3 * Copyright (C) 2009 Didier Villevalois
5 * This library is free software; you can redistribute it and/or
6 * modify it under the terms of the GNU Lesser General Public
7 * License as published by the Free Software Foundation; either
8 * version 2.1 of the License, or (at your option) any later version.
10 * This library is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 * Lesser General Public License for more details.
15 * You should have received a copy of the GNU Lesser General Public
16 * License along with this library; if not, write to the Free Software
17 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20 * Didier 'Ptitjes Villevalois <ptitjes@free.fr>
24 * A collection designed for holding elements prior to processing.
26 * Although all Queue implementations do not limit the amount of elements they
27 * can contain, this interface supports for capacity-bounded queues. When
28 * capacity is not bound, then the {@link capacity} and
29 * {@link remaining_capacity} both return {@link UNBOUNDED_CAPACITY}.
31 * This interface defines methods that will never fail whatever the state of
32 * the queue is. For capacity-bounded queues, those methods will either return
33 * ``false`` or ``null`` to specify that the insert or retrieval did not occur
34 * because the queue was full or empty.
36 * Queue implementations are not limited to First-In-First-Out behavior and can
37 * propose different ordering of their elements. Each Queue implementation have
38 * to specify how it orders its elements.
40 * Queue implementations do not allow insertion of ``null`` elements, although
41 * some implementations, such as {@link LinkedList}, do not prohibit insertion
42 * of ``null``. Even in the implementations that permit it, ``null`` should not be
43 * inserted into a Queue, as ``null`` is also used as a special return value by
44 * the poll method to indicate that the queue contains no elements.
47 public interface Gee.Queue<G> : Collection<G> {
50 * The unbounded capacity value.
52 public static const int UNBOUNDED_CAPACITY = -1;
55 * The capacity of this queue (or ``null`` if capacity is not bound).
57 public abstract int capacity { get; }
60 * The remaining capacity of this queue (or ``null`` if capacity is not
63 public abstract int remaining_capacity { get; }
66 * Specifies whether this queue is full.
68 public abstract bool is_full { get; }
71 * Offers the specified element to this queue.
73 * @param element the element to offer to the queue
75 * @return ``true`` if the element was added to the queue
77 public virtual bool offer (G element) {
82 * Peeks (retrieves, but not remove) an element from this queue.
84 * @return the element peeked from the queue (or ``null`` if none was
87 public abstract G? peek ();
90 * Polls (retrieves and remove) an element from this queue.
92 * @return the element polled from the queue (or ``null`` if none was
95 public abstract G? poll ();
98 * Drains the specified amount of elements from this queue in the specified
99 * recipient collection.
101 * @param recipient the recipient collection to drain the elements to
102 * @param amount the amount of elements to drain
104 * @return the amount of elements that were actually drained
106 public virtual int drain (Collection<G> recipient, int amount = -1) {
109 while((amount == -1 || --amount >= 0) && (item = poll ()) != null) {
110 recipient.add (item);