string to array, split by single and double quotes

Question

i'm trying to use php to split a string into array components using either " or ' as the delimiter. i just want to split by the outermost string. here are four examples and the desired result for each:

$pattern = "?????";
$str = "the cat 'sat on' the mat";
$res = preg_split($pattern, $str);
print_r($res);
/*output:
Array
(
    [0] => the cat 
    [1] => 'sat on'
    [2] =>  the mat
)*/

$str = "the cat \"sat on\" the mat";
$res = preg_split($pattern, $str);
print_r($res);
/*output:
Array
(
    [0] => the cat 
    [1] => "sat on"
    [2] =>  the mat
)*/

$str = "the \"cat 'sat' on\" the mat";
$res = preg_split($pattern, $str);
print_r($res);
/*output:
Array
(
    [0] => the
    [1] => "cat 'sat' on"
    [2] =>  the mat
)*/

$str = "the 'cat \"sat\" on' the mat 'when \"it\" was' seventeen";
$res = preg_split($pattern, $str);
print_r($res);
/*output:
Array
(
    [0] => the
    [1] => 'cat "sat" on'
    [2] =>  the mat
    [3] => 'when "it" was'
    [4] =>  seventeen
)*/

as you can see i only want to split by the outermost quotation, and i want to ignore any quotations within quotations.

the closest i have come up with for $pattern is

$pattern = "/((?P<quot>['\"])[^(?P=quot)]*?(?P=quot))/";

but obviously this is not working.

Answer 1

You can use preg_split with the PREG_SPLIT_DELIM_CAPTURE option. The regular expressions is not quite as elegant as @Jan Turoň's back reference approach because the required capture group messes up the results.

$str = "the 'cat \"sat\" on' the mat the \"cat 'sat' on\" the mat";
$match = preg_split("/('[^']*'|\"[^\"]*\")/U", $str, null, PREG_SPLIT_DELIM_CAPTURE);
print_r($match);