/*
* Copyright 2015 Lars Uebernickel
* Copyright 2015 Ryan Lortie
*
* 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/>.
*
* Authors:
* Lars Uebernickel <lars@uebernic.de>
* Ryan Lortie <desrt@desrt.ca>
*/
#include "config.h"
#include "glistmodel.h"
#include "glibintl.h"
G_DEFINE_INTERFACE (GListModel, g_list_model, G_TYPE_OBJECT)
/**
* SECTION:glistmodel
* @title: GListModel
* @short_description: An interface describing a dynamic list of objects
* @include: gio/gio.h
* @see_also: #GListStore
*
* #GListModel is an interface that represents a mutable list of
* #GObjects. Its main intention is as a model for various widgets in
* user interfaces, such as list views, but it can also be used as a
* convenient method of returning lists of data, with support for
* updates.
*
* Each object in the list may also report changes in itself via some
* mechanism (normally the #GObject::notify signal). Taken together
* with the #GListModel::items-changed signal, this provides for a list
* that can change its membership, and in which the members can change
* their individual properties.
*
* A good example would be the list of visible wireless network access
* points, where each access point can report dynamic properties such as
* signal strength.
*
* It is important to note that the #GListModel itself does not report
* changes to the individual items. It only reports changes to the list
* membership. If you want to observe changes to the objects themselves
* then you need to connect signals to the objects that you are
* interested in.
*
* All items in a #GListModel are of (or derived from) the same type.
* g_list_model_get_item_type() returns that type. The type may be an
* interface, in which case all objects in the list must implement it.
*
* The semantics are close to that of an array:
* g_list_model_get_n_items() returns the number of items in the list and
* g_list_model_get_item() returns an item at a (0-based) position. In
* order to allow implementations to calculate the list length lazily,
* you can also iterate over items: starting from 0, repeatedly call
* g_list_model_get_item() until it returns %NULL.
*
* An implementation may create objects lazily, but must take care to
* return the same object for a given position until all references to
* it are gone.
*
* On the other side, a consumer is expected only to hold references on
* objects that are currently "user visible", in order to faciliate the
* maximum level of laziness in the implementation of the list and to
* reduce the required number of signal connections at a given time.
*
* This interface is intended only to be used from a single thread. The
* thread in which it is appropriate to use it depends on the particular
* implementation, but typically it will be from the thread that owns
* the [thread-default main context][g-main-context-push-thread-default]
* in effect at the time that the model was created.
*/
/**
* GListModelInterface:
* @g_iface: parent #GTypeInterface
* @get_item_type: the virtual function pointer for g_list_model_get_item_type()
* @get_n_items: the virtual function pointer for g_list_model_get_n_items()
* @get_item: the virtual function pointer for g_list_model_get_item()
*
* The virtual function table for #GListModel.
*
* Since: 2.44
*/
/**
* GListModelInterface::get_item:
* @list: a #GListModel
* @position: the position of the item to fetch
*
* Get the item at @position. If @position is greater than the number of
* items in @list, %NULL is returned.
*
* %NULL is never returned for an index that is smaller than the length
* of the list. See g_list_model_get_n_items().
*
* Returns: (type GObject) (transfer full) (nullable): the object at @position.
*
* Since: 2.44
*/
/**
* GListModel:
*
* #GListModel is an opaque data structure and can only be accessed
* using the following functions.
**/
static guint g_list_model_changed_signal;
static void
g_list_model_default_init (GListModelInterface *iface)
{
/**
* GListModel::items-changed:
* @list: the #GListModel that changed
* @position: the position at which @list changed
* @removed: the number of items removed
* @added: the number of items added
*
* This signal is emitted whenever items were added or removed to
* @list. At @position, @removed items were removed and @added items
* were added in their place.
*
* Since: 2.44
*/
g_list_model_changed_signal = g_signal_new (I_("items-changed"),
G_TYPE_LIST_MODEL,
G_SIGNAL_RUN_LAST,
0,
NULL, NULL,
g_cclosure_marshal_generic,
G_TYPE_NONE,
3, G_TYPE_UINT, G_TYPE_UINT, G_TYPE_UINT);
}
/**
* g_list_model_get_item_type:
* @list: a #GListModel
*
* Gets the type of the items in @list. All items returned from
* g_list_model_get_type() are of that type or a subtype, or are an
* implementation of that interface.
*
* The item type of a #GListModel can not change during the life of the
* model.
*
* Returns: the #GType of the items contained in @list.
*
* Since: 2.44
*/
GType
g_list_model_get_item_type (GListModel *list)
{
g_return_val_if_fail (G_IS_LIST_MODEL (list), G_TYPE_NONE);
return G_LIST_MODEL_GET_IFACE (list)->get_item_type (list);
}
/**
* g_list_model_get_n_items:
* @list: a #GListModel
*
* Gets the number of items in @list.
*
* Depending on the model implementation, calling this function may be
* less efficient than iterating the list with increasing values for
* @position until g_list_model_get_item() returns %NULL.
*
* Returns: the number of items in @list.
*
* Since: 2.44
*/
guint
g_list_model_get_n_items (GListModel *list)
{
g_return_val_if_fail (G_IS_LIST_MODEL (list), 0);
return G_LIST_MODEL_GET_IFACE (list)->get_n_items (list);
}
/**
* g_list_model_get_item: (skip)
* @list: a #GListModel
* @position: the position of the item to fetch
*
* Get the item at @position. If @position is greater than the number of
* items in @list, %NULL is returned.
*
* %NULL is never returned for an index that is smaller than the length
* of the list. See g_list_model_get_n_items().
*
* Returns: (transfer full) (nullable): the item at @position.
*
* Since: 2.44
*/
gpointer
g_list_model_get_item (GListModel *list,
guint position)
{
g_return_val_if_fail (G_IS_LIST_MODEL (list), NULL);
return G_LIST_MODEL_GET_IFACE (list)->get_item (list, position);
}
/**
* g_list_model_get_object: (rename-to g_list_model_get_item)
* @list: a #GListModel
* @position: the position of the item to fetch
*
* Get the item at @position. If @position is greater than the number of
* items in @list, %NULL is returned.
*
* %NULL is never returned for an index that is smaller than the length
* of the list. See g_list_model_get_n_items().
*
* Returns: (transfer full) (nullable): the object at @position.
*
* Since: 2.44
*/
GObject *
g_list_model_get_object (GListModel *list,
guint position)
{
gpointer item;
g_return_val_if_fail (G_IS_LIST_MODEL (list), NULL);
item = g_list_model_get_item (list, position);
return G_OBJECT (item);
}
/**
* g_list_model_items_changed:
* @list: a #GListModel
* @position: the position at which @list changed
* @removed: the number of items removed
* @added: the number of items added
*
* Emits the #GListModel::items-changed signal on @list.
*
* This function should only be called by classes implementing
* #GListModel. It has to be called after the internal representation
* of @list has been updated, because handlers connected to this signal
* might query the new state of the list.
*
* Implementations must only make changes to the model (as visible to
* its consumer) in places that will not cause problems for that
* consumer. For models that are driven directly by a write API (such
* as #GListStore), changes can be reported in response to uses of that
* API. For models that represent remote data, changes should only be
* made from a fresh mainloop dispatch. It is particularly not
* permitted to make changes in response to a call to the #GListModel
* consumer API.
*
* Stated another way: in general, it is assumed that code making a
* series of accesses to the model via the API, without returning to the
* mainloop, and without calling other code, will continue to view the
* same contents of the model.
*
* Since: 2.44
*/
void
g_list_model_items_changed (GListModel *list,
guint position,
guint removed,
guint added)
{
g_return_if_fail (G_IS_LIST_MODEL (list));
g_signal_emit (list, g_list_model_changed_signal, 0, position, removed, added);
}