[edit] Last updated: Fri, 26 Apr 2013

The SplPriorityQueue class

(PHP 5 >= 5.3.0)

Introduction

The SplPriorityQueue class provides the main functionalities of an prioritized queue, implemented using a max heap.

Class synopsis

SplPriorityQueue implements Iterator , Countable {

/* Methods */

__construct ( void )

int compare ( mixed $priority1 , mixed $priority2 )

int count ( void )

mixed current ( void )

mixed extract ( void )

void insert ( mixed $value , mixed $priority )

bool isEmpty ( void )

mixed key ( void )

void next ( void )

void recoverFromCorruption ( void )

void rewind ( void )

void setExtractFlags ( int $flags )

mixed top ( void )

bool valid ( void )

}

SplPriorityQueue::compare — Compare priorities in order to place elements correctly in the heap while sifting up.
SplPriorityQueue::__construct — Constructs a new empty queue
SplPriorityQueue::count — Counts the number of elements in the queue.
SplPriorityQueue::current — Return current node pointed by the iterator
SplPriorityQueue::extract — Extracts a node from top of the heap and sift up.
SplPriorityQueue::insert — Inserts an element in the queue by sifting it up.
SplPriorityQueue::isEmpty — Checks whether the queue is empty.
SplPriorityQueue::key — Return current node index
SplPriorityQueue::next — Move to the next node
SplPriorityQueue::recoverFromCorruption — Recover from the corrupted state and allow further actions on the queue.
SplPriorityQueue::rewind — Rewind iterator back to the start (no-op)
SplPriorityQueue::setExtractFlags — Sets the mode of extraction
SplPriorityQueue::top — Peeks at the node from the top of the queue
SplPriorityQueue::valid — Check whether the queue contains more nodes

add a note User Contributed Notes SplPriorityQueue - [2 notes]

down

rajatn at rediff dot co dot in ¶

2 years ago


quick implementation of SPL Priority Queue:





<?php





class PQtest extends SplPriorityQueue


{


    public function compare($priority1, $priority2)


    {


        if ($priority1 === $priority2) return 0;


        return $priority1 < $priority2 ? -1 : 1;


    }


}





$objPQ = new PQtest();





$objPQ->insert('A',3);


$objPQ->insert('B',6);


$objPQ->insert('C',1);


$objPQ->insert('D',2);





echo "COUNT->".$objPQ->count()."<BR>";





//mode of extraction


$objPQ->setExtractFlags(PQtest::EXTR_BOTH);





//Go to TOP


$objPQ->top();





while($objPQ->valid()){


    print_r($objPQ->current());


    echo "<BR>";


    $objPQ->next();


}





?>





output:





COUNT->4


Array ( [data] => B [priority] => 6 ) 


Array ( [data] => A [priority] => 3 ) 


Array ( [data] => D [priority] => 2 ) 


Array ( [data] => C [priority] => 1 )

down

Anonymous ¶

2 years ago


This documentation does not mention whether this is a min-heap or a max-heap.

add a note

The SplPriorityQueue class

Introduction

Class synopsis

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