glib/glibmm/objectbase.h

#ifndef _GLIBMM_OBJECTBASE_H
#define _GLIBMM_OBJECTBASE_H

/* Copyright 2002 The gtkmm Development Team
 *
 * This library 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 2.1 of the License, or (at your option) any later version.
 *
 * This library 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 this library.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <glibmmconfig.h>
#include <glibmm/class.h>
#include <glibmm/signalproxy.h>
#include <glibmm/propertyproxy.h>
#include <glibmm/ustring.h>
#include <glibmm/value.h>
#include <glibmm/quark.h>
#include <glibmm/debug.h>
#include <sigc++/trackable.h>
#include <typeinfo>
#include <map> // Needed until the next ABI break.
#include <memory> // Not used by ObjectBase any more, but user code may rely on it being here.
#include <mutex>

#ifndef DOXYGEN_SHOULD_SKIP_THIS
extern "C" {
using GObject = struct _GObject;
}
#endif

namespace Glib
{

#ifndef DOXYGEN_SHOULD_SKIP_THIS
class GLIBMM_API GSigConnectionNode;
class GLIBMM_API Interface_Class;
#endif

// This inherits virtually from sigc::trackable so that people can multiply inherit glibmm classes
// from other sigc::trackable-derived classes.
// See bugzilla.gnome.org bug # 116280
/** Glib::ObjectBase is a common base class for Objects and Interfaces.
 *
 * This is used as virtual base class.  This means the ObjectBase
 * constructor runs before all others, either implicitly or explicitly.  Each of
 * the available constructors initializes custom_type_name_ in a different way.
 */
class GLIBMM_API ObjectBase : virtual public sigc::trackable
{
public:
  // noncopyable
  ObjectBase(const ObjectBase&) = delete;
  ObjectBase& operator=(const ObjectBase&) = delete;

protected:
  /** This default constructor is called implicitly from the constructor of user-derived
   * classes, even if, for instance, Gtk::Button calls a different ObjectBase constructor.
   * This is normal behaviour for C++ virtual inheritance.
   *
   * The GType name will be gtkmm__anonymous_custom_type.
   */
  ObjectBase();

  /** A derived constructor always overrides this choice.
   * The C++ language itself ensures that the constructor
   * is only invoked once.
   *
   * All classes generated by gtkmmproc use this constructor, with custom_type_name = nullptr,
   * which essentially means it's not a custom type.  This is used to optimize
   * vfunc and signal handler callbacks -- since the C++ virtual methods are
   * not overridden, invocation can be skipped.
   *
   * The GType name will be @a custom_type_name.
   */
  explicit ObjectBase(const char* custom_type_name);

  /** This constructor is a special feature to allow creation of derived types on the
   * fly, without having to use g_object_new() manually.  This feature is
   * sometimes necessary, e.g. to implement a custom Gtk::CellRenderer.  The
   * neat trick with the virtual base class ctor makes it possible to reuse
   * the same direct base class' constructor as with non-custom types.
   *
   * The GType name will be @a custom_type_info.name().
   */
  explicit ObjectBase(const std::type_info& custom_type_info);

  ObjectBase(ObjectBase&& src) noexcept;
  ObjectBase& operator=(ObjectBase&& src) noexcept;

  virtual ~ObjectBase() noexcept = 0;

  // Called by Glib::Object and Glib::Interface constructors. See comments there.
  void initialize(GObject* castitem);

  // Called by Glib::Object and Glib::Interface C++ move operations.
  void initialize_move(GObject* castitem, Glib::ObjectBase* previous_wrapper);

public:
  /// You probably want to use a specific property_*() accessor method instead.
  void set_property_value(const Glib::ustring& property_name, const Glib::ValueBase& value);

  /// You probably want to use a specific property_*() accessor method instead.
  void get_property_value(const Glib::ustring& property_name, Glib::ValueBase& value) const;

  /// You probably want to use a specific property_*() accessor method instead.
  template <class PropertyType>
  void set_property(const Glib::ustring& property_name, const PropertyType& value);

  /// You probably want to use a specific property_*() accessor method instead.
  template <class PropertyType>
  void get_property(const Glib::ustring& property_name, PropertyType& value) const;

  // TODO: At the next ABI break, delete connect_property_changed_with_return()
  // and let connect_property_changed() return sigc::connection.
  /** You can use the signal_changed() signal of the property proxy instead.
   *
   * See also connect_property_changed_with_return().
   */
  void connect_property_changed(const Glib::ustring& property_name, const sigc::slot<void>& slot);

  /** You can use the signal_changed() signal of the property proxy instead.
   *
   * @newin{2,48}
   */
  void connect_property_changed(const Glib::ustring& property_name, sigc::slot<void>&& slot);

  /** You can use the signal_changed() signal of the property proxy instead.
   *
   * This method was added because connect_property_changed() does not return a sigc::connection,
   * and we could not break the ABI by changing that function.
   */
  sigc::connection connect_property_changed_with_return(
    const Glib::ustring& property_name, const sigc::slot<void>& slot);

  /** You can use the signal_changed() signal of the property proxy instead.
   *
   * @newin{2,48}
   */
  sigc::connection connect_property_changed_with_return(
    const Glib::ustring& property_name, sigc::slot<void>&& slot);

  /** Increases the freeze count on object. If the freeze count is non-zero, the
   * emission of "notify" signals on object is stopped. The signals are queued
   * until the freeze count is decreased to zero.
   *
   * This is necessary for accessors that modify multiple properties to prevent
   * premature notification while the object is still being modified.
   */
  void freeze_notify();

  /**
   * Reverts the effect of a previous call to freeze_notify(). The freeze count
   * is decreased on object and when it reaches zero, all queued "notify"
   * signals are emitted.
   *
   * It is an error to call this function when the freeze count is zero.
   */
  void thaw_notify();

  // Why are these virtual?
  // Don't know why they were originally made virtual, but it came in handy when
  // I wrapped GBinding in Glib::Binding. /Kjell
  /** Increment the reference count for this object.
   * You should never need to do this manually - use the object via a RefPtr instead.
   */
  virtual void reference() const;

  /** Decrement the reference count for this object.
   * You should never need to do this manually - use the object via a RefPtr instead.
   */
  virtual void unreference() const;

  /// Provides access to the underlying C GObject.
  inline GObject* gobj() { return gobject_; }

  /// Provides access to the underlying C GObject.
  inline const GObject* gobj() const { return gobject_; }

  /// Give a ref-ed copy to someone. Use for direct struct access.
  GObject* gobj_copy() const;

#ifndef DOXYGEN_SHOULD_SKIP_THIS

  /// This is for use by gtkmm wrappers only, and not by applications.
  static ObjectBase* _get_current_wrapper(
    GObject* object); // We keep this non-inline version, to preserve ABI.

  // This is commented-out because it's not clear yet whether it's a worthwhile optimization.
  /// This is for use by gtkmm wrappers only, and not by applications.
  //
  // inline static ObjectBase* _get_current_wrapper_inline(GObject* object)
  //{
  //  // This is what g_object_get_qdata does internally. However,
  //  // g_object_get_qdata does an addition G_IS_OBJECT(object) check that
  //  // needs three times as much time as the actual lookup.
  //  if(object)
  //    return static_cast<ObjectBase*>(g_datalist_id_get_data(&object->qdata, Glib::quark_));
  //  else
  //    return 0;
  //}

  bool _cpp_destruction_is_in_progress() const;
#endif // DOXYGEN_SHOULD_SKIP_THIS

protected:
#ifndef DOXYGEN_SHOULD_SKIP_THIS
  GObject* gobject_; // the GLib/GDK/GTK+ object instance
  const char* custom_type_name_;
  bool cpp_destruction_in_progress_;

  bool is_anonymous_custom_() const;

  // The following 7 methods are used by Glib::ExtraClassInit, Glib::Interface
  // and Glib::Object during construction of a named custom type.
  void add_custom_interface_class(const Interface_Class* iface_class);
  void add_custom_class_init_function(GClassInitFunc class_init_func, void* class_data = nullptr);
  void set_custom_instance_init_function(GInstanceInitFunc instance_init_func);
  const Class::interface_class_vector_type* get_custom_interface_classes() const;
  const Class::class_init_funcs_type* get_custom_class_init_functions() const;
  GInstanceInitFunc get_custom_instance_init_function() const;
  void custom_class_init_finished();

public:
  //  is_derived_() must be public, so that overridden vfuncs and signal handlers can call it
  //  via ObjectBase.
  /// This is for use by gtkmm wrappers only, and not by applications.
  bool is_derived_() const; // We keep this non-inline version, to preserve ABI.

  // This is commented-out because it's not clear yet whether it's a worthwhile optimization.
  //
  /// This is for use by gtkmm wrappers only, and not by applications.
  // inline bool is_derived_inline_() const
  //{
  //  return (custom_type_name_ != nullptr);
  //}

protected:
  static void destroy_notify_callback_(void* data);
  virtual void destroy_notify_();

  void _set_current_wrapper(GObject* object);

  /// For (indirect) use by C++ move operations.
  void _move_current_wrapper(GObject* object, Glib::ObjectBase* previous_wrapper) noexcept;
#endif // DOXYGEN_SHOULD_SKIP_THIS

private:
#ifndef DOXYGEN_SHOULD_SKIP_THIS
  virtual void set_manage(); // calls g_error()

  // TODO: At the next ABI break, replace extra_object_base_data by a non-static
  // data member.
  // Private part of implementation.
  // Used only during construction of named custom types.
  // This is a new data member that can't be added as instance data to
  // ObjectBase now, because it would break ABI.
  struct ExtraObjectBaseData
  {
    // Pointers to the interfaces of custom types.
    Class::interface_class_vector_type custom_interface_classes;
    // Pointers to extra class init functions.
    Class::class_init_funcs_type custom_class_init_functions;
    // Pointer to the instance init function.
    GInstanceInitFunc custom_instance_init_function = nullptr;
  };

  using extra_object_base_data_type = std::map<const ObjectBase*, ExtraObjectBaseData>;
  static extra_object_base_data_type extra_object_base_data;
  // ObjectBase instances may be used in different threads.
  // Accesses to extra_object_base_data must be thread-safe.
  static std::mutex extra_object_base_data_mutex;
#endif // DOXYGEN_SHOULD_SKIP_THIS

#ifndef DOXYGEN_SHOULD_SKIP_THIS
  friend class Glib::GSigConnectionNode; // for GSigConnectionNode::notify()
#endif
};

#ifndef DOXYGEN_SHOULD_SKIP_THIS

template <class PropertyType>
inline void
ObjectBase::set_property(const Glib::ustring& property_name, const PropertyType& value)
{
  Glib::Value<PropertyType> property_value;
  property_value.init(Glib::Value<PropertyType>::value_type());

  property_value.set(value);
  this->set_property_value(property_name, property_value);
}

template <class PropertyType>
inline void
ObjectBase::get_property(const Glib::ustring& property_name, PropertyType& value) const
{
  Glib::Value<PropertyType> property_value;
  property_value.init(Glib::Value<PropertyType>::value_type());

  this->get_property_value(property_name, property_value);

  value = property_value.get();
}

#endif /* DOXYGEN_SHOULD_SKIP_THIS */

GLIBMM_API
bool _gobject_cppinstance_already_deleted(GObject* gobject);

} // namespace Glib

#endif /* _GLIBMM_OBJECTBASE_H */