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Keyed Data ListsKeyed Data Lists — lists of data elements which are accessible by a string or GQuark identifier |
Functions
void | g_datalist_init () |
#define | g_datalist_id_set_data() |
void | g_datalist_id_set_data_full () |
gpointer | g_datalist_id_get_data () |
#define | g_datalist_id_remove_data() |
gpointer | g_datalist_id_remove_no_notify () |
gpointer | (*GDuplicateFunc) () |
gpointer | g_datalist_id_dup_data () |
gboolean | g_datalist_id_replace_data () |
#define | g_datalist_set_data() |
#define | g_datalist_set_data_full() |
gpointer | g_datalist_get_data () |
#define | g_datalist_remove_data() |
#define | g_datalist_remove_no_notify() |
void | g_datalist_foreach () |
void | g_datalist_clear () |
void | g_datalist_set_flags () |
void | g_datalist_unset_flags () |
guint | g_datalist_get_flags () |
Description
Keyed data lists provide lists of arbitrary data elements which can be accessed either with a string or with a GQuark corresponding to the string.
The GQuark methods are quicker, since the strings have to be converted to GQuarks anyway.
Data lists are used for associating arbitrary data with GObjects,
using g_object_set_data()
and related functions.
To create a datalist, use g_datalist_init()
.
To add data elements to a datalist use g_datalist_id_set_data()
,
g_datalist_id_set_data_full()
, g_datalist_set_data()
and
g_datalist_set_data_full()
.
To get data elements from a datalist use g_datalist_id_get_data()
and g_datalist_get_data()
.
To iterate over all data elements in a datalist use
g_datalist_foreach()
(not thread-safe).
To remove data elements from a datalist use
g_datalist_id_remove_data()
and g_datalist_remove_data()
.
To remove all data elements from a datalist, use g_datalist_clear()
.
Functions
g_datalist_init ()
void
g_datalist_init (GData **datalist
);
Resets the datalist to NULL
. It does not free any memory or call
any destroy functions.
g_datalist_id_set_data()
#define g_datalist_id_set_data(dl, q, d)
Sets the data corresponding to the given GQuark id. Any previous data with the same key is removed, and its destroy function is called.
g_datalist_id_set_data_full ()
void g_datalist_id_set_data_full (GData **datalist
,GQuark key_id
,gpointer data
,GDestroyNotify destroy_func
);
Sets the data corresponding to the given GQuark id, and the function to be called when the element is removed from the datalist. Any previous data with the same key is removed, and its destroy function is called.
Parameters
datalist |
a datalist. |
|
key_id |
the GQuark to identify the data element. |
|
data |
the data element or |
[allow-none] |
destroy_func |
the function to call when the data element is
removed. This function will be called with the data
element and can be used to free any memory allocated
for it. If |
g_datalist_id_get_data ()
gpointer g_datalist_id_get_data (GData **datalist
,GQuark key_id
);
Retrieves the data element corresponding to key_id
.
g_datalist_id_remove_data()
#define g_datalist_id_remove_data(dl, q)
Removes an element, using its GQuark identifier.
g_datalist_id_remove_no_notify ()
gpointer g_datalist_id_remove_no_notify (GData **datalist
,GQuark key_id
);
Removes an element, without calling its destroy notification function.
GDuplicateFunc ()
gpointer (*GDuplicateFunc) (gpointer data
,gpointer user_data
);
The type of functions that are used to 'duplicate' an object.
What this means depends on the context, it could just be
incrementing the reference count, if data
is a ref-counted
object.
Parameters
data |
the data to duplicate |
|
user_data |
user data that was specified in |
g_datalist_id_dup_data ()
gpointer g_datalist_id_dup_data (GData **datalist
,GQuark key_id
,GDuplicateFunc dup_func
,gpointer user_data
);
This is a variant of g_datalist_id_get_data()
which
returns a 'duplicate' of the value. dup_func
defines the
meaning of 'duplicate' in this context, it could e.g.
take a reference on a ref-counted object.
If the key_id
is not set in the datalist then dup_func
will be called with a NULL
argument.
Note that dup_func
is called while the datalist is locked, so it
is not allowed to read or modify the datalist.
This function can be useful to avoid races when multiple threads are using the same datalist and the same key.
Parameters
datalist |
location of a datalist |
|
key_id |
the GQuark identifying a data element |
|
dup_func |
function to duplicate the old value. |
[allow-none] |
user_data |
passed as user_data to |
[allow-none] |
Returns
the result of calling dup_func
on the value
associated with key_id
in datalist
, or NULL
if not set.
If dup_func
is NULL
, the value is returned unmodified.
Since 2.34
g_datalist_id_replace_data ()
gboolean g_datalist_id_replace_data (GData **datalist
,GQuark key_id
,gpointer oldval
,gpointer newval
,GDestroyNotify destroy
,GDestroyNotify *old_destroy
);
Compares the member that is associated with key_id
in
datalist
to oldval
, and if they are the same, replace
oldval
with newval
.
This is like a typical atomic compare-and-exchange
operation, for a member of datalist
.
If the previous value was replaced then ownership of the
old value (oldval
) is passed to the caller, including
the registred destroy notify for it (passed out in old_destroy
).
Its up to the caller to free this as he wishes, which may
or may not include using old_destroy
as sometimes replacement
should not destroy the object in the normal way.
Return: TRUE
if the existing value for key_id
was replaced
by newval
, FALSE
otherwise.
Parameters
datalist |
location of a datalist |
|
key_id |
the GQuark identifying a data element |
|
oldval |
the old value to compare against. |
[allow-none] |
newval |
the new value to replace it with. |
[allow-none] |
destroy |
destroy notify for the new value. |
[allow-none] |
old_destroy |
destroy notify for the existing value. |
[allow-none] |
Since 2.34
g_datalist_set_data()
#define g_datalist_set_data(dl, k, d)
Sets the data element corresponding to the given string identifier.
Parameters
dl |
a datalist. |
|
k |
the string to identify the data element. |
|
d |
the data element, or |
[allow-none] |
g_datalist_set_data_full()
#define g_datalist_set_data_full(dl, k, d, f)
Sets the data element corresponding to the given string identifier, and the function to be called when the data element is removed.
Parameters
dl |
a datalist. |
|
k |
the string to identify the data element. |
|
d |
the data element, or |
[allow-none] |
f |
the function to call when the data element is removed. This
function will be called with the data element and can be used to
free any memory allocated for it. If |
g_datalist_get_data ()
gpointer g_datalist_get_data (GData **datalist
,const gchar *key
);
Gets a data element, using its string identifier. This is slower than
g_datalist_id_get_data()
because it compares strings.
g_datalist_remove_data()
#define g_datalist_remove_data(dl, k)
Removes an element using its string identifier. The data element's destroy function is called if it has been set.
g_datalist_remove_no_notify()
#define g_datalist_remove_no_notify(dl, k)
Removes an element, without calling its destroy notifier.
g_datalist_foreach ()
void g_datalist_foreach (GData **datalist
,GDataForeachFunc func
,gpointer user_data
);
Calls the given function for each data element of the datalist. The
function is called with each data element's GQuark id and data,
together with the given user_data
parameter. Note that this
function is NOT thread-safe. So unless datalist
can be protected
from any modifications during invocation of this function, it should
not be called.
g_datalist_clear ()
void
g_datalist_clear (GData **datalist
);
Frees all the data elements of the datalist. The data elements' destroy functions are called if they have been set.
g_datalist_set_flags ()
void g_datalist_set_flags (GData **datalist
,guint flags
);
Turns on flag values for a data list. This function is used to keep a small number of boolean flags in an object with a data list without using any additional space. It is not generally useful except in circumstances where space is very tight. (It is used in the base GObject type, for example.)
Parameters
datalist |
pointer to the location that holds a list |
|
flags |
the flags to turn on. The values of the flags are
restricted by |
Since 2.8
g_datalist_unset_flags ()
void g_datalist_unset_flags (GData **datalist
,guint flags
);
Turns off flag values for a data list. See g_datalist_unset_flags()
Parameters
datalist |
pointer to the location that holds a list |
|
flags |
the flags to turn off. The values of the flags are
restricted by |
Since 2.8
g_datalist_get_flags ()
guint
g_datalist_get_flags (GData **datalist
);
Gets flags values packed in together with the datalist.
See g_datalist_set_flags()
.
Since 2.8
Types and Values
GData
typedef struct _GData GData;
The GData struct is an opaque data structure to represent a Keyed Data List. It should only be accessed via the following functions.
G_DATALIST_FLAGS_MASK
#define G_DATALIST_FLAGS_MASK 0x3
A bitmask that restricts the possible flags passed to
g_datalist_set_flags()
. Passing a flags value where
flags & ~G_DATALIST_FLAGS_MASK != 0 is an error.