php - preg_replace replace line breaks across multiple lines between two symbols

Solution:

You can use

{-code-1}

See the regex demo{-code-7} Details:

• {-code-2} - end of the previous successful match ({-code-3}) or ({-code-4}) start of string ({-code-5}) and then {-code-6} or {-code-7}
• [{-code-5}{]*? - any zero or more (but as few as possible) chars other than {
• \K - match reset operator that discards all text matched so far in the overall match memory buffer
• \s+ - any one or more whitespace chars{-code-7}

Note the m flag that is necessary to make {-code-5} match start of a line, not just start of a whole string{-code-7}

See the PHP demo:

$text = "{-code-7}a {\r\n    // rules\r\n}\r\n\r\n{-code-7}a-b,\r\n{-code-7}a-b {-code-7}b, {-code-7}a-b{-code-7}s\r\n{-code-7}x {-code-7}y, {-code-7}x {\r\n    // rules\r\n}\r\n\r\n{-code-6}a {\r\n    // rules\r\n}\r\n\r\n{-code-6}k {\r\n    // rules\r\n}";
echo {-code-1};

Solution{-code-10}

Update{-code-10} Stupildy, I missed that this was a PHP question, not a JS one{{-code-9}code{-code-9}5} My answer is JS{-code-9}based; however it is easily adapted to PHP{{-code-9}code{-code-9}5} PHP has {{-code-9}code{-code-9}1} for the replacement callback, and the pattern will be the same{{-code-9}code{-code-9}5}

If I understand you right, you want to collapse multi{-code-9}selector CSS rules and media queries into single lines{{-code-9}code{-code-9}5}

The first thing to point out is that your current pattern isn't safe for all CSS selectors{{-code-9}code{-code-9}5} It won't cover those that start with {{-code-9}code{-code-9}2} or {{-code-9}code{-code-9}3}, for example{{-code-9}code{-code-9}5}

Try this{-code-10}

let edited = str{{-code-9}code{-code-9}5}replace(/^{-code-11}\{{-code-9}code{-code-9}3}\{{-code-9}code{-code-9}5}{{-code-9}code{-code-9}2}{{-code-9}code{-code-9}8}{-code-10}\{-code-9}\{-code-11}]{-code-11}\s\S]+?(?=\{)/mg, match => {
    return match{{-code-9}code{-code-9}5}replace(/\n/g, ' ');
});

Demo{{-code-9}code{-code-9}5}

Pattern explanation{-code-10}

• Anchor to the start of a line
• The line must start with {{-code-9}code{-code-9}5}, {{-code-9}code{-code-9}2}, {{-code-9}code{-code-9}3}, {{-code-9}code{-code-9}8}, {-code-9}, {-code-10} or {-code-11}, covering most CSS selectors{{-code-9}code{-code-9}5}
• Following the selector(s), match whatever comes after, until{{-code-9}code{-code-9}5}{{-code-9}code{-code-9}5}{{-code-9}code{-code-9}5}
• }
• We run each match through a callback, replacing line breaks with spaces{{-code-9}code{-code-9}5}

The m (multi{-code-9}line) flag tells JS to interpret our anchor (^) as pertaining to any line, not just the first{{-code-9}code{-code-9}5}

The g (global) flag handles all instances, not just the first found{{-code-9}code{-code-9}5}