How to make this weird string explode in PHP?

Question

I have a string like the following

DAS-1111[DR-Helpfull-R]-RUN--[121668688374]-N-[+helpfull_+string]

The above string is a kind of formatted in groups that looks like the following:

A-B[C]-D-E-[F]-G-[H]

The think is that I like to process some of those groups, and I like to make something like explode.

I say like, because I have try this code:

$string = 'DAS-1111[DR-Helpfull-R]-RUN--[121668688374]-N-[+helpfull_+string]';
$parts = explode( '-', $string );
print_r( $parts );

and I get the following result:

Array
(
    [0] => DAS
    [1] => 1111[DR
    [2] => Helpfull
    [3] => R]
    [4] => RUN
    [5] => 
    [6] => [121668688374]
    [7] => N
    [8] => [+helpfull_+string]
)

that it is not what I need.

What I need is the following output:

Array
(
    [0] => DAS
    [1] => 1111[DR-Helpfull-R]
    [2] => RUN
    [3] => 
    [4] => [121668688374]
    [5] => N
    [6] => [+helpfull_+string]
)

Can someone please suggest a nice and elegant way to explode this string in the way I need it ?

what I forgot to mention, is that the string can have more or less groups. Examples:

DAS-1111[DR-Helpfull-R]-RUN--[121668688374]-N-[+helpfull_+string]
DAS-1111[DR-Helpfull-R]-RUN--[121668688374]
DAS-1111[DR-Helpfull-R]-RUN--[121668688374]-N-[+helpfull_+string]-anotherPart

Update 1

As mentioned by @axiac, the preg_split can do the work. But can you please help with the regex now ?

I have try this but it seems that it is incorrect:

(?!\]\-)\-

Answer 1

The code:

$str = 'DAS-1111[DR-Helpfull-R]-RUN--[121668688374]-N-[+helpfull_+string]';
$re  = '/([^-[]*(?:\[[^\]]*\])?[^-]*)-?/';

$matches = array();
preg_match_all($re, $str, $matches);
print_r($matches[1]);

Its output:

Array
(
    [0] => DAS
    [1] => 1111[DR-Helpfull-R]
    [2] => RUN
    [3] =>
    [4] => [121668688374]
    [5] => N
    [6] => [+helpfull_+string]
    [7] =>
)

There is an extra empty value at position 7 in the output. It appears because of the zero-or-one repetitions quantifier (?) placed at the end of the regex. The quantifier is needed because without it the last piece (at index 6) is not matched.

You can remove the ? after the last - and ask this way the dash (-) always match. In this case you must append an extra - to your input string.

The regex

(              # start of the 1st subpattern
               # the captured value is returned in $matches[1]
  [^-[]*       # match any character but '-' and '[', zero or more times
  (?:          # start of a non-capturing subpattern
    \[         # match an opening square bracket ('[')
    [^\]]*     # match any character but ']', zero or more times
    \]         # match a closing square bracket (']')
  )?           # end of the subpattern; it is optional (can appear 0 or 1 times)
  [^-]*        # match any character but '-', zero or more times
)              # end of the 1st subpattern
-?             # match an optional dash ('-')

Answer 2

Instead of exploding you should try to match the following pattern:

(?:^|-)([^-\[]*(?:\[[^\]]+\])?)

Here is an example:

$regex = '/(?:^|-)([^-\[]*(?:\[[^\]]+\])?)/';
$tests = array(
    'DAS-1111[DR-Helpfull-R]-RUN--[121668688374]-N-[+helpfull_+string]',
    'DAS-1111[DR-Helpfull-R]-RUN--[121668688374]',
    'DAS-1111[DR-Helpfull-R]-RUN--[121668688374]-N-[+helpfull_+string]-anotherPart'
);
foreach ($tests as $test) {
    preg_match_all($regex, $test, $result);
    print_r($result[1]);
}

Output:

// DAS-1111[DR-Helpfull-R]-RUN--[121668688374]-N-[+helpfull_+string]
Array
(
    [0] => DAS
    [1] => 1111[DR-Helpfull-R]
    [2] => RUN
    [3] => 
    [4] => [121668688374]
    [5] => N
    [6] => [+helpfull_+string]
)

// DAS-1111[DR-Helpfull-R]-RUN--[121668688374]
Array
(
    [0] => DAS
    [1] => 1111[DR-Helpfull-R]
    [2] => RUN
    [3] => 
    [4] => [121668688374]
)

// DAS-1111[DR-Helpfull-R]-RUN--[121668688374]-N-[+helpfull_+string]-anotherPart
Array
(
    [0] => DAS
    [1] => 1111[DR-Helpfull-R]
    [2] => RUN
    [3] => 
    [4] => [121668688374]
    [5] => N
    [6] => [+helpfull_+string]
    [7] => anotherPart
)