dlib.container.queue source code

1 /*
2 Copyright (c) 2011-2021 Timur Gafarov
3 
4 Boost Software License - Version 1.0 - August 17th, 2003
5 
6 Permission is hereby granted, free of charge, to any person or organization
7 obtaining a copy of the software and accompanying documentation covered by
8 this license (the "Software") to use, reproduce, display, distribute,
9 execute, and transmit the Software, and to prepare derivative works of the
10 Software, and to permit third-parties to whom the Software is furnished to
11 do so, all subject to the following:
12 
13 The copyright notices in the Software and this entire statement, including
14 the above license grant, this restriction and the following disclaimer,
15 must be included in all copies of the Software, in whole or in part, and
16 all derivative works of the Software, unless such copies or derivative
17 works are solely in the form of machine-executable object code generated by
18 a source language processor.
19 
20 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
21 IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
22 FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
23 SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
24 FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
25 ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
26 DEALINGS IN THE SOFTWARE.
27 */
28 
29 /**
30  * Queue (based on linked list)
31  *
32  * Copyright: Timur Gafarov 2011-2021.
33  * License: $(LINK2 boost.org/LICENSE_1_0.txt, Boost License 1.0).
34  * Authors: Timur Gafarov, Andrey Penechko, Roman Chistokhodov
35  */
36 module dlib.container.queue;
37 
38 import dlib.container.array;
39 
40 /**
41  * Queue implementation based on Array.
42  */
43 struct Queue(T)
44 {
45     private:
46     Array!T array;
47 
48     public:
49     /**
50      * Check if stack has no elements.
51      */
52     @property bool empty()
53     {
54         return array.length == 0;
55     }
56 
57     /**
58      * Add element to queue.
59      */
60     void enqueue(const(T) v)
61     {
62         array.insertBack(v);
63     }
64 
65     /**
66      * Remove element from queue.
67      * Returns: Removed element.
68      * Throws: Exception if queue is empty.
69      */
70     T dequeue()
71     {
72         if (empty)
73             throw new Exception("Queue!(T): queue is empty");
74 
75         T res = array[0];
76         array.removeFront(1);
77         return res;
78     }
79 
80     /**
81      * Non-throwing version of dequeue.
82      * Returns: true on success, false on failure.
83      * Element is stored in value.
84      */
85     bool dequeue(ref T value) nothrow
86     {
87         if (empty)
88             return false;
89 
90         value = array[0];
91         array.removeFront(1);
92         return true;
93     }
94 
95     /**
96      * Free memory allocated by Queue.
97      */
98     void free()
99     {
100         array.free();
101     }
102 }
103 
104 ///
105 unittest
106 {
107     import std.exception: assertThrown;
108 
109     Queue!int q;
110     assertThrown(q.dequeue());
111     assert (q.empty);
112 
113     q.enqueue(50);
114     q.enqueue(30);
115     q.enqueue(900);
116 
117     int v;
118     q.dequeue(v);
119     assert (v == 50);
120     assert (q.dequeue() == 30);
121     assert (q.dequeue() == 900);
122     assert (q.empty);
123 
124     q.free();
125 }