PHP get text within brackets deep

Question

I have text like this between brackets [ and ]:

$commands = "[CMD1,[CMD2],[CMD3,[CMD4],[CMD5]]]";

and execute with this PHP function:

preg_match_all('/\\[(.*?)\\]/', $commands, $matches);

And output of index 1 is:

array(2) (
    ...
    1 => array(3) (
        0 => string(10) "CMD1,[CMD2"
        1 => string(10) "CMD3,[CMD4"
        2 => string(4) "CMD5"
    )
)

however I want to process the deepest one first, output like this:

array(2) (
    ...
    1 => array(3) (
        0 => string(4) "CMD5"
        1 => string(4) "CMD4"
        2 => string(4) "CMD3"
        3 => string(4) "CMD2"
        4 => string(4) "CMD1"
    )
)

Can preg_match_all do that?

You may need to write an expression parser to get this behavior. — Tim Biegeleisen, Jul 17 '21 at 07:00
Regex is evaluated from left to right. You cannot make it move back and forth. You can get the matches from regex and later do some post processing to get desired result. — anubhava, Jul 17 '21 at 07:02
Not sure if https://stackoverflow.com/questions/14952113/how-can-i-match-nested-brackets-using-regex helps. — Nigel Ren, Jul 17 '21 at 07:02

score 1 · Answer 1 · answered Jul 17 '21 at 07:22

1

You can use this below code.

$commands = "[CMD1,[CMD2],[CMD3,[CMD7],[CMD4],[CMD5]]]";
$array = explode(",", $commands);

array_walk($array, function(&$val, $key){
     $val = trim( trim($val,"]") ,"[");
});

rsort($array);

print_r($array);

Output will be:

Array
(
    [0] => CMD7
    [1] => CMD5
    [2] => CMD4
    [3] => CMD3
    [4] => CMD2
    [5] => CMD1
)

answered Jul 17 '21 at 07:22

shiyani suresh

778
12
12

no, CMD? is not shorted number, it can anytext. – Tomero Indonesia Jul 17 '21 at 07:25

score 1 · Accepted Answer · answered Jul 17 '21 at 07:40

You can use

preg_match_all('/[^][,]+/', $commands, $matches)

See the regex demo. The [^][,]+ regex matches one or more occurrences of any char other than ], [ and ,.

Since the regex engine processes the string (i.e. searched for pattern matches) from left to right, you cannot get the matches in the order you specified in the question. If you want to reverse them, use rsort.

See this PHP demo:

$commands = "[CMD1,[CMD2],[CMD3,[CMD4],[CMD5]]]";
if (preg_match_all('/[^][,]+/', $commands, $matches)) {
    $array = $matches[0];
    rsort($array);
    print_r($array);
}
// => Array( [0] => CMD5 [1] => CMD4  [2] => CMD3 [3] => CMD2 [4] => CMD1 )

PHP get text within brackets deep

2 Answers2