Function is_array_span

cpp/src/arrow/compute/exec.h:354–354

  ArraySpan* array_span_mutable() { return &std::get<ArraySpan>(this->value); }

  bool is_array_span() const { return this->value.index() == 0; }

  const std::shared_ptr<ArrayData>& array_data() const {
    return std::get<std::shared_ptr<ArrayData>>(this->value);