Wildcard-pattern.cpp

#include "matchit.h"
#include <iostream>
#include <optional>
using namespace matchit;

void sample1()
{
  constexpr auto x = 20;
  Id<int32_t> a;
  match(10, x)(
      // the x is always matched by _
      pattern | ds(a, _) = [&]
      { assert(*a == 10); });
}

void sample2()
{
  // ignore a function/closure param
  constexpr auto real_part = [](float a, float)
  { return a; };
  static_cast<void>(real_part);

  // ignore a field from a struct
  struct RGBA
  {
    float r;
    float g;
    float b;
    float a;
  };

  constexpr auto color = RGBA{0.4f, 0.1f, 0.9f, 0.5f};

  constexpr auto dsRGBA = dsVia(&RGBA::r, &RGBA::g, &RGBA::b, &RGBA::a);

  Id<float> red, green, blue;
  match(color)(pattern | dsRGBA(red, green, blue, _) = [&]
               {
                 assert(color.r == *red);
                 assert(color.g == *green);
                 assert(color.b == *blue);
               });

  // accept any Some, with any value
  constexpr auto x = std::make_optional(10);
  match(x)(
      // the x is always matched by _
      pattern | some(_) = [] {});
}

int32_t main()
{
  sample1();
  sample2();
  return 0;
}