good-and-bad-fibonacci-test.php

<?php

// The slow, although default way of doing fibonacci ---------------------------

function _fibs($n)
{
    if ($n < 2)
        return $n;
    else
        return _fibs($n-1) + _fibs($n-2);
}

function fibs()
{
    $i = 0;
    while (1)
        yield _fibs($i++);
}

// The speedy way to do fibonacci-----------------------------------------------

function fibf()
{
    $a = 0;
    $b = 0;
    $t = 1;
    while (1)
    {
        yield $b;
        if ($b > 0) {
            $t = $a;
            $a = $b;
        }
        $b += $t;
    }
}

// Test utils ------------------------------------------------------------------
//
// function to test an iterator by iterating it until the $compare function
// returns false
//
// print the result visually because its sexy

function visual_iterator_tester($fn, $cmpr)
{
    echo "timing $fn ";

    $then = time();

    foreach ($fn() as $f)
    {
        if ($cmpr($f)) break;
        echo ".";
    }

    $now = time();
    $diff = $now - $then;

    echo "\n$fn completed in $diff second(s)\n";
}

// Run the damn thing ----------------------------------------------------------

$fns = ['fibs', 'fibf'];
$runs = 9999999;

foreach ($fns as $fn)
    visual_iterator_tester($fn, function($a) use($runs) { return $a > $runs; });