generalized to multidimensional

src/main.cpp

@@ -40,12 +40,13 @@ struct bounds_checked_layout_policy {
  struct mapping : stdex::layout_right::mapping<Extents> {
  using base_t = stdex::layout_right::mapping<Extents>;
  using base_t::base_t;
- static_assert(Extents::rank() == 1, "Only supporting 1-D mappings for brevity");
- std::ptrdiff_t operator()(auto idx) const {
- if (idx < 0 || idx > this->extents().extent(0)) {
- throw std::out_of_range("Invalid bin index");
- }
- return idx;
+ std::ptrdiff_t operator()(auto... idxs) const {
+ [&]<size_t... Is>(std::index_sequence<Is...>) {
+ if (((idxs < 0 || idxs > this->extents().extent(Is)) || ...)) {
+ throw std::out_of_range("Invalid bin index");
+ }
+ }(std::make_index_sequence<sizeof...(idxs)>{});
+ return this->base_t::operator()(idxs...);
  }
  };
 };
@@ -65,8 +66,8 @@ struct robot_command_accessor {
 };
 
 using bin_view = stdex::mdspan<bin_state, 
- // We know statically that there are 4 bins
- stdex::extents<uint32_t, 6>,
+ // We're treating our 6 bins as a 3x2 matrix
+ stdex::extents<uint32_t, 3, 2>,
  // Our layout should do bounds-checking
  bounds_checked_layout_policy,
  // Our accessor should tell the robot to asynchronously access the bin
@@ -77,22 +78,24 @@ int main() {
  auto arm = robot_arm{"/dev/ttyACM0", 9600};
  auto bins = bin_view(&arm);
  while(true) {
- for (auto ndx = 0u; ndx < bins.extent(0); ++ndx) {
- std::cout << "Bin " << ndx << " is ";
- try {
- auto state = bins(ndx).get();
- switch (state) {
- case bin_state::OCCUPIED:
- std::cout << "OCCUPIED";
- break;
- case bin_state::EMPTY:
- std::cout << "EMPTY";
- break;
+ for (auto i = 0u; i < bins.extent(0); ++i) {
+ for (auto j = 0u; j < bins.extent(1); ++j) {
+ std::cout << "Bin " << i << ", " << j << " is ";
+ try {
+ auto state = bins(i, j).get();
+ switch (state) {
+ case bin_state::OCCUPIED:
+ std::cout << "OCCUPIED";
+ break;
+ case bin_state::EMPTY:
+ std::cout << "EMPTY";
+ break;
+ }
+ } catch (std::exception const& e) {
+ std::cout << "¯\\_(ツ)_/¯ " << e.what();
  }
- } catch (std::exception const& e) {
- std::cout << "¯\\_(ツ)_/¯ " << e.what();
+ std::cout << "\n";
  }
- std::cout << "\n";
  }
  std::cout << "====================\n";
  }