Test if value is array or not, when value mostly is null

_benchmark.php

<?php

/**
 * Compare performance of alternative functions
 *
 * Cases functions in `$functions` are all should perform the same task, but in different
 * implementation. This benchmark function runs every cases functions and display a report to
 * STDOUT, so you can compare performance.
 *
 * Example:
 * 
 * ```php
 * $array = [42, 42, 42, 42, 42, 'foo' => null, 'bar' => 37, 42, 42, 42, 42, 42];
 * 
 * foreach (
 *     [
 *         'existing foo' => [true, $array, 'foo'],
 *         'existing bar' => [true, $array, 'bar'],
 *         'unknown baz' => [false, $array, 'baz'],
 *     ]
 *     as $describe => [$return, $arr, $key]
 * ) {
 *     countthese($describe, 5, [
 *         'array_key_exists()' => function () use ($arr, $key) {
 *             return array_key_exists($key, $arr);
 *         },
 *         'isset() || array_key_exists()' => function () use ($arr, $key) {
 *             return isset($arr[$key]) || array_key_exists($key, $arr);
 *         },
 *     ], $return);
 * }
 * ```
 * 
 * Output:
 * 
 * ```
 * ==========[ existing foo ]======================================================
 * Benchmark: counting 5 seconds of `array_key_exists()`, `isset() || array_key_exists()`
 * 
 *  function                     :      count @  iterations/sec. / total sec.
 * --------------------------------------------------------------------------
 *  array_key_exists()           :   30315947 @     6063189.4000 /      5.000 
 *  isset() || array_key_exists():   26433156 @     5286631.2000 /      5.000 
 * 
 *  array_key_exists()            ######################################### 100.0%
 *  isset() || array_key_exists() ####################################       87.2%
 * 
 * ==========[ existing bar ]======================================================
 * Benchmark: counting 5 seconds of `array_key_exists()`, `isset() || array_key_exists()`
 * 
 *  function                     :      count @  iterations/sec. / total sec.
 * --------------------------------------------------------------------------
 *  array_key_exists()           :   30914238 @     6182847.6000 /      5.000 
 *  isset() || array_key_exists():   33205106 @     6641021.2000 /      5.000 
 * 
 *  array_key_exists()            ######################################     93.1%
 *  isset() || array_key_exists() ######################################### 100.0%
 * 
 * ==========[ unknown baz ]=======================================================
 * Benchmark: counting 5 seconds of `array_key_exists()`, `isset() || array_key_exists()`
 * 
 *  function                     :      count @  iterations/sec. / total sec.
 * --------------------------------------------------------------------------
 *  array_key_exists()           :   31766575 @     6353315.0000 /      5.000 
 *  isset() || array_key_exists():   28409213 @     5681842.6000 /      5.000 
 * 
 *  array_key_exists()            ######################################### 100.0%
 *  isset() || array_key_exists() #####################################      89.4%
 * ```
 *
 * @param string $describe Short description
 * @param int $timeout Duration in seconds for every case function
 * @param \Closure[] $functions Case functions. Array keys are short names for cases.
 * @param mixed $checkReturnValue Optional. The extected return value to check. To NOT check return
 * value this parameter must be omitted, sot the function should be called with only 3 parameters.
 */
function countthese($describe, $timeout, array $functions, $checkReturnValue = null) {
    if (!$functions) {
        throw new LogicException("No callback function specified");
    }

    if (func_num_args() >= 4) {
        foreach ($functions as $name => $function) {
            $result = $function();
            if ($checkReturnValue !== $result) {
                var_dump($result);
                throw new RuntimeException("Return value mismatch for `$name`");
            }
        }
    }

    $names = array_keys($functions);
    $width = max(8, ...array_map('strlen', $names));

    echo "==========[ $describe ]", str_repeat("=", max(0, 80 - strlen($describe) - 14)), PHP_EOL;
    printf(
        "Benchmark: counting %d seconds of %s" . PHP_EOL
        , number_format($timeout, 0, "", "_")
        , join(", ", array_map(function ($name) { return "`$name`"; }, $names))
    );
    echo PHP_EOL;
    printf(" %-{$width}s: %10s @ %16s / %10s", "function", "count", "iterations/sec.", "total sec.");
    echo PHP_EOL, "---------", str_repeat("-", $width + 10 + 16 + 10), PHP_EOL;
    $totals = [];
    foreach ($functions as $name => $function) {
        printf(" %-{$width}s: ", $name);
        $start = microtime(true);
        $end   = $start + $timeout;
        $count = 0;
        while ( ($now = microtime(true)) < $end ) {
            $function();
            ++$count;
        }

        $total = $now - $start;
        $speed = $count / $total;
        $totals[$name] = $speed;

        printf("%10d @ %16.4F / %10.3F ", $count, $speed, $total);
        echo PHP_EOL;
    }

    echo PHP_EOL;

    $bar_width = 80 - 4 - $width - 5 - 1;
    $max_speed = max($totals);
    foreach ($totals as $name => $speed) {
        $coeff = $speed / $max_speed;

        printf(" %-{$width}s %-{$bar_width}s %5.1F%%"
            , $name
            , str_repeat("#", round($bar_width * $coeff))
            , $coeff * 100
        );
        echo PHP_EOL;
    }
    echo PHP_EOL;
}

null_is_array.php

<?php
require_once '_benchmark.php';

foreach (
    [
        'null' => [false, null],
        '42' => [false, 42],
        'array' => [true, []],
    ]
    as $describe => [$return, $value]
) {
    countthese($describe, 5, array(
        'is_array()' => function () use ($value) {
            return is_array($value);
        },
        'null !== && is_array()' => function () use ($value) {
            return null !== $value && is_array($value);
        },
    ), $return);
}

null_is_array.txt

==========[ null ]==============================================================
Benchmark: counting 5 seconds of `is_array()`, `null !== && is_array()`

 function              :      count @  iterations/sec. / total sec.
-------------------------------------------------------------------
 is_array()            :   40115122 @     8023024.4000 /      5.000 
 null !== && is_array():   37800462 @     7560092.4000 /      5.000 

 is_array()             ################################################ 100.0%
 null !== && is_array() #############################################     94.2%

==========[ 42 ]================================================================
Benchmark: counting 5 seconds of `is_array()`, `null !== && is_array()`

 function              :      count @  iterations/sec. / total sec.
-------------------------------------------------------------------
 is_array()            :   39369570 @     7873914.0000 /      5.000 
 null !== && is_array():   36663397 @     7332679.4000 /      5.000 

 is_array()             ################################################ 100.0%
 null !== && is_array() #############################################     93.1%

==========[ array ]=============================================================
Benchmark: counting 5 seconds of `is_array()`, `null !== && is_array()`

 function              :      count @  iterations/sec. / total sec.
-------------------------------------------------------------------
 is_array()            :   39915046 @     7983009.2000 /      5.000 
 null !== && is_array():   37932799 @     7586559.8000 /      5.000 

 is_array()             ################################################ 100.0%
 null !== && is_array() ##############################################    95.0%