for the visitor pattern.
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template<class... Ts> struct overloaded : Ts... { using Ts::operator()...; };
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template<class... Ts> overloaded(Ts...) -> overloaded<Ts...>;
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int main() {
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Color c = Color::RED;
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auto lambda = [] (auto value) {
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std::cout << DoWork<value>() << std::endl;
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};
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magic_enum::enum_switch(lambda, c); // prints "default"
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c = Color::GREEN;
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magic_enum::enum_switch(lambda, c); // prints "override"
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// with object, explicit enum type
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auto switcher1 = overloaded{
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[] (magic_enum::enum_constant<Color::BLUE>) {
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std::cout << "Blue" << std::endl;
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},
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[] (magic_enum::enum_constant<Color::RED>) {
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std::cout << "Red" << std::endl;
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}
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};
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magic_enum::enum_switch(switcher1, Color::GREEN); // prints nothing
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magic_enum::enum_switch(switcher1, Color::BLUE); // prints "Blue"
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magic_enum::enum_switch(switcher1, Color::RED); // prints "Red"
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// explicit result type
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auto switcher2 = overloaded{
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[] (magic_enum::enum_constant<Color::GREEN>) {
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return "called with green argument";
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},
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[] (Color other) { // default case
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auto name = magic_enum::enum_name(other); // not empty
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return "default: " + std::string{name};
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}
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};
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std::cout << magic_enum::enum_switch<std::string>(switcher2, Color::GREEN) << std::endl; // prints "called with green argument"
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std::cout << magic_enum::enum_switch<std::string>(switcher2, Color::RED) << std::endl; // prints "default: RED"
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auto empty = magic_enum::enum_switch<std::string>(switcher2, static_cast<Color>(-3)); // returns an empty string
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assert(empty.empty());
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// result with default object
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std::cout << magic_enum::enum_switch<std::string>(switcher2, static_cast<Color>(-3), "unrecognized") << std::endl; // prints "unrecognized"
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auto switcher3 = overloaded{
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[] (magic_enum::enum_constant<Color::RED>) -> std::optional<std::string> {
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return "red result";
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},
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[] (magic_enum::enum_constant<Color::BLUE>) -> std::optional<std::string> {
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return std::nullopt;
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}
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};
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std::cout << std::boolalpha;
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std::cout << magic_enum::enum_switch(switcher3, Color::GREEN, std::make_optional("cica")).value() << std::endl; // prints default: "cica"
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std::cout << magic_enum::enum_switch(switcher3, Color::RED, std::make_optional("cica")).value() << std::endl; // prints: "red result"
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std::cout << magic_enum::enum_switch(switcher3, Color::BLUE, std::make_optional("cica")).has_value() << std::endl; // prints: false
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}
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