Method RunStep

apps/gdalalg_vector_sql.cpp:164–395

};

class GDALVectorSQLAlgorithmDatasetMultiLayer final : public GDALDataset
{
    // We can't safely have 2 SQL layers active simultaneously on the same
    // source dataset. So each time we access one, we must close the last
    // active one.
    OGRLayerPool m_oPool{1};
    GDALDataset &m_oSrcDS;
    std::vector<std::unique_ptr<ProxiedSQLLayer>> m_layers{};

    struct UserData
    {
        GDALDataset &oSrcDS;
        std::string osSQL{};
        std::string osDialect{};
        std::string osLayerName{};

        UserData(GDALDataset &oSrcDSIn, const std::string &osSQLIn,
                 const std::string &osDialectIn,
                 const std::string &osLayerNameIn)
            : oSrcDS(oSrcDSIn), osSQL(osSQLIn), osDialect(osDialectIn),
              osLayerName(osLayerNameIn)
        {
        }
        CPL_DISALLOW_COPY_ASSIGN(UserData)
    };

    CPL_DISALLOW_COPY_ASSIGN(GDALVectorSQLAlgorithmDatasetMultiLayer)

  public:
    explicit GDALVectorSQLAlgorithmDatasetMultiLayer(GDALDataset &oSrcDS)
        : m_oSrcDS(oSrcDS)
    {
        m_oSrcDS.Reference();
    }

    ~GDALVectorSQLAlgorithmDatasetMultiLayer() override
    {
        m_layers.clear();
        m_oSrcDS.ReleaseRef();
    }

    void AddLayer(const std::string &osSQL, const std::string &osDialect,
                  const std::string &osLayerName)
    {
        const auto OpenLayer = [](void *pUserDataIn)
        {
            UserData *pUserData = static_cast<UserData *>(pUserDataIn);
            return pUserData->oSrcDS.ExecuteSQL(
                pUserData->osSQL.c_str(), nullptr,
                pUserData->osDialect.empty() ? nullptr
                                             : pUserData->osDialect.c_str());
        };

        const auto CloseLayer = [](OGRLayer *poLayer, void *pUserDataIn)
        {
            UserData *pUserData = static_cast<UserData *>(pUserDataIn);
            pUserData->oSrcDS.ReleaseResultSet(poLayer);
        };