/* GObject - GLib Type, Object, Parameter and Signal Library

  * Copyright (C) 2000-2001 Red Hat, Inc.

  * Copyright (C) 2005 Imendio AB

  * Portions copyright (c) 2006-2009 Nokia Corporation.  All rights reserved.

  *

  * 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 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, write to the

  * Free Software Foundation, Inc., 59 Temple Place, Suite 330,

  * Boston, MA 02111-1307, USA.

  */

 /*

  * MT safe with regards to reference counting.

  */

 #include "config.h"

 #include <string.h>

 #include "gclosure.h"

 #include "gvalue.h"

 #include "gobjectalias.h"

 /**

  * SECTION:gclosure

  * @short_description: Functions as first-class objects

  * @title: Closures

  *

  * A #GClosure represents a callback supplied by the programmer. It

  * will generally comprise a function of some kind and a marshaller

  * used to call it. It is the reponsibility of the marshaller to

  * convert the arguments for the invocation from #GValue<!-- -->s into

  * a suitable form, perform the callback on the converted arguments,

  * and transform the return value back into a #GValue.

  *

  * In the case of C programs, a closure usually just holds a pointer

  * to a function and maybe a data argument, and the marshaller

  * converts between #GValue<!-- --> and native C types. The GObject

  * library provides the #GCClosure type for this purpose. Bindings for

  * other languages need marshallers which convert between #GValue<!--

  * -->s and suitable representations in the runtime of the language in

  * order to use functions written in that languages as callbacks.

  *

  * Within GObject, closures play an important role in the

  * implementation of signals. When a signal is registered, the

  * @c_marshaller argument to g_signal_new() specifies the default C

  * marshaller for any closure which is connected to this

  * signal. GObject provides a number of C marshallers for this

  * purpose, see the g_cclosure_marshal_*() functions. Additional C

  * marshallers can be generated with the <link

  * linkend="glib-genmarshal">glib-genmarshal</link> utility.  Closures

  * can be explicitly connected to signals with

  * g_signal_connect_closure(), but it usually more convenient to let

  * GObject create a closure automatically by using one of the

  * g_signal_connect_*() functions which take a callback function/user

  * data pair.

  *

  * Using closures has a number of important advantages over a simple

  * callback function/data pointer combination:

  * <itemizedlist>

  * <listitem><para>

  * Closures allow the callee to get the types of the callback parameters,

  * which means that language bindings don't have to write individual glue

  * for each callback type.

  * </para></listitem>

  * <listitem><para>

  * The reference counting of #GClosure makes it easy to handle reentrancy

  * right; if a callback is removed while it is being invoked, the closure

  * and its parameters won't be freed until the invocation finishes.

  * </para></listitem>

  * <listitem><para>

  * g_closure_invalidate() and invalidation notifiers allow callbacks to be

  * automatically removed when the objects they point to go away.

  * </para></listitem>

  * </itemizedlist>

  */

 #define	CLOSURE_MAX_REF_COUNT		((1 << 15) - 1)

 #define	CLOSURE_MAX_N_GUARDS		((1 << 1) - 1)

 #define	CLOSURE_MAX_N_FNOTIFIERS	((1 << 2) - 1)

 #define	CLOSURE_MAX_N_INOTIFIERS	((1 << 8) - 1)

 #define	CLOSURE_N_MFUNCS(cl)		((cl)->meta_marshal + \

                                          ((cl)->n_guards << 1L))

 /* same as G_CLOSURE_N_NOTIFIERS() (keep in sync) */

 #define	CLOSURE_N_NOTIFIERS(cl)		(CLOSURE_N_MFUNCS (cl) + \

                                          (cl)->n_fnotifiers + \

                                          (cl)->n_inotifiers)

 typedef union {

   GClosure closure;

   volatile gint vint;

 } ClosureInt;

 #define CHANGE_FIELD(_closure, _field, _OP, _value, _must_set, _SET_OLD, _SET_NEW)      \

 G_STMT_START {                                                                          \

   ClosureInt *cunion = (ClosureInt*) _closure;                 		                \

   gint new_int, old_int, success;                              		                \

   do                                                    		                \

     {                                                   		                \

       ClosureInt tmp;                                   		                \

       tmp.vint = old_int = cunion->vint;                		                \

       _SET_OLD tmp.closure._field;                                                      \

       tmp.closure._field _OP _value;                      		                \

       _SET_NEW tmp.closure._field;                                                      \

       new_int = tmp.vint;                               		                \

       success = g_atomic_int_compare_and_exchange (&cunion->vint, old_int, new_int);    \

     }                                                   		                \

   while (!success && _must_set);                                                        \

 } G_STMT_END

 #define SWAP(_closure, _field, _value, _oldv)   CHANGE_FIELD (_closure, _field, =, _value, TRUE, *(_oldv) =,     (void) )

 #define SET(_closure, _field, _value)           CHANGE_FIELD (_closure, _field, =, _value, TRUE,     (void),     (void) )

 #define INC(_closure, _field)                   CHANGE_FIELD (_closure, _field, +=,     1, TRUE,     (void),     (void) )

 #define INC_ASSIGN(_closure, _field, _newv)     CHANGE_FIELD (_closure, _field, +=,     1, TRUE,     (void), *(_newv) = )

 #define DEC(_closure, _field)                   CHANGE_FIELD (_closure, _field, -=,     1, TRUE,     (void),     (void) )

 #define DEC_ASSIGN(_closure, _field, _newv)     CHANGE_FIELD (_closure, _field, -=,     1, TRUE,     (void), *(_newv) = )

 #if 0   /* for non-thread-safe closures */

 #define SWAP(cl,f,v,o)     (void) (*(o) = cl->f, cl->f = v)

 #define SET(cl,f,v)        (void) (cl->f = v)

 #define INC(cl,f)          (void) (cl->f += 1)

 #define INC_ASSIGN(cl,f,n) (void) (cl->f += 1, *(n) = cl->f)

 #define DEC(cl,f)          (void) (cl->f -= 1)

 #define DEC_ASSIGN(cl,f,n) (void) (cl->f -= 1, *(n) = cl->f)

 #endif

 enum {

   FNOTIFY,

   INOTIFY,

   PRE_NOTIFY,

   POST_NOTIFY

 };

 /* --- functions --- */

 /**

  * g_closure_new_simple:

  * @sizeof_closure: the size of the structure to allocate, must be at least

  *                  <literal>sizeof (GClosure)</literal>

  * @data: data to store in the @data field of the newly allocated #GClosure

  *

  * Allocates a struct of the given size and initializes the initial

  * part as a #GClosure. This function is mainly useful when

  * implementing new types of closures.

  *

  * |[

  * typedef struct _MyClosure MyClosure;

  * struct _MyClosure

  * {

  *   GClosure closure;

  *   // extra data goes here

  * };

  *

  * static void

  * my_closure_finalize (gpointer  notify_data,

  *                      GClosure *closure)

  * {

  *   MyClosure *my_closure = (MyClosure *)closure;

  *

  *   // free extra data here

  * }

  *

  * MyClosure *my_closure_new (gpointer data)

  * {

  *   GClosure *closure;

  *   MyClosure *my_closure;

  *

  *   closure = g_closure_new_simple (sizeof (MyClosure), data);

  *   my_closure = (MyClosure *) closure;

  *

  *   // initialize extra data here

  *

  *   g_closure_add_finalize_notifier (closure, notify_data,

  *                                    my_closure_finalize);

  *   return my_closure;

  * }

  * ]|

  *

  * Returns: a newly allocated #GClosure

  */

 EXPORT_C GClosure*

 g_closure_new_simple (guint           sizeof_closure,

 		      gpointer        data)

 {

   GClosure *closure;

   g_return_val_if_fail (sizeof_closure >= sizeof (GClosure), NULL);

   closure = g_malloc0 (sizeof_closure);

   SET (closure, ref_count, 1);

   SET (closure, meta_marshal, 0);

   SET (closure, n_guards, 0);

   SET (closure, n_fnotifiers, 0);

   SET (closure, n_inotifiers, 0);

   SET (closure, in_inotify, FALSE);

   SET (closure, floating, TRUE);

   SET (closure, derivative_flag, 0);

   SET (closure, in_marshal, FALSE);

   SET (closure, is_invalid, FALSE);

   closure->marshal = NULL;

   closure->data = data;

   closure->notifiers = NULL;

   memset (G_STRUCT_MEMBER_P (closure, sizeof (*closure)), 0, sizeof_closure - sizeof (*closure));

   return closure;

 }

 static inline void

 closure_invoke_notifiers (GClosure *closure,

 			  guint     notify_type)

 {

   /* notifier layout:

    *     meta_marshal  n_guards    n_guards     n_fnotif.  n_inotifiers

    * ->[[meta_marshal][pre_guards][post_guards][fnotifiers][inotifiers]]

    *

    * CLOSURE_N_MFUNCS(cl)    = meta_marshal + n_guards + n_guards;

    * CLOSURE_N_NOTIFIERS(cl) = CLOSURE_N_MFUNCS(cl) + n_fnotifiers + n_inotifiers

    *

    * constrains/catches:

    * - closure->notifiers may be reloacted during callback

    * - closure->n_fnotifiers and closure->n_inotifiers may change during callback

    * - i.e. callbacks can be removed/added during invocation

    * - must prepare for callback removal during FNOTIFY and INOTIFY (done via ->marshal= & ->data=)

    * - must distinguish (->marshal= & ->data=) for INOTIFY vs. FNOTIFY (via ->in_inotify)

    * + closure->n_guards is const during PRE_NOTIFY & POST_NOTIFY

    * + closure->meta_marshal is const for all cases

    * + none of the callbacks can cause recursion

    * + closure->n_inotifiers is const 0 during FNOTIFY

    */

   switch (notify_type)

     {

       GClosureNotifyData *ndata;

       guint i, offs;

     case FNOTIFY:

       while (closure->n_fnotifiers)

 	{

           guint n;

 	  DEC_ASSIGN (closure, n_fnotifiers, &n);

 	  ndata = closure->notifiers + CLOSURE_N_MFUNCS (closure) + n;

 	  closure->marshal = (GClosureMarshal) ndata->notify;

 	  closure->data = ndata->data;

 	  ndata->notify (ndata->data, closure);

 	}

       closure->marshal = NULL;

       closure->data = NULL;

       break;

     case INOTIFY:

       SET (closure, in_inotify, TRUE);

       while (closure->n_inotifiers)

 	{

           guint n;

           DEC_ASSIGN (closure, n_inotifiers, &n);

 	  ndata = closure->notifiers + CLOSURE_N_MFUNCS (closure) + closure->n_fnotifiers + n;

 	  closure->marshal = (GClosureMarshal) ndata->notify;

 	  closure->data = ndata->data;

 	  ndata->notify (ndata->data, closure);

 	}

       closure->marshal = NULL;

       closure->data = NULL;

       SET (closure, in_inotify, FALSE);

       break;

     case PRE_NOTIFY:

       i = closure->n_guards;

       offs = closure->meta_marshal;

       while (i--)

 	{

 	  ndata = closure->notifiers + offs + i;

 	  ndata->notify (ndata->data, closure);

 	}

       break;

     case POST_NOTIFY:

       i = closure->n_guards;

       offs = closure->meta_marshal + i;

       while (i--)

 	{

 	  ndata = closure->notifiers + offs + i;

 	  ndata->notify (ndata->data, closure);

 	}

       break;

     }

 }

 /**

  * g_closure_set_meta_marshal:

  * @closure: a #GClosure

  * @marshal_data: context-dependent data to pass to @meta_marshal

  * @meta_marshal: a #GClosureMarshal function

  *

  * Sets the meta marshaller of @closure.  A meta marshaller wraps

  * @closure->marshal and modifies the way it is called in some

  * fashion. The most common use of this facility is for C callbacks.

  * The same marshallers (generated by <link

  * linkend="glib-genmarshal">glib-genmarshal</link>) are used

  * everywhere, but the way that we get the callback function

  * differs. In most cases we want to use @closure->callback, but in

  * other cases we want to use some different technique to retrieve the

  * callback function.

  *

  * For example, class closures for signals (see

  * g_signal_type_cclosure_new()) retrieve the callback function from a

  * fixed offset in the class structure.  The meta marshaller retrieves

  * the right callback and passes it to the marshaller as the

  * @marshal_data argument.

  */

 EXPORT_C void

 g_closure_set_meta_marshal (GClosure       *closure,

 			    gpointer        marshal_data,

 			    GClosureMarshal meta_marshal)

 {

   GClosureNotifyData *notifiers;

   g_return_if_fail (closure != NULL);

   g_return_if_fail (meta_marshal != NULL);

   g_return_if_fail (closure->is_invalid == FALSE);

   g_return_if_fail (closure->in_marshal == FALSE);

   g_return_if_fail (closure->meta_marshal == 0);

   notifiers = closure->notifiers;

   closure->notifiers = g_renew (GClosureNotifyData, NULL, CLOSURE_N_NOTIFIERS (closure) + 1);

   if (notifiers)

     {

       /* usually the meta marshal will be setup right after creation, so the

        * g_memmove() should be rare-case scenario

        */

       g_memmove (closure->notifiers + 1, notifiers, CLOSURE_N_NOTIFIERS (closure) * sizeof (notifiers[0]));

       g_free (notifiers);

     }

   closure->notifiers[0].data = marshal_data;

   closure->notifiers[0].notify = (GClosureNotify) meta_marshal;

   SET (closure, meta_marshal, 1);

 }

 /**

  * g_closure_add_marshal_guards:

  * @closure: a #GClosure

  * @pre_marshal_data: data to pass to @pre_marshal_notify

  * @pre_marshal_notify: a function to call before the closure callback

  * @post_marshal_data: data to pass to @post_marshal_notify

  * @post_marshal_notify: a function to call after the closure callback

  *

  * Adds a pair of notifiers which get invoked before and after the

  * closure callback, respectively. This is typically used to protect

  * the extra arguments for the duration of the callback. See

  * g_object_watch_closure() for an example of marshal guards.

  */

 EXPORT_C void

 g_closure_add_marshal_guards (GClosure      *closure,

 			      gpointer       pre_marshal_data,

 			      GClosureNotify pre_marshal_notify,

 			      gpointer       post_marshal_data,

 			      GClosureNotify post_marshal_notify)

 {

   guint i;

   g_return_if_fail (closure != NULL);

   g_return_if_fail (pre_marshal_notify != NULL);

   g_return_if_fail (post_marshal_notify != NULL);

   g_return_if_fail (closure->is_invalid == FALSE);

   g_return_if_fail (closure->in_marshal == FALSE);

   g_return_if_fail (closure->n_guards < CLOSURE_MAX_N_GUARDS);

   closure->notifiers = g_renew (GClosureNotifyData, closure->notifiers, CLOSURE_N_NOTIFIERS (closure) + 2);

   if (closure->n_inotifiers)

     closure->notifiers[(CLOSURE_N_MFUNCS (closure) +

 			closure->n_fnotifiers +

 			closure->n_inotifiers + 1)] = closure->notifiers[(CLOSURE_N_MFUNCS (closure) +

 									  closure->n_fnotifiers + 0)];

   if (closure->n_inotifiers > 1)

     closure->notifiers[(CLOSURE_N_MFUNCS (closure) +

 			closure->n_fnotifiers +

 			closure->n_inotifiers)] = closure->notifiers[(CLOSURE_N_MFUNCS (closure) +

 								      closure->n_fnotifiers + 1)];

   if (closure->n_fnotifiers)

     closure->notifiers[(CLOSURE_N_MFUNCS (closure) +

 			closure->n_fnotifiers + 1)] = closure->notifiers[CLOSURE_N_MFUNCS (closure) + 0];

   if (closure->n_fnotifiers > 1)

     closure->notifiers[(CLOSURE_N_MFUNCS (closure) +

 			closure->n_fnotifiers)] = closure->notifiers[CLOSURE_N_MFUNCS (closure) + 1];

   if (closure->n_guards)

     closure->notifiers[(closure->meta_marshal +

 			closure->n_guards +

 			closure->n_guards + 1)] = closure->notifiers[closure->meta_marshal + closure->n_guards];

   i = closure->n_guards;

   closure->notifiers[closure->meta_marshal + i].data = pre_marshal_data;

   closure->notifiers[closure->meta_marshal + i].notify = pre_marshal_notify;

   closure->notifiers[closure->meta_marshal + i + 1].data = post_marshal_data;

   closure->notifiers[closure->meta_marshal + i + 1].notify = post_marshal_notify;

   INC (closure, n_guards);

 }

 /**

  * g_closure_add_finalize_notifier:

  * @closure: a #GClosure

  * @notify_data: data to pass to @notify_func

  * @notify_func: the callback function to register

  *

  * Registers a finalization notifier which will be called when the

  * reference count of @closure goes down to 0. Multiple finalization

  * notifiers on a single closure are invoked in unspecified order. If

  * a single call to g_closure_unref() results in the closure being

  * both invalidated and finalized, then the invalidate notifiers will

  * be run before the finalize notifiers.

  */

 EXPORT_C void

 g_closure_add_finalize_notifier (GClosure      *closure,

 				 gpointer       notify_data,

 				 GClosureNotify notify_func)

 {

   guint i;

   g_return_if_fail (closure != NULL);

   g_return_if_fail (notify_func != NULL);

   g_return_if_fail (closure->n_fnotifiers < CLOSURE_MAX_N_FNOTIFIERS);

   closure->notifiers = g_renew (GClosureNotifyData, closure->notifiers, CLOSURE_N_NOTIFIERS (closure) + 1);

   if (closure->n_inotifiers)

     closure->notifiers[(CLOSURE_N_MFUNCS (closure) +

 			closure->n_fnotifiers +

 			closure->n_inotifiers)] = closure->notifiers[(CLOSURE_N_MFUNCS (closure) +

 								      closure->n_fnotifiers + 0)];

   i = CLOSURE_N_MFUNCS (closure) + closure->n_fnotifiers;

   closure->notifiers[i].data = notify_data;

   closure->notifiers[i].notify = notify_func;

   INC (closure, n_fnotifiers);

 }

 /**

  * g_closure_add_invalidate_notifier:

  * @closure: a #GClosure

  * @notify_data: data to pass to @notify_func

  * @notify_func: the callback function to register

  *

  * Registers an invalidation notifier which will be called when the

  * @closure is invalidated with g_closure_invalidate(). Invalidation

  * notifiers are invoked before finalization notifiers, in an

  * unspecified order.

  */

 EXPORT_C void

 g_closure_add_invalidate_notifier (GClosure      *closure,

 				   gpointer       notify_data,

 				   GClosureNotify notify_func)

 {

   guint i;

   g_return_if_fail (closure != NULL);

   g_return_if_fail (notify_func != NULL);

   g_return_if_fail (closure->is_invalid == FALSE);

   g_return_if_fail (closure->n_inotifiers < CLOSURE_MAX_N_INOTIFIERS);

   closure->notifiers = g_renew (GClosureNotifyData, closure->notifiers, CLOSURE_N_NOTIFIERS (closure) + 1);

   i = CLOSURE_N_MFUNCS (closure) + closure->n_fnotifiers + closure->n_inotifiers;

   closure->notifiers[i].data = notify_data;

   closure->notifiers[i].notify = notify_func;

   INC (closure, n_inotifiers);

 }

 static inline gboolean

 closure_try_remove_inotify (GClosure       *closure,

 			    gpointer       notify_data,

 			    GClosureNotify notify_func)

 {

   GClosureNotifyData *ndata, *nlast;

   nlast = closure->notifiers + CLOSURE_N_NOTIFIERS (closure) - 1;

   for (ndata = nlast + 1 - closure->n_inotifiers; ndata <= nlast; ndata++)

     if (ndata->notify == notify_func && ndata->data == notify_data)

       {

 	DEC (closure, n_inotifiers);

 	if (ndata < nlast)

 	  *ndata = *nlast;

 	return TRUE;

       }

   return FALSE;

 }

 static inline gboolean

 closure_try_remove_fnotify (GClosure       *closure,

 			    gpointer       notify_data,

 			    GClosureNotify notify_func)

 {

   GClosureNotifyData *ndata, *nlast;

   nlast = closure->notifiers + CLOSURE_N_NOTIFIERS (closure) - closure->n_inotifiers - 1;

   for (ndata = nlast + 1 - closure->n_fnotifiers; ndata <= nlast; ndata++)

     if (ndata->notify == notify_func && ndata->data == notify_data)

       {

 	DEC (closure, n_fnotifiers);

 	if (ndata < nlast)

 	  *ndata = *nlast;

 	if (closure->n_inotifiers)

 	  closure->notifiers[(CLOSURE_N_MFUNCS (closure) +

 			      closure->n_fnotifiers)] = closure->notifiers[(CLOSURE_N_MFUNCS (closure) +

 									    closure->n_fnotifiers +

 									    closure->n_inotifiers)];

 	return TRUE;

       }

   return FALSE;

 }

 /**

  * g_closure_ref:

  * @closure: #GClosure to increment the reference count on

  *

  * Increments the reference count on a closure to force it staying

  * alive while the caller holds a pointer to it.

  *

  * Returns: The @closure passed in, for convenience

  */

 EXPORT_C GClosure*

 g_closure_ref (GClosure *closure)

 {

   guint new_ref_count;

   g_return_val_if_fail (closure != NULL, NULL);

   g_return_val_if_fail (closure->ref_count > 0, NULL);

   g_return_val_if_fail (closure->ref_count < CLOSURE_MAX_REF_COUNT, NULL);

   INC_ASSIGN (closure, ref_count, &new_ref_count);

   g_return_val_if_fail (new_ref_count > 1, NULL);

   return closure;

 }

 /**

  * g_closure_invalidate:

  * @closure: GClosure to invalidate

  *

  * Sets a flag on the closure to indicate that its calling

  * environment has become invalid, and thus causes any future

  * invocations of g_closure_invoke() on this @closure to be

  * ignored. Also, invalidation notifiers installed on the closure will

  * be called at this point. Note that unless you are holding a

  * reference to the closure yourself, the invalidation notifiers may

  * unref the closure and cause it to be destroyed, so if you need to

  * access the closure after calling g_closure_invalidate(), make sure

  * that you've previously called g_closure_ref().

  *

  * Note that g_closure_invalidate() will also be called when the

  * reference count of a closure drops to zero (unless it has already

  * been invalidated before).

  */

 EXPORT_C void

 g_closure_invalidate (GClosure *closure)

 {

   g_return_if_fail (closure != NULL);

   if (!closure->is_invalid)

     {

       gboolean was_invalid;

       g_closure_ref (closure);           /* preserve floating flag */

       SWAP (closure, is_invalid, TRUE, &was_invalid);

       /* invalidate only once */

       if (!was_invalid)

         closure_invoke_notifiers (closure, INOTIFY);

       g_closure_unref (closure);

     }

 }

 /**

  * g_closure_unref:

  * @closure: #GClosure to decrement the reference count on

  *

  * Decrements the reference count of a closure after it was previously

  * incremented by the same caller. If no other callers are using the

  * closure, then the closure will be destroyed and freed.

  */

 EXPORT_C void

 g_closure_unref (GClosure *closure)

 {

   guint new_ref_count;

   g_return_if_fail (closure != NULL);

   g_return_if_fail (closure->ref_count > 0);

   if (closure->ref_count == 1)	/* last unref, invalidate first */

     g_closure_invalidate (closure);

   DEC_ASSIGN (closure, ref_count, &new_ref_count);

   if (new_ref_count == 0)

     {

       closure_invoke_notifiers (closure, FNOTIFY);

       g_free (closure->notifiers);

       g_free (closure);

     }

 }

 /**

  * g_closure_sink:

  * @closure: #GClosure to decrement the initial reference count on, if it's

  *           still being held

  *

  * Takes over the initial ownership of a closure.  Each closure is

  * initially created in a <firstterm>floating</firstterm> state, which

  * means that the initial reference count is not owned by any caller.

  * g_closure_sink() checks to see if the object is still floating, and

  * if so, unsets the floating state and decreases the reference

  * count. If the closure is not floating, g_closure_sink() does

  * nothing. The reason for the existance of the floating state is to

  * prevent cumbersome code sequences like:

  * |[

  * closure = g_cclosure_new (cb_func, cb_data);

  * g_source_set_closure (source, closure);

  * g_closure_unref (closure); // XXX GObject doesn't really need this

  * ]|

  * Because g_source_set_closure() (and similar functions) take ownership of the

  * initial reference count, if it is unowned, we instead can write:

  * |[

  * g_source_set_closure (source, g_cclosure_new (cb_func, cb_data));

  * ]|

  *

  * Generally, this function is used together with g_closure_ref(). Ane example

  * of storing a closure for later notification looks like:

  * |[

  * static GClosure *notify_closure = NULL;

  * void

  * foo_notify_set_closure (GClosure *closure)

  * {

  *   if (notify_closure)

  *     g_closure_unref (notify_closure);

  *   notify_closure = closure;

  *   if (notify_closure)

  *     {

  *       g_closure_ref (notify_closure);

  *       g_closure_sink (notify_closure);

  *     }

  * }

  * ]|

  *

  * Because g_closure_sink() may decrement the reference count of a closure

  * (if it hasn't been called on @closure yet) just like g_closure_unref(),

  * g_closure_ref() should be called prior to this function.

  */

 EXPORT_C void

 g_closure_sink (GClosure *closure)

 {

   g_return_if_fail (closure != NULL);

   g_return_if_fail (closure->ref_count > 0);

   /* floating is basically a kludge to avoid creating closures

    * with a ref_count of 0. so the intial ref_count a closure has

    * is unowned. with invoking g_closure_sink() code may

    * indicate that it takes over that intiial ref_count.

    */

   if (closure->floating)

     {

       gboolean was_floating;

       SWAP (closure, floating, FALSE, &was_floating);

       /* unref floating flag only once */

       if (was_floating)

         g_closure_unref (closure);

     }

 }

 /**

  * g_closure_remove_invalidate_notifier:

  * @closure: a #GClosure

  * @notify_data: data which was passed to g_closure_add_invalidate_notifier()

  *               when registering @notify_func

  * @notify_func: the callback function to remove

  *

  * Removes an invalidation notifier.

  *

  * Notice that notifiers are automatically removed after they are run.

  */

 EXPORT_C void

 g_closure_remove_invalidate_notifier (GClosure      *closure,

 				      gpointer       notify_data,

 				      GClosureNotify notify_func)

 {

   g_return_if_fail (closure != NULL);

   g_return_if_fail (notify_func != NULL);

   if (closure->is_invalid && closure->in_inotify && /* account removal of notify_func() while it's called */

       ((gpointer) closure->marshal) == ((gpointer) notify_func) &&

       closure->data == notify_data)

     closure->marshal = NULL;

   else if (!closure_try_remove_inotify (closure, notify_data, notify_func))

     g_warning (G_STRLOC ": unable to remove uninstalled invalidation notifier: %p (%p)",

 	       notify_func, notify_data);

 }

 /**

  * g_closure_remove_finalize_notifier:

  * @closure: a #GClosure

  * @notify_data: data which was passed to g_closure_add_finalize_notifier()

  *  when registering @notify_func

  * @notify_func: the callback function to remove

  *

  * Removes a finalization notifier.

  *

  * Notice that notifiers are automatically removed after they are run.

  */

 EXPORT_C void

 g_closure_remove_finalize_notifier (GClosure      *closure,

 				    gpointer       notify_data,

 				    GClosureNotify notify_func)

 {

   g_return_if_fail (closure != NULL);

   g_return_if_fail (notify_func != NULL);

   if (closure->is_invalid && !closure->in_inotify && /* account removal of notify_func() while it's called */

       ((gpointer) closure->marshal) == ((gpointer) notify_func) &&

       closure->data == notify_data)

     closure->marshal = NULL;

   else if (!closure_try_remove_fnotify (closure, notify_data, notify_func))

     g_warning (G_STRLOC ": unable to remove uninstalled finalization notifier: %p (%p)",

                notify_func, notify_data);

 }

 /**

  * g_closure_invoke:

  * @closure: a #GClosure

  * @return_value: a #GValue to store the return value. May be %NULL if the

  *                callback of @closure doesn't return a value.

  * @n_param_values: the length of the @param_values array

  * @param_values: an array of #GValue<!-- -->s holding the arguments on

  *                which to invoke the callback of @closure

  * @invocation_hint: a context-dependent invocation hint

  *

  * Invokes the closure, i.e. executes the callback represented by the @closure.

  */

 EXPORT_C void

 g_closure_invoke (GClosure       *closure,

 		  GValue /*out*/ *return_value,

 		  guint           n_param_values,

 		  const GValue   *param_values,

 		  gpointer        invocation_hint)

 {

   g_return_if_fail (closure != NULL);

   g_closure_ref (closure);      /* preserve floating flag */

   if (!closure->is_invalid)

     {

       GClosureMarshal marshal;

       gpointer marshal_data;

       gboolean in_marshal = closure->in_marshal;

       g_return_if_fail (closure->marshal || closure->meta_marshal);

       SET (closure, in_marshal, TRUE);

       if (closure->meta_marshal)

 	{

 	  marshal_data = closure->notifiers[0].data;

 	  marshal = (GClosureMarshal) closure->notifiers[0].notify;

 	}

       else

 	{

 	  marshal_data = NULL;

 	  marshal = closure->marshal;

 	}

       if (!in_marshal)

 	closure_invoke_notifiers (closure, PRE_NOTIFY);

       marshal (closure,

 	       return_value,

 	       n_param_values, param_values,

 	       invocation_hint,

 	       marshal_data);

       if (!in_marshal)

 	closure_invoke_notifiers (closure, POST_NOTIFY);

       SET (closure, in_marshal, in_marshal);

     }

   g_closure_unref (closure);

 }

 /**

  * g_closure_set_marshal:

  * @closure: a #GClosure

  * @marshal: a #GClosureMarshal function

  *

  * Sets the marshaller of @closure. The <literal>marshal_data</literal>

  * of @marshal provides a way for a meta marshaller to provide additional

  * information to the marshaller. (See g_closure_set_meta_marshal().) For

  * GObject's C predefined marshallers (the g_cclosure_marshal_*()

  * functions), what it provides is a callback function to use instead of

  * @closure->callback.

  */

 EXPORT_C void

 g_closure_set_marshal (GClosure       *closure,

 		       GClosureMarshal marshal)

 {

   g_return_if_fail (closure != NULL);

   g_return_if_fail (marshal != NULL);

   if (closure->marshal && closure->marshal != marshal)

     g_warning ("attempt to override closure->marshal (%p) with new marshal (%p)",

 	       closure->marshal, marshal);

   else

     closure->marshal = marshal;

 }

 /**

  * g_cclosure_new:

  * @callback_func: the function to invoke

  * @user_data: user data to pass to @callback_func

  * @destroy_data: destroy notify to be called when @user_data is no longer used

  *

  * Creates a new closure which invokes @callback_func with @user_data as

  * the last parameter.

  *

  * Returns: a new #GCClosure

  */

 EXPORT_C GClosure*

 g_cclosure_new (GCallback      callback_func,

 		gpointer       user_data,

 		GClosureNotify destroy_data)

 {

   GClosure *closure;

   g_return_val_if_fail (callback_func != NULL, NULL);

   closure = g_closure_new_simple (sizeof (GCClosure), user_data);

   if (destroy_data)

     g_closure_add_finalize_notifier (closure, user_data, destroy_data);

   ((GCClosure*) closure)->callback = (gpointer) callback_func;

   return closure;

 }

 /**

  * g_cclosure_new_swap:

  * @callback_func: the function to invoke

  * @user_data: user data to pass to @callback_func

  * @destroy_data: destroy notify to be called when @user_data is no longer used

  *

  * Creates a new closure which invokes @callback_func with @user_data as

  * the first parameter.

  *

  * Returns: a new #GCClosure

  */

 EXPORT_C GClosure*

 g_cclosure_new_swap (GCallback      callback_func,

 		     gpointer       user_data,

 		     GClosureNotify destroy_data)

 {

   GClosure *closure;

   g_return_val_if_fail (callback_func != NULL, NULL);

   closure = g_closure_new_simple (sizeof (GCClosure), user_data);

   if (destroy_data)

     g_closure_add_finalize_notifier (closure, user_data, destroy_data);

   ((GCClosure*) closure)->callback = (gpointer) callback_func;

   SET (closure, derivative_flag, TRUE);

   return closure;

 }

 static void

 g_type_class_meta_marshal (GClosure       *closure,

 			   GValue /*out*/ *return_value,

 			   guint           n_param_values,

 			   const GValue   *param_values,

 			   gpointer        invocation_hint,

 			   gpointer        marshal_data)

 {

   GTypeClass *class;

   gpointer callback;

   /* GType itype = (GType) closure->data; */

   guint offset = GPOINTER_TO_UINT (marshal_data);

   class = G_TYPE_INSTANCE_GET_CLASS (g_value_peek_pointer (param_values + 0), itype, GTypeClass);

   callback = G_STRUCT_MEMBER (gpointer, class, offset);

   if (callback)

     closure->marshal (closure,

 		      return_value,

 		      n_param_values, param_values,

 		      invocation_hint,

 		      callback);

 }

 static void

 g_type_iface_meta_marshal (GClosure       *closure,

 			   GValue /*out*/ *return_value,

 			   guint           n_param_values,

 			   const GValue   *param_values,

 			   gpointer        invocation_hint,

 			   gpointer        marshal_data)

 {

   GTypeClass *class;

   gpointer callback;

   GType itype = (GType) closure->data;

   guint offset = GPOINTER_TO_UINT (marshal_data);

   class = G_TYPE_INSTANCE_GET_INTERFACE (g_value_peek_pointer (param_values + 0), itype, GTypeClass);

   callback = G_STRUCT_MEMBER (gpointer, class, offset);

   if (callback)

     closure->marshal (closure,

 		      return_value,

 		      n_param_values, param_values,

 		      invocation_hint,

 		      callback);

 }

 /**

  * g_signal_type_cclosure_new:

  * @itype: the #GType identifier of an interface or classed type

  * @struct_offset: the offset of the member function of @itype's class

  *  structure which is to be invoked by the new closure

  *

  * Creates a new closure which invokes the function found at the offset

  * @struct_offset in the class structure of the interface or classed type

  * identified by @itype.

  *

  * Returns: a new #GCClosure

  */

 EXPORT_C GClosure*

 g_signal_type_cclosure_new (GType    itype,

 			    guint    struct_offset)

 {

   GClosure *closure;

   g_return_val_if_fail (G_TYPE_IS_CLASSED (itype) || G_TYPE_IS_INTERFACE (itype), NULL);

   g_return_val_if_fail (struct_offset >= sizeof (GTypeClass), NULL);

   closure = g_closure_new_simple (sizeof (GClosure), (gpointer) itype);

   if (G_TYPE_IS_INTERFACE (itype))

     g_closure_set_meta_marshal (closure, GUINT_TO_POINTER (struct_offset), g_type_iface_meta_marshal);

   else

     g_closure_set_meta_marshal (closure, GUINT_TO_POINTER (struct_offset), g_type_class_meta_marshal);

   return closure;

 }

 /**

  * g_cclosure_marshal_VOID__VOID:

  * @closure: the #GClosure to which the marshaller belongs

  * @return_value: ignored

  * @n_param_values: 1

  * @param_values: a #GValue array holding only the instance

  * @invocation_hint: the invocation hint given as the last argument

  *  to g_closure_invoke()

  * @marshal_data: additional data specified when registering the marshaller

  *

  * A marshaller for a #GCClosure with a callback of type

  * <literal>void (*callback) (gpointer instance, gpointer user_data)</literal>.

  */

 /**

  * g_cclosure_marshal_VOID__BOOLEAN:

  * @closure: the #GClosure to which the marshaller belongs

  * @return_value: ignored

  * @n_param_values: 2

  * @param_values: a #GValue array holding the instance and the #gboolean parameter

  * @invocation_hint: the invocation hint given as the last argument

  *  to g_closure_invoke()

  * @marshal_data: additional data specified when registering the marshaller

  *

  * A marshaller for a #GCClosure with a callback of type

  * <literal>void (*callback) (gpointer instance, gboolean arg1, gpointer user_data)</literal>.

  */

 /**

  * g_cclosure_marshal_VOID__CHAR:

  * @closure: the #GClosure to which the marshaller belongs

  * @return_value: ignored

  * @n_param_values: 2

  * @param_values: a #GValue array holding the instance and the #gchar parameter

  * @invocation_hint: the invocation hint given as the last argument

  *  to g_closure_invoke()

  * @marshal_data: additional data specified when registering the marshaller

  *

  * A marshaller for a #GCClosure with a callback of type

  * <literal>void (*callback) (gpointer instance, gchar arg1, gpointer user_data)</literal>.

  */

 /**

  * g_cclosure_marshal_VOID__UCHAR:

  * @closure: the #GClosure to which the marshaller belongs

  * @return_value: ignored

  * @n_param_values: 2

  * @param_values: a #GValue array holding the instance and the #guchar parameter

  * @invocation_hint: the invocation hint given as the last argument

  *  to g_closure_invoke()

  * @marshal_data: additional data specified when registering the marshaller

  *

  * A marshaller for a #GCClosure with a callback of type

  * <literal>void (*callback) (gpointer instance, guchar arg1, gpointer user_data)</literal>.

  */

 /**

  * g_cclosure_marshal_VOID__INT:

  * @closure: the #GClosure to which the marshaller belongs

  * @return_value: ignored

  * @n_param_values: 2

  * @param_values: a #GValue array holding the instance and the #gint parameter

  * @invocation_hint: the invocation hint given as the last argument

  *  to g_closure_invoke()

  * @marshal_data: additional data specified when registering the marshaller

  *

  * A marshaller for a #GCClosure with a callback of type

  * <literal>void (*callback) (gpointer instance, gint arg1, gpointer user_data)</literal>.

  */

 /**

  * g_cclosure_marshal_VOID__UINT:

  * @closure: the #GClosure to which the marshaller belongs

  * @return_value: ignored

  * @n_param_values: 2

  * @param_values: a #GValue array holding the instance and the #guint parameter

  * @invocation_hint: the invocation hint given as the last argument

  *  to g_closure_invoke()

  * @marshal_data: additional data specified when registering the marshaller

  *

  * A marshaller for a #GCClosure with a callback of type

  * <literal>void (*callback) (gpointer instance, guint arg1, gpointer user_data)</literal>.

  */

 /**

  * g_cclosure_marshal_VOID__LONG:

  * @closure: the #GClosure to which the marshaller belongs

  * @return_value: ignored

  * @n_param_values: 2

  * @param_values: a #GValue array holding the instance and the #glong parameter

  * @invocation_hint: the invocation hint given as the last argument

  *  to g_closure_invoke()

  * @marshal_data: additional data specified when registering the marshaller

  *

  * A marshaller for a #GCClosure with a callback of type

  * <literal>void (*callback) (gpointer instance, glong arg1, gpointer user_data)</literal>.

  */

 /**

  * g_cclosure_marshal_VOID__ULONG:

  * @closure: the #GClosure to which the marshaller belongs

  * @return_value: ignored

  * @n_param_values: 2

  * @param_values: a #GValue array holding the instance and the #gulong parameter

  * @invocation_hint: the invocation hint given as the last argument

  *  to g_closure_invoke()

  * @marshal_data: additional data specified when registering the marshaller

  *

  * A marshaller for a #GCClosure with a callback of type

  * <literal>void (*callback) (gpointer instance, gulong arg1, gpointer user_data)</literal>.

  */

 /**

  * g_cclosure_marshal_VOID__ENUM:

  * @closure: the #GClosure to which the marshaller belongs

  * @return_value: ignored

  * @n_param_values: 2

  * @param_values: a #GValue array holding the instance and the enumeration parameter

  * @invocation_hint: the invocation hint given as the last argument

  *  to g_closure_invoke()

  * @marshal_data: additional data specified when registering the marshaller

  *

  * A marshaller for a #GCClosure with a callback of type

  * <literal>void (*callback) (gpointer instance, gint arg1, gpointer user_data)</literal> where the #gint parameter denotes an enumeration type..

  */

 /**

  * g_cclosure_marshal_VOID__FLAGS:

  * @closure: the #GClosure to which the marshaller belongs

  * @return_value: ignored

  * @n_param_values: 2

  * @param_values: a #GValue array holding the instance and the flags parameter

  * @invocation_hint: the invocation hint given as the last argument

  *  to g_closure_invoke()

  * @marshal_data: additional data specified when registering the marshaller

  *

  * A marshaller for a #GCClosure with a callback of type

  * <literal>void (*callback) (gpointer instance, gint arg1, gpointer user_data)</literal> where the #gint parameter denotes a flags type.

  */

 /**

  * g_cclosure_marshal_VOID__FLOAT:

  * @closure: the #GClosure to which the marshaller belongs

  * @return_value: ignored

  * @n_param_values: 2

  * @param_values: a #GValue array holding the instance and the #gfloat parameter

  * @invocation_hint: the invocation hint given as the last argument

  *  to g_closure_invoke()

  * @marshal_data: additional data specified when registering the marshaller

  *

  * A marshaller for a #GCClosure with a callback of type

  * <literal>void (*callback) (gpointer instance, gfloat arg1, gpointer user_data)</literal>.

  */

 /**

  * g_cclosure_marshal_VOID__DOUBLE:

  * @closure: the #GClosure to which the marshaller belongs

  * @return_value: ignored

  * @n_param_values: 2

  * @param_values: a #GValue array holding the instance and the #gdouble parameter

  * @invocation_hint: the invocation hint given as the last argument

  *  to g_closure_invoke()

  * @marshal_data: additional data specified when registering the marshaller

  *

  * A marshaller for a #GCClosure with a callback of type

  * <literal>void (*callback) (gpointer instance, gdouble arg1, gpointer user_data)</literal>.

  */

 /**

  * g_cclosure_marshal_VOID__STRING:

  * @closure: the #GClosure to which the marshaller belongs

  * @return_value: ignored

  * @n_param_values: 2

  * @param_values: a #GValue array holding the instance and the #gchar* parameter

  * @invocation_hint: the invocation hint given as the last argument

  *  to g_closure_invoke()

  * @marshal_data: additional data specified when registering the marshaller

  *

  * A marshaller for a #GCClosure with a callback of type

  * <literal>void (*callback) (gpointer instance, const gchar *arg1, gpointer user_data)</literal>.

  */

 /**

  * g_cclosure_marshal_VOID__PARAM:

  * @closure: the #GClosure to which the marshaller belongs

  * @return_value: ignored

  * @n_param_values: 2

  * @param_values: a #GValue array holding the instance and the #GParamSpec* parameter

  * @invocation_hint: the invocation hint given as the last argument

  *  to g_closure_invoke()

  * @marshal_data: additional data specified when registering the marshaller

  *

  * A marshaller for a #GCClosure with a callback of type

  * <literal>void (*callback) (gpointer instance, GParamSpec *arg1, gpointer user_data)</literal>.

  */

 /**

  * g_cclosure_marshal_VOID__BOXED:

  * @closure: the #GClosure to which the marshaller belongs

  * @return_value: ignored

  * @n_param_values: 2

  * @param_values: a #GValue array holding the instance and the #GBoxed* parameter

  * @invocation_hint: the invocation hint given as the last argument

  *  to g_closure_invoke()

  * @marshal_data: additional data specified when registering the marshaller

  *

  * A marshaller for a #GCClosure with a callback of type

  * <literal>void (*callback) (gpointer instance, GBoxed *arg1, gpointer user_data)</literal>.

  */

 /**

  * g_cclosure_marshal_VOID__POINTER:

  * @closure: the #GClosure to which the marshaller belongs

  * @return_value: ignored

  * @n_param_values: 2

  * @param_values: a #GValue array holding the instance and the #gpointer parameter

  * @invocation_hint: the invocation hint given as the last argument

  *  to g_closure_invoke()

  * @marshal_data: additional data specified when registering the marshaller

  *

  * A marshaller for a #GCClosure with a callback of type

  * <literal>void (*callback) (gpointer instance, gpointer arg1, gpointer user_data)</literal>.

  */

 /**

  * g_cclosure_marshal_VOID__OBJECT:

  * @closure: the #GClosure to which the marshaller belongs

  * @return_value: ignored

  * @n_param_values: 2

  * @param_values: a #GValue array holding the instance and the #GObject* parameter

  * @invocation_hint: the invocation hint given as the last argument

  *  to g_closure_invoke()

  * @marshal_data: additional data specified when registering the marshaller

  *

  * A marshaller for a #GCClosure with a callback of type

  * <literal>void (*callback) (gpointer instance, GOBject *arg1, gpointer user_data)</literal>.

  */

 /**

  * g_cclosure_marshal_VOID__UINT_POINTER:

  * @closure: the #GClosure to which the marshaller belongs

  * @return_value: ignored

  * @n_param_values: 3

  * @param_values: a #GValue array holding instance, arg1 and arg2

  * @invocation_hint: the invocation hint given as the last argument

  *  to g_closure_invoke()

  * @marshal_data: additional data specified when registering the marshaller

  *

  * A marshaller for a #GCClosure with a callback of type

  * <literal>void (*callback) (gpointer instance, guint arg1, gpointer arg2, gpointer user_data)</literal>.

  */

 /**

  * g_cclosure_marshal_BOOLEAN__FLAGS:

  * @closure: the #GClosure to which the marshaller belongs

  * @return_value: a #GValue which can store the returned #gboolean

  * @n_param_values: 2

  * @param_values: a #GValue array holding instance and arg1

  * @invocation_hint: the invocation hint given as the last argument

  *  to g_closure_invoke()

  * @marshal_data: additional data specified when registering the marshaller

  *

  * A marshaller for a #GCClosure with a callback of type

  * <literal>gboolean (*callback) (gpointer instance, gint arg1, gpointer user_data)</literal> where the #gint parameter

  * denotes a flags type.

  */

 /**

  * g_cclosure_marshal_BOOL__FLAGS:

  *

  * Another name for g_cclosure_marshal_BOOLEAN__FLAGS().

  */

 /**

  * g_cclosure_marshal_STRING__OBJECT_POINTER:

  * @closure: the #GClosure to which the marshaller belongs

  * @return_value: a #GValue, which can store the returned string

  * @n_param_values: 3

  * @param_values: a #GValue array holding instance, arg1 and arg2

  * @invocation_hint: the invocation hint given as the last argument

  *  to g_closure_invoke()

  * @marshal_data: additional data specified when registering the marshaller

  *

  * A marshaller for a #GCClosure with a callback of type

  * <literal>gchar* (*callback) (gpointer instance, GObject *arg1, gpointer arg2, gpointer user_data)</literal>.

  */

 #define __G_CLOSURE_C__

 #include "gobjectaliasdef.c"