FromItem.h

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/*  Copyright (C) 2008 National Institute For Space Research (INPE) - Brazil.
 
    This file is part of the TerraLib - a Framework for building GIS enabled applications.
 
    TerraLib is free software: you can redistribute it and/or modify
    it under the terms of the GNU Lesser General Public License as published by
    the Free Software Foundation, either version 3 of the License,
    or (at your option) any later version.
 
    TerraLib is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
    GNU Lesser General Public License for more details.
 
    You should have received a copy of the GNU Lesser General Public License
    along with TerraLib. See COPYING. If not, write to
    TerraLib Team at <terralib-team@terralib.org>.
 */
 
/*!
  \file terralib/dataaccess/query/FromItem.h
 
  \brief An abstract class that models a source of data in a query.
*/
 
#ifndef __TERRALIB_DATAACCESS_INTERNAL_FROMITEM_H
#define __TERRALIB_DATAACCESS_INTERNAL_FROMITEM_H
 
// TerraLib
#include "../../common/BaseVisitable.h"
#include "QueryVisitor.h"
 
// STL
#include <string>
 
namespace te
{
  namespace da
  {
// Forward declarations
    class Expression;
 
    /*!
      \class FromItem
      
      \brief An abstract class that models a source of data in a query.
 
      \sa From, DataSetType, DataSetName, SubSelect, DataSet, FromFunctionCall, Join
    */
    class TEDATAACCESSEXPORT FromItem : public te::common::BaseVisitable<QueryVisitor>
    {
      public:
 
        TE_DEFINE_VISITABLE
 
        /*!
          \brief Constructor.
 
          \param alias An alias to the source data item.
        */
        FromItem(const std::string& alias) : m_alias(alias) {}
 
        /*! \brief Copy constructor. */
        FromItem(const FromItem& rhs);
 
        /*! \brief Virtual destructor. */
        virtual ~FromItem() {}
 
        /*! Assignment operator.  */
        FromItem& operator=(const FromItem& rhs);
 
        /*! \brief It creates a new copy of this FromItem. */
        virtual FromItem* clone() const = 0;
 
        /*!
          \brief It sets the alias for a from source item.
 
          \param alias The alias for a from source item.
 
          \note The FromItem will take the ownership of the given alias.
        */
        void setAlias(const std::string& alias);
 
        /*!
          \brief It returns the alias associated to the source item.
 
          \return The alias for the source item.
        */
        const std::string& getAlias() const;
 
      protected:
 
        std::string m_alias; //!< An alias for the output name.
    };
 
    /*! \brief For use with boost conteiners. */
    inline FromItem* new_clone(const FromItem& a)
    {
      return a.clone();
    }
 
  } // end namespace da
}   // end namespace te
 
#endif  // __TERRALIB_DATAACCESS_INTERNAL_FROMITEM_H