Function FilteredObject

Source/cmJSONHelpers.h:360–510

  /// container of pairs (key, value).
  template <typename Container, typename F, typename Filter>
  static cmJSONHelper<Container> FilteredObject(
    JsonErrors::ErrorGenerator const& error, F func, Filter filter)
  {
    return [error, func, filter](Container& out, Json::Value const* value,
                                 cmJSONState* state) -> bool {
      // NOTE Some compile-time code path don't use `filter` at all.
      // So, suppress "unused lambda capture" warning is needed.
      static_cast<void>(filter);

      if (!value) {
        out.clear();
        return true;
      }
      if (!value->isObject()) {
        error(value, state);
        return false;
      }
      out.clear();
      auto outIt = std::inserter(out, out.end());
      bool success = true;
      for (auto const& key : value->getMemberNames()) {
        state->push_stack(key, &(*value)[key]);
#if __cplusplus >= 201703L
        if constexpr (std::is_same_v<Filter, std::true_type>) {
          // Filtering functionality isn't needed at all...
        } else if constexpr (details::is_bool_filter<Filter>::value) {
          // A given `Filter` is `bool(const std::string&)` callable.
          if (!filter(key)) {
            state->pop_stack();
            continue;
          }
        } else {
#endif
          // A full-featured `Filter` has been given
          auto res = filter(key, &(*value)[key], state);
          if (res == FilterResult::Skip) {
            state->pop_stack();
            continue;
          }
          if (res == FilterResult::Error) {
            state->pop_stack();
            success = false;
            break;
          }
#if __cplusplus >= 201703L
        }
#endif
        typename Container::value_type::second_type t;
        // ATTENTION Call the function first (for it's side-effects),
        // then accumulate the result!
        success = func(t, &(*value)[key], state) && success;
        outIt = typename Container::value_type{ key, std::move(t) };
        state->pop_stack();
      }
      return success;
    };
  }