Method GetFragmentsImpl

cpp/src/arrow/dataset/dataset_internal.h:109–130

 protected:
  Result<FragmentIterator> GetFragmentsImpl(compute::Expression predicate) override {
    if (fragment_gen_) {
      // TODO(ARROW-8163): Async fragment scanning can be forwarded rather than waiting
      // for the whole generator here. For now, all Dataset impls have a vector of
      // Fragments anyway
      auto fragments_fut = CollectAsyncGenerator(std::move(fragment_gen_));
      ARROW_ASSIGN_OR_RAISE(fragments_, fragments_fut.result());
    }

    // TODO(ARROW-12891) Provide subtree pruning for any vector of fragments
    FragmentVector fragments;
    for (const auto& fragment : fragments_) {
      ARROW_ASSIGN_OR_RAISE(
          auto simplified_filter,
          compute::SimplifyWithGuarantee(predicate, fragment->partition_expression()));

      if (simplified_filter.IsSatisfiable()) {
        fragments.push_back(fragment);
      }
    }
    return MakeVectorIterator(std::move(fragments));
  }

  FragmentVector fragments_;
  AsyncGenerator<std::shared_ptr<Fragment>> fragment_gen_;