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CdbBdbObjectVisitor.hh

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#ifndef CDBBDB_OBJECT_VISITOR_HH
#define CDBBDB_OBJECT_VISITOR_HH

// File and Version Information:
//      $Id: CdbBdbObjectVisitor.hh,v 1.2 2004/10/21 20:35:50 gapon Exp $

#include "CdbBase/CdbCommon.hh"

#include <oo.h>     // ooRef(ooObj), ooHandle(ooObj)

// Forward declarations

class CdbBdbObjectVisitorUserAction;
class CdbBdbObjectVisitorImpl;

/// This class provides "object visitor" facility for persistent objects.
/**
  * This facility uses the Objectivity/DB Active Schema API to navigate accross
  * an arbitrary graph of objects by visiting each node and calling a user defined
  * action at each node. Each node is visited just once. A user defined action object
  * provides a feedback wether the visiting should propagate beyond a visited
  * node or it should stop at this node or it should break visiting due to a error.
  * 
  * IMPLEMENTATION NOTES:
  *
  *   (1) This class uses PIMPL idiom to protect end users
  *       of the class from being exposed to the buggy header
  *       files of the Objectivity/DB Active Schema API.
  *
  *   (2) This class violates CDB API convention on the inclusion
  *       of "CdbBase/CdbCommon.hh" header file to avoid STD namespace
  *       conflicts of the kind described above.
  *
  * ATTENTION:
  *
  *   - This group of classes has nothing in common with the famous "Visitor"
  *     pattern ("Go4").
  */
class CdbBdbObjectVisitor {

private:

  /// Default constructor (NOT IMPLEMENTED)
  /**
    * There is no way to get the consistent object's context without user defined
    * parameters passed through the normal constructor.
    */
    CdbBdbObjectVisitor( );

public:

  /// Normal constructor
  /**
    * Sets the initial context for the visiting. This context can be reused
    * accross multiple calls to the visiting method itself.
    *
    * A non-zero pointer onto a user defined action is required.
    *
    * The ownership to a user action does not get transferred
    * into the current object. We may need non-const pointer to let a user
    * to maintain the context of user action between calls.
    *
    * Note, a user action object can be overriden by passing another user action
    * object by calling a special "setUserAction" method.
    */
    CdbBdbObjectVisitor( CdbBdbObjectVisitorUserAction* theUserAction,
                                                   bool verboseMode = false,
                                                   bool debugMode   = false );

  /// Destructor
  /**
    * More details...
    */
    virtual ~CdbBdbObjectVisitor( );

  /// Visit the specified object
  /**
    * The operation will return "true" in case of success, it will return "false"
    * in case of any errors.
    */
    bool visit( const ooHandle(ooObj)& theInputH );

  /// Set user action
  /**
    * If 0 pointer is passed then the current user action will be reset
    * and it will not be called anymore.
    *
    * The method will return a pointer onto the previous action (if any).
    *
    * @see class CdbBdbObjectVisitorUserAction
    */
    CdbBdbObjectVisitorUserAction* setUserAction( CdbBdbObjectVisitorUserAction* theUserAction );

private:

  // Here is my implementation

    CdbBdbObjectVisitorImpl* _myImpl;
};

#endif  // CDBBDB_OBJECT_VISITOR_HH

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