SelectIterator.h

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/*
 * (C) Copyright 1996-2012 ECMWF.
 * 
 * This software is licensed under the terms of the Apache Licence Version 2.0
 * which can be obtained at http://www.apache.org/licenses/LICENSE-2.0. 
 * In applying this licence, ECMWF does not waive the privileges and immunities 
 * granted to it by virtue of its status as an intergovernmental organisation nor
 * does it submit to any jurisdiction.
 */
 
/// @author Piotr Kuchta
/// @author Simon Smart
/// @date Feb 2009
 
#ifndef odc_SelectIterator_H
#define odc_SelectIterator_H
 
#include "eckit/sql/expression/SQLExpressions.h"
#include "odc/api/ColumnType.h"
#include "odc/sql/SQLSelectOutput.h"
#include "eckit/sql/SQLSession.h"
 
 
// Forward declarations
 
namespace odc {
    class Select;
    template <typename I, typename O, typename D> class IteratorProxy;
    namespace core {
        class MetaData;
    }
}
 
namespace eckit {
    namespace SQL {
        class SQLSelect;
    }
}
 
 
namespace odc {
 
//----------------------------------------------------------------------------------------------------------------------
 
class SelectIterator : private eckit::NonCopyable {
public:
    
    SelectIterator (const std::string& select, eckit::sql::SQLSession& session, sql::SQLSelectOutput& output);
    ~SelectIterator();
 
    // TODO: New dataset
    bool isNewDataset() { return false; }
    const double* data() const { return output_.data(); }
//    double* data() { return data_; }
    double& data(size_t i) { return output_.data(i); }
 
    const core::MetaData& columns() const { return output_.metadata(); }
    const core::MetaData& columns(const core::MetaData&) { NOTIMP; }
    void setNumberOfColumns(size_t) { NOTIMP; }
 
    const std::map<std::string, std::string>& properties() const { NOTIMP; }
 
    int close() { NOTIMP; }
    int setColumn(size_t index, std::string name, api::ColumnType type) { NOTIMP; }
    void writeHeader() { NOTIMP; }
    int setBitfieldColumn(size_t index, std::string name, api::ColumnType type, eckit::sql::BitfieldDef b) { NOTIMP; }
    void missingValue(size_t, double) { NOTIMP; }
    
    /// Set an output buffer for retrieving the next row(s)
    void setOutputRowBuffer(double* data, size_t count=0);
 
    /// The offset of a given column in the doubles[] data array
    size_t dataOffset(size_t i) const { return output_.dataOffset(i); }
 
    // Get the number of doubles per row.
    size_t rowDataSizeDoubles() const { return output_.rowDataSizeDoubles(); }
 
    bool next();
 
private:
 
    void parse();
 
    std::string select_;
 
    sql::SQLSelectOutput& output_;
 
    eckit::sql::SQLSelect* selectStmt_; // n.b. non-owning
 
    eckit::sql::SQLSession& session_;
 
    // Just for integration with IteratorProxy. Yeaurgh.
    // TODO: Remove this hack
    bool noMore_;
 
protected:
    int refCount_;
 
    // This is a bit yucky, but the IteratorProxy essentially reimplements std::shared_ptr
    // but not in a threadsafe way.
    friend class odc::IteratorProxy<odc::SelectIterator, odc::Select, const double>;
};
 
//----------------------------------------------------------------------------------------------------------------------
 
} // namespace odc 
 
#endif