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This file is part of Logtalk https://logtalk.org/ SPDX-FileCopyrightText: 1998-2023 Paulo Moura <pmoura@logtalk.org> SPDX-License-Identifier: Apache-2.0

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.

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.