Destructuring-Nested-Structs-and-Enums.cpp

#include "matchit.h"
#include <iostream>
#include <optional>
#include <stack>

struct Rgb : std::array<int32_t, 3>
{
};
struct Hsv : std::array<int32_t, 3>
{
};
using Color = std::variant<Rgb, Hsv>;

struct Quit
{
};
using Move = std::array<int32_t, 2>;
using Write = std::string;
using ChangeColor = Color;
using Message = std::variant<Quit, Move, Write, ChangeColor>;

int32_t main()
{
  Message const msg = ChangeColor{Hsv{{0, 160, 255}}};

  using namespace matchit;
  Id<int32_t> r, g, b;
  Id<int32_t> h, s, v;
  match(msg)(
      pattern | as<ChangeColor>(as<Rgb>(ds(r, g, b))) =
          [&]
      {
        std::cout << "Change the color to red " << *r << ", green " << *g
                  << ", and blue " << *b << std::endl;
      },
      pattern | as<ChangeColor>(as<Hsv>(ds(h, s, v))) =
          [&]
      {
        std::cout << "Change the color to hue " << *h << ", saturation "
                  << *s << ", and value " << *v << std::endl;
      });
}