PHP function to expand strings array using {a,b,c} and {1..5}

expandBashRepeat.php

<?php

function expandBashRepeat($sourceStrings)
{
    if (is_string($sourceStrings)) $sourceStrings = [$sourceStrings];
    $outputs = [];
    foreach($sourceStrings as $str) {
        $i=0;
        $arrays = [];
        $str2 = preg_replace_callback('/\{([^{}]+)\}/', function($m) use(&$i, &$arrays) {
            $seq = explode(',',$m[1]);
            if(count($seq)>=2) {
                $arrays[$i] = $seq;
            } else {
                $ab = explode('..',$m[1]);
                if (!$ab) { $outputs[] = $str; return $m[0]; }
                $a = intval($ab[0]);
                $b = intval($ab[1]);
                $arrays[$i] = range($a, $b);
            }
            
            return '{{'.($i++).'}}';
        }, $str);
        
        $strs = [$str2];
        $tmpstrs = [];
        for($n=count($arrays)-1;$n>=0;$n--) {
            $arr = $arrays[$n];
            $tmpstrs = [];
            
            foreach($arr as $subs) {
                foreach($strs as $ss) {
                    $tmpstrs[] = str_replace('{{'.$n.'}}', $subs, $ss);
                }
            }
            
            $strs = $tmpstrs;
        }
        
        $outputs = array_merge($outputs, $strs);
    }
    return $outputs;
}