rowcallback.hpp

/******************************************************************************
 ------------- Copyright (c) 2009-2023 H a r a l d  A c h i t z ---------------
 ---------- < h a r a l d dot a c h i t z at g m a i l dot c o m > ------------
 ---- This Source Code Form is subject to the terms of the Mozilla Public -----
 ---- License, v. 2.0. If a copy of the MPL was not distributed with this -----
 ---------- file, You can obtain one at http://mozilla.org/MPL/2.0/. ----------
 ******************************************************************************/
 
#ifndef SL3_RowCallback_HPP
#define SL3_RowCallback_HPP
 
#include <functional>
 
#include <sl3/columns.hpp>
#include <sl3/config.hpp>
 
namespace sl3
{
  class Columns;
 
  /**
   * \brief Callback for SQL SELECT statements
   *
   * This interface can be used to process the result of
   * a SQL statement.
   *
   *
   */
  class LIBSL3_API RowCallback
  {
    friend class Command;
 
  public:
    /**
     * \brief Destructor
     */
    virtual ~RowCallback () noexcept;
 
  protected:
    /**
     * \brief Constructor
     */
    RowCallback () noexcept;
 
    /**
     * \brief Process one row of the result from  a SELECT statement
     *
     * @param columns Columns object for accessing values.
     *
     * @return false if processing the query result shall stop
     *       \n true otherwise
     */
    virtual bool onRow (Columns columns) = 0;
 
    /**
     * \brief Called before a query result will be processed
     *
     * The default implementation does nothing.
     */
    virtual void onStart ();
 
    /**
     * \brief Called after a query result has been processed
     *
     * The default implementation does nothing.
     */
    virtual void onEnd ();
  };
}
 
#endif