<?php

/**

* Compacts output of queues for an experiment, handling edge cases.

*

* @param array $queue An array representing the queue of items.

* @param string $prefix A string to prepend to each output line.

* @param int $max_lines Maximum number of lines to output. Prevents runaway output.

* @return string Compacted output string.

*/

function compactQueueOutput(array $queue, string $prefix = '', int $max_lines = 100): string

{

$output = '';

$line_count = 0;

foreach ($queue as $item) {

//Handle potential null or undefined item values.

if ($item === null || $item === undefined) {

$output .= $prefix . "Null/Undefined item\n";

} else {

$output .= $prefix . print_r($item, true) . "\n"; //Use print_r for complex data structures

}

$line_count++;

if ($line_count >= $max_lines) {

$output .= "\n... (truncated after $max_lines lines)\n"; // Indicate truncation

break; // Stop processing if max lines reached.

}

}

return $output;

}

//Example Usage (for testing)

if (isset($_SERVER['argv'][1])) {

$queue = ['item1', 'item2', null, 'item4', ['a', 'b'], 'item6', 'item7', 'item8', 'item9', 'item10', 'item11', 'item12', 'item13', 'item14', 'item15'];

$prefix = 'Experiment Data: ';

$max_lines = 5;

echo compactQueueOutput($queue, $prefix, $max_lines) . "\n";

}

?>