PHP 7.0.6 Released

    The SplHeap class

    (PHP 5 >= 5.3.0, PHP 7)

    Introduction

    The SplHeap class provides the main functionalities of a Heap.

    Class synopsis

    abstract SplHeap implements Iterator , Countable {
    /* Methods */
    public __construct ( void )
    abstract protected int compare ( mixed $value1 , mixed $value2 )
    public int count ( void )
    public mixed current ( void )
    public mixed extract ( void )
    public void insert ( mixed $value )
    public bool isEmpty ( void )
    public mixed key ( void )
    public void next ( void )
    public void recoverFromCorruption ( void )
    public void rewind ( void )
    public mixed top ( void )
    public bool valid ( void )
    }

    Table of Contents

    User Contributed Notes

    Michelangelo van Dam
    6 years ago
    To have a good idea what you can do with SplHeap, I created a little example script that will show the rankings of Belgian soccer teams in the Jupiler League.

    <?php
    /**
    * A class that extends SplHeap for showing rankings in the Belgian
    * soccer tournament JupilerLeague
    */
    class JupilerLeague extends SplHeap
    {
            /**
         * We modify the abstract method compare so we can sort our
         * rankings using the values of a given array
         */
            public function compare($array1, $array2)
        {
                $values1 = array_values($array1);
                $values2 = array_values($array2);
            if (    $values1[0] === $values2[0]) return 0;
            return     $values1[0] < $values2[0] ? -1 : 1;
        }
    }

    // Let's populate our heap here (data of 2009)
    $heap = new JupilerLeague();
    $heap->insert(array ('AA Gent' => 15));
    $heap->insert(array ('Anderlecht' => 20));
    $heap->insert(array ('Cercle Brugge' => 11));
    $heap->insert(array ('Charleroi' => 12));
    $heap->insert(array ('Club Brugge' => 21));
    $heap->insert(array ('G. Beerschot' => 15));
    $heap->insert(array ('Kortrijk' => 10));
    $heap->insert(array ('KV Mechelen' => 18));
    $heap->insert(array ('Lokeren' => 10));
    $heap->insert(array ('Moeskroen' => 7));
    $heap->insert(array ('Racing Genk' => 11));
    $heap->insert(array ('Roeselare' => 6));
    $heap->insert(array ('Standard' => 20));
    $heap->insert(array ('STVV' => 17));
    $heap->insert(array ('Westerlo' => 10));
    $heap->insert(array ('Zulte Waregem' => 15));

    // For displaying the ranking we move up to the first node
    $heap->top();

    // Then we iterate through each node for displaying the result
    while ($heap->valid()) {
      list (    $team, $score) = each ($heap->current());
      echo     $team . ': ' . $score . PHP_EOL;
          $heap->next();
    }
    ?>

    This results in the following output:
    Club Brugge: 21
    Anderlecht: 20
    Standard: 20
    KV Mechelen: 18
    STVV: 17
    Zulte Waregem: 15
    AA Gent: 15
    G. Beerschot: 15
    Charleroi: 12
    Racing Genk: 11
    Cercle Brugge: 11
    Kortrijk: 10
    Lokeren: 10
    Westerlo: 10
    Moeskroen: 7
    Roeselare: 6

    Hope this example paved the way for more complex implementations of SplHeap.
    igorsantos07 at gmail dot com
    1 year ago
    While Michelangelo Van Dam example (http://br2.php.net/manual/en/class.splheap.php#93930) is a great demonstration of what can be done with SplHeap, this implementation is exactly what SplPriorityQueue does - based on SplMaxHeap. If you're planning to copy that snippet, go no further! There's a SPL class that does exactly what you want :)
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