AuroraMiddleware/gtk2
1
0
Fork 0
forked from AuroraMiddleware/gtk
Code Issues Pull Requests Projects Releases Wiki Activity
7a56aa910e
gtk2/gtk/gtkexpression.c
Matthias Clasen 8696b78e59 expression: Tweak docs
2021-03-11 16:37:35 +00:00

2175 lines
62 KiB
C
Raw Blame History

This file contains ambiguous Unicode characters

This file contains Unicode characters that might be confused with other characters. If you think that this is intentional, you can safely ignore this warning. Use the Escape button to reveal them.

/*
* 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"
/* XXX: For g_memdup2() */
#include "gtkprivate.h"
#include <gobject/gvaluecollector.h>
/**
* 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)
*
* `GtkExpression` provides a way to describe references to values.
*
* An important aspect of expressions is that the value can be obtained
* from a source that is several steps away. For example, an expression
* may describe ‘the value of property A of `object1`, which is itself the
* value of a property of `object2`’. And `object1` may not even exist yet
* at the time that the expression is created. This is contrast to `GObject`
* property bindings, which can only create direct connections between
* the properties of two objects that must both exist for the duration
* of the binding.
*
* 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
* [method@Gtk.Expression.evaluate] for evaluating an expression.
*
* Various methods for defining expressions exist, from simple constants via
* [ctor@Gtk.ConstantExpression.new] to looking up properties in a `GObject`
* (even recursively) via [ctor@Gtk.PropertyExpression.new] or providing
* custom functions to transform and combine expressions via
* [ctor@Gtk.ClosureExpression.new].
*
* Here is an example of a complex expression:
*
* ```c
* color_expr = gtk_property_expression_new (GTK_TYPE_LIST_ITEM,
* NULL, "item");
* expression = gtk_property_expression_new (GTK_TYPE_COLOR,
* color_expr, "name");
* ```
*
* when evaluated with `this` being a `GtkListItem`, it will obtain the
* "item" property from the `GtkListItem`, and then obtain the "name" property
* from the resulting object (which is assumed to be of type `GTK_TYPE_COLOR`).
*
* A more concise way to describe this would be
*
* ```
* this->item->name
* ```
*
* The most likely place where you will encounter expressions is in the context
* of list models and list widgets using them. For example, `GtkDropDown` is
* evaluating a `GtkExpression` to obtain strings from the items in its model
* that it can then use to match against the contents of its search entry.
* `GtkStringFilter` is using a `GtkExpression` for similar reasons.
*
* 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 [struct@Gtk.ExpressionWatch],
* which will cause a callback to be called whenever the value of the expression may
* have changed; [method@Gtk.Expression.watch] starts watching an expression, and
* [method@Gtk.ExpressionWatch.unwatch] stops.
*
* Watches can be created for automatically updating the property of an object,
* similar to GObject's `GBinding` mechanism, by using [method@Gtk.Expression.bind].
*
* ## GtkExpression in GObject properties
*
* In order to use a `GtkExpression` as a `GObject` property, you must use the
* [id@gtk_param_spec_expression] when creating a `GParamSpec` to install in the
* `GObject` class being defined; for instance:
*
* ```c
* 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 [id@gtk_value_get_expression], to retrieve the
* stored `GtkExpression` from the `GValue` container, and [id@gtk_value_set_expression],
* to store the `GtkExpression` into the `GValue`; for instance:
*
* ```c
* // 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:
*
* ```xml
* <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. For instance:
*
* ```xml
* <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. For instance:
*
* ```xml
* <closure type='gchararray' function='combine_args_somehow'>
* <constant type='gchararray'>File size:</constant>
* <lookup type='GFile' name='size'>myfile</lookup>
* </closure>
* ```
*/
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);
};
/**
* GtkExpressionWatch:
*
* An opaque structure representing a watched `GtkExpression`.
*
* The contents of `GtkExpressionWatch` should only be accessed through the
* provided API.
*/
struct _GtkExpressionWatch
{
GtkExpression *expression;
GObject *this;
GDestroyNotify user_destroy;
GtkExpressionNotify notify;
gpointer user_data;
guchar sub[0];
};
G_DEFINE_BOXED_TYPE (GtkExpressionWatch, gtk_expression_watch,
gtk_expression_watch_ref,
gtk_expression_watch_unref)
#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 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 char *
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 int
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 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 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_memdup2 (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 */
/**
* GtkConstantExpression:
*
* A constant value in a `GtkExpression`.
*/
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: (transfer full) (type GtkConstantExpression): 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: (constructor)
* @value: a `GValue`
*
* Creates an expression that always evaluates to the given `value`.
*
* Returns: (transfer full) (type GtkConstantExpression): 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;
}
/**
* gtk_constant_expression_get_value:
* @expression: (type GtkConstantExpression): a constant `GtkExpression`
*
* Gets the value that a constant expression evaluates to.
*
* Returns: (transfer none): the value
*/
const GValue *
gtk_constant_expression_get_value (GtkExpression *expression)
{
GtkConstantExpression *self = (GtkConstantExpression *) expression;
g_return_val_if_fail (G_TYPE_CHECK_INSTANCE_TYPE (expression, GTK_TYPE_CONSTANT_EXPRESSION), NULL);
return &self->value;
}
/* }}} */
/* {{{ GtkObjectExpression */
typedef struct _GtkObjectExpressionWatch GtkObjectExpressionWatch;
/**
* GtkObjectExpression:
*
* A `GObject` value in a `GtkExpression`.
*/
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: (constructor)
* @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 [ctor@Gtk.ConstantExpression.new].
*
* Returns: (type GtkObjectExpression) (transfer full): 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;
}
/**
* gtk_object_expression_get_object:
* @expression: (type GtkObjectExpression): an object `GtkExpression`
*
* Gets the object that the expression evaluates to.
*
* Returns: (transfer none) (nullable): the object, or `NULL`
*/
GObject *
gtk_object_expression_get_object (GtkExpression *expression)
{
GtkObjectExpression *self = (GtkObjectExpression *) expression;
g_return_val_if_fail (G_TYPE_CHECK_INSTANCE_TYPE (expression, GTK_TYPE_OBJECT_EXPRESSION), NULL);
return self->object;
}
/* }}} */
/* {{{ GtkPropertyExpression */
/**
* GtkPropertyExpression:
*
* A `GObject` property value in a `GtkExpression`.
*/
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: (constructor)
* @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: (type GtkPropertyExpression) (transfer full): a new `GtkExpression`
**/
GtkExpression *
gtk_property_expression_new (GType this_type,
GtkExpression *expression,
const char *property_name)
{
GParamSpec *pspec;
if (g_type_fundamental (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_fundamental (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: (constructor)
* @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: (type GtkPropertyExpression) (transfer full): 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;
}
/**
* gtk_property_expression_get_expression:
* @expression: (type GtkPropertyExpression): a property `GtkExpression`
*
* Gets the expression specifying the object of
* a property expression.
*
* Returns: (transfer none): the object expression
*/
GtkExpression *
gtk_property_expression_get_expression (GtkExpression *expression)
{
GtkPropertyExpression *self = (GtkPropertyExpression *) expression;
g_return_val_if_fail (G_TYPE_CHECK_INSTANCE_TYPE (expression, GTK_TYPE_PROPERTY_EXPRESSION), NULL);
return self->expr;
}
/**
* gtk_property_expression_get_pspec:
* @expression: (type GtkPropertyExpression): a property `GtkExpression`
*
* Gets the `GParamSpec` specifying the property of
* a property expression.
*
* Returns: (transfer none): the `GParamSpec` for the property
*/
GParamSpec *
gtk_property_expression_get_pspec (GtkExpression *expression)
{
GtkPropertyExpression *self = (GtkPropertyExpression *) expression;
g_return_val_if_fail (G_TYPE_CHECK_INSTANCE_TYPE (expression, GTK_TYPE_PROPERTY_EXPRESSION), NULL);
return self->pspec;
}
/* }}} */
/* {{{ GtkClosureExpression */
/**
* GtkClosureExpression:
*
* An expression using a custom `GClosure` to compute the value from
* its parameters.
*/
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: (constructor)
* @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: (nullable) (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: (transfer full) (type GtkClosureExpression): 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 */
/**
* GtkCClosureExpression:
*
* A variant of `GtkClosureExpression` using a C closure.
*/
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: (constructor)
* @value_type: the type of the value that this expression evaluates to
* @marshal: (scope call) (nullable): 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: (nullable): user data used for creating a closure
* @user_destroy: (nullable): destroy notify for @user_data
*
* This function is a variant of [ctor@Gtk.ClosureExpression.new] that
* creates a `GClosure` by calling `g_cclosure_new()` with the given
* `callback_func`, `user_data` and `user_destroy`.
*
* Returns: (transfer full) (type GtkCClosureExpression): 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: a `GtkExpression`
*
* Acquires a reference on the given `GtkExpression`.
*
* Returns: (transfer full): 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: (transfer full): 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 [method@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
* [method@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
* [method@Gtk.Expression.evaluate] is called on it with the same arguments.
*
* That means a call to [method@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 the `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
* [method@Gtk.ExpressionWatch.unwatch]. You should call [method@Gtk.ExpressionWatch.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: a `GtkExpressionWatch`
*
* Acquires a reference on the given `GtkExpressionWatch`.
*
* Returns: (transfer full): the `GtkExpressionWatch` 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: (transfer full): 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.
*
* See [method@Gtk.Expression.watch] for how the watch
* was established.
*/
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 [method@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) (nullable): 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 [method@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);
g_return_val_if_fail (this_ == NULL || G_IS_OBJECT (this_), 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;
}
/* }}} */
Reference in New Issue View Git Blame Copy Permalink