PG_Property_Set.h

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// -*- C++ -*-

//=============================================================================
/**
 *  @file    PG_Property_Set.h
 *
 *  $Id: PG_Property_Set.h 77001 2007-02-12 07:54:49Z johnnyw $
 *
 *  This file declares classes to help manage the Properties
 *  defined in the Portable Object Group.
 *
 *  Note: this started as a simple helper class to make decoding sets of properties
 *  easier, but expanded to provide more general support for managing sets of properties.
 *
 *  A more appropriate name would be PG_Properties_Set.  Maybe this can be changed someday.
 *
 *  @author Dale Wilson <wilson_d@ociweb.com>
 */
//=============================================================================
#ifndef TAO_PG_PROPERTY_SET
#define TAO_PG_PROPERTY_SET
#include /**/ "ace/pre.h"

#include "orbsvcs/PortableGroup/portablegroup_export.h"
#include "orbsvcs/PortableGroupS.h"
#include "orbsvcs/CosNamingC.h"
#include "ace/Hash_Map_Manager.h"
#include "ace/SString.h"
#include "ace/Null_Mutex.h"

TAO_BEGIN_VERSIONED_NAMESPACE_DECL

namespace TAO
{

  /**
   * The PG_Property_Set captures the set of properties from a
   * PortableGroup::Properties structure in a more usable format (a
   * hash map), and provides methods for operating on these properties.
   *
   * It supports "chains" of property sets to implement default value semantics.
   * If a requested property is not found in this set, the default set(s) are searched.
   * Thus, any property found at this level overrides the defaults.
   *
   * See: PG_Properties_Support for more details on use of this object.
   *
   * A PG_Property_Set may also be used for it's original purpose as a stand-alone
   * helper class for extracting values from PortableGroup::Properties.
   */

  class TAO_PortableGroup_Export PG_Property_Set
  {
    typedef ACE_Hash_Map_Manager<
      ACE_CString,
      const PortableGroup::Value *,
      ACE_SYNCH_NULL_MUTEX> ValueMap;
    typedef ACE_Hash_Map_Iterator<
      ACE_CString,
      const PortableGroup::Value *,
      ACE_SYNCH_NULL_MUTEX> ValueMapIterator;

  public:

    /**
     * constructor: empty set with no defaults.
     */
    PG_Property_Set (void);

    /**
     * constructor
     * @param property_set the properties to be decoded
     */
    PG_Property_Set (const PortableGroup::Properties & property_set);

    /**
     * constructor with defaults
     * @param property_set the properties to be decoded
     * @param defaults a propert set decoder that supplies default values.
     */
    PG_Property_Set (const PortableGroup::Properties & property_set,
                     PG_Property_Set * defaults);

    /**
     * constructor with defaults, but no properties (yet)
     * (note this is not a copy constructor)
     * @param defaults a propert set decoder that supplies default values.
     */
    PG_Property_Set (PG_Property_Set * defaults);


    ~PG_Property_Set ();

    /**
     * general purpose find. returns a pointer to an Any
     *  if templated methods were available:
     *    template <typename TYPE >
     *    int find (const ACE_CString & key, TYPE & value) const;
     *    instead, see global function below
     * @param key the (simple) name of the property
     * @param pValue an out parameter to receive a pointer to the Any containing the value
     * @returns boolean true if found
     */
    int find (const ACE_CString & key, const PortableGroup::Value *& pValue)const;


    /**
     * Decode additional properties
     * Duplicate values replace previous values.
     * @param property_set the properties to be decoded
     */
    void decode (const PortableGroup::Properties & property_set);

    /**
     * Clear properties
     * Does not clear default properties.
     */
    void clear ();

    void remove (const PortableGroup::Properties & property_set);

    /**
     * set or replace a single property
     */
    void set_property (
      const char * name,
      const PortableGroup::Value & value);


    /**
     * Export the properties to a PortableGroup::Properties
     *
     * This method is intended to be used to implement the PropertyManager::get_*_properties
     * methods.  If you want to access the properties for any purpose other than exporting
     * them across a CORBA interface, it is much more efficient to use the find interface.
     *
     */
    void export_properties(PortableGroup::Properties & property_set) const;

    /////////////////////////
    // Implementation Methods
 private:
    /**
     * populate a ValueMap with the properties known to this decoder
     * including but overriding default values
     */
    void merge_properties (ValueMap & merged_values) const;

    ////////////////////
    // Forbidden methods
  private:
    PG_Property_Set(const PG_Property_Set & rhs);
    PG_Property_Set & operator = (const PG_Property_Set & rhs);

    ///////////////
    // Data Members
  private:

    /**
     * Protect internal state.
     */
    mutable TAO_SYNCH_MUTEX internals_;

    ValueMap values_;
    /**
     * a parent to another property decoder that provides default values
     * these can be chained indefinitely.
     * @todo reference counted pointers would be a good idea here.
     */
    PG_Property_Set * defaults_;
  };


#ifdef PG_PS_UNIT_TEST

  /**
   * unit test: encode and decode properties.
   * Initialize CORBA before calling this function.
   * Success is silent, failure prints on cerr.
   * @returns 1 if test passed; 0 if test failed.
   */
  int test_encode_decode();
#endif // PG_PS_UNIT_TEST
} //namespace TAO

TAO_END_VERSIONED_NAMESPACE_DECL

////////////////////////////////////
// include templated helper function
#include "orbsvcs/PortableGroup/PG_Property_Set_Find.h"

#include /**/ "ace/post.h"

#endif // TAO_PG_PROPERTY_SET

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