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//
// G4FieldManagerStore
//
// Class description:
//
// Container for all FieldManagers, with functionality derived
// from std::vector<T>. The class is a 'singleton', in that only
// one can exist, and access is provided via the static function
// G4FieldManagerStore::GetInstance().
//
// All FieldManagers should be registered with G4FieldManagerStore,
// and removed on their destruction. 
// Intended principally to enable resetting of 'state' at start of event.
// The underlying container initially has a capacity of 100.

// Author: John Apostolakis (CERN), 07.12.2007 - Initial version
// --------------------------------------------------------------------
#ifndef G4FIELDMANAGERSTORE_HH
#define G4FIELDMANAGERSTORE_HH

#include <vector>

#include "G4FieldManager.hh"

/**
 * @brief G4FieldManagerStore is a container for all field managers, with
 * functionality derived from std::vector<T>. The class is a singleton.
 * All field managers should be registered with G4FieldManagerStore,
 * and removed on their destruction. Intended principally to enable resetting
 * of 'state' at start of an event.
 */

class G4FieldManagerStore : public std::vector<G4FieldManager*>
{
  public:

    /**
     * Gets a pointer to the unique G4FieldManagerStore, creating it if
     * necessary.
     */
    static G4FieldManagerStore* GetInstance();
    static G4FieldManagerStore* GetInstanceIfExist();

    /**
     * Adds the field manager to the collection.
     */
    static void Register(G4FieldManager* pFieldMan);

    /**
     * Removes the field manager from the collection.
     */
    static void DeRegister(G4FieldManager* pFieldMan);

    /**
     * Deletes all managers from the store.
     */
    static void Clean();

    /**
     * Loops over all field managers and calls each one to reset step estimate.
     */
    void ClearAllChordFindersState();

    /**
     * Destructor: takes care to delete the allocated field managers.
     */
    ~G4FieldManagerStore();

  private:
  
    /**
     * Private constructor.
     */
    G4FieldManagerStore();

  private:

    static G4ThreadLocal G4FieldManagerStore* fgInstance;
    static G4ThreadLocal G4bool locked;
};

#endif