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<h1>Datastructures</h1>
<h2>Table of Contents</h2><ul class="chunklist chunklist_part"><li><a href="class.spldoublylinkedlist.html">SplDoublyLinkedList</a></li><li><a href="class.splstack.html">SplStack</a></li><li><a href="class.splqueue.html">SplQueue</a></li><li><a href="class.splheap.html">SplHeap</a></li><li><a href="class.splmaxheap.html">SplMaxHeap</a></li><li><a href="class.splminheap.html">SplMinHeap</a></li><li><a href="class.splpriorityqueue.html">SplPriorityQueue</a></li><li><a href="class.splfixedarray.html">SplFixedArray</a></li><li><a href="class.splobjectstorage.html">SplObjectStorage</a></li></ul>
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<p class="para">
SPL provides a set of standard datastructures. They are grouped here by their
underlying implementation which usually defines their general field of
application.
</p>
<div class="section">
<h2 class="title">Doubly Linked Lists</h2>
<p class="para">
A Doubly Linked List (DLL) is a list of nodes linked in both directions to
each others. Iterator's operations, access to both ends, addition or
removal of nodes have a cost of O(1) when the underlying structure is a DLL.
It hence provides a decent implementation for stacks and queues.
</p>
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<span class="simpara"><a href="class.spldoublylinkedlist.html" class="classname">SplDoublyLinkedList</a></span>
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<li class="listitem"><span class="simpara"><a href="class.splstack.html" class="classname">SplStack</a></span></li>
<li class="listitem"><span class="simpara"><a href="class.splqueue.html" class="classname">SplQueue</a></span></li>
</ul>
</li>
</ul>
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<div class="section">
<h2 class="title">Heaps</h2>
<p class="para">
Heaps are tree-like structures that follow the heap-property: each node
is greater than or equal to its children, when compared using the
implemented compare method which is global to the heap.
</p>
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<span class="simpara"><a href="class.splheap.html" class="classname">SplHeap</a></span>
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<li class="listitem"><span class="simpara"><a href="class.splmaxheap.html" class="classname">SplMaxHeap</a></span></li>
<li class="listitem"><span class="simpara"><a href="class.splminheap.html" class="classname">SplMinHeap</a></span></li>
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<span class="simpara"><a href="class.splpriorityqueue.html" class="classname">SplPriorityQueue</a></span>
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<div class="section">
<h2 class="title">Arrays</h2>
<p class="para">
Arrays are structures that store the data in a continuous way, accessible
via indexes. Don't confuse them with PHP arrays: PHP arrays are in fact
implemented as ordered hashtables.
</p>
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<span class="simpara"><a href="class.splfixedarray.html" class="classname">SplFixedArray</a></span>
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<h2 class="title">Map</h2>
<p class="para">
A map is a datastructure holding key-value pairs. PHP arrays can be seen as maps from integers/strings to values. SPL provides a map from objects to data. This map can also be used as an object set.
</p>
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<span class="simpara"><a href="class.splobjectstorage.html" class="classname">SplObjectStorage</a></span>
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