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gtk/gtk/gtkexpression.c
Emmanuele Bassi 8daaafc864 Document how to define properties using GtkExpression 
Use the GtkParamSpecExpression type to describe the property, and the
GValue API to set and get the expression instance.
2020-06-01 21:17:34 +01:00

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/*
* Copyright © 2019 Benjamin Otte
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library. If not, see <http://www.gnu.org/licenses/>.
*
* Authors: Benjamin Otte <otte@gnome.org>
*/
#include "config.h"
#include "gtkexpression.h"
#include <gobject/gvaluecollector.h>
/**
* SECTION:gtkexpression
* @Short_description: Expressions to values
* @Title: GtkExpression
*
* GtkExpression provides a way to describe references to #GValues.
*
* An expression needs to be "evaluated" to obtain the value that it currently refers
* to. An evaluation always happens in the context of a current object called `this`
* (it mirrors the behavior of object-oriented languages), which may or may not
* influence the result of the evaluation. Use gtk_expression_evaluate() for
* evaluating an expression.
*
* Various methods for defining expressions exist, from simple constants via
* gtk_constant_expression_new() to looking up properties in a #GObject (even
* recursively) via gtk_property_expression_new() or providing custom functions to
* transform and combine expressions via gtk_closure_expression_new().
*
* By default, expressions are not paying attention to changes and evaluation is
* just a snapshot of the current state at a given time. To get informed about
* changes, an expression needs to be "watched" via a #GtkExpressionWatch, which
* will cause a callback to be called whenever the value of the expression may
* have changed. gtk_expression_watch() starts watching an expression, and
* gtk_expression_watch_unwatch() stops.
*
* Watches can be created for automatically updating the propery of an object,
* similar to GObject's #GBinding mechanism, by using gtk_expression_bind().
*
* # GtkExpression in GObject properties
*
* In order to use a #GtkExpression as a #GObject property, you must use the
* gtk_param_spec_expression() when creating a #GParamSpec to install in the
* #GObject class being defined; for instance:
*
* |[
* obj_props[PROP_EXPRESSION] =
* gtk_param_spec_expression ("expression",
* "Expression",
* "The expression used by the widget",
* G_PARAM_READWRITE |
* G_PARAM_STATIC_STRINGS |
* G_PARAM_EXPLICIT_NOTIFY);
* ]|
*
* When implementing the #GObjectClass.set_property() and #GObjectClass.get_property()
* virtual functions, you must use gtk_value_get_expression(), to retrieve the
* stored #GtkExpression from the #GValue container, and gtk_value_set_expression(),
* to store the #GtkExpression into the #GValue; for instance:
*
* |[
* // in set_property()...
* case PROP_EXPRESSION:
* foo_widget_set_expression (foo, gtk_value_get_expression (value));
* break;
*
* // in get_property()...
* case PROP_EXPRESSION:
* gtk_value_set_expression (value, foo->expression);
* break;
* ]|
*
* # GtkExpression in .ui files
*
* GtkBuilder has support for creating expressions. The syntax here can be used where
* a #GtkExpression object is needed like in a <property> tag for an expression
* property, or in a <binding> tag to bind a property to an expression.
*
* To create an property expression, use the <lookup> element. It can have a `type`
* attribute to specify the object type, and a `name` attribute to specify the property
* to look up. The content of <lookup> can either be an element specfiying the expression
* to use the object, or a string that specifies the name of the object to use.
*
* Example:
* |[
* <lookup name='search'>string_filter</lookup>
* |]
*
* To create a constant expression, use the <constant> element. If the type attribute
* is specified, the element content is interpreted as a value of that type. Otherwise,
* it is assumed to be an object.
*
* Example:
* |[
* <constant>string_filter</constant>
* <constant type='gchararray'>Hello, world</constant>
* ]|
*
* To create a closure expression, use the <closure> element. The `type` and `function`
* attributes specify what function to use for the closure, the content of the element
* contains the expressions for the parameters.
*
* Example:
* |[
* <closure type='gchararray' function='combine_args_somehow'>
* <constant type='gchararray'>File size:</constant>
* <lookup type='GFile' name='size'>myfile</lookup>
* </closure>
* ]|
*/
/**
* GtkExpression: (ref-func gtk_expression_ref) (unref-func gtk_expression_unref) (set-value-func gtk_value_set_expression) (get-value-func gtk_value_get_expression)
*
* The `GtkExpression` structure contains only private data.
*/
typedef struct _GtkExpressionClass GtkExpressionClass;
typedef struct _GtkExpressionSubWatch GtkExpressionSubWatch;
typedef struct _GtkExpressionTypeInfo GtkExpressionTypeInfo;
struct _GtkExpression
{
GTypeInstance parent_instance;
gatomicrefcount ref_count;
GType value_type;
GtkExpression *owner;
};
struct _GtkExpressionClass
{
GTypeClass parent_class;
void (* finalize) (GtkExpression *expr);
gboolean (* is_static) (GtkExpression *expr);
gboolean (* evaluate) (GtkExpression *expr,
gpointer this,
GValue *value);
gsize (* watch_size) (GtkExpression *expr);
void (* watch) (GtkExpression *self,
GtkExpressionSubWatch *watch,
gpointer this_,
GtkExpressionNotify notify,
gpointer user_data);
void (* unwatch) (GtkExpression *self,
GtkExpressionSubWatch *watch);
};
struct _GtkExpressionTypeInfo
{
gsize instance_size;
void (* instance_init) (GtkExpression *expr);
void (* finalize) (GtkExpression *expr);
gboolean (* is_static) (GtkExpression *expr);
gboolean (* evaluate) (GtkExpression *expr,
gpointer this,
GValue *value);
gsize (* watch_size) (GtkExpression *expr);
void (* watch) (GtkExpression *self,
GtkExpressionSubWatch *watch,
gpointer this_,
GtkExpressionNotify notify,
gpointer user_data);
void (* unwatch) (GtkExpression *self,
GtkExpressionSubWatch *watch);
};
struct _GtkExpressionWatch
{
GtkExpression *expression;
GObject *this;
GDestroyNotify user_destroy;
GtkExpressionNotify notify;
gpointer user_data;
guchar sub[0];
};
#define GTK_EXPRESSION_GET_CLASS(obj) (G_TYPE_INSTANCE_GET_CLASS ((obj), GTK_TYPE_EXPRESSION, GtkExpressionClass))
/*< private >
* GTK_DEFINE_EXPRESSION_TYPE:
* @TypeName: the type name, in camel case
* @type_name: the type name, in snake case
* @type_info: the address of the #GtkExpressionTypeInfo for the expression type
*
* Registers a new #GtkExpression subclass with the given @TypeName and @type_info.
*
* Similarly to %G_DEFINE_TYPE, this macro will generate a `get_type()`
* function that registers the event type.
*
* You can specify code to be run after the type registration; the #GType of
* the event is available in the `gtk_define_expression_type_id` variable.
*/
#define GTK_DEFINE_EXPRESSION_TYPE(TypeName, type_name, type_info) \
GType \
type_name ## _get_type (void) \
{ \
static volatile gsize gtk_define_expression_type_id__volatile; \
if (g_once_init_enter (&gtk_define_expression_type_id__volatile)) \
{ \
GType gtk_define_expression_type_id = \
gtk_expression_type_register_static (g_intern_static_string (#TypeName), type_info); \
g_once_init_leave (&gtk_define_expression_type_id__volatile, gtk_define_expression_type_id); \
} \
return gtk_define_expression_type_id__volatile; \
}
#define GTK_EXPRESSION_SUPER(expr) \
((GtkExpressionClass *) g_type_class_peek (g_type_parent (G_TYPE_FROM_INSTANCE (expr))))
/* {{{ GtkExpression internals */
static void
value_expression_init (GValue *value)
{
value->data[0].v_pointer = NULL;
}
static void
value_expression_free_value (GValue *value)
{
if (value->data[0].v_pointer != NULL)
gtk_expression_unref (value->data[0].v_pointer);
}
static void
value_expression_copy_value (const GValue *src,
GValue *dst)
{
if (src->data[0].v_pointer != NULL)
dst->data[0].v_pointer = gtk_expression_ref (src->data[0].v_pointer);
else
dst->data[0].v_pointer = NULL;
}
static gpointer
value_expression_peek_pointer (const GValue *value)
{
return value->data[0].v_pointer;
}
static char *
value_expression_collect_value (GValue *value,
guint n_collect_values,
GTypeCValue *collect_values,
guint collect_flags)
{
GtkExpression *expression = collect_values[0].v_pointer;
if (expression == NULL)
{
value->data[0].v_pointer = NULL;
return NULL;
}
if (expression->parent_instance.g_class == NULL)
return g_strconcat ("invalid unclassed GtkExpression pointer for "
"value type '",
G_VALUE_TYPE_NAME (value),
"'",
NULL);
value->data[0].v_pointer = gtk_expression_ref (expression);
return NULL;
}
static gchar *
value_expression_lcopy_value (const GValue *value,
guint n_collect_values,
GTypeCValue *collect_values,
guint collect_flags)
{
GtkExpression **expression_p = collect_values[0].v_pointer;
if (expression_p == NULL)
return g_strconcat ("value location for '",
G_VALUE_TYPE_NAME (value),
"' passed as NULL",
NULL);
if (value->data[0].v_pointer == NULL)
*expression_p = NULL;
else if (collect_flags & G_VALUE_NOCOPY_CONTENTS)
*expression_p = value->data[0].v_pointer;
else
*expression_p = gtk_expression_ref (value->data[0].v_pointer);
return NULL;
}
/**
* gtk_value_set_expression:
* @value: a #GValue initialized with type %GTK_TYPE_EXPRESSION
* @expression: a #GtkExpression
*
* Stores the given #GtkExpression inside @value.
*
* The #GValue will acquire a reference to the @expression.
*/
void
gtk_value_set_expression (GValue *value,
GtkExpression *expression)
{
g_return_if_fail (G_VALUE_HOLDS (value, GTK_TYPE_EXPRESSION));
GtkExpression *old_expression = value->data[0].v_pointer;
if (expression != NULL)
{
g_return_if_fail (GTK_IS_EXPRESSION (expression));
value->data[0].v_pointer = gtk_expression_ref (expression);
}
else
{
value->data[0].v_pointer = NULL;
}
if (old_expression != NULL)
gtk_expression_unref (old_expression);
}
/**
* gtk_value_take_expression:
* @value: a #GValue initialized with type %GTK_TYPE_EXPRESSION
* @expression: (transfer full) (nullable): a #GtkExpression
*
* Stores the given #GtkExpression inside @value.
*
* This function transfers the ownership of the @expression to the #GValue.
*/
void
gtk_value_take_expression (GValue *value,
GtkExpression *expression)
{
g_return_if_fail (G_VALUE_HOLDS (value, GTK_TYPE_EXPRESSION));
GtkExpression *old_expression = value->data[0].v_pointer;
if (expression != NULL)
{
g_return_if_fail (GTK_IS_EXPRESSION (expression));
value->data[0].v_pointer = expression;
}
else
{
value->data[0].v_pointer = NULL;
}
if (old_expression != NULL)
gtk_expression_unref (old_expression);
}
/**
* gtk_value_get_expression:
* @value: a #GValue initialized with type %GTK_TYPE_EXPRESSION
*
* Retrieves the #GtkExpression stored inside the given @value.
*
* Returns: (transfer none) (nullable): a #GtkExpression
*/
GtkExpression *
gtk_value_get_expression (const GValue *value)
{
g_return_val_if_fail (G_VALUE_HOLDS (value, GTK_TYPE_EXPRESSION), NULL);
return value->data[0].v_pointer;
}
/**
* gtk_value_dup_expression:
* @value: a #GValue initialized with type %GTK_TYPE_EXPRESSION
*
* Retrieves the #GtkExpression stored inside the given @value, and acquires
* a reference to it.
*
* Returns: (transfer full) (nullable): a #GtkExpression
*/
GtkExpression *
gtk_value_dup_expression (const GValue *value)
{
g_return_val_if_fail (G_VALUE_HOLDS (value, GTK_TYPE_EXPRESSION), NULL);
if (value->data[0].v_pointer == NULL)
return NULL;
GtkExpression *expression = value->data[0].v_pointer;
return gtk_expression_ref (expression);
}
static void
param_expression_init (GParamSpec *pspec)
{
}
static void
param_expression_set_default (GParamSpec *pspec,
GValue *value)
{
value->data[0].v_pointer = NULL;
}
static gboolean
param_expression_validate (GParamSpec *pspec,
GValue *value)
{
GtkParamSpecExpression *espec = GTK_PARAM_SPEC_EXPRESSION (pspec);
GtkExpression *expr = value->data[0].v_pointer;
guint changed = 0;
if (expr != NULL &&
!g_value_type_compatible (G_TYPE_FROM_INSTANCE (expr), G_PARAM_SPEC_VALUE_TYPE (espec)))
{
gtk_expression_unref (expr);
value->data[0].v_pointer = NULL;
changed++;
}
return changed;
}
static gint
param_expression_values_cmp (GParamSpec *pspec,
const GValue *value1,
const GValue *value2)
{
guint8 *p1 = value1->data[0].v_pointer;
guint8 *p2 = value2->data[0].v_pointer;
return p1 < p2 ? -1 : p1 > p2;
}
GType
gtk_param_expression_get_type (void)
{
static volatile gsize param_expression_type__volatile;
if (g_once_init_enter (&param_expression_type__volatile))
{
const GParamSpecTypeInfo pspec_info = {
sizeof (GtkParamSpecExpression),
16,
param_expression_init,
GTK_TYPE_EXPRESSION,
NULL,
param_expression_set_default,
param_expression_validate,
param_expression_values_cmp,
};
GType param_expression_type =
g_param_type_register_static (g_intern_static_string ("GtkParamSpecExpression"),
&pspec_info);
g_once_init_leave (&param_expression_type__volatile, param_expression_type);
}
return param_expression_type__volatile;
}
/**
* gtk_param_spec_expression:
* @name: canonical name of the property
* @nick: a user-readable name for the property
* @blurb: a user-readable description of the property
* @flags: flags for the property
*
* Creates a new #GParamSpec instance for a property holding a #GtkExpression.
*
* See g_param_spec_internal() for details on the property strings.
*
* Returns: (transfer full): a newly created property specification
*/
GParamSpec *
gtk_param_spec_expression (const char *name,
const char *nick,
const char *blurb,
GParamFlags flags)
{
GParamSpec *pspec = g_param_spec_internal (GTK_TYPE_PARAM_SPEC_EXPRESSION,
name, nick, blurb,
flags);
pspec->value_type = GTK_TYPE_EXPRESSION;
return pspec;
}
/* }}} */
/* {{{ GtkExpression internals */
static void
gtk_expression_real_finalize (GtkExpression *self)
{
g_type_free_instance ((GTypeInstance *) self);
}
static gsize
gtk_expression_real_watch_size (GtkExpression *self)
{
return 0;
}
static void
gtk_expression_real_watch (GtkExpression *self,
GtkExpressionSubWatch *watch,
gpointer this_,
GtkExpressionNotify notify,
gpointer user_data)
{
}
static void
gtk_expression_real_unwatch (GtkExpression *self,
GtkExpressionSubWatch *watch)
{
}
static gsize
gtk_expression_watch_size (GtkExpression *self)
{
return GTK_EXPRESSION_GET_CLASS (self)->watch_size (self);
}
static void
gtk_expression_class_init (GtkExpressionClass *klass)
{
klass->finalize = gtk_expression_real_finalize;
klass->watch_size = gtk_expression_real_watch_size;
klass->watch = gtk_expression_real_watch;
klass->unwatch = gtk_expression_real_unwatch;
}
static void
gtk_expression_init (GtkExpression *self)
{
g_atomic_ref_count_init (&self->ref_count);
}
GType
gtk_expression_get_type (void)
{
static volatile gsize expression_type__volatile;
if (g_once_init_enter (&expression_type__volatile))
{
static const GTypeFundamentalInfo finfo = {
(G_TYPE_FLAG_CLASSED |
G_TYPE_FLAG_INSTANTIATABLE |
G_TYPE_FLAG_DERIVABLE |
G_TYPE_FLAG_DEEP_DERIVABLE),
};
static const GTypeValueTable value_table = {
value_expression_init,
value_expression_free_value,
value_expression_copy_value,
value_expression_peek_pointer,
"p",
value_expression_collect_value,
"p",
value_expression_lcopy_value,
};
const GTypeInfo event_info = {
/* Class */
sizeof (GtkExpressionClass),
(GBaseInitFunc) NULL,
(GBaseFinalizeFunc) NULL,
(GClassInitFunc) gtk_expression_class_init,
(GClassFinalizeFunc) NULL,
NULL,
/* Instance */
sizeof (GtkExpression),
0,
(GInstanceInitFunc) gtk_expression_init,
/* GValue */
&value_table,
};
GType expression_type =
g_type_register_fundamental (g_type_fundamental_next (),
g_intern_static_string ("GtkExpression"),
&event_info, &finfo,
G_TYPE_FLAG_ABSTRACT);
g_once_init_leave (&expression_type__volatile, expression_type);
}
return expression_type__volatile;
}
static void
gtk_expression_generic_class_init (gpointer g_class,
gpointer class_data)
{
GtkExpressionTypeInfo *info = class_data;
GtkExpressionClass *expression_class = g_class;
/* Mandatory */
expression_class->is_static = info->is_static;
expression_class->evaluate = info->evaluate;
/* Optional */
if (info->finalize != NULL)
expression_class->finalize = info->finalize;
if (info->watch_size != NULL)
expression_class->watch_size = info->watch_size;
if (info->watch != NULL)
expression_class->watch = info->watch;
if (info->unwatch != NULL)
expression_class->unwatch = info->unwatch;
g_free (info);
}
static GType
gtk_expression_type_register_static (const char *type_name,
const GtkExpressionTypeInfo *type_info)
{
GTypeInfo info;
info.class_size = sizeof (GtkExpressionClass);
info.base_init = NULL;
info.base_finalize = NULL;
info.class_init = gtk_expression_generic_class_init;
info.class_finalize = NULL;
info.class_data = g_memdup (type_info, sizeof (GtkExpressionTypeInfo));
info.instance_size = type_info->instance_size;
info.n_preallocs = 0;
info.instance_init = (GInstanceInitFunc) type_info->instance_init;
info.value_table = NULL;
return g_type_register_static (GTK_TYPE_EXPRESSION, type_name, &info, 0);
}
/*< private >
* gtk_expression_alloc:
* @expression_type: the type of expression to create
* @value_type: the type of the value returned by this expression
*
* Returns: (transfer full): the newly created #GtkExpression
*/
static gpointer
gtk_expression_alloc (GType expression_type,
GType value_type)
{
GtkExpression *self;
self = (GtkExpression *) g_type_create_instance (expression_type);
self->value_type = value_type;
return self;
}
static void
gtk_expression_subwatch_init (GtkExpression *self,
GtkExpressionSubWatch *watch,
gpointer this,
GtkExpressionNotify notify,
gpointer user_data)
{
GTK_EXPRESSION_GET_CLASS (self)->watch (self, watch, this, notify, user_data);
}
static void
gtk_expression_subwatch_finish (GtkExpression *self,
GtkExpressionSubWatch *watch)
{
GTK_EXPRESSION_GET_CLASS (self)->unwatch (self, watch);
}
/* }}} */
/* {{{ GtkConstantExpression */
typedef struct _GtkConstantExpression GtkConstantExpression;
struct _GtkConstantExpression
{
GtkExpression parent;
GValue value;
};
static void
gtk_constant_expression_finalize (GtkExpression *expr)
{
GtkConstantExpression *self = (GtkConstantExpression *) expr;
g_value_unset (&self->value);
GTK_EXPRESSION_SUPER (expr)->finalize (expr);
}
static gboolean
gtk_constant_expression_is_static (GtkExpression *expr)
{
return TRUE;
}
static gboolean
gtk_constant_expression_evaluate (GtkExpression *expr,
gpointer this,
GValue *value)
{
GtkConstantExpression *self = (GtkConstantExpression *) expr;
g_value_init (value, G_VALUE_TYPE (&self->value));
g_value_copy (&self->value, value);
return TRUE;
}
static const GtkExpressionTypeInfo gtk_constant_expression_info =
{
sizeof (GtkConstantExpression),
NULL,
gtk_constant_expression_finalize,
gtk_constant_expression_is_static,
gtk_constant_expression_evaluate,
NULL,
NULL,
NULL,
};
GTK_DEFINE_EXPRESSION_TYPE (GtkConstantExpression,
gtk_constant_expression,
&gtk_constant_expression_info)
/**
* gtk_constant_expression_new:
* @value_type: The type of the object
* @...: arguments to create the object from
*
* Creates a GtkExpression that evaluates to the
* object given by the arguments.
*
* Returns: a new #GtkExpression
*/
GtkExpression *
gtk_constant_expression_new (GType value_type,
...)
{
GValue value = G_VALUE_INIT;
GtkExpression *result;
va_list args;
char *error;
va_start (args, value_type);
G_VALUE_COLLECT_INIT (&value, value_type,
args, G_VALUE_NOCOPY_CONTENTS,
&error);
if (error)
{
g_critical ("%s: %s", G_STRLOC, error);
g_free (error);
/* we purposely leak the value here, it might not be
* in a sane state if an error condition occurred
*/
return NULL;
}
result = gtk_constant_expression_new_for_value (&value);
g_value_unset (&value);
va_end (args);
return result;
}
/**
* gtk_constant_expression_new_for_value:
* @value: a #GValue
*
* Creates an expression that always evaluates to the given @value.
*
* Returns: a new #GtkExpression
**/
GtkExpression *
gtk_constant_expression_new_for_value (const GValue *value)
{
GtkExpression *result;
GtkConstantExpression *self;
g_return_val_if_fail (G_IS_VALUE (value), NULL);
result = gtk_expression_alloc (GTK_TYPE_CONSTANT_EXPRESSION, G_VALUE_TYPE (value));
self = (GtkConstantExpression *) result;
g_value_init (&self->value, G_VALUE_TYPE (value));
g_value_copy (value, &self->value);
return result;
}
/* }}} */
/* {{{ GtkObjectExpression */
typedef struct _GtkObjectExpression GtkObjectExpression;
typedef struct _GtkObjectExpressionWatch GtkObjectExpressionWatch;
struct _GtkObjectExpression
{
GtkExpression parent;
GObject *object;
GSList *watches;
};
struct _GtkObjectExpressionWatch
{
GtkExpressionNotify notify;
gpointer user_data;
};
static void
gtk_object_expression_weak_ref_cb (gpointer data,
GObject *object)
{
GtkObjectExpression *self = (GtkObjectExpression *) data;
GSList *l;
self->object = NULL;
for (l = self->watches; l; l = l->next)
{
GtkObjectExpressionWatch *owatch = l->data;
owatch->notify (owatch->user_data);
}
}
static void
gtk_object_expression_finalize (GtkExpression *expr)
{
GtkObjectExpression *self = (GtkObjectExpression *) expr;
if (self->object)
g_object_weak_unref (self->object, gtk_object_expression_weak_ref_cb, self);
g_assert (self->watches == NULL);
GTK_EXPRESSION_SUPER (expr)->finalize (expr);
}
static gboolean
gtk_object_expression_is_static (GtkExpression *expr)
{
return FALSE;
}
static gboolean
gtk_object_expression_evaluate (GtkExpression *expr,
gpointer this,
GValue *value)
{
GtkObjectExpression *self = (GtkObjectExpression *) expr;
if (self->object == NULL)
return FALSE;
g_value_init (value, gtk_expression_get_value_type (expr));
g_value_set_object (value, self->object);
return TRUE;
}
static gsize
gtk_object_expression_watch_size (GtkExpression *expr)
{
return sizeof (GtkObjectExpressionWatch);
}
static void
gtk_object_expression_watch (GtkExpression *expr,
GtkExpressionSubWatch *watch,
gpointer this_,
GtkExpressionNotify notify,
gpointer user_data)
{
GtkObjectExpression *self = (GtkObjectExpression *) expr;
GtkObjectExpressionWatch *owatch = (GtkObjectExpressionWatch *) watch;
owatch->notify = notify;
owatch->user_data = user_data;
self->watches = g_slist_prepend (self->watches, owatch);
}
static void
gtk_object_expression_unwatch (GtkExpression *expr,
GtkExpressionSubWatch *watch)
{
GtkObjectExpression *self = (GtkObjectExpression *) expr;
self->watches = g_slist_remove (self->watches, watch);
}
static const GtkExpressionTypeInfo gtk_object_expression_info =
{
sizeof (GtkObjectExpression),
NULL,
gtk_object_expression_finalize,
gtk_object_expression_is_static,
gtk_object_expression_evaluate,
gtk_object_expression_watch_size,
gtk_object_expression_watch,
gtk_object_expression_unwatch
};
GTK_DEFINE_EXPRESSION_TYPE (GtkObjectExpression,
gtk_object_expression,
&gtk_object_expression_info)
/**
* gtk_object_expression_new:
* @object: (transfer none): object to watch
*
* Creates an expression evaluating to the given @object with a weak reference.
* Once the @object is disposed, it will fail to evaluate.
* This expression is meant to break reference cycles.
*
* If you want to keep a reference to @object, use gtk_constant_expression_new().
*
* Returns: a new #GtkExpression
**/
GtkExpression *
gtk_object_expression_new (GObject *object)
{
GtkExpression *result;
GtkObjectExpression *self;
g_return_val_if_fail (G_IS_OBJECT (object), NULL);
result = gtk_expression_alloc (GTK_TYPE_OBJECT_EXPRESSION, G_OBJECT_TYPE (object));
self = (GtkObjectExpression *) result;
self->object = object;
g_object_weak_ref (object, gtk_object_expression_weak_ref_cb, self);
return result;
}
/* }}} */
/* {{{ GtkPropertyExpression */
typedef struct _GtkPropertyExpression GtkPropertyExpression;
struct _GtkPropertyExpression
{
GtkExpression parent;
GtkExpression *expr;
GParamSpec *pspec;
};
static void
gtk_property_expression_finalize (GtkExpression *expr)
{
GtkPropertyExpression *self = (GtkPropertyExpression *) expr;
g_clear_pointer (&self->expr, gtk_expression_unref);
GTK_EXPRESSION_SUPER (expr)->finalize (expr);
}
static gboolean
gtk_property_expression_is_static (GtkExpression *expr)
{
return FALSE;
}
static GObject *
gtk_property_expression_get_object (GtkPropertyExpression *self,
gpointer this)
{
GValue expr_value = G_VALUE_INIT;
GObject *object;
if (self->expr == NULL)
{
if (this)
return g_object_ref (this);
else
return NULL;
}
if (!gtk_expression_evaluate (self->expr, this, &expr_value))
return NULL;
if (!G_VALUE_HOLDS_OBJECT (&expr_value))
{
g_value_unset (&expr_value);
return NULL;
}
object = g_value_dup_object (&expr_value);
g_value_unset (&expr_value);
if (object == NULL)
return NULL;
if (!G_TYPE_CHECK_INSTANCE_TYPE (object, self->pspec->owner_type))
{
g_object_unref (object);
return NULL;
}
return object;
}
static gboolean
gtk_property_expression_evaluate (GtkExpression *expr,
gpointer this,
GValue *value)
{
GtkPropertyExpression *self = (GtkPropertyExpression *) expr;
GObject *object;
object = gtk_property_expression_get_object (self, this);
if (object == NULL)
return FALSE;
g_object_get_property (object, self->pspec->name, value);
g_object_unref (object);
return TRUE;
}
typedef struct _GtkPropertyExpressionWatch GtkPropertyExpressionWatch;
struct _GtkPropertyExpressionWatch
{
GtkExpressionNotify notify;
gpointer user_data;
GtkPropertyExpression *expr;
gpointer this;
GClosure *closure;
guchar sub[0];
};
static void
gtk_property_expression_watch_destroy_closure (GtkPropertyExpressionWatch *pwatch)
{
if (pwatch->closure == NULL)
return;
g_closure_invalidate (pwatch->closure);
g_closure_unref (pwatch->closure);
pwatch->closure = NULL;
}
static void
gtk_property_expression_watch_notify_cb (GObject *object,
GParamSpec *pspec,
GtkPropertyExpressionWatch *pwatch)
{
pwatch->notify (pwatch->user_data);
}
static void
gtk_property_expression_watch_create_closure (GtkPropertyExpressionWatch *pwatch)
{
GObject *object;
object = gtk_property_expression_get_object (pwatch->expr, pwatch->this);
if (object == NULL)
return;
pwatch->closure = g_cclosure_new (G_CALLBACK (gtk_property_expression_watch_notify_cb), pwatch, NULL);
if (!g_signal_connect_closure_by_id (object,
g_signal_lookup ("notify", G_OBJECT_TYPE (object)),
g_quark_from_string (pwatch->expr->pspec->name),
g_closure_ref (pwatch->closure),
FALSE))
{
g_assert_not_reached ();
}
g_object_unref (object);
}
static void
gtk_property_expression_watch_expr_notify_cb (gpointer data)
{
GtkPropertyExpressionWatch *pwatch = data;
gtk_property_expression_watch_destroy_closure (pwatch);
gtk_property_expression_watch_create_closure (pwatch);
pwatch->notify (pwatch->user_data);
}
static gsize
gtk_property_expression_watch_size (GtkExpression *expr)
{
GtkPropertyExpression *self = (GtkPropertyExpression *) expr;
gsize result;
result = sizeof (GtkPropertyExpressionWatch);
if (self->expr)
result += gtk_expression_watch_size (self->expr);
return result;
}
static void
gtk_property_expression_watch (GtkExpression *expr,
GtkExpressionSubWatch *watch,
gpointer this_,
GtkExpressionNotify notify,
gpointer user_data)
{
GtkPropertyExpressionWatch *pwatch = (GtkPropertyExpressionWatch *) watch;
GtkPropertyExpression *self = (GtkPropertyExpression *) expr;
pwatch->notify = notify;
pwatch->user_data = user_data;
pwatch->expr = self;
pwatch->this = this_;
if (self->expr && !gtk_expression_is_static (self->expr))
{
gtk_expression_subwatch_init (self->expr,
(GtkExpressionSubWatch *) pwatch->sub,
this_,
gtk_property_expression_watch_expr_notify_cb,
pwatch);
}
gtk_property_expression_watch_create_closure (pwatch);
}
static void
gtk_property_expression_unwatch (GtkExpression *expr,
GtkExpressionSubWatch *watch)
{
GtkPropertyExpressionWatch *pwatch = (GtkPropertyExpressionWatch *) watch;
GtkPropertyExpression *self = (GtkPropertyExpression *) expr;
gtk_property_expression_watch_destroy_closure (pwatch);
if (self->expr && !gtk_expression_is_static (self->expr))
gtk_expression_subwatch_finish (self->expr, (GtkExpressionSubWatch *) pwatch->sub);
}
static const GtkExpressionTypeInfo gtk_property_expression_info =
{
sizeof (GtkPropertyExpression),
NULL,
gtk_property_expression_finalize,
gtk_property_expression_is_static,
gtk_property_expression_evaluate,
gtk_property_expression_watch_size,
gtk_property_expression_watch,
gtk_property_expression_unwatch
};
GTK_DEFINE_EXPRESSION_TYPE (GtkPropertyExpression,
gtk_property_expression,
&gtk_property_expression_info)
/**
* gtk_property_expression_new:
* @this_type: The type to expect for the this type
* @expression: (nullable) (transfer full): Expression to
* evaluate to get the object to query or %NULL to
* query the `this` object
* @property_name: name of the property
*
* Creates an expression that looks up a property via the
* given @expression or the `this` argument when @expression
* is %NULL.
*
* If the resulting object conforms to @this_type, its property
* named @property_name will be queried.
* Otherwise, this expression's evaluation will fail.
*
* The given @this_type must have a property with @property_name.
*
* Returns: a new #GtkExpression
**/
GtkExpression *
gtk_property_expression_new (GType this_type,
GtkExpression *expression,
const char *property_name)
{
GParamSpec *pspec;
if (g_type_is_a (this_type, G_TYPE_OBJECT))
{
GObjectClass *class = g_type_class_ref (this_type);
pspec = g_object_class_find_property (class, property_name);
g_type_class_unref (class);
}
else if (g_type_is_a (this_type, G_TYPE_INTERFACE))
{
GTypeInterface *iface = g_type_default_interface_ref (this_type);
pspec = g_object_interface_find_property (iface, property_name);
g_type_default_interface_unref (iface);
}
else
{
g_critical ("Type `%s` does not support properties", g_type_name (this_type));
return NULL;
}
if (pspec == NULL)
{
g_critical ("Type `%s` does not have a property named `%s`", g_type_name (this_type), property_name);
return NULL;
}
return gtk_property_expression_new_for_pspec (expression, pspec);
}
/**
* gtk_property_expression_new_for_pspec:
* @expression: (nullable) (transfer full): Expression to
* evaluate to get the object to query or %NULL to
* query the `this` object
* @pspec: the #GParamSpec for the property to query
*
* Creates an expression that looks up a property via the
* given @expression or the `this` argument when @expression
* is %NULL.
*
* If the resulting object conforms to @this_type, its
* property specified by @pspec will be queried.
* Otherwise, this expression's evaluation will fail.
*
* Returns: a new #GtkExpression
**/
GtkExpression *
gtk_property_expression_new_for_pspec (GtkExpression *expression,
GParamSpec *pspec)
{
GtkExpression *result;
GtkPropertyExpression *self;
result = gtk_expression_alloc (GTK_TYPE_PROPERTY_EXPRESSION, pspec->value_type);
self = (GtkPropertyExpression *) result;
self->pspec = pspec;
self->expr = expression;
return result;
}
/* }}} */
/* {{{ GtkClosureExpression */
typedef struct _GtkClosureExpression GtkClosureExpression;
struct _GtkClosureExpression
{
GtkExpression parent;
GClosure *closure;
guint n_params;
GtkExpression **params;
};
static void
gtk_closure_expression_finalize (GtkExpression *expr)
{
GtkClosureExpression *self = (GtkClosureExpression *) expr;
guint i;
for (i = 0; i < self->n_params; i++)
{
gtk_expression_unref (self->params[i]);
}
g_free (self->params);
g_closure_unref (self->closure);
GTK_EXPRESSION_SUPER (expr)->finalize (expr);
}
static gboolean
gtk_closure_expression_is_static (GtkExpression *expr)
{
GtkClosureExpression *self = (GtkClosureExpression *) expr;
guint i;
for (i = 0; i < self->n_params; i++)
{
if (!gtk_expression_is_static (self->params[i]))
return FALSE;
}
return TRUE;
}
static gboolean
gtk_closure_expression_evaluate (GtkExpression *expr,
gpointer this,
GValue *value)
{
GtkClosureExpression *self = (GtkClosureExpression *) expr;
GValue *instance_and_params;
gboolean result = TRUE;
guint i;
instance_and_params = g_alloca (sizeof (GValue) * (self->n_params + 1));
memset (instance_and_params, 0, sizeof (GValue) * (self->n_params + 1));
for (i = 0; i < self->n_params; i++)
{
if (!gtk_expression_evaluate (self->params[i], this, &instance_and_params[i + 1]))
{
result = FALSE;
goto out;
}
}
if (this)
g_value_init_from_instance (instance_and_params, this);
else
g_value_init (instance_and_params, G_TYPE_OBJECT);
g_value_init (value, expr->value_type);
g_closure_invoke (self->closure,
value,
self->n_params + 1,
instance_and_params,
NULL);
out:
for (i = 0; i < self->n_params + 1; i++)
g_value_unset (&instance_and_params[i]);
return result;
}
typedef struct _GtkClosureExpressionWatch GtkClosureExpressionWatch;
struct _GtkClosureExpressionWatch
{
GtkExpressionNotify notify;
gpointer user_data;
guchar sub[0];
};
static void
gtk_closure_expression_watch_notify_cb (gpointer data)
{
GtkClosureExpressionWatch *cwatch = data;
cwatch->notify (cwatch->user_data);
}
static gsize
gtk_closure_expression_watch_size (GtkExpression *expr)
{
GtkClosureExpression *self = (GtkClosureExpression *) expr;
gsize size;
guint i;
size = sizeof (GtkClosureExpressionWatch);
for (i = 0; i < self->n_params; i++)
{
if (gtk_expression_is_static (self->params[i]))
continue;
size += gtk_expression_watch_size (self->params[i]);
}
return size;
}
static void
gtk_closure_expression_watch (GtkExpression *expr,
GtkExpressionSubWatch *watch,
gpointer this_,
GtkExpressionNotify notify,
gpointer user_data)
{
GtkClosureExpressionWatch *cwatch = (GtkClosureExpressionWatch *) watch;
GtkClosureExpression *self = (GtkClosureExpression *) expr;
guchar *sub;
guint i;
cwatch->notify = notify;
cwatch->user_data = user_data;
sub = cwatch->sub;
for (i = 0; i < self->n_params; i++)
{
if (gtk_expression_is_static (self->params[i]))
continue;
gtk_expression_subwatch_init (self->params[i],
(GtkExpressionSubWatch *) sub,
this_,
gtk_closure_expression_watch_notify_cb,
watch);
sub += gtk_expression_watch_size (self->params[i]);
}
}
static void
gtk_closure_expression_unwatch (GtkExpression *expr,
GtkExpressionSubWatch *watch)
{
GtkClosureExpressionWatch *cwatch = (GtkClosureExpressionWatch *) watch;
GtkClosureExpression *self = (GtkClosureExpression *) expr;
guchar *sub;
guint i;
sub = cwatch->sub;
for (i = 0; i < self->n_params; i++)
{
if (gtk_expression_is_static (self->params[i]))
continue;
gtk_expression_subwatch_finish (self->params[i],
(GtkExpressionSubWatch *) sub);
sub += gtk_expression_watch_size (self->params[i]);
}
}
static const GtkExpressionTypeInfo gtk_closure_expression_info =
{
sizeof (GtkClosureExpression),
NULL,
gtk_closure_expression_finalize,
gtk_closure_expression_is_static,
gtk_closure_expression_evaluate,
gtk_closure_expression_watch_size,
gtk_closure_expression_watch,
gtk_closure_expression_unwatch
};
GTK_DEFINE_EXPRESSION_TYPE (GtkClosureExpression,
gtk_closure_expression,
&gtk_closure_expression_info)
/**
* gtk_closure_expression_new:
* @value_type: the type of the value that this expression evaluates to
* @closure: closure to call when evaluating this expression. If closure is floating, it is adopted
* @n_params: the number of params needed for evaluating @closure
* @params: (array length=n_params) (transfer full): expressions for each parameter
*
* Creates a GtkExpression that calls @closure when it is evaluated.
* @closure is called with the @this object and the results of evaluating
* the @params expressions.
*
* Returns: a new #GtkExpression
*/
GtkExpression *
gtk_closure_expression_new (GType value_type,
GClosure *closure,
guint n_params,
GtkExpression **params)
{
GtkExpression *result;
GtkClosureExpression *self;
guint i;
g_return_val_if_fail (closure != NULL, NULL);
g_return_val_if_fail (n_params == 0 || params != NULL, NULL);
result = gtk_expression_alloc (GTK_TYPE_CLOSURE_EXPRESSION, value_type);
self = (GtkClosureExpression *) result;
self->closure = g_closure_ref (closure);
g_closure_sink (closure);
if (G_CLOSURE_NEEDS_MARSHAL (closure))
g_closure_set_marshal (closure, g_cclosure_marshal_generic);
self->n_params = n_params;
self->params = g_new (GtkExpression *, n_params);
for (i = 0; i < n_params; i++)
self->params[i] = params[i];
return result;
}
/* }}} */
/* {{{ GtkCClosureExpression */
typedef struct _GtkCClosureExpression GtkCClosureExpression;
struct _GtkCClosureExpression
{
GtkClosureExpression parent;
};
static const GtkExpressionTypeInfo gtk_cclosure_expression_info =
{
sizeof (GtkClosureExpression),
NULL,
gtk_closure_expression_finalize,
gtk_closure_expression_is_static,
gtk_closure_expression_evaluate,
gtk_closure_expression_watch_size,
gtk_closure_expression_watch,
gtk_closure_expression_unwatch
};
GTK_DEFINE_EXPRESSION_TYPE (GtkCClosureExpression,
gtk_cclosure_expression,
&gtk_cclosure_expression_info)
/**
* gtk_cclosure_expression_new:
* @value_type: the type of the value that this expression evaluates to
* @marshal: (scope call): marshaller used for creating a closure
* @n_params: the number of params needed for evaluating @closure
* @params: (array length=n_params) (transfer full): expressions for each parameter
* @callback_func: (scope notified) (closure user_data) (destroy user_destroy): callback used for creating a closure
* @user_data: user data used for creating a closure
* @user_destroy: destroy notify for @user_data
*
* This function is a variant of gtk_closure_expression_new() that
* creates a #GClosure by calling gtk_cclosure_new() with the given
* @callback_func, @user_data and @user_destroy.
*
* Returns: a new #GtkExpression
*/
GtkExpression *
gtk_cclosure_expression_new (GType value_type,
GClosureMarshal marshal,
guint n_params,
GtkExpression **params,
GCallback callback_func,
gpointer user_data,
GClosureNotify user_destroy)
{
GtkExpression *result;
GtkClosureExpression *self;
GClosure *closure;
guint i;
g_return_val_if_fail (callback_func != NULL, NULL);
g_return_val_if_fail (n_params == 0 || params != NULL, NULL);
result = gtk_expression_alloc (GTK_TYPE_CCLOSURE_EXPRESSION, value_type);
self = (GtkClosureExpression *) result;
closure = g_cclosure_new (callback_func, user_data, user_destroy);
if (marshal)
g_closure_set_marshal (closure, marshal);
self->closure = g_closure_ref (closure);
g_closure_sink (closure);
if (G_CLOSURE_NEEDS_MARSHAL (closure))
g_closure_set_marshal (closure, g_cclosure_marshal_generic);
self->n_params = n_params;
self->params = g_new (GtkExpression *, n_params);
for (i = 0; i < n_params; i++)
self->params[i] = params[i];
return result;
}
/* }}} */
/* {{{ GtkExpression public API */
/**
* gtk_expression_ref:
* @self: (allow-none): a #GtkExpression
*
* Acquires a reference on the given #GtkExpression.
*
* Returns: (transfer none): the #GtkExpression with an additional reference
*/
GtkExpression *
gtk_expression_ref (GtkExpression *self)
{
g_return_val_if_fail (GTK_IS_EXPRESSION (self), NULL);
g_atomic_ref_count_inc (&self->ref_count);
return self;
}
/**
* gtk_expression_unref:
* @self: (allow-none): a #GtkExpression
*
* Releases a reference on the given #GtkExpression.
*
* If the reference was the last, the resources associated to the @self are
* freed.
*/
void
gtk_expression_unref (GtkExpression *self)
{
g_return_if_fail (GTK_IS_EXPRESSION (self));
if (g_atomic_ref_count_dec (&self->ref_count))
GTK_EXPRESSION_GET_CLASS (self)->finalize (self);
}
/**
* gtk_expression_get_value_type:
* @self: a #GtkExpression
*
* Gets the #GType that this expression evaluates to. This type
* is constant and will not change over the lifetime of this expression.
*
* Returns: The type returned from gtk_expression_evaluate()
**/
GType
gtk_expression_get_value_type (GtkExpression *self)
{
g_return_val_if_fail (GTK_IS_EXPRESSION (self), G_TYPE_INVALID);
return self->value_type;
}
/**
* gtk_expression_evaluate:
* @self: a #GtkExpression
* @this_: (transfer none) (type GObject) (nullable): the this argument for the evaluation
* @value: an empty #GValue
*
* Evaluates the given expression and on success stores the result
* in @value. The #GType of @value will be the type given by
* gtk_expression_get_value_type().
*
* It is possible that expressions cannot be evaluated - for example
* when the expression references objects that have been destroyed or
* set to %NULL. In that case @value will remain empty and %FALSE
* will be returned.
*
* Returns: %TRUE if the expression could be evaluated
**/
gboolean
gtk_expression_evaluate (GtkExpression *self,
gpointer this_,
GValue *value)
{
g_return_val_if_fail (GTK_IS_EXPRESSION (self), FALSE);
g_return_val_if_fail (this_ == NULL || G_IS_OBJECT (this_), FALSE);
g_return_val_if_fail (value != NULL, FALSE);
return GTK_EXPRESSION_GET_CLASS (self)->evaluate (self, this_, value);
}
/**
* gtk_expression_is_static:
* @self: a #GtkExpression
*
* Checks if the expression is static.
*
* A static expression will never change its result when
* gtk_expression_evaluate() is called on it with the same arguments.
*
* That means a call to gtk_expression_watch() is not necessary because
* it will never trigger a notify.
*
* Returns: %TRUE if the expression is static
**/
gboolean
gtk_expression_is_static (GtkExpression *self)
{
g_return_val_if_fail (GTK_IS_EXPRESSION (self), FALSE);
return GTK_EXPRESSION_GET_CLASS (self)->is_static (self);
}
static gboolean
gtk_expression_watch_is_watching (GtkExpressionWatch *watch)
{
return watch->expression != NULL;
}
static void
gtk_expression_watch_this_cb (gpointer data,
GObject *this)
{
GtkExpressionWatch *watch = data;
watch->this = NULL;
watch->notify (watch->user_data);
gtk_expression_watch_unwatch (watch);
}
static void
gtk_expression_watch_cb (gpointer data)
{
GtkExpressionWatch *watch = data;
if (!gtk_expression_watch_is_watching (watch))
return;
watch->notify (watch->user_data);
}
/**
* gtk_expression_watch:
* @self: a #GtkExpression
* @this_: (transfer none) (type GObject) (nullable): the `this` argument to
* watch
* @notify: (closure user_data): callback to invoke when the
* expression changes
* @user_data: user data to pass to @notify callback
* @user_destroy: destroy notify for @user_data
*
* Installs a watch for the given @expression that calls the @notify function
* whenever the evaluation of @self may have changed.
*
* GTK cannot guarantee that the evaluation did indeed change when the @notify
* gets invoked, but it guarantees the opposite: When it did in fact change,
* the @notify will be invoked.
*
* Returns: (transfer none): The newly installed watch. Note that the only
* reference held to the watch will be released when the watch is unwatched
* which can happen automatically, and not just via
* gtk_expression_watch_unwatch(). You should call gtk_expression_watch_ref()
* if you want to keep the watch around.
**/
GtkExpressionWatch *
gtk_expression_watch (GtkExpression *self,
gpointer this_,
GtkExpressionNotify notify,
gpointer user_data,
GDestroyNotify user_destroy)
{
GtkExpressionWatch *watch;
g_return_val_if_fail (self != NULL, NULL);
g_return_val_if_fail (this_ == NULL || G_IS_OBJECT (this_), NULL);
g_return_val_if_fail (notify != NULL, NULL);
watch = g_atomic_rc_box_alloc0 (sizeof (GtkExpressionWatch) + gtk_expression_watch_size (self));
watch->expression = gtk_expression_ref (self);
watch->this = this_;
if (this_)
g_object_weak_ref (this_, gtk_expression_watch_this_cb, watch);
watch->notify = notify;
watch->user_data = user_data;
watch->user_destroy = user_destroy;
gtk_expression_subwatch_init (self,
(GtkExpressionSubWatch *) watch->sub,
this_,
gtk_expression_watch_cb,
watch);
return watch;
}
/**
* gtk_expression_watch_ref:
* @watch: (allow-none): a #GtkExpressionWatch
*
* Acquires a reference on the given #GtkExpressionWatch.
*
* Returns: (transfer none): the #GtkExpression with an additional reference
*/
GtkExpressionWatch *
gtk_expression_watch_ref (GtkExpressionWatch *watch)
{
return g_atomic_rc_box_acquire (watch);
}
static void
gtk_expression_watch_finalize (gpointer data)
{
GtkExpressionWatch *watch = data;
g_assert (!gtk_expression_watch_is_watching (watch));
}
/**
* gtk_expression_watch_unref:
* @watch: (allow-none): a #GtkExpressionWatch
*
* Releases a reference on the given #GtkExpressionWatch.
*
* If the reference was the last, the resources associated to @self are
* freed.
*/
void
gtk_expression_watch_unref (GtkExpressionWatch *watch)
{
g_atomic_rc_box_release_full (watch, gtk_expression_watch_finalize);
}
/**
* gtk_expression_watch_unwatch:
* @watch: (transfer none): watch to release
*
* Stops watching an expression that was established via gtk_expression_watch().
**/
void
gtk_expression_watch_unwatch (GtkExpressionWatch *watch)
{
if (!gtk_expression_watch_is_watching (watch))
return;
gtk_expression_subwatch_finish (watch->expression, (GtkExpressionSubWatch *) watch->sub);
if (watch->this)
g_object_weak_unref (watch->this, gtk_expression_watch_this_cb, watch);
if (watch->user_destroy)
watch->user_destroy (watch->user_data);
g_clear_pointer (&watch->expression, gtk_expression_unref);
gtk_expression_watch_unref (watch);
}
/**
* gtk_expression_watch_evaluate:
* @watch: a #GtkExpressionWatch
* @value: an empty #GValue to be set
*
* Evaluates the watched expression and on success stores the result
* in @value.
*
* This is equivalent to calling gtk_expression_evaluate() with the
* expression and this pointer originally used to create @watch.
*
* Returns: %TRUE if the expression could be evaluated and @value was set
**/
gboolean
gtk_expression_watch_evaluate (GtkExpressionWatch *watch,
GValue *value)
{
g_return_val_if_fail (watch != NULL, FALSE);
if (!gtk_expression_watch_is_watching (watch))
return FALSE;
return gtk_expression_evaluate (watch->expression, watch->this, value);
}
typedef struct {
GtkExpressionWatch *watch;
GObject *target;
GParamSpec *pspec;
} GtkExpressionBind;
static void
invalidate_binds (gpointer unused,
GObject *object)
{
GSList *l, *binds;
binds = g_object_get_data (object, "gtk-expression-binds");
for (l = binds; l; l = l->next)
{
GtkExpressionBind *bind = l->data;
/* This guarantees we neither try to update bindings
* (which would wreck havoc because the object is
* dispose()ing itself) nor try to destroy bindings
* anymore, so destruction can be done in free_binds().
*/
bind->target = NULL;
}
}
static void
free_binds (gpointer data)
{
GSList *l;
for (l = data; l; l = l->next)
{
GtkExpressionBind *bind = l->data;
g_assert (bind->target == NULL);
if (bind->watch)
gtk_expression_watch_unwatch (bind->watch);
g_slice_free (GtkExpressionBind, bind);
}
g_slist_free (data);
}
static void
gtk_expression_bind_free (gpointer data)
{
GtkExpressionBind *bind = data;
if (bind->target)
{
GSList *binds;
binds = g_object_steal_data (bind->target, "gtk-expression-binds");
binds = g_slist_remove (binds, bind);
if (binds)
g_object_set_data_full (bind->target, "gtk-expression-binds", binds, free_binds);
else
g_object_weak_unref (bind->target, invalidate_binds, NULL);
g_slice_free (GtkExpressionBind, bind);
}
else
{
/* If a bind gets unwatched after invalidate_binds() but
* before free_binds(), we end up here. This can happen if
* the bind was watching itself or if the target's dispose()
* function freed the object that was watched.
* We make sure we don't destroy the binding or free_binds() will do
* bad stuff, but we clear the watch, so free_binds() won't try to
* unwatch() it.
*/
bind->watch = NULL;
}
}
static void
gtk_expression_bind_notify (gpointer data)
{
GValue value = G_VALUE_INIT;
GtkExpressionBind *bind = data;
if (bind->target == NULL)
return;
if (!gtk_expression_watch_evaluate (bind->watch, &value))
return;
g_object_set_property (bind->target, bind->pspec->name, &value);
g_value_unset (&value);
}
/**
* gtk_expression_bind:
* @self: (transfer full): a #GtkExpression
* @target: (transfer none) (type GObject): the target object to bind to
* @property: name of the property on @target to bind to
* @this_: (transfer none) (type GObject): the this argument for
* the evaluation of @self
*
* Bind @target's property named @property to @self.
*
* The value that @self evaluates to is set via g_object_set() on
* @target. This is repeated whenever @self changes to ensure that
* the object's property stays synchronized with @self.
*
* If @self's evaluation fails, @target's @property is not updated.
* You can ensure that this doesn't happen by using a fallback
* expression.
*
* Note that this function takes ownership of @self. If you want
* to keep it around, you should gtk_expression_ref() it beforehand.
*
* Returns: (transfer none): a #GtkExpressionWatch
**/
GtkExpressionWatch *
gtk_expression_bind (GtkExpression *self,
gpointer target,
const char *property,
gpointer this_)
{
GtkExpressionBind *bind;
GParamSpec *pspec;
GSList *binds;
g_return_val_if_fail (GTK_IS_EXPRESSION (self), NULL);
g_return_val_if_fail (G_IS_OBJECT (target), NULL);
g_return_val_if_fail (property != NULL, NULL);
pspec = g_object_class_find_property (G_OBJECT_GET_CLASS (target), property);
if (G_UNLIKELY (pspec == NULL))
{
g_critical ("%s: Class '%s' has no property named '%s'",
G_STRFUNC, G_OBJECT_TYPE_NAME (target), property);
return NULL;
}
if (G_UNLIKELY ((pspec->flags & (G_PARAM_WRITABLE | G_PARAM_CONSTRUCT_ONLY)) != G_PARAM_WRITABLE))
{
g_critical ("%s: property '%s' of class '%s' is not writable",
G_STRFUNC, pspec->name, G_OBJECT_TYPE_NAME (target));
return NULL;
}
bind = g_slice_new0 (GtkExpressionBind);
binds = g_object_steal_data (target, "gtk-expression-binds");
if (binds == NULL)
g_object_weak_ref (target, invalidate_binds, NULL);
bind->target = target;
bind->pspec = pspec;
bind->watch = gtk_expression_watch (self,
this_,
gtk_expression_bind_notify,
bind,
gtk_expression_bind_free);
binds = g_slist_prepend (binds, bind);
g_object_set_data_full (target, "gtk-expression-binds", binds, free_binds);
gtk_expression_unref (self);
gtk_expression_bind_notify (bind);
return bind->watch;
}
/* }}} */
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