Parse square brace tagged text into an associative array

I have a php string that looks like this...

[line1]this is some test text[/line1][line2]This is line 2 text[/line2][line3]This is line 3 text[/line3]

I am trying to take this and create an array that looks like this..

array(
    "line1" => "this is some test text",
    "line2" => "This is line 2 text",
    "line3" => "This is line 3 text"
)

The string is dynamically created so it could consist of line1 - line 99 and so on.

What is the best way to do this and keep it scalable? Does anybody have an example they can point me at?

Solution

You may take this approach (by splitting the input string multiple times) with explode in order to isolate the relevant data: line-id and the line-text:

$text = "[line1]this is some test text[/line1][line2]This is line 2 text[/line2][line3]This is line 3 text[/line3]";

$text = explode( '][line', ']'.$text.'[line');

// you'll get a spurious item at index 0 and at the end, they'll be skipped

$n = count( $text );

$output = array();

for( $i = 1; $i < $n - 1; $i++ )
{
    $line = explode( ']', $text[ $i] );
    $id = 'line' . $line[ 0 ];
    $line = explode( '[', $line[ 1 ] );
    $value = $line[ 0 ];
    $output[ $id ] = $value;
}

var_export( $output );
echo "\n";

You get:

array (
  'line1' => 'this is some test text',
  'line2' => 'This is line 2 text',
  'line3' => 'This is line 3 text',
)

Note:

Empty "lines" are tolerated and preperly handled

A square brake inside the line text would break the code and screw everything up.

The input format must be scrictly in the form

[linen]text[/linen]....

If you have further requirements you may adjust the code.

I think this may be a good starting point.

Note (again):

This is a working solution (given the restictions mentinoned above).

Another approach is to go with regular expressions and preg_match_all() using capturing groups to retrieve line id and line text.