Question

I need change background of all text that have two spaces from the start of the line.

  text

shold be converted to “<div class='special'>text</div>“

That is easy:

$text = preg_replace("|^  (.+)|um", "<div class='special'>$1</div>", $text);

But

  line1
  line2

Is converted to

<div class='special'>line1</div>
<div class='special'>line2</div>

Though

<div class='special'>line1
line2</div>

is needed.

How that can be achieved?

Answer 1

Replace

((?:^  [^\r\n]*(?:\R(?=  ))?)+)

with <div class='special'>$1</div>.

But this will convert

  line1
  line2

to this:

<div class='special'>  line1
  line2</div>

If you want to remove the spaces, you should match the text, remove the spaces and then replace.