1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
|
<?xml version="1.0" encoding="utf-8"?>
<!-- $Revision$ -->
<reference xml:id="class.ds-deque" role="class" xmlns="http://docbook.org/ns/docbook" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xi="http://www.w3.org/2001/XInclude">
<title>The Deque class</title>
<titleabbrev>Ds\Deque</titleabbrev>
<partintro>
<!-- {{{ Ds\Deque intro -->
<section xml:id="ds-deque.intro">
&reftitle.intro;
<para>
A Deque (pronounced “deck”) is a sequence of values
in a contiguous buffer that grows and shrinks automatically.
The name is a common abbreviation of “double-ended queue” and is used
internally by <classname>Ds\Queue</classname>.
</para>
<para>
Two pointers are used to keep track of a head and a tail. The pointers can
“wrap around” the end of the buffer, which avoids the need to move other
values around to make room. This makes shift and unshift very fast —
something a <classname>Ds\Vector</classname> can’t compete with.
</para>
<para>
Accessing a value by index requires a translation between the index and its
corresponding position in the buffer: <code>((head + position) % capacity)</code>.
</para>
</section>
<!-- }}} -->
<section xml:id="ds-deque.strengths">
<title xmlns="http://docbook.org/ns/docbook">Strengths</title>
<para>
<simplelist>
<member>Supports array syntax (square brackets).</member>
<member>Uses less overall memory than an &array; for the same number of values.</member>
<member>Automatically frees allocated memory when its size drops low enough.</member>
<member>
<function>get</function>,
<function>set</function>,
<function>push</function>,
<function>pop</function>,
<function>shift</function>, and
<function>unshift</function> are all O(1).
</member>
</simplelist>
</para>
</section>
<section xml:id="ds-deque.weaknesses">
<title xmlns="http://docbook.org/ns/docbook">Weaknesses</title>
<para>
<simplelist>
<member>Capacity must be a power of 2.</member>
<member>
<function>insert</function> and
<function>remove</function> are O(n).
</member>
</simplelist>
</para>
</section>
<section xml:id="ds-deque.synopsis">
&reftitle.classsynopsis;
<!-- {{{ Synopsis -->
<classsynopsis>
<ooclass><classname>Ds\Deque</classname></ooclass>
<!-- {{{ Class synopsis -->
<classsynopsisinfo>
<ooclass>
<classname>Ds\Deque</classname>
</ooclass>
<oointerface>
<interfacename>Ds\Sequence</interfacename>
</oointerface>
<oointerface>
<interfacename>ArrayAccess</interfacename>
</oointerface>
</classsynopsisinfo>
<!-- }}} -->
<classsynopsisinfo role="comment">&Constants;</classsynopsisinfo>
<fieldsynopsis>
<modifier>const</modifier>
<type>int</type>
<varname linkend="ds-deque.constants.min-capacity">Ds\Deque::MIN_CAPACITY</varname>
<initializer>8</initializer>
</fieldsynopsis>
<classsynopsisinfo role="comment">&Methods;</classsynopsisinfo>
<xi:include xpointer="xmlns(db=http://docbook.org/ns/docbook) xpointer(id('class.ds-deque')/db:refentry/db:refsect1[@role='description']/descendant::db:methodsynopsis)">
<xi:fallback/>
</xi:include>
</classsynopsis>
<!-- }}} -->
</section>
<!-- {{{ Ds\Deque constants -->
<section xml:id="ds-deque.constants">
&reftitle.constants;
<variablelist>
<varlistentry xml:id="ds-deque.constants.min-capacity">
<term><constant>Ds\Deque::MIN_CAPACITY</constant></term>
<listitem>
<para></para>
</listitem>
</varlistentry>
</variablelist>
</section>
<!-- }}} -->
<section role="changelog">
&reftitle.changelog;
<para>
<informaltable>
<tgroup cols="2">
<thead>
<row>
<entry>&Version;</entry>
<entry>&Description;</entry>
</row>
</thead>
<tbody>
<row>
<entry>PECL ds 1.3.0</entry>
<entry>
The class now implements <classname>ArrayAccess</classname>.
</entry>
</row>
</tbody>
</tgroup>
</informaltable>
</para>
</section>
</partintro>
&reference.ds.ds.entities.deque;
</reference>
<!-- Keep this comment at the end of the file
Local variables:
mode: sgml
sgml-omittag:t
sgml-shorttag:t
sgml-minimize-attributes:nil
sgml-always-quote-attributes:t
sgml-indent-step:1
sgml-indent-data:t
indent-tabs-mode:nil
sgml-parent-document:nil
sgml-default-dtd-file:"~/.phpdoc/manual.ced"
sgml-exposed-tags:nil
sgml-local-catalogs:nil
sgml-local-ecat-files:nil
End:
vim600: syn=xml fen fdm=syntax fdl=2 si
vim: et tw=78 syn=sgml
vi: ts=1 sw=1
-->
|
