gobject/gclosure.h

   1 /* GObject - GLib Type, Object, Parameter and Signal Library
   2  * Copyright (C) 2000-2001 Red Hat, Inc.
   3  * Copyright (C) 2005 Imendio AB
   4  *
   5  * SPDX-License-Identifier: LGPL-2.1-or-later
   6  *
   7  * This library is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU Lesser General Public
   9  * License as published by the Free Software Foundation; either
  10  * version 2.1 of the License, or (at your option) any later version.
  11  *
  12  * This library is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15  * Lesser General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU Lesser General
  18  * Public License along with this library; if not, see <http://www.gnu.org/licenses/>.
  19  */
  20 #ifndef __G_CLOSURE_H__
  21 #define __G_CLOSURE_H__
  22
  23 #if !defined (__GLIB_GOBJECT_H_INSIDE__) && !defined (GOBJECT_COMPILATION)
  24 #error "Only <glib-object.h> can be included directly."
  25 #endif
  26
  27 #include        <gobject/gtype.h>
  28
  29 G_BEGIN_DECLS
  30
  31 /* --- defines --- */
  32 /**
  33  * G_CLOSURE_NEEDS_MARSHAL:
  34  * @closure: a #GClosure
  35  *
  36  * Check if the closure still needs a marshaller. See g_closure_set_marshal().
  37  *
  38  * Returns: %TRUE if a #GClosureMarshal marshaller has not yet been set on
  39  * @closure.
  40  */
  41 #define G_CLOSURE_NEEDS_MARSHAL(closure) (((GClosure*) (closure))->marshal == NULL)
  42 /**
  43  * G_CLOSURE_N_NOTIFIERS:
  44  * @cl: a #GClosure
  45  *
  46  * Get the total number of notifiers connected with the closure @cl.
  47  *
  48  * The count includes the meta marshaller, the finalize and invalidate notifiers
  49  * and the marshal guards. Note that each guard counts as two notifiers.
  50  * See g_closure_set_meta_marshal(), g_closure_add_finalize_notifier(),
  51  * g_closure_add_invalidate_notifier() and g_closure_add_marshal_guards().
  52  *
  53  * Returns: number of notifiers
  54  */
  55 #define G_CLOSURE_N_NOTIFIERS(cl)        (((cl)->n_guards << 1L) + \
  56                                           (cl)->n_fnotifiers + (cl)->n_inotifiers)
  57 /**
  58  * G_CCLOSURE_SWAP_DATA:
  59  * @cclosure: a #GCClosure
  60  *
  61  * Checks whether the user data of the #GCClosure should be passed as the
  62  * first parameter to the callback. See g_cclosure_new_swap().
  63  *
  64  * Returns: %TRUE if data has to be swapped.
  65  */
  66 #define G_CCLOSURE_SWAP_DATA(cclosure)   (((GClosure*) (cclosure))->derivative_flag)
  67 /**
  68  * G_CALLBACK:
  69  * @f: a function pointer.
  70  *
  71  * Cast a function pointer to a #GCallback.
  72  */
  73 #define G_CALLBACK(f)                    ((GCallback) (f))
  74
  75
  76 /* -- typedefs --- */
  77 typedef struct _GClosure                 GClosure;
  78 typedef struct _GClosureNotifyData       GClosureNotifyData;
  79
  80 /**
  81  * GCallback:
  82  *
  83  * The type used for callback functions in structure definitions and function
  84  * signatures.
  85  *
  86  * This doesn't mean that all callback functions must take no  parameters and
  87  * return void. The required signature of a callback function is determined by
  88  * the context in which is used (e.g. the signal to which it is connected).
  89  *
  90  * Use G_CALLBACK() to cast the callback function to a #GCallback.
  91  */
  92 typedef void  (*GCallback)              (void);
  93 /**
  94  * GClosureNotify:
  95  * @data: data specified when registering the notification callback
  96  * @closure: the #GClosure on which the notification is emitted
  97  *
  98  * The type used for the various notification callbacks which can be registered
  99  * on closures.
 100  */
 101 typedef void  (*GClosureNotify)         (gpointer        data,
 102                                          GClosure       *closure);
 103 /**
 104  * GClosureMarshal:
 105  * @closure: the #GClosure to which the marshaller belongs
 106  * @return_value: (nullable): a #GValue to store the return
 107  *  value. May be %NULL if the callback of @closure doesn't return a
 108  *  value.
 109  * @n_param_values: the length of the @param_values array
 110  * @param_values: (array length=n_param_values): an array of
 111  *  #GValues holding the arguments on which to invoke the
 112  *  callback of @closure
 113  * @invocation_hint: (nullable): the invocation hint given as the
 114  *  last argument to g_closure_invoke()
 115  * @marshal_data: (nullable): additional data specified when
 116  *  registering the marshaller, see g_closure_set_marshal() and
 117  *  g_closure_set_meta_marshal()
 118  *
 119  * The type used for marshaller functions.
 120  */
 121 typedef void  (*GClosureMarshal)        (GClosure       *closure,
 122                                          GValue         *return_value,
 123                                          guint           n_param_values,
 124                                          const GValue   *param_values,
 125                                          gpointer        invocation_hint,
 126                                          gpointer        marshal_data);
 127
 128 /**
 129  * GVaClosureMarshal:
 130  * @closure: the #GClosure to which the marshaller belongs
 131  * @return_value: (nullable): a #GValue to store the return
 132  *  value. May be %NULL if the callback of @closure doesn't return a
 133  *  value.
 134  * @instance: (type GObject.TypeInstance): the instance on which the closure is
 135  *  invoked.
 136  * @args: va_list of arguments to be passed to the closure.
 137  * @marshal_data: (nullable): additional data specified when
 138  *  registering the marshaller, see g_closure_set_marshal() and
 139  *  g_closure_set_meta_marshal()
 140  * @n_params: the length of the @param_types array
 141  * @param_types: (array length=n_params): the #GType of each argument from
 142  *  @args.
 143  *
 144  * This is the signature of va_list marshaller functions, an optional
 145  * marshaller that can be used in some situations to avoid
 146  * marshalling the signal argument into GValues.
 147  */
 148 typedef void (* GVaClosureMarshal) (GClosure *closure,
 149                                     GValue   *return_value,
 150                                     gpointer  instance,
 151                                     va_list   args,
 152                                     gpointer  marshal_data,
 153                                     int       n_params,
 154                                     GType    *param_types);
 155
 156 /**
 157  * GCClosure:
 158  * @closure: the #GClosure
 159  * @callback: the callback function
 160  *
 161  * A #GCClosure is a specialization of #GClosure for C function callbacks.
 162  */
 163 typedef struct _GCClosure                GCClosure;
 164
 165
 166 /* --- structures --- */
 167 struct _GClosureNotifyData
 168 {
 169   gpointer       data;
 170   GClosureNotify notify;
 171 };
 172 /**
 173  * GClosure:
 174  * @in_marshal: Indicates whether the closure is currently being invoked with
 175  *  g_closure_invoke()
 176  * @is_invalid: Indicates whether the closure has been invalidated by
 177  *  g_closure_invalidate()
 178  *
 179  * A #GClosure represents a callback supplied by the programmer.
 180  */
 181 struct _GClosure
 182 {
 183   /*< private >*/
 184   guint ref_count : 15;  /* (atomic) */
 185   /* meta_marshal is not used anymore but must be zero for historical reasons
 186      as it was exposed in the G_CLOSURE_N_NOTIFIERS macro */
 187   guint meta_marshal_nouse : 1;  /* (atomic) */
 188   guint n_guards : 1;  /* (atomic) */
 189   guint n_fnotifiers : 2;  /* finalization notifiers (atomic) */
 190   guint n_inotifiers : 8;  /* invalidation notifiers (atomic) */
 191   guint in_inotify : 1;  /* (atomic) */
 192   guint floating : 1;  /* (atomic) */
 193   /*< protected >*/
 194   guint derivative_flag : 1;  /* (atomic) */
 195   /*< public >*/
 196   guint in_marshal : 1;  /* (atomic) */
 197   guint is_invalid : 1;  /* (atomic) */
 198
 199   /*< private >*/       void   (*marshal)  (GClosure       *closure,
 200                                             GValue /*out*/ *return_value,
 201                                             guint           n_param_values,
 202                                             const GValue   *param_values,
 203                                             gpointer        invocation_hint,
 204                                             gpointer        marshal_data);
 205   /*< protected >*/     gpointer data;
 206
 207   /*< private >*/       GClosureNotifyData *notifiers;
 208
 209   /* invariants/constraints:
 210    * - ->marshal and ->data are _invalid_ as soon as ->is_invalid==TRUE
 211    * - invocation of all inotifiers occurs prior to fnotifiers
 212    * - order of inotifiers is random
 213    *   inotifiers may _not_ free/invalidate parameter values (e.g. ->data)
 214    * - order of fnotifiers is random
 215    * - each notifier may only be removed before or during its invocation
 216    * - reference counting may only happen prior to fnotify invocation
 217    *   (in that sense, fnotifiers are really finalization handlers)
 218    */
 219 };
 220 /* closure for C function calls, callback() is the user function
 221  */
 222 struct _GCClosure
 223 {
 224   GClosure      closure;
 225   gpointer      callback;
 226 };
 227
 228
 229 /* --- prototypes --- */
 230 GOBJECT_AVAILABLE_IN_ALL
 231 GClosure* g_cclosure_new                        (GCallback      callback_func,
 232                                                  gpointer       user_data,
 233                                                  GClosureNotify destroy_data);
 234 GOBJECT_AVAILABLE_IN_ALL
 235 GClosure* g_cclosure_new_swap                   (GCallback      callback_func,
 236                                                  gpointer       user_data,
 237                                                  GClosureNotify destroy_data);
 238 GOBJECT_AVAILABLE_IN_ALL
 239 GClosure* g_signal_type_cclosure_new            (GType          itype,
 240                                                  guint          struct_offset);
 241
 242
 243 /* --- prototypes --- */
 244 GOBJECT_AVAILABLE_IN_ALL
 245 GClosure* g_closure_ref                         (GClosure       *closure);
 246 GOBJECT_AVAILABLE_IN_ALL
 247 void      g_closure_sink                        (GClosure       *closure);
 248 GOBJECT_AVAILABLE_IN_ALL
 249 void      g_closure_unref                       (GClosure       *closure);
 250 /* intimidating */
 251 GOBJECT_AVAILABLE_IN_ALL
 252 GClosure* g_closure_new_simple                  (guint           sizeof_closure,
 253                                                  gpointer        data);
 254 GOBJECT_AVAILABLE_IN_ALL
 255 void      g_closure_add_finalize_notifier       (GClosure       *closure,
 256                                                  gpointer        notify_data,
 257                                                  GClosureNotify  notify_func);
 258 GOBJECT_AVAILABLE_IN_ALL
 259 void      g_closure_remove_finalize_notifier    (GClosure       *closure,
 260                                                  gpointer        notify_data,
 261                                                  GClosureNotify  notify_func);
 262 GOBJECT_AVAILABLE_IN_ALL
 263 void      g_closure_add_invalidate_notifier     (GClosure       *closure,
 264                                                  gpointer        notify_data,
 265                                                  GClosureNotify  notify_func);
 266 GOBJECT_AVAILABLE_IN_ALL
 267 void      g_closure_remove_invalidate_notifier  (GClosure       *closure,
 268                                                  gpointer        notify_data,
 269                                                  GClosureNotify  notify_func);
 270 GOBJECT_AVAILABLE_IN_ALL
 271 void      g_closure_add_marshal_guards          (GClosure       *closure,
 272                                                  gpointer        pre_marshal_data,
 273                                                  GClosureNotify  pre_marshal_notify,
 274                                                  gpointer        post_marshal_data,
 275                                                  GClosureNotify  post_marshal_notify);
 276 GOBJECT_AVAILABLE_IN_ALL
 277 void      g_closure_set_marshal                 (GClosure       *closure,
 278                                                  GClosureMarshal marshal);
 279 GOBJECT_AVAILABLE_IN_ALL
 280 void      g_closure_set_meta_marshal            (GClosure       *closure,
 281                                                  gpointer        marshal_data,
 282                                                  GClosureMarshal meta_marshal);
 283 GOBJECT_AVAILABLE_IN_ALL
 284 void      g_closure_invalidate                  (GClosure       *closure);
 285 GOBJECT_AVAILABLE_IN_ALL
 286 void      g_closure_invoke                      (GClosure       *closure,
 287                                                  GValue /*out*/ *return_value,
 288                                                  guint           n_param_values,
 289                                                  const GValue   *param_values,
 290                                                  gpointer        invocation_hint);
 291
 292 /* FIXME:
 293    OK:  data_object::destroy            -> closure_invalidate();
 294    MIS: closure_invalidate()            -> disconnect(closure);
 295    MIS: disconnect(closure)             -> (unlink) closure_unref();
 296    OK:  closure_finalize()              -> g_free (data_string);
 297
 298    random remarks:
 299    - need marshaller repo with decent aliasing to base types
 300    - provide marshaller collection, virtually covering anything out there
 301 */
 302
 303 GOBJECT_AVAILABLE_IN_ALL
 304 void g_cclosure_marshal_generic (GClosure     *closure,
 305                                  GValue       *return_gvalue,
 306                                  guint         n_param_values,
 307                                  const GValue *param_values,
 308                                  gpointer      invocation_hint,
 309                                  gpointer      marshal_data);
 310
 311 GOBJECT_AVAILABLE_IN_ALL
 312 void g_cclosure_marshal_generic_va (GClosure *closure,
 313                                     GValue   *return_value,
 314                                     gpointer  instance,
 315                                     va_list   args_list,
 316                                     gpointer  marshal_data,
 317                                     int       n_params,
 318                                     GType    *param_types);
 319
 320
 321 G_END_DECLS
 322
 323 #endif /* __G_CLOSURE_H__ */