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<title>The Deque class</title>
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<h1 class="title">The Deque class</h1>
<div class="partintro"><p class="verinfo">(No version information available, might only be in Git)</p>
<div class="section" id="ds-deque.intro">
<h2 class="title">Introduction</h2>
<p class="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 <strong class="classname">Ds\Queue</strong>.
</p>
<p class="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 <strong class="classname">Ds\Vector</strong> can’t compete with.
</p>
<p class="para">
Accessing a value by index requires a translation between the index and its
corresponding position in the buffer: <code class="code">((head + position) % capacity)</code>.
</p>
</div>
<div class="section" id="ds-deque.strengths">
<h2 class="title">Strengths</h2>
<p class="para">
<ul class="simplelist">
<li class="member">Supports array syntax (square brackets).</li>
<li class="member">Uses less overall memory than an <span class="type"><a href="language.types.array.html" class="type array">array</a></span> for the same number of values.</li>
<li class="member">Automatically frees allocated memory when its size drops low enough.</li>
<li class="member">
<span class="function"><strong>get()</strong></span>,
<span class="function"><strong>set()</strong></span>,
<span class="function"><strong>push()</strong></span>,
<span class="function"><strong>pop()</strong></span>,
<span class="function"><strong>shift()</strong></span>, and
<span class="function"><strong>unshift()</strong></span> are all O(1).
</li>
</ul>
</p>
</div>
<div class="section" id="ds-deque.weaknesses">
<h2 class="title">Weaknesses</h2>
<p class="para">
<ul class="simplelist">
<li class="member">Capacity must be a power of 2.</li>
<li class="member">
<span class="function"><strong>insert()</strong></span> and
<span class="function"><strong>remove()</strong></span> are O(n).
</li>
</ul>
</p>
</div>
<div class="section" id="ds-deque.synopsis">
<h2 class="title">Class synopsis</h2>
<div class="classsynopsis">
<div class="ooclass"></div>
<div class="classsynopsisinfo">
<span class="ooclass">
<strong class="classname">Ds\Deque</strong>
</span>
<span class="oointerface">implements
<span class="interfacename"><strong class="interfacename">Ds\Sequence</strong></span>
</span>
{</div>
<div class="classsynopsisinfo classsynopsisinfo_comment">/* Constants */</div>
<div class="fieldsynopsis">
<span class="modifier">const</span>
<span class="type">int</span>
<var class="fieldsynopsis_varname"><a href="class.ds-deque.html#ds-deque.constants.min-capacity"><var class="varname">MIN_CAPACITY</var></a></var>
<span class="initializer"> = 8</span>
;</div>
<div class="classsynopsisinfo classsynopsisinfo_comment">/* Methods */</div>
<div class="methodsynopsis dc-description">
<span class="modifier">public</span> <span class="type">void</span> <span class="methodname"><a href="ds-deque.allocate.html" class="methodname">allocate</a></span>
( <span class="methodparam"><span class="type">int</span> <code class="parameter">$capacity</code></span>
)</div>
<div class="methodsynopsis dc-description">
<span class="modifier">public</span> <span class="type">void</span> <span class="methodname"><a href="ds-deque.apply.html" class="methodname">apply</a></span>
( <span class="methodparam"><span class="type"><a href="language.types.callable.html" class="type callable">callable</a></span> <code class="parameter">$callback</code></span>
)</div>
<div class="methodsynopsis dc-description">
<span class="modifier">public</span> <span class="type">int</span> <span class="methodname"><a href="ds-deque.capacity.html" class="methodname">capacity</a></span>
( <span class="methodparam">void</span>
)</div>
<div class="methodsynopsis dc-description">
<span class="modifier">public</span> <span class="type">void</span> <span class="methodname"><a href="ds-deque.clear.html" class="methodname">clear</a></span>
( <span class="methodparam">void</span>
)</div>
<div class="methodsynopsis dc-description">
<span class="modifier">public</span> <span class="type">bool</span> <span class="methodname"><a href="ds-deque.contains.html" class="methodname">contains</a></span>
([ <span class="methodparam"><span class="type"><a href="language.pseudo-types.html#language.types.mixed" class="type mixed">mixed</a></span> <code class="parameter">$...values</code></span>
] )</div>
<div class="methodsynopsis dc-description">
<span class="modifier">public</span> <span class="type">Ds\Deque</span> <span class="methodname"><a href="ds-deque.copy.html" class="methodname">copy</a></span>
( <span class="methodparam">void</span>
)</div>
<div class="methodsynopsis dc-description">
<span class="modifier">public</span> <span class="type">Ds\Deque</span> <span class="methodname"><a href="ds-deque.filter.html" class="methodname">filter</a></span>
([ <span class="methodparam"><span class="type"><a href="language.types.callable.html" class="type callable">callable</a></span> <code class="parameter">$callback</code></span>
] )</div>
<div class="methodsynopsis dc-description">
<span class="modifier">public</span> <span class="type">mixed</span> <span class="methodname"><a href="ds-deque.find.html" class="methodname">find</a></span>
( <span class="methodparam"><span class="type"><a href="language.pseudo-types.html#language.types.mixed" class="type mixed">mixed</a></span> <code class="parameter">$value</code></span>
)</div>
<div class="methodsynopsis dc-description">
<span class="modifier">public</span> <span class="type">mixed</span> <span class="methodname"><a href="ds-deque.first.html" class="methodname">first</a></span>
( <span class="methodparam">void</span>
)</div>
<div class="methodsynopsis dc-description">
<span class="modifier">public</span> <span class="type">mixed</span> <span class="methodname"><a href="ds-deque.get.html" class="methodname">get</a></span>
( <span class="methodparam"><span class="type">int</span> <code class="parameter">$index</code></span>
)</div>
<div class="methodsynopsis dc-description">
<span class="modifier">public</span> <span class="type">void</span> <span class="methodname"><a href="ds-deque.insert.html" class="methodname">insert</a></span>
( <span class="methodparam"><span class="type">int</span> <code class="parameter">$index</code></span>
[, <span class="methodparam"><span class="type"><a href="language.pseudo-types.html#language.types.mixed" class="type mixed">mixed</a></span> <code class="parameter">$...values</code></span>
] )</div>
<div class="methodsynopsis dc-description">
<span class="modifier">public</span> <span class="type">bool</span> <span class="methodname"><a href="ds-deque.isempty.html" class="methodname">isEmpty</a></span>
( <span class="methodparam">void</span>
)</div>
<div class="methodsynopsis dc-description">
<span class="modifier">public</span> <span class="type">string</span> <span class="methodname"><a href="ds-deque.join.html" class="methodname">join</a></span>
([ <span class="methodparam"><span class="type">string</span> <code class="parameter">$glue</code></span>
] )</div>
<div class="methodsynopsis dc-description">
<span class="modifier">public</span> <span class="type">mixed</span> <span class="methodname"><a href="ds-deque.last.html" class="methodname">last</a></span>
( <span class="methodparam">void</span>
)</div>
<div class="methodsynopsis dc-description">
<span class="modifier">public</span> <span class="type">Ds\Deque</span> <span class="methodname"><a href="ds-deque.map.html" class="methodname">map</a></span>
( <span class="methodparam"><span class="type"><a href="language.types.callable.html" class="type callable">callable</a></span> <code class="parameter">$callback</code></span>
)</div>
<div class="methodsynopsis dc-description">
<span class="modifier">public</span> <span class="type">Ds\Deque</span> <span class="methodname"><a href="ds-deque.merge.html" class="methodname">merge</a></span>
( <span class="methodparam"><span class="type"><a href="language.pseudo-types.html#language.types.mixed" class="type mixed">mixed</a></span> <code class="parameter">$values</code></span>
)</div>
<div class="methodsynopsis dc-description">
<span class="modifier">public</span> <span class="type">mixed</span> <span class="methodname"><a href="ds-deque.pop.html" class="methodname">pop</a></span>
( <span class="methodparam">void</span>
)</div>
<div class="methodsynopsis dc-description">
<span class="modifier">public</span> <span class="type">void</span> <span class="methodname"><a href="ds-deque.push.html" class="methodname">push</a></span>
([ <span class="methodparam"><span class="type"><a href="language.pseudo-types.html#language.types.mixed" class="type mixed">mixed</a></span> <code class="parameter">$...values</code></span>
] )</div>
<div class="methodsynopsis dc-description">
<span class="modifier">public</span> <span class="type">mixed</span> <span class="methodname"><a href="ds-deque.reduce.html" class="methodname">reduce</a></span>
( <span class="methodparam"><span class="type"><a href="language.types.callable.html" class="type callable">callable</a></span> <code class="parameter">$callback</code></span>
[, <span class="methodparam"><span class="type"><a href="language.pseudo-types.html#language.types.mixed" class="type mixed">mixed</a></span> <code class="parameter">$initial</code></span>
] )</div>
<div class="methodsynopsis dc-description">
<span class="modifier">public</span> <span class="type">mixed</span> <span class="methodname"><a href="ds-deque.remove.html" class="methodname">remove</a></span>
( <span class="methodparam"><span class="type">int</span> <code class="parameter">$index</code></span>
)</div>
<div class="methodsynopsis dc-description">
<span class="modifier">public</span> <span class="type">void</span> <span class="methodname"><a href="ds-deque.reverse.html" class="methodname">reverse</a></span>
( <span class="methodparam">void</span>
)</div>
<div class="methodsynopsis dc-description">
<span class="modifier">public</span> <span class="type">Ds\Deque</span> <span class="methodname"><a href="ds-deque.reversed.html" class="methodname">reversed</a></span>
( <span class="methodparam">void</span>
)</div>
<div class="methodsynopsis dc-description">
<span class="modifier">public</span> <span class="type">void</span> <span class="methodname"><a href="ds-deque.rotate.html" class="methodname">rotate</a></span>
( <span class="methodparam"><span class="type">int</span> <code class="parameter">$rotations</code></span>
)</div>
<div class="methodsynopsis dc-description">
<span class="modifier">public</span> <span class="type">void</span> <span class="methodname"><a href="ds-deque.set.html" class="methodname">set</a></span>
( <span class="methodparam"><span class="type">int</span> <code class="parameter">$index</code></span>
, <span class="methodparam"><span class="type"><a href="language.pseudo-types.html#language.types.mixed" class="type mixed">mixed</a></span> <code class="parameter">$value</code></span>
)</div>
<div class="methodsynopsis dc-description">
<span class="modifier">public</span> <span class="type">mixed</span> <span class="methodname"><a href="ds-deque.shift.html" class="methodname">shift</a></span>
( <span class="methodparam">void</span>
)</div>
<div class="methodsynopsis dc-description">
<span class="modifier">public</span> <span class="type">Ds\Deque</span> <span class="methodname"><a href="ds-deque.slice.html" class="methodname">slice</a></span>
( <span class="methodparam"><span class="type">int</span> <code class="parameter">$index</code></span>
[, <span class="methodparam"><span class="type">int</span> <code class="parameter">$length</code></span>
] )</div>
<div class="methodsynopsis dc-description">
<span class="modifier">public</span> <span class="type">void</span> <span class="methodname"><a href="ds-deque.sort.html" class="methodname">sort</a></span>
([ <span class="methodparam"><span class="type"><a href="language.types.callable.html" class="type callable">callable</a></span> <code class="parameter">$comparator</code></span>
] )</div>
<div class="methodsynopsis dc-description">
<span class="modifier">public</span> <span class="type">Ds\Deque</span> <span class="methodname"><a href="ds-deque.sorted.html" class="methodname">sorted</a></span>
([ <span class="methodparam"><span class="type"><a href="language.types.callable.html" class="type callable">callable</a></span> <code class="parameter">$comparator</code></span>
] )</div>
<div class="methodsynopsis dc-description">
<span class="modifier">public</span> <span class="type">number</span> <span class="methodname"><a href="ds-deque.sum.html" class="methodname">sum</a></span>
( <span class="methodparam">void</span>
)</div>
<div class="methodsynopsis dc-description">
<span class="modifier">public</span> <span class="type">array</span> <span class="methodname"><a href="ds-deque.toarray.html" class="methodname">toArray</a></span>
( <span class="methodparam">void</span>
)</div>
<div class="methodsynopsis dc-description">
<span class="modifier">public</span> <span class="type">void</span> <span class="methodname"><a href="ds-deque.unshift.html" class="methodname">unshift</a></span>
([ <span class="methodparam"><span class="type"><a href="language.pseudo-types.html#language.types.mixed" class="type mixed">mixed</a></span> <code class="parameter">$values</code></span>
] )</div>
}</div>
</div>
<div class="section" id="ds-deque.constants">
<h2 class="title">Predefined Constants</h2>
<dl>
<dt id="ds-deque.constants.min-capacity"><strong><code>Ds\Deque::MIN_CAPACITY</code></strong></dt>
<dd>
<p class="para"/>
</dd>
</dl>
</div>
</div>
<h2>Table of Contents</h2><ul class="chunklist chunklist_reference"><li><a href="ds-deque.allocate.html">Ds\Deque::allocate</a> — Allocates enough memory for a required capacity</li><li><a href="ds-deque.apply.html">Ds\Deque::apply</a> — Updates all values by applying a callback function to each value</li><li><a href="ds-deque.capacity.html">Ds\Deque::capacity</a> — Returns the current capacity</li><li><a href="ds-deque.clear.html">Ds\Deque::clear</a> — Removes all values from the deque</li><li><a href="ds-deque.construct.html">Ds\Deque::__construct</a> — Creates a new instance</li><li><a href="ds-deque.contains.html">Ds\Deque::contains</a> — Determines if the deque contains given values</li><li><a href="ds-deque.copy.html">Ds\Deque::copy</a> — Returns a shallow copy of the deque</li><li><a href="ds-deque.count.html">Ds\Deque::count</a> — Returns the number of values in the collection</li><li><a href="ds-deque.filter.html">Ds\Deque::filter</a> — Creates a new deque using a callable to
determine which values to include</li><li><a href="ds-deque.find.html">Ds\Deque::find</a> — Attempts to find a value's index</li><li><a href="ds-deque.first.html">Ds\Deque::first</a> — Returns the first value in the deque</li><li><a href="ds-deque.get.html">Ds\Deque::get</a> — Returns the value at a given index</li><li><a href="ds-deque.insert.html">Ds\Deque::insert</a> — Inserts values at a given index</li><li><a href="ds-deque.isempty.html">Ds\Deque::isEmpty</a> — Returns whether the deque is empty</li><li><a href="ds-deque.join.html">Ds\Deque::join</a> — Joins all values together as a string</li><li><a href="ds-deque.jsonserialize.html">Ds\Deque::jsonSerialize</a> — Returns a representation that can be converted to JSON</li><li><a href="ds-deque.last.html">Ds\Deque::last</a> — Returns the last value</li><li><a href="ds-deque.map.html">Ds\Deque::map</a> — Returns the result of applying a callback to each value</li><li><a href="ds-deque.merge.html">Ds\Deque::merge</a> — Returns the result of adding all given values to the deque</li><li><a href="ds-deque.pop.html">Ds\Deque::pop</a> — Removes and returns the last value</li><li><a href="ds-deque.push.html">Ds\Deque::push</a> — Adds values to the end of the deque</li><li><a href="ds-deque.reduce.html">Ds\Deque::reduce</a> — Reduces the deque to a single value using a callback function</li><li><a href="ds-deque.remove.html">Ds\Deque::remove</a> — Removes and returns a value by index</li><li><a href="ds-deque.reverse.html">Ds\Deque::reverse</a> — Reverses the deque in-place</li><li><a href="ds-deque.reversed.html">Ds\Deque::reversed</a> — Returns a reversed copy</li><li><a href="ds-deque.rotate.html">Ds\Deque::rotate</a> — Rotates the deque by a given number of rotations</li><li><a href="ds-deque.set.html">Ds\Deque::set</a> — Updates a value at a given index</li><li><a href="ds-deque.shift.html">Ds\Deque::shift</a> — Removes and returns the first value</li><li><a href="ds-deque.slice.html">Ds\Deque::slice</a> — Returns a sub-deque of a given range</li><li><a href="ds-deque.sort.html">Ds\Deque::sort</a> — Sorts the deque in-place</li><li><a href="ds-deque.sorted.html">Ds\Deque::sorted</a> — Returns a sorted copy</li><li><a href="ds-deque.sum.html">Ds\Deque::sum</a> — Returns the sum of all values in the deque</li><li><a href="ds-deque.toarray.html">Ds\Deque::toArray</a> — Converts the deque to an array</li><li><a href="ds-deque.unshift.html">Ds\Deque::unshift</a> — Adds values to the front of the deque</li></ul>
</div>
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