gio/gmenumodel.c

   1 /*
   2  * Copyright © 2011 Canonical Ltd.
   3  *
   4  * This library is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU Lesser General Public License as
   6  * published by the Free Software Foundation; either version 2 of the
   7  * licence, or (at your option) any later version.
   8  *
   9  * This library is distributed in the hope that it will be useful, but
  10  * WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  * Lesser General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU Lesser General Public
  15  * License along with this library; if not, write to the Free Software
  16  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
  17  * USA.
  18  *
  19  * Author: Ryan Lortie <desrt@desrt.ca>
  20  */
  21
  22 #include "gmenumodel.h"
  23
  24 /**
  25  * SECTION:gmenumodel
  26  * @title: GMenuModel
  27  * @short_description: An abstract class representing the contents of a menu
  28  * @see_also: #GActionGroup
  29  *
  30  * #GMenuModel represents the contents of a menu -- an ordered list of
  31  * menu items. The items are associated with actions, which can be
  32  * activated through them. Items can be grouped in sections, and may
  33  * have submenus associated with them. Both items and sections usually
  34  * have some representation data, such as labels or icons. The type of
  35  * the associated action (ie whether it is stateful, and what kind of
  36  * state it has) can influence the representation of the item.
  37  *
  38  * The conceptual model of menus in #GMenuModel is hierarchical:
  39  * sections and submenus are again represented by #GMenuModels.
  40  * Menus themselves do not define their own roles. Rather, the role
  41  * of a particular #GMenuModel is defined by the item that references
  42  * it (or, in the case of the 'root' menu, is defined by the context
  43  * in which it is used).
  44  *
  45  * As an example, consider the visible portions of the menu in
  46  * <xref linkend="menu-example"/>.
  47  *
  48  * <figure id="menu-example">
  49  *   <title>An example menu</title>
  50  *   <graphic fileref="menu-example.png" format="PNG"></graphic>
  51  * </figure>
  52  *
  53  * There are 8 "menus" visible in the screenshot: one menubar, two
  54  * submenus and 5 sections:
  55  * <itemizedlist>
  56  * <listitem>the toplevel menubar (containing 4 items)</listitem>
  57  * <listitem>the View submenu (containing 3 sections)</listitem>
  58  * <listitem>the first section of the View submenu (containing 2 items)</listitem>
  59  * <listitem>the second section of the View submenu (containing 1 item)</listitem>
  60  * <listitem>the final section of the View submenu (containing 1 item)</listitem>
  61  * <listitem>the Highlight Mode submenu (containing 2 sections)</listitem>
  62  * <listitem>the Sources section (containing 2 items)</listitem>
  63  * <listitem>the Markup section (containing 2 items)</listitem>
  64  * </itemizedlist>
  65  *
  66  * <xref linkend="menu-model"/> illustrates the conceptual connection between
  67  * these 8 menus. Each large block in the figure represents a menu and the
  68  * smaller blocks within the large block represent items in that menu. Some
  69  * items contain references to other menus.
  70  *
  71  * <figure id="menu-model">
  72  *   <title>A menu model</title>
  73  *   <graphic fileref="menu-model.png" format="PNG"></graphic>
  74  * </figure>
  75  *
  76  * Notice that the separators visible in <xref linkend="menu-example"/>
  77  * appear nowhere in <xref linkend="menu-model"/>. This is because
  78  * separators are not explicitly represented in the menu model. Instead,
  79  * a separator is inserted between any two non-empty sections of a menu.
  80  * Section items can have labels just like any other item. In that case,
  81  * a display system may show a section header instead of a separator.
  82  *
  83  * The motivation for this abstract model of application controls is
  84  * that modern user interfaces tend to make these controls available
  85  * outside the application. Examples include global menus, jumplists,
  86  * dash boards, etc. To support such uses, it is necessary to 'export'
  87  * information about actions and their representation in menus, which
  88  * is exactly what the
  89  * <link linkend="gio-GActionGroup-exporter">GActionGroup exporter</link>
  90  * and the
  91  * <link linkend="gio-GMenuModel-exporter">GMenuModel exporter</link>
  92  * do for #GActionGroup and #GMenuModel. The client-side counterparts
  93  * to make use of the exported information are #GDBusActionGroup and
  94  * #GDBusMenuModel.
  95  *
  96  * The API of #GMenuModel is very generic, with iterators for the
  97  * attributes and links of an item, see g_menu_model_iterate_item_attributes()
  98  * and g_menu_model_iterate_item_links(). The 'standard' attributes and
  99  * link types have predefined names: %G_MENU_ATTRIBUTE_LABEL,
 100  * %G_MENU_ATTRIBUTE_ACTION, %G_MENU_ATTRIBUTE_TARGET, %G_MENU_LINK_SECTION
 101  * and %G_MENU_LINK_SUBMENU.
 102  *
 103  * Items in a #GMenuModel represent active controls if they refer to
 104  * an action that can get activated when the user interacts with the
 105  * menu item. The reference to the action is encoded by the string id
 106  * in the %G_MENU_ATTRIBUTE_ACTION attribute. An action id uniquely
 107  * identifies an action in an action group. Which action group(s) provide
 108  * actions depends on the context in which the menu model is used.
 109  * E.g. when the model is exported as the application menu of a
 110  * #GtkApplication, actions can be application-wide or window-specific
 111  * (and thus come from two different action groups). By convention, the
 112  * application-wide actions have names that start with "app.", while the
 113  * names of window-specific actions start with "win.".
 114  *
 115  * While a wide variety of stateful actions is possible, the following
 116  * is the minimum that is expected to be supported by all users of exported
 117  * menu information:
 118  * <itemizedlist>
 119  * <listitem>an action with no parameter type and no state</listitem>
 120  * <listitem>an action with no parameter type and boolean state</listitem>
 121  * <listitem>an action with string parameter type and string state</listitem>
 122  * </itemizedlist>
 123  *
 124  * <formalpara><title>Stateless</title>
 125  * <para>
 126  * A stateless action typically corresponds to an ordinary menu item.
 127  * </para>
 128  * <para>
 129  * Selecting such a menu item will activate the action (with no parameter).
 130  * </para>
 131  * </formalpara>
 132  *
 133  * <formalpara><title>Boolean State</title>
 134  * <para>
 135  * An action with a boolean state will most typically be used with a "toggle"
 136  * or "switch" menu item. The state can be set directly, but activating the
 137  * action (with no parameter) results in the state being toggled.
 138  * </para>
 139  * <para>
 140  * Selecting a toggle menu item will activate the action. The menu item should
 141  * be rendered as "checked" when the state is true.
 142  * </para>
 143  * </formalpara>
 144  *
 145  * <formalpara><title>String Parameter and State</title>
 146  * <para>
 147  * Actions with string parameters and state will most typically be used to
 148  * represent an enumerated choice over the items available for a group of
 149  * radio menu items. Activating the action with a string parameter is
 150  * equivalent to setting that parameter as the state.
 151  * </para>
 152  * <para>
 153  * Radio menu items, in addition to being associated with the action, will
 154  * have a target value. Selecting that menu item will result in activation
 155  * of the action with the target value as the parameter. The menu item should
 156  * be rendered as "selected" when the state of the action is equal to the
 157  * target value of the menu item.
 158  * </para>
 159  * </formalpara>
 160  */
 161
 162 /**
 163  * GMenuModel:
 164  *
 165  * #GMenuModel is an opaque structure type.  You must access it using the
 166  * functions below.
 167  *
 168  * Since: 2.32
 169  */
 170
 171 /**
 172  * GMenuAttributeIter:
 173  *
 174  * #GMenuAttributeIter is an opaque structure type.  You must access it
 175  * using the functions below.
 176  *
 177  * Since: 2.32
 178  */
 179
 180 /**
 181  * GMenuLinkIter:
 182  *
 183  * #GMenuLinkIter is an opaque structure type.  You must access it using
 184  * the functions below.
 185  *
 186  * Since: 2.32
 187  */
 188
 189 typedef struct
 190 {
 191   GMenuLinkIter parent_instance;
 192   GHashTableIter iter;
 193   GHashTable *table;
 194 } GMenuLinkHashIter;
 195
 196 typedef GMenuLinkIterClass GMenuLinkHashIterClass;
 197
 198 G_DEFINE_TYPE (GMenuLinkHashIter, g_menu_link_hash_iter, G_TYPE_MENU_LINK_ITER)
 199
 200 static gboolean
 201 g_menu_link_hash_iter_get_next (GMenuLinkIter  *link_iter,
 202                                 const gchar   **out_name,
 203                                 GMenuModel    **value)
 204 {
 205   GMenuLinkHashIter *iter = (GMenuLinkHashIter *) link_iter;
 206   gpointer keyptr, valueptr;
 207
 208   if (!g_hash_table_iter_next (&iter->iter, &keyptr, &valueptr))
 209     return FALSE;
 210
 211   *out_name = keyptr;
 212   *value = g_object_ref (valueptr);
 213
 214   return TRUE;
 215 }
 216
 217 static void
 218 g_menu_link_hash_iter_finalize (GObject *object)
 219 {
 220   GMenuLinkHashIter *iter = (GMenuLinkHashIter *) object;
 221
 222   g_hash_table_unref (iter->table);
 223
 224   G_OBJECT_CLASS (g_menu_link_hash_iter_parent_class)
 225     ->finalize (object);
 226 }
 227
 228 static void
 229 g_menu_link_hash_iter_init (GMenuLinkHashIter *iter)
 230 {
 231 }
 232
 233 static void
 234 g_menu_link_hash_iter_class_init (GMenuLinkHashIterClass *class)
 235 {
 236   GObjectClass *object_class = G_OBJECT_CLASS (class);
 237
 238   object_class->finalize = g_menu_link_hash_iter_finalize;
 239   class->get_next = g_menu_link_hash_iter_get_next;
 240 }
 241
 242
 243 typedef struct
 244 {
 245   GMenuAttributeIter parent_instance;
 246   GHashTableIter iter;
 247   GHashTable *table;
 248 } GMenuAttributeHashIter;
 249
 250 typedef GMenuAttributeIterClass GMenuAttributeHashIterClass;
 251
 252 G_DEFINE_TYPE (GMenuAttributeHashIter, g_menu_attribute_hash_iter, G_TYPE_MENU_ATTRIBUTE_ITER)
 253
 254 static gboolean
 255 g_menu_attribute_hash_iter_get_next (GMenuAttributeIter  *attr_iter,
 256                                      const gchar        **name,
 257                                      GVariant           **value)
 258 {
 259   GMenuAttributeHashIter *iter = (GMenuAttributeHashIter *) attr_iter;
 260   gpointer keyptr, valueptr;
 261
 262   if (!g_hash_table_iter_next (&iter->iter, &keyptr, &valueptr))
 263     return FALSE;
 264
 265   *name = keyptr;
 266
 267   *value = g_variant_ref (valueptr);
 268
 269   return TRUE;
 270 }
 271
 272 static void
 273 g_menu_attribute_hash_iter_finalize (GObject *object)
 274 {
 275   GMenuAttributeHashIter *iter = (GMenuAttributeHashIter *) object;
 276
 277   g_hash_table_unref (iter->table);
 278
 279   G_OBJECT_CLASS (g_menu_attribute_hash_iter_parent_class)
 280     ->finalize (object);
 281 }
 282
 283 static void
 284 g_menu_attribute_hash_iter_init (GMenuAttributeHashIter *iter)
 285 {
 286 }
 287
 288 static void
 289 g_menu_attribute_hash_iter_class_init (GMenuAttributeHashIterClass *class)
 290 {
 291   GObjectClass *object_class = G_OBJECT_CLASS (class);
 292
 293   object_class->finalize = g_menu_attribute_hash_iter_finalize;
 294   class->get_next = g_menu_attribute_hash_iter_get_next;
 295 }
 296
 297 G_DEFINE_ABSTRACT_TYPE (GMenuModel, g_menu_model, G_TYPE_OBJECT)
 298
 299
 300 guint g_menu_model_items_changed_signal;
 301
 302 static GMenuAttributeIter *
 303 g_menu_model_real_iterate_item_attributes (GMenuModel *model,
 304                                            gint        item_index)
 305 {
 306   GHashTable *table = NULL;
 307   GMenuAttributeIter *result;
 308
 309   G_MENU_MODEL_GET_CLASS (model)->get_item_attributes (model, item_index, &table);
 310
 311   if (table)
 312     {
 313       GMenuAttributeHashIter *iter = g_object_new (g_menu_attribute_hash_iter_get_type (), NULL);
 314       g_hash_table_iter_init (&iter->iter, table);
 315       iter->table = g_hash_table_ref (table);
 316       result = G_MENU_ATTRIBUTE_ITER (iter);
 317     }
 318   else
 319     {
 320       g_critical ("GMenuModel implementation '%s' doesn't override iterate_item_attributes() "
 321                   "and fails to return sane values from get_item_attributes()",
 322                   G_OBJECT_TYPE_NAME (model));
 323       result = NULL;
 324     }
 325
 326   if (table != NULL)
 327     g_hash_table_unref (table);
 328
 329   return result;
 330 }
 331
 332 static GVariant *
 333 g_menu_model_real_get_item_attribute_value (GMenuModel         *model,
 334                                             gint                item_index,
 335                                             const gchar        *attribute,
 336                                             const GVariantType *expected_type)
 337 {
 338   GHashTable *table = NULL;
 339   GVariant *value = NULL;
 340
 341   G_MENU_MODEL_GET_CLASS (model)
 342     ->get_item_attributes (model, item_index, &table);
 343
 344   if (table != NULL)
 345     {
 346       value = g_hash_table_lookup (table, attribute);
 347
 348       if (value != NULL)
 349         {
 350           if (expected_type == NULL || g_variant_is_of_type (value, expected_type))
 351             value = g_variant_ref (value);
 352           else
 353             value = NULL;
 354         }
 355     }
 356   else
 357     g_assert_not_reached ();
 358
 359   if (table != NULL)
 360     g_hash_table_unref (table);
 361
 362   return value;
 363 }
 364
 365 static GMenuLinkIter *
 366 g_menu_model_real_iterate_item_links (GMenuModel *model,
 367                                       gint        item_index)
 368 {
 369   GHashTable *table = NULL;
 370   GMenuLinkIter *result;
 371
 372   G_MENU_MODEL_GET_CLASS (model)
 373     ->get_item_links (model, item_index, &table);
 374
 375   if (table)
 376     {
 377       GMenuLinkHashIter *iter = g_object_new (g_menu_link_hash_iter_get_type (), NULL);
 378       g_hash_table_iter_init (&iter->iter, table);
 379       iter->table = g_hash_table_ref (table);
 380       result = G_MENU_LINK_ITER (iter);
 381     }
 382   else
 383     {
 384       g_critical ("GMenuModel implementation '%s' doesn't override iterate_item_links() "
 385                   "and fails to return sane values from get_item_links()",
 386                   G_OBJECT_TYPE_NAME (model));
 387       result = NULL;
 388     }
 389
 390   if (table != NULL)
 391     g_hash_table_unref (table);
 392
 393   return result;
 394 }
 395
 396 static GMenuModel *
 397 g_menu_model_real_get_item_link (GMenuModel  *model,
 398                                  gint         item_index,
 399                                  const gchar *link)
 400 {
 401   GHashTable *table = NULL;
 402   GMenuModel *value = NULL;
 403
 404   G_MENU_MODEL_GET_CLASS (model)
 405     ->get_item_links (model, item_index, &table);
 406
 407   if (table != NULL)
 408     value = g_hash_table_lookup (table, link);
 409   else
 410     g_assert_not_reached ();
 411
 412   if (value != NULL)
 413     g_object_ref (value);
 414
 415   if (table != NULL)
 416     g_hash_table_unref (table);
 417
 418   return value;
 419 }
 420
 421 static void
 422 g_menu_model_init (GMenuModel *model)
 423 {
 424 }
 425
 426 static void
 427 g_menu_model_class_init (GMenuModelClass *class)
 428 {
 429   class->iterate_item_attributes = g_menu_model_real_iterate_item_attributes;
 430   class->get_item_attribute_value = g_menu_model_real_get_item_attribute_value;
 431   class->iterate_item_links = g_menu_model_real_iterate_item_links;
 432   class->get_item_link = g_menu_model_real_get_item_link;
 433
 434   /**
 435    * GMenuModel::items-changed:
 436    * @model: the #GMenuModel that is changing
 437    * @position: the position of the change
 438    * @removed: the number of items removed
 439    * @added: the number of items added
 440    *
 441    * Emitted when a change has occured to the menu.
 442    *
 443    * The only changes that can occur to a menu is that items are removed
 444    * or added.  Items may not change (except by being removed and added
 445    * back in the same location).  This signal is capable of describing
 446    * both of those changes (at the same time).
 447    *
 448    * The signal means that starting at the index @position, @removed
 449    * items were removed and @added items were added in their place.  If
 450    * @removed is zero then only items were added.  If @added is zero
 451    * then only items were removed.
 452    *
 453    * As an example, if the menu contains items a, b, c, d (in that
 454    * order) and the signal (2, 1, 3) occurs then the new composition of
 455    * the menu will be a, b, _, _, _, d (with each _ representing some
 456    * new item).
 457    *
 458    * Signal handlers may query the model (particularly the added items)
 459    * and expect to see the results of the modification that is being
 460    * reported.  The signal is emitted after the modification.
 461    **/
 462   g_menu_model_items_changed_signal =
 463     g_signal_new ("items-changed", G_TYPE_MENU_MODEL,
 464                   G_SIGNAL_RUN_LAST, 0, NULL, NULL,
 465                   g_cclosure_marshal_generic, G_TYPE_NONE,
 466                   3, G_TYPE_INT, G_TYPE_INT, G_TYPE_INT);
 467 }
 468
 469 /**
 470  * g_menu_model_is_mutable:
 471  * @model: a #GMenuModel
 472  *
 473  * Queries if @model is mutable.
 474  *
 475  * An immutable #GMenuModel will never emit the #GMenuModel::items-changed
 476  * signal. Consumers of the model may make optimisations accordingly.
 477  *
 478  * Returns: %TRUE if the model is mutable (ie: "items-changed" may be
 479  *     emitted).
 480  *
 481  * Since: 2.32
 482  */
 483 gboolean
 484 g_menu_model_is_mutable (GMenuModel *model)
 485 {
 486   return G_MENU_MODEL_GET_CLASS (model)
 487     ->is_mutable (model);
 488 }
 489
 490 /**
 491  * g_menu_model_get_n_items:
 492  * @model: a #GMenuModel
 493  *
 494  * Query the number of items in @model.
 495  *
 496  * Returns: the number of items
 497  *
 498  * Since: 2.32
 499  */
 500 gint
 501 g_menu_model_get_n_items (GMenuModel *model)
 502 {
 503   return G_MENU_MODEL_GET_CLASS (model)
 504     ->get_n_items (model);
 505 }
 506
 507 /**
 508  * g_menu_model_iterate_item_attributes:
 509  * @model: a #GMenuModel
 510  * @item_index: the index of the item
 511  *
 512  * Creates a #GMenuAttributeIter to iterate over the attributes of
 513  * the item at position @item_index in @model.
 514  *
 515  * You must free the iterator with g_object_unref() when you are done.
 516  *
 517  * Returns: (transfer full): a new #GMenuAttributeIter
 518  *
 519  * Since: 2.32
 520  */
 521 GMenuAttributeIter *
 522 g_menu_model_iterate_item_attributes (GMenuModel *model,
 523                                       gint        item_index)
 524 {
 525   return G_MENU_MODEL_GET_CLASS (model)
 526     ->iterate_item_attributes (model, item_index);
 527 }
 528
 529 /**
 530  * g_menu_model_get_item_attribute_value:
 531  * @model: a #GMenuModel
 532  * @item_index: the index of the item
 533  * @attribute: the attribute to query
 534  * @expected_type: (allow-none): the expected type of the attribute, or
 535  *     %NULL
 536  *
 537  * Queries the item at position @item_index in @model for the attribute
 538  * specified by @attribute.
 539  *
 540  * If @expected_type is non-%NULL then it specifies the expected type of
 541  * the attribute.  If it is %NULL then any type will be accepted.
 542  *
 543  * If the attribute exists and matches @expected_type (or if the
 544  * expected type is unspecified) then the value is returned.
 545  *
 546  * If the attribute does not exist, or does not match the expected type
 547  * then %NULL is returned.
 548  *
 549  * Returns: (transfer full): the value of the attribute
 550  *
 551  * Since: 2.32
 552  */
 553 GVariant *
 554 g_menu_model_get_item_attribute_value (GMenuModel         *model,
 555                                        gint                item_index,
 556                                        const gchar        *attribute,
 557                                        const GVariantType *expected_type)
 558 {
 559   return G_MENU_MODEL_GET_CLASS (model)
 560     ->get_item_attribute_value (model, item_index, attribute, expected_type);
 561 }
 562
 563 /**
 564  * g_menu_model_get_item_attribute:
 565  * @model: a #GMenuModel
 566  * @item_index: the index of the item
 567  * @attribute: the attribute to query
 568  * @format_string: a #GVariant format string
 569  * @...: positional parameters, as per @format_string
 570  *
 571  * Queries item at position @item_index in @model for the attribute
 572  * specified by @attribute.
 573  *
 574  * If the attribute exists and matches the #GVariantType corresponding
 575  * to @format_string then @format_string is used to deconstruct the
 576  * value into the positional parameters and %TRUE is returned.
 577  *
 578  * If the attribute does not exist, or it does exist but has the wrong
 579  * type, then the positional parameters are ignored and %FALSE is
 580  * returned.
 581  *
 582  * Returns: %TRUE if the named attribute was found with the expected
 583  *     type
 584  *
 585  * Since: 2.32
 586  */
 587 gboolean
 588 g_menu_model_get_item_attribute (GMenuModel  *model,
 589                                  gint         item_index,
 590                                  const gchar *attribute,
 591                                  const gchar *format_string,
 592                                  ...)
 593 {
 594   const GVariantType *expected_type;
 595   GVariant *value;
 596   va_list ap;
 597
 598   expected_type = NULL; /* XXX devine the type, ensure no '&' */
 599
 600   value = g_menu_model_get_item_attribute_value (model, item_index, attribute, expected_type);
 601   if (value == NULL)
 602     return FALSE;
 603
 604   va_start (ap, format_string);
 605   g_variant_get_va (value, format_string, NULL, &ap);
 606   g_variant_unref (value);
 607   va_end (ap);
 608
 609   return TRUE;
 610 }
 611
 612 /**
 613  * g_menu_model_iterate_item_links:
 614  * @model: a #GMenuModel
 615  * @item_index: the index of the item
 616  *
 617  * Creates a #GMenuLinkIter to iterate over the links of the item at
 618  * position @item_index in @model.
 619  *
 620  * You must free the iterator with g_object_unref() when you are done.
 621  *
 622  * Returns: (transfer full): a new #GMenuLinkIter
 623  *
 624  * Since: 2.32
 625  */
 626 GMenuLinkIter *
 627 g_menu_model_iterate_item_links (GMenuModel *model,
 628                                  gint        item_index)
 629 {
 630   return G_MENU_MODEL_GET_CLASS (model)
 631     ->iterate_item_links (model, item_index);
 632 }
 633
 634 /**
 635  * g_menu_model_get_item_link:
 636  * @model: a #GMenuModel
 637  * @item_index: the index of the item
 638  * @link: the link to query
 639  *
 640  * Queries the item at position @item_index in @model for the link
 641  * specified by @link.
 642  *
 643  * If the link exists, the linked #GMenuModel is returned.  If the link
 644  * does not exist, %NULL is returned.
 645  *
 646  * Returns: (transfer full): the linked #GMenuModel, or %NULL
 647  *
 648  * Since: 2.32
 649  */
 650 GMenuModel *
 651 g_menu_model_get_item_link (GMenuModel *model,
 652                             gint        item_index,
 653                             const gchar *link)
 654 {
 655   return G_MENU_MODEL_GET_CLASS (model)
 656     ->get_item_link (model, item_index, link);
 657 }
 658
 659 /**
 660  * g_menu_model_items_changed:
 661  * @model: a #GMenuModel
 662  * @position: the position of the change
 663  * @removed: the number of items removed
 664  * @added: the number of items added
 665  *
 666  * Requests emission of the #GMenuModel::items-changed signal on @model.
 667  *
 668  * This function should never be called except by #GMenuModel
 669  * subclasses.  Any other calls to this function will very likely lead
 670  * to a violation of the interface of the model.
 671  *
 672  * The implementation should update its internal representation of the
 673  * menu before emitting the signal.  The implementation should further
 674  * expect to receive queries about the new state of the menu (and
 675  * particularly added menu items) while signal handlers are running.
 676  *
 677  * The implementation must dispatch this call directly from a mainloop
 678  * entry and not in response to calls -- particularly those from the
 679  * #GMenuModel API.  Said another way: the menu must not change while
 680  * user code is running without returning to the mainloop.
 681  *
 682  * Since: 2.32
 683  */
 684 void
 685 g_menu_model_items_changed (GMenuModel *model,
 686                             gint        position,
 687                             gint        removed,
 688                             gint        added)
 689 {
 690   g_signal_emit (model, g_menu_model_items_changed_signal, 0, position, removed, added);
 691 }
 692
 693 G_DEFINE_ABSTRACT_TYPE (GMenuAttributeIter, g_menu_attribute_iter, G_TYPE_OBJECT)
 694
 695 struct _GMenuAttributeIterPrivate
 696 {
 697   GQuark name;
 698   GVariant *value;
 699   gboolean valid;
 700 };
 701
 702 /**
 703  * g_menu_attribute_iter_get_next:
 704  * @iter: a #GMenuAttributeIter
 705  * @out_name: (out) (allow-none) (transfer none): the type of the attribute
 706  * @value: (out) (allow-none) (transfer full): the attribute value
 707  *
 708  * This function combines g_menu_attribute_iter_next() with
 709  * g_menu_attribute_iter_get_name() and g_menu_attribute_iter_get_value().
 710  *
 711  * First the iterator is advanced to the next (possibly first) attribute.
 712  * If that fails, then %FALSE is returned and there are no other
 713  * effects.
 714  *
 715  * If successful, @name and @value are set to the name and value of the
 716  * attribute that has just been advanced to.  At this point,
 717  * g_menu_attribute_iter_get_name() and g_menu_attribute_iter_get_value() will
 718  * return the same values again.
 719  *
 720  * The value returned in @name remains valid for as long as the iterator
 721  * remains at the current position.  The value returned in @value must
 722  * be unreffed using g_variant_unref() when it is no longer in use.
 723  *
 724  * Returns: %TRUE on success, or %FALSE if there is no additional
 725  *     attribute
 726  *
 727  * Since: 2.32
 728  */
 729 gboolean
 730 g_menu_attribute_iter_get_next (GMenuAttributeIter  *iter,
 731                                 const gchar        **out_name,
 732                                 GVariant           **value)
 733 {
 734   const gchar *name;
 735
 736   if (iter->priv->value)
 737     {
 738       g_variant_unref (iter->priv->value);
 739       iter->priv->value = NULL;
 740     }
 741
 742   iter->priv->valid = G_MENU_ATTRIBUTE_ITER_GET_CLASS (iter)
 743     ->get_next (iter, &name, &iter->priv->value);
 744
 745   if (iter->priv->valid)
 746     {
 747       iter->priv->name = g_quark_from_string (name);
 748       if (out_name)
 749         *out_name = g_quark_to_string (iter->priv->name);
 750
 751       if (value)
 752         *value = g_variant_ref (iter->priv->value);
 753     }
 754
 755   return iter->priv->valid;
 756 }
 757
 758 /**
 759  * g_menu_attribute_iter_next:
 760  * @iter: a #GMenuAttributeIter
 761  *
 762  * Attempts to advance the iterator to the next (possibly first)
 763  * attribute.
 764  *
 765  * %TRUE is returned on success, or %FALSE if there are no more
 766  * attributes.
 767  *
 768  * You must call this function when you first acquire the iterator
 769  * to advance it to the first attribute (and determine if the first
 770  * attribute exists at all).
 771  *
 772  * Returns: %TRUE on success, or %FALSE when there are no more attributes
 773  *
 774  * Since: 2.32
 775  */
 776 gboolean
 777 g_menu_attribute_iter_next (GMenuAttributeIter *iter)
 778 {
 779   return g_menu_attribute_iter_get_next (iter, NULL, NULL);
 780 }
 781
 782 /**
 783  * g_menu_attribute_iter_get_name:
 784  * @iter: a #GMenuAttributeIter
 785  *
 786  * Gets the name of the attribute at the current iterator position, as
 787  * a string.
 788  *
 789  * The iterator is not advanced.
 790  *
 791  * Returns: the name of the attribute
 792  *
 793  * Since: 2.32
 794  */
 795 const gchar *
 796 g_menu_attribute_iter_get_name (GMenuAttributeIter *iter)
 797 {
 798   g_return_val_if_fail (iter->priv->valid, 0);
 799
 800   return g_quark_to_string (iter->priv->name);
 801 }
 802
 803 /**
 804  * g_menu_attribute_iter_get_value:
 805  * @iter: a #GMenuAttributeIter
 806  *
 807  * Gets the value of the attribute at the current iterator position.
 808  *
 809  * The iterator is not advanced.
 810  *
 811  * Returns: (transfer full): the value of the current attribute
 812  *
 813  * Since: 2.32
 814  */
 815 GVariant *
 816 g_menu_attribute_iter_get_value (GMenuAttributeIter *iter)
 817 {
 818   g_return_val_if_fail (iter->priv->valid, NULL);
 819
 820   return g_variant_ref (iter->priv->value);
 821 }
 822
 823 static void
 824 g_menu_attribute_iter_finalize (GObject *object)
 825 {
 826   GMenuAttributeIter *iter = G_MENU_ATTRIBUTE_ITER (object);
 827
 828   if (iter->priv->value)
 829     g_variant_unref (iter->priv->value);
 830
 831   G_OBJECT_CLASS (g_menu_attribute_iter_parent_class)
 832     ->finalize (object);
 833 }
 834
 835 static void
 836 g_menu_attribute_iter_init (GMenuAttributeIter *iter)
 837 {
 838   iter->priv = G_TYPE_INSTANCE_GET_PRIVATE (iter, G_TYPE_MENU_ATTRIBUTE_ITER, GMenuAttributeIterPrivate);
 839 }
 840
 841 static void
 842 g_menu_attribute_iter_class_init (GMenuAttributeIterClass *class)
 843 {
 844   GObjectClass *object_class = G_OBJECT_CLASS (class);
 845
 846   object_class->finalize = g_menu_attribute_iter_finalize;
 847
 848   g_type_class_add_private (class, sizeof (GMenuAttributeIterPrivate));
 849 }
 850
 851 G_DEFINE_ABSTRACT_TYPE (GMenuLinkIter, g_menu_link_iter, G_TYPE_OBJECT)
 852
 853 struct _GMenuLinkIterPrivate
 854 {
 855   GQuark name;
 856   GMenuModel *value;
 857   gboolean valid;
 858 };
 859
 860 /**
 861  * g_menu_link_iter_get_next:
 862  * @iter: a #GMenuLinkIter
 863  * @out_link: (out) (allow-none) (transfer none): the name of the link
 864  * @value: (out) (allow-none) (transfer full): the linked #GMenuModel
 865  *
 866  * This function combines g_menu_link_iter_next() with
 867  * g_menu_link_iter_get_name() and g_menu_link_iter_get_value().
 868  *
 869  * First the iterator is advanced to the next (possibly first) link.
 870  * If that fails, then %FALSE is returned and there are no other effects.
 871  *
 872  * If successful, @out_link and @value are set to the name and #GMenuModel
 873  * of the link that has just been advanced to.  At this point,
 874  * g_menu_link_iter_get_name() and g_menu_link_iter_get_value() will return the
 875  * same values again.
 876  *
 877  * The value returned in @out_link remains valid for as long as the iterator
 878  * remains at the current position.  The value returned in @value must
 879  * be unreffed using g_object_unref() when it is no longer in use.
 880  *
 881  * Returns: %TRUE on success, or %FALSE if there is no additional link
 882  *
 883  * Since: 2.32
 884  */
 885 gboolean
 886 g_menu_link_iter_get_next (GMenuLinkIter  *iter,
 887                            const gchar   **out_link,
 888                            GMenuModel    **value)
 889 {
 890   const gchar *name;
 891
 892   if (iter->priv->value)
 893     {
 894       g_object_unref (iter->priv->value);
 895       iter->priv->value = NULL;
 896     }
 897
 898   iter->priv->valid = G_MENU_LINK_ITER_GET_CLASS (iter)
 899     ->get_next (iter, &name, &iter->priv->value);
 900
 901   if (iter->priv->valid)
 902     {
 903       g_assert (name != NULL);
 904
 905       iter->priv->name = g_quark_from_string (name);
 906       if (out_link)
 907         *out_link = g_quark_to_string (iter->priv->name);
 908
 909       if (value)
 910         *value = g_object_ref (iter->priv->value);
 911     }
 912
 913   return iter->priv->valid;
 914 }
 915
 916 /**
 917  * g_menu_link_iter_next:
 918  * @iter: a #GMenuLinkIter
 919  *
 920  * Attempts to advance the iterator to the next (possibly first)
 921  * link.
 922  *
 923  * %TRUE is returned on success, or %FALSE if there are no more links.
 924  *
 925  * You must call this function when you first acquire the iterator to
 926  * advance it to the first link (and determine if the first link exists
 927  * at all).
 928  *
 929  * Returns: %TRUE on success, or %FALSE when there are no more links
 930  *
 931  * Since: 2.32
 932  */
 933 gboolean
 934 g_menu_link_iter_next (GMenuLinkIter *iter)
 935 {
 936   return g_menu_link_iter_get_next (iter, NULL, NULL);
 937 }
 938
 939 /**
 940  * g_menu_link_iter_get_name:
 941  * @iter: a #GMenuLinkIter
 942  *
 943  * Gets the name of the link at the current iterator position.
 944  *
 945  * The iterator is not advanced.
 946  *
 947  * Returns: the type of the link
 948  *
 949  * Since: 2.32
 950  */
 951 const gchar *
 952 g_menu_link_iter_get_name (GMenuLinkIter *iter)
 953 {
 954   g_return_val_if_fail (iter->priv->valid, 0);
 955
 956   return g_quark_to_string (iter->priv->name);
 957 }
 958
 959 /**
 960  * g_menu_link_iter_get_value:
 961  * @iter: a #GMenuLinkIter
 962  *
 963  * Gets the linked #GMenuModel at the current iterator position.
 964  *
 965  * The iterator is not advanced.
 966  *
 967  * Returns: (transfer full): the #GMenuModel that is linked to
 968  *
 969  * Since: 2.32
 970  */
 971 GMenuModel *
 972 g_menu_link_iter_get_value (GMenuLinkIter *iter)
 973 {
 974   g_return_val_if_fail (iter->priv->valid, NULL);
 975
 976   return g_object_ref (iter->priv->value);
 977 }
 978
 979 static void
 980 g_menu_link_iter_finalize (GObject *object)
 981 {
 982   GMenuLinkIter *iter = G_MENU_LINK_ITER (object);
 983
 984   if (iter->priv->value)
 985     g_object_unref (iter->priv->value);
 986
 987   G_OBJECT_CLASS (g_menu_link_iter_parent_class)
 988     ->finalize (object);
 989 }
 990
 991 static void
 992 g_menu_link_iter_init (GMenuLinkIter *iter)
 993 {
 994   iter->priv = G_TYPE_INSTANCE_GET_PRIVATE (iter, G_TYPE_MENU_LINK_ITER, GMenuLinkIterPrivate);
 995 }
 996
 997 static void
 998 g_menu_link_iter_class_init (GMenuLinkIterClass *class)
 999 {
1000   GObjectClass *object_class = G_OBJECT_CLASS (class);
1001
1002   object_class->finalize = g_menu_link_iter_finalize;
1003
1004   g_type_class_add_private (class, sizeof (GMenuLinkIterPrivate));
1005 }