.. _library_queues:

queues

This library implements queues. The queue representation should be regarded as an opaque term and only accessed using the library predicates.

API documentation

Open the `../../docs/library_index.html#queues <../../docs/library_index.html#queues>`__ link in a web browser.

Loading

To load all entities in this library, load the loader.lgt file:

::

| ?- logtalk_load(queues(loader)).

Testing

To test this library predicates, load the tester.lgt file:

::

| ?- logtalk_load(queues(tester)).

Usage

To create a new queue, use the new/1 predicate:

::

| ?- queue::new(Queue). Queue = ... yes

Elements can be added to either the end of the queue or the front of the queue using, respectively, the join/3 and join_all/3 predicates or the jump/3 and jump_all/3. For example:

::

| ?- queue::(new(Queue0), join_all([1,2,3], Queue0, Queue1)). Queue0 = ..., Queue1 = ... yes

We can query the head of the queue or remove the head of the queue using, respectively, the head/2 and serve/3 predicates. For example:

::

| ?- queue::(new(Queue0), join(1, Queue0, Queue1), head(Queue1, Head)). Queue0 = ..., Queue1 = ..., Head = 1 yes

For details on these and other provided predicates, consult the library API documentation.