<GHashTable>

<GHashTable>

Description

The GHashTable struct is an opaque data structure to represent a [Hash Table][glib-Hash-Tables]. It should only be accessed via the following functions.

Functions

hash-table:add?

(define-values (%return) (hash-table:add? hash-table key))

This is a convenience function for using a GHashTable as a set. It is equivalent to calling g_hash_table_replace() with key as both the key and the value.

In particular, this means that if key already exists in the hash table, then the old copy of key in the hash table is freed and key replaces it in the table.

When a hash table only ever contains keys that have themselves as the corresponding value it is able to be stored more efficiently. See the discussion in the section description.

Starting from GLib 2.40, this function returns a boolean value to indicate whether the newly added value was already in the hash table or not.

Parameters

hash_table

a GHashTable

Passed as hash-table

key

a key to insert

Passed as key

hash-table:contains?

(define-values (%return) (hash-table:contains? hash-table key))

Checks if key is in hash_table.

Parameters

hash_table

a GHashTable

Passed as hash-table

key

a key to check

Passed as key

hash-table:destroy

(define-values () (hash-table:destroy hash-table))

Destroys all keys and values in the GHashTable and decrements its reference count by 1. If keys and/or values are dynamically allocated, you should either free them first or create the GHashTable with destroy notifiers using g_hash_table_new_full(). In the latter case the destroy functions you supplied will be called on all keys and values during the destruction phase.

Parameters

hash_table

a GHashTable

Passed as hash-table

hash-table:insert?

(define-values (%return) (hash-table:insert? hash-table key value))

Inserts a new key and value into a GHashTable.

If the key already exists in the GHashTable its current value is replaced with the new value. If you supplied a value_destroy_func when creating the GHashTable, the old value is freed using that function. If you supplied a key_destroy_func when creating the GHashTable, the passed key is freed using that function.

Starting from GLib 2.40, this function returns a boolean value to indicate whether the newly added value was already in the hash table or not.

Parameters

hash_table

a GHashTable

Passed as hash-table

key

a key to insert

Passed as key

value

the value to associate with the key

Passed as value

hash-table:lookup

(define-values (%return) (hash-table:lookup hash-table key))

Looks up a key in a GHashTable. Note that this function cannot distinguish between a key that is not present and one which is present and has the value NULL. If you need this distinction, use g_hash_table_lookup_extended().

Parameters

hash_table

a GHashTable

Passed as hash-table

key

the key to look up

Passed as key

hash-table:lookup-extended

(define-values
  (%return orig-key value)
  (hash-table:lookup-extended hash-table lookup-key))

Looks up a key in the GHashTable, returning the original key and the associated value and a gboolean which is TRUE if the key was found. This is useful if you need to free the memory allocated for the original key, for example before calling g_hash_table_remove().

You can actually pass NULL for lookup_key to test whether the NULL key exists, provided the hash and equal functions of hash_table are NULL-safe.

Parameters

hash_table

a GHashTable

Passed as hash-table

lookup_key

the key to look up

Passed as lookup-key

orig_key

return location for the original key

Passed as orig-key

value

return location for the value associated with the key

Passed as value

hash-table:remove?

(define-values (%return) (hash-table:remove? hash-table key))

Removes a key and its associated value from a GHashTable.

If the GHashTable was created using g_hash_table_new_full(), the key and value are freed using the supplied destroy functions, otherwise you have to make sure that any dynamically allocated values are freed yourself.

Parameters

hash_table

a GHashTable

Passed as hash-table

key

the key to remove

Passed as key

hash-table:remove-all

(define-values () (hash-table:remove-all hash-table))

Removes all keys and their associated values from a GHashTable.

If the GHashTable was created using g_hash_table_new_full(), the keys and values are freed using the supplied destroy functions, otherwise you have to make sure that any dynamically allocated values are freed yourself.

Parameters

hash_table

a GHashTable

Passed as hash-table

hash-table:replace?

(define-values (%return) (hash-table:replace? hash-table key value))

Inserts a new key and value into a GHashTable similar to g_hash_table_insert(). The difference is that if the key already exists in the GHashTable, it gets replaced by the new key. If you supplied a value_destroy_func when creating the GHashTable, the old value is freed using that function. If you supplied a key_destroy_func when creating the GHashTable, the old key is freed using that function.

Starting from GLib 2.40, this function returns a boolean value to indicate whether the newly added value was already in the hash table or not.

Parameters

hash_table

a GHashTable

Passed as hash-table

key

a key to insert

Passed as key

value

the value to associate with the key

Passed as value

hash-table:size

(define-values (%return) (hash-table:size hash-table))

Returns the number of elements contained in the GHashTable.

Parameters

hash_table

a GHashTable

Passed as hash-table

hash-table:steal?

(define-values (%return) (hash-table:steal? hash-table key))

Removes a key and its associated value from a GHashTable without calling the key and value destroy functions.

Parameters

hash_table

a GHashTable

Passed as hash-table

key

the key to remove

Passed as key

hash-table:steal-all

(define-values () (hash-table:steal-all hash-table))

Removes all keys and their associated values from a GHashTable without calling the key and value destroy functions.

Parameters

hash_table

a GHashTable

Passed as hash-table

hash-table:steal-extended

(define-values
  (%return stolen-key stolen-value)
  (hash-table:steal-extended hash-table lookup-key))

Looks up a key in the GHashTable, stealing the original key and the associated value and returning TRUE if the key was found. If the key was not found, FALSE is returned.

If found, the stolen key and value are removed from the hash table without calling the key and value destroy functions, and ownership is transferred to the caller of this method; as with g_hash_table_steal().

You can pass NULL for lookup_key, provided the hash and equal functions of hash_table are NULL-safe.

Parameters

hash_table

a GHashTable

Passed as hash-table

lookup_key

the key to look up

Passed as lookup-key

stolen_key

return location for the original key

Passed as stolen-key

stolen_value

return location for the value associated with the key

Passed as stolen-value

hash-table:unref

(define-values () (hash-table:unref hash-table))

Atomically decrements the reference count of hash_table by one. If the reference count drops to 0, all keys and values will be destroyed, and all memory allocated by the hash table is released. This function is MT-safe and may be called from any thread.

Parameters

hash_table

a valid GHashTable

Passed as hash-table