Hook Functions

Hook Functions — support for manipulating lists of hook functions

Synopsis


#include <glib.h>

                    GHookList;
void                (*GHookFinalizeFunc)                (GHookList *hook_list,
                                                         GHook *hook);
                    GHook;
void                (*GHookFunc)                        (gpointer data);
gboolean            (*GHookCheckFunc)                   (gpointer data);

void                g_hook_list_init                    (GHookList *hook_list,
                                                         guint hook_size);
void                g_hook_list_invoke                  (GHookList *hook_list,
                                                         gboolean may_recurse);
void                g_hook_list_invoke_check            (GHookList *hook_list,
                                                         gboolean may_recurse);
void                g_hook_list_marshal                 (GHookList *hook_list,
                                                         gboolean may_recurse,
                                                         GHookMarshaller marshaller,
                                                         gpointer marshal_data);
void                (*GHookMarshaller)                  (GHook *hook,
                                                         gpointer marshal_data);
void                g_hook_list_marshal_check           (GHookList *hook_list,
                                                         gboolean may_recurse,
                                                         GHookCheckMarshaller marshaller,
                                                         gpointer marshal_data);
gboolean            (*GHookCheckMarshaller)             (GHook *hook,
                                                         gpointer marshal_data);
void                g_hook_list_clear                   (GHookList *hook_list);

GHook*              g_hook_alloc                        (GHookList *hook_list);
#define             g_hook_append                       ( hook_list, hook )
void                g_hook_prepend                      (GHookList *hook_list,
                                                         GHook *hook);
void                g_hook_insert_before                (GHookList *hook_list,
                                                         GHook *sibling,
                                                         GHook *hook);
void                g_hook_insert_sorted                (GHookList *hook_list,
                                                         GHook *hook,
                                                         GHookCompareFunc func);
gint                (*GHookCompareFunc)                 (GHook *new_hook,
                                                         GHook *sibling);
gint                g_hook_compare_ids                  (GHook *new_hook,
                                                         GHook *sibling);

GHook*              g_hook_get                          (GHookList *hook_list,
                                                         gulong hook_id);
GHook*              g_hook_find                         (GHookList *hook_list,
                                                         gboolean need_valids,
                                                         GHookFindFunc func,
                                                         gpointer data);
gboolean            (*GHookFindFunc)                    (GHook *hook,
                                                         gpointer data);
GHook*              g_hook_find_data                    (GHookList *hook_list,
                                                         gboolean need_valids,
                                                         gpointer data);
GHook*              g_hook_find_func                    (GHookList *hook_list,
                                                         gboolean need_valids,
                                                         gpointer func);
GHook*              g_hook_find_func_data               (GHookList *hook_list,
                                                         gboolean need_valids,
                                                         gpointer func,
                                                         gpointer data);

GHook*              g_hook_first_valid                  (GHookList *hook_list,
                                                         gboolean may_be_in_call);
GHook*              g_hook_next_valid                   (GHookList *hook_list,
                                                         GHook *hook,
                                                         gboolean may_be_in_call);
enum                GHookFlagMask;
#define             G_HOOK_FLAGS                        (hook)
#define             G_HOOK_FLAG_USER_SHIFT

#define             G_HOOK                              (hook)
#define             G_HOOK_IS_VALID                     (hook)
#define             G_HOOK_ACTIVE                       (hook)
#define             G_HOOK_IN_CALL                      (hook)
#define             G_HOOK_IS_UNLINKED                  (hook)

GHook*              g_hook_ref                          (GHookList *hook_list,
                                                         GHook *hook);
void                g_hook_unref                        (GHookList *hook_list,
                                                         GHook *hook);
void                g_hook_free                         (GHookList *hook_list,
                                                         GHook *hook);
gboolean            g_hook_destroy                      (GHookList *hook_list,
                                                         gulong hook_id);
void                g_hook_destroy_link                 (GHookList *hook_list,
                                                         GHook *hook);

Description

The GHookList, GHook and their related functions provide support for lists of hook functions. Functions can be added and removed from the lists, and the list of hook functions can be invoked.

Details

GHookList

typedef struct {
  gulong	    seq_id;
  guint		    hook_size : 16;
  guint		    is_setup : 1;
  GHook		   *hooks;
  gpointer	    dummy3;
  GHookFinalizeFunc finalize_hook;
  gpointer	    dummy[2];
} GHookList;

The GHookList struct represents a list of hook functions.

gulong `seq_id`;	the next free GHook id
guint `hook_size` : 16;	the size of the GHookList elements, in bytes
guint `is_setup` : 1;	1 if the GHookList has been initialized
GHook *`hooks`;	the first GHook element in the list
gpointer `dummy3`;	unused
GHookFinalizeFunc `finalize_hook`;	the function to call to finalize a GHook element. The default behaviour is to call the hooks `destroy` function
gpointer `dummy`[2];	unused

GHookFinalizeFunc ()

void                (*GHookFinalizeFunc)                (GHookList *hook_list,
                                                         GHook *hook);

Defines the type of function to be called when a hook in a list of hooks gets finalized.

`hook_list` :	a GHookList
`hook` :	the hook in `hook_list` that gets finalized

GHook

typedef struct {
  gpointer	 data;
  GHook		*next;
  GHook		*prev;
  guint		 ref_count;
  gulong	 hook_id;
  guint		 flags;
  gpointer	 func;
  GDestroyNotify destroy;
} GHook;

The GHook struct represents a single hook function in a GHookList.

gpointer `data`;	data which is passed to func when this hook is invoked
GHook *`next`;	pointer to the next hook in the list
GHook *`prev`;	pointer to the previous hook in the list
guint `ref_count`;	the reference count of this hook
gulong `hook_id`;	the id of this hook, which is unique within its list
guint `flags`;	flags which are set for this hook. See GHookFlagMask for predefined flags
gpointer `func`;	the function to call when this hook is invoked. The possible signatures for this function are GHookFunc and GHookCheckFunc
GDestroyNotify `destroy`;	the default `finalize_hook` function of a GHookList calls this member of the hook that is being finalized

GHookFunc ()

void                (*GHookFunc)                        (gpointer data);

Defines the type of a hook function that can be invoked by g_hook_list_invoke().

data : the data field of the GHook is passed to the hook function here

GHookCheckFunc ()

gboolean            (*GHookCheckFunc)                   (gpointer data);

Defines the type of a hook function that can be invoked by g_hook_list_invoke_check().

`data` :	the data field of the GHook is passed to the hook function here
Returns :	`FALSE` if the GHook should be destroyed

g_hook_list_init ()

void                g_hook_list_init                    (GHookList *hook_list,
                                                         guint hook_size);

Initializes a GHookList. This must be called before the GHookList is used.

`hook_list` :	a GHookList
`hook_size` :	the size of each element in the GHookList, typically `sizeof (GHook)`

g_hook_list_invoke ()

void                g_hook_list_invoke                  (GHookList *hook_list,
                                                         gboolean may_recurse);

Calls all of the GHook functions in a GHookList.

`hook_list` :	a GHookList
`may_recurse` :	`TRUE` if functions which are already running (e.g. in another thread) can be called. If set to `FALSE`, these are skipped

g_hook_list_invoke_check ()

void                g_hook_list_invoke_check            (GHookList *hook_list,
                                                         gboolean may_recurse);

Calls all of the GHook functions in a GHookList. Any function which returns FALSE is removed from the GHookList.

`hook_list` :	a GHookList
`may_recurse` :	`TRUE` if functions which are already running (e.g. in another thread) can be called. If set to `FALSE`, these are skipped

g_hook_list_marshal ()

void                g_hook_list_marshal                 (GHookList *hook_list,
                                                         gboolean may_recurse,
                                                         GHookMarshaller marshaller,
                                                         gpointer marshal_data);

Calls a function on each valid GHook.

`hook_list` :	a GHookList
`may_recurse` :	`TRUE` if hooks which are currently running (e.g. in another thread) are considered valid. If set to `FALSE`, these are skipped
`marshaller` :	the function to call for each GHook
`marshal_data` :	data to pass to `marshaller`

GHookMarshaller ()

void                (*GHookMarshaller)                  (GHook *hook,
                                                         gpointer marshal_data);

Defines the type of function used by g_hook_list_marshal().

`hook` :	a GHook
`marshal_data` :	user data

g_hook_list_marshal_check ()

void                g_hook_list_marshal_check           (GHookList *hook_list,
                                                         gboolean may_recurse,
                                                         GHookCheckMarshaller marshaller,
                                                         gpointer marshal_data);

Calls a function on each valid GHook and destroys it if the function returns FALSE.

`hook_list` :	a GHookList
`may_recurse` :	`TRUE` if hooks which are currently running (e.g. in another thread) are considered valid. If set to `FALSE`, these are skipped
`marshaller` :	the function to call for each GHook
`marshal_data` :	data to pass to `marshaller`

GHookCheckMarshaller ()

gboolean            (*GHookCheckMarshaller)             (GHook *hook,
                                                         gpointer marshal_data);

Defines the type of function used by g_hook_list_marshal_check().

`hook` :	a GHook
`marshal_data` :	user data
Returns :	`FALSE` if `hook` should be destroyed

g_hook_list_clear ()

void                g_hook_list_clear                   (GHookList *hook_list);

Removes all the GHook elements from a GHookList.

hook_list : a GHookList

g_hook_alloc ()

GHook*              g_hook_alloc                        (GHookList *hook_list);

Allocates space for a GHook and initializes it.

`hook_list` :	a GHookList
Returns :	a new GHook

g_hook_append()

#define             g_hook_append( hook_list, hook )

Appends a GHook onto the end of a GHookList.

`hook_list` :	a GHookList
`hook` :	the GHook to add to the end of `hook_list`

g_hook_prepend ()

void                g_hook_prepend                      (GHookList *hook_list,
                                                         GHook *hook);

Prepends a GHook on the start of a GHookList.

`hook_list` :	a GHookList
`hook` :	the GHook to add to the start of `hook_list`

g_hook_insert_before ()

void                g_hook_insert_before                (GHookList *hook_list,
                                                         GHook *sibling,
                                                         GHook *hook);

Inserts a GHook into a GHookList, before a given GHook.

`hook_list` :	a GHookList
`sibling` :	the GHook to insert the new GHook before
`hook` :	the GHook to insert

g_hook_insert_sorted ()

void                g_hook_insert_sorted                (GHookList *hook_list,
                                                         GHook *hook,
                                                         GHookCompareFunc func);

Inserts a GHook into a GHookList, sorted by the given function.

`hook_list` :	a GHookList
`hook` :	the GHook to insert
`func` :	the comparison function used to sort the GHook elements

GHookCompareFunc ()

gint                (*GHookCompareFunc)                 (GHook *new_hook,
                                                         GHook *sibling);

Defines the type of function used to compare GHook elements in g_hook_insert_sorted().

`new_hook` :	the GHook being inserted
`sibling` :	the GHook to compare with `new_hook`
Returns :	a value <= 0 if `new_hook` should be before `sibling`

g_hook_compare_ids ()

gint                g_hook_compare_ids                  (GHook *new_hook,
                                                         GHook *sibling);

Compares the ids of two GHook elements, returning a negative value if the second id is greater than the first.

`new_hook` :	a GHook
`sibling` :	a GHook to compare with `new_hook`
Returns :	a value <= 0 if the id of `sibling` is >= the id of `new_hook`

g_hook_get ()

GHook*              g_hook_get                          (GHookList *hook_list,
                                                         gulong hook_id);

Returns the GHook with the given id, or NULL if it is not found.

`hook_list` :	a GHookList
`hook_id` :	a hook id
Returns :	the GHook with the given id, or `NULL` if it is not found

g_hook_find ()

GHook*              g_hook_find                         (GHookList *hook_list,
                                                         gboolean need_valids,
                                                         GHookFindFunc func,
                                                         gpointer data);

Finds a GHook in a GHookList using the given function to test for a match.

`hook_list` :	a GHookList
`need_valids` :	`TRUE` if GHook elements which have been destroyed should be skipped
`func` :	the function to call for each GHook, which should return `TRUE` when the GHook has been found
`data` :	the data to pass to `func`
Returns :	the found GHook or `NULL` if no matching GHook is found

GHookFindFunc ()

gboolean            (*GHookFindFunc)                    (GHook *hook,
                                                         gpointer data);

Defines the type of the function passed to g_hook_find().

`hook` :	a GHook
`data` :	user data passed to `g_hook_find_func()`
Returns :	`TRUE` if the required GHook has been found

g_hook_find_data ()

GHook*              g_hook_find_data                    (GHookList *hook_list,
                                                         gboolean need_valids,
                                                         gpointer data);

Finds a GHook in a GHookList with the given data.

`hook_list` :	a GHookList
`need_valids` :	`TRUE` if GHook elements which have been destroyed should be skipped
`data` :	the data to find
Returns :	the GHook with the given `data` or `NULL` if no matching GHook is found

g_hook_find_func ()

GHook*              g_hook_find_func                    (GHookList *hook_list,
                                                         gboolean need_valids,
                                                         gpointer func);

Finds a GHook in a GHookList with the given function.

`hook_list` :	a GHookList
`need_valids` :	`TRUE` if GHook elements which have been destroyed should be skipped
`func` :	the function to find
Returns :	the GHook with the given `func` or `NULL` if no matching GHook is found

g_hook_find_func_data ()

GHook*              g_hook_find_func_data               (GHookList *hook_list,
                                                         gboolean need_valids,
                                                         gpointer func,
                                                         gpointer data);

Finds a GHook in a GHookList with the given function and data.

`hook_list` :	a GHookList
`need_valids` :	`TRUE` if GHook elements which have been destroyed should be skipped
`func` :	the function to find
`data` :	the data to find
Returns :	the GHook with the given `func` and `data` or `NULL` if no matching GHook is found

g_hook_first_valid ()

GHook*              g_hook_first_valid                  (GHookList *hook_list,
                                                         gboolean may_be_in_call);

Returns the first GHook in a GHookList which has not been destroyed. The reference count for the GHook is incremented, so you must call g_hook_unref() to restore it when no longer needed. (Or call g_hook_next_valid() if you are stepping through the GHookList.)

`hook_list` :	a GHookList
`may_be_in_call` :	`TRUE` if hooks which are currently running (e.g. in another thread) are considered valid. If set to `FALSE`, these are skipped
Returns :	the first valid GHook, or `NULL` if none are valid

g_hook_next_valid ()

GHook*              g_hook_next_valid                   (GHookList *hook_list,
                                                         GHook *hook,
                                                         gboolean may_be_in_call);

Returns the next GHook in a GHookList which has not been destroyed. The reference count for the GHook is incremented, so you must call g_hook_unref() to restore it when no longer needed. (Or continue to call g_hook_next_valid() until NULL is returned.)

`hook_list` :	a GHookList
`hook` :	the current GHook
`may_be_in_call` :	`TRUE` if hooks which are currently running (e.g. in another thread) are considered valid. If set to `FALSE`, these are skipped
Returns :	the next valid GHook, or `NULL` if none are valid

enum GHookFlagMask

typedef enum
{
  G_HOOK_FLAG_ACTIVE	    = 1 << 0,
  G_HOOK_FLAG_IN_CALL	    = 1 << 1,
  G_HOOK_FLAG_MASK	    = 0x0f
} GHookFlagMask;

Flags used internally in the GHook implementation.

`G_HOOK_FLAG_ACTIVE`	set if the hook has not been destroyed
`G_HOOK_FLAG_IN_CALL`	set if the hook is currently being run
`G_HOOK_FLAG_MASK`	A mask covering all bits reserved for hook flags; see G_HOOK_FLAGS_USER_SHIFT

G_HOOK_FLAGS()

#define	G_HOOK_FLAGS(hook)		(G_HOOK (hook)->flags)

Returns the flags of a hook.

hook : a GHook

G_HOOK_FLAG_USER_SHIFT

#define G_HOOK_FLAG_USER_SHIFT	(4)

The position of the first bit which is not reserved for internal use be the GHook implementation, i.e. 1 << G_HOOK_FLAG_USER_SHIFT is the first bit which can be used for application-defined flags.

G_HOOK()

#define	G_HOOK(hook)			((GHook*) (hook))

Casts a pointer to a GHook*.

hook : a pointer

G_HOOK_IS_VALID()

#define             G_HOOK_IS_VALID(hook)

Returns TRUE if the GHook is valid, i.e. it is in a GHookList, it is active and it has not been destroyed.

`hook` :	a GHook
Returns :	`TRUE` if the GHook is valid

G_HOOK_ACTIVE()

#define             G_HOOK_ACTIVE(hook)

Returns TRUE if the GHook is active, which is normally TRUE until the GHook is destroyed.

`hook` :	a GHook
Returns :	`TRUE` if the GHook is active

G_HOOK_IN_CALL()

#define             G_HOOK_IN_CALL(hook)

Returns TRUE if the GHook function is currently executing.

`hook` :	a GHook
Returns :	`TRUE` if the GHook function is currently executing

G_HOOK_IS_UNLINKED()

#define             G_HOOK_IS_UNLINKED(hook)

Returns TRUE if the GHook is not in a GHookList.

`hook` :	a GHook
Returns :	`TRUE` if the GHook is not in a GHookList

g_hook_ref ()

GHook*              g_hook_ref                          (GHookList *hook_list,
                                                         GHook *hook);

Increments the reference count for a GHook.

`hook_list` :	a GHookList
`hook` :	the GHook to increment the reference count of
Returns :	the `hook` that was passed in (since 2.6)

g_hook_unref ()

void                g_hook_unref                        (GHookList *hook_list,
                                                         GHook *hook);

Decrements the reference count of a GHook. If the reference count falls to 0, the GHook is removed from the GHookList and g_hook_free() is called to free it.

`hook_list` :	a GHookList
`hook` :	the GHook to unref

g_hook_free ()

void                g_hook_free                         (GHookList *hook_list,
                                                         GHook *hook);

Calls the GHookList finalize_hook function if it exists, and frees the memory allocated for the GHook.

`hook_list` :	a GHookList
`hook` :	the GHook to free

g_hook_destroy ()

gboolean            g_hook_destroy                      (GHookList *hook_list,
                                                         gulong hook_id);

Destroys a GHook, given its ID.

`hook_list` :	a GHookList
`hook_id` :	a hook ID
Returns :	`TRUE` if the GHook was found in the GHookList and destroyed

g_hook_destroy_link ()

void                g_hook_destroy_link                 (GHookList *hook_list,
                                                         GHook *hook);

Removes one GHook from a GHookList, marking it inactive and calling g_hook_unref() on it.

`hook_list` :	a GHookList
`hook` :	the GHook to remove

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