index_element.h

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   it under the terms of the GNU General Public License, version 2.0,
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   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
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   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA */
 
#ifndef DD__INDEX_ELEMENT_INCLUDED
#define DD__INDEX_ELEMENT_INCLUDED
 
#include "m_string.h"
#include "my_inttypes.h"
#include "sql/dd/sdi_fwd.h"            // dd::Sdi_wcontext
#include "sql/dd/types/weak_object.h"  // dd::Weak_object
 
namespace dd {
 
///////////////////////////////////////////////////////////////////////////
 
class Column;
class Index;
class Index_element_impl;
 
namespace tables {
class Index_column_usage;
}
 
///////////////////////////////////////////////////////////////////////////
 
class Index_element : virtual public Weak_object {
 public:
  typedef Index_element_impl Impl;
  typedef tables::Index_column_usage DD_table;
 
 public:
  enum enum_index_element_order { ORDER_UNDEF = 1, ORDER_ASC, ORDER_DESC };
 
 public:
  ~Index_element() override = default;
 
  /////////////////////////////////////////////////////////////////////////
  // index.
  /////////////////////////////////////////////////////////////////////////
 
  virtual const Index &index() const = 0;
 
  virtual Index &index() = 0;
 
  /////////////////////////////////////////////////////////////////////////
  // column.
  /////////////////////////////////////////////////////////////////////////
 
  virtual const Column &column() const = 0;
 
  virtual Column &column() = 0;
 
  /////////////////////////////////////////////////////////////////////////
  // ordinal_position.
  /////////////////////////////////////////////////////////////////////////
 
  virtual uint ordinal_position() const = 0;
 
  /////////////////////////////////////////////////////////////////////////
  // length.
  /////////////////////////////////////////////////////////////////////////
 
  virtual uint length() const = 0;
  virtual void set_length(uint length) = 0;
  virtual void set_length_null(bool is_null) = 0;
  virtual bool is_length_null() const = 0;
 
  /////////////////////////////////////////////////////////////////////////
  // order.
  /////////////////////////////////////////////////////////////////////////
 
  virtual enum_index_element_order order() const = 0;
  virtual void set_order(enum_index_element_order order) = 0;
 
  /////////////////////////////////////////////////////////////////////////
  // hidden.
  /////////////////////////////////////////////////////////////////////////
 
  virtual bool is_hidden() const = 0;
  virtual void set_hidden(bool hidden) = 0;
 
  /**
    Converts *this into json.
 
    Converts all member variables that are to be included in the sdi
    into json by transforming them appropriately and passing them to
    the rapidjson writer provided.
 
    @param wctx opaque context for data needed by serialization
    @param w rapidjson writer which will perform conversion to json
 
  */
 
  virtual void serialize(Sdi_wcontext *wctx, Sdi_writer *w) const = 0;
 
  /**
    Re-establishes the state of *this by reading sdi information from
    the rapidjson DOM subobject provided.
 
    Cross-references encountered within this object are tracked in
    sdictx, so that they can be updated when the entire object graph
    has been established.
 
    @param rctx stores book-keeping information for the
    deserialization process
    @param val subobject of rapidjson DOM containing json
    representation of this object
  */
 
  virtual bool deserialize(Sdi_rcontext *rctx, const RJ_Value &val) = 0;
 
  /**
    Check if index element (a.k.a. key part) is a prefix of the column used.
  */
  virtual bool is_prefix() const = 0;
};
 
///////////////////////////////////////////////////////////////////////////
 
}  // namespace dd
 
#endif  // DD__INDEX_ELEMENT_INCLUDED