Similar to parse_str but don't mangle parameters with dots or spaces

parse_query_string.php

<?php

declare(strict_types=1);
/**
 * Similar to parse_str, parses a query string and returns the resulting array.
 * Does not replace '.' and ' ' with underscores.
 *
 * @param string $string
 * @return array
 */
function parse_query_string($string, ?callable $onError)
{
    $parts = explode('&', $string);
    $result = [];

    foreach ($parts as $part) {
        if (str_contains($part, '=')) {
            $off = strpos($part, '=');
            $name = substr($part, 0, $off);
            $value = substr($part, $off + 1);

            $value = urldecode($value);
        } else {
            $name = $part;
            $value = null;
        }
        $name = urldecode($name);
        $fullName = $name;
        $indexes = [];

        if (str_contains($name, '[')) {
            $off = strpos($name, '[');
            $base = substr($name, 0, $off);
            $index = substr($name, $off + 1);
            if ($base === '') {
                continue;
            }

            $name = $base;

            if (str_contains($index, ']')) {
                $off = strpos($index, ']');
                $idx = substr($index, 0, $off);
                $index = substr($index, $off + 1);

                $indexes[] = $idx;

                while (str_starts_with($index, '[')) {
                    if (str_contains($index, ']')) {
                        $index = substr($index, 1);
                        $off = strpos($index, ']');
                        $idx = substr($index, 0, $off);
                        $index = substr($index, $off + 1);

                        $indexes[] = $idx;
                    } else {
                        if ($onError !== null) {
                            $onError($fullName, $value);
                        }

                        break;
                    }
                }
            } else {
                if ($onError !== null) {
                    $onError($fullName, $value);
                }
            }
        }

        if (count($indexes) === 0) {
            $result[$name] = $value;

            continue;
        }

        array_unshift($indexes, $name);
        $last = array_pop($indexes);

        $ref = &$result;
        foreach ($indexes as $idx) {
            if ($idx === '') {
                $ref[] = [];
                $ref = &$ref[count($ref) - 1];
            } else {
                if (!isset($ref[$idx]) || !is_array($ref[$idx])) {
                    $ref[$idx] = [];
                }
                $ref = &$ref[$idx];
            }
        }
        if ($last === '') {
            $ref[] = $value;
        } else {
            $ref[$last] = $value;
        }
    }

    return $result;
}