simple array to simple text; simple text to simple array

array2text.php

<?php
$cats = array(
    array(
        'id' => 1,
        'name' => 'level1_1',
        'children' => array(
            array(
                'id' => 1,
                'name' => 'level2_1',
                'children' => array(
                    array(
                        'id' => 1,
                        'name' => 'level3_1',
                        'children' => null,
                    ),
                    array(
                        'id' => 1,
                        'name' => 'level3_2',
                        'children' => array(
                            array(
                                'id' => 1,
                                'name' => 'level4_1',
                                'children' => null,
                            ),
                            array(
                                'id' => 1,
                                'name' => 'level4_2',
                                'children' => null,
                            ),
                        ),
                    ),
                ),
            ),
            array(
                'id' => 1,
                'name' => 'level2_2',
                'children' => array(
                    array(
                        'id' => 1,
                        'name' => 'level3_1',
                        'children' => null,
                    ),
                    array(
                        'id' => 1,
                        'name' => 'level3_2',
                        'children' => null,
                    ),
                ),
            ),
        ),
    ),
    array(
        'id' => 2,
        'name' => 'level1_2',
        'children' => array(
            array(
                'id' => 1,
                'name' => 'level2_1',
                'children' => null,
            ),
            // ...
        ),
    ),
    array(
        'id' => 3,
        'name' => 'level1_3',
        'children' => array(
            array(
                'id' => 1,
                'name' => 'level2_1',
                'children' => null,
            ),
            // ...
        ),
    ),
    array(
        'id' => 4,
        'name' => 'level1_4',
        'children' => array(
            array(
                'id' => 1,
                'name' => 'level2_1',
                'children' => null,
            ),
            // ...
        ),
    ),
);

function toTxt($children, $level) {
    if (is_array($children)) {
        $str = '';
        foreach ($children as $row) {
            if (strlen($str) != 0) {
                $str .=  "\n";
            }
            $str .= str_repeat('    ', $level) . $row['id'] . '=>' . $row['name'];
            $children_str = toTxt($row['children'], $level + 1);
            if (strlen($children_str) != 0) {
                $str .=  "\n" . toTxt($row['children'], $level + 1);
            }
        }
        return $str;
    } else {
        return '';
    }
}

$str = toTxt($cats, 0);
file_put_contents("./output.txt", $str);

function toArray($str) {
    preg_match_all("/(^|\n)(((\s{4})*)([^\s]+))/", $str, $matches);
    $arr = array();
    foreach ($matches[3] as $index => $row) {
        $strs = explode("=>", $matches[5][$index]);
        $current_level = strlen($row)/4;
        if ($current_level == 0) {
            $tmp = &$arr;
        } else {
            $tmp = &$arr;
            for ($i=0; $i < $current_level; $i++) {
                $tmp = &$tmp[count($tmp)-1];
                if ($tmp['children'] == null) {
                    $tmp['children'] = array();
                }
                $tmp = &$tmp['children'];
            }
        }
        $tmp[count($tmp)] = array(
                'id' => $strs[0],
                'name' => $strs[1],
                'children' => null
            );
        unset($tmp);
    }
    return $arr;
}

$data = file_get_contents("./output.txt");
$array = toArray($data);
var_export($array);