get_result.h

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#ifndef cetlib_sqlite_detail_get_result_h
#define cetlib_sqlite_detail_get_result_h

#include "cetlib/sqlite/detail/convert.h"
#include "cetlib/sqlite/query_result.h"

#include <cassert>
#include <tuple>

namespace cet {
  namespace sqlite {
    namespace detail {

      template <std::size_t I, typename Tuple>
      std::enable_if_t<(I == std::tuple_size<Tuple>::value)>
      fillData(Tuple&,
               int const ncols [[gnu::unused]],
               int const currentcol [[gnu::unused]],
               char**)
      {
        assert(currentcol == ncols);
      }

      template <std::size_t I, typename Tuple>
      std::enable_if_t<(I < std::tuple_size<Tuple>::value)>
      fillData(Tuple& data, int const ncols, int currentcol, char** results)
      {
        assert(currentcol != ncols);
        using ET = std::tuple_element_t<I, Tuple>;
        std::get<I>(data) = detail::convertTo<ET>(results[currentcol]);
        fillData<I + 1>(data, ncols, ++currentcol, results);
      }

      template <typename... Args>
      int
      get_result(void* data, int ncols, char** results, char** cnames)
      {
        assert(ncols >= 1);
        auto j = static_cast<cet::sqlite::query_result<Args...>*>(data);
        if (j->columns.empty()) {
          for (int i{}; i < ncols; ++i)
            j->columns.push_back(cnames[i]);
        }

        assert(sizeof...(Args) == ncols);
        std::tuple<Args...> rowdata;
        int currentCol{};
        fillData<0u>(rowdata, ncols, currentCol, results);
        j->data.emplace_back(rowdata);
        return 0;
      }

    } // detail
  }   // sqlite
} // cet

#endif /* cetlib_sqlite_detail_get_result_h */

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