Q:

PHP bufffer output minify, NOT textarea/pre

I'm using the buffer sanitizer, as seen in a PHP manual comment, but having trouble with double newlines in textareas. 
When pulling a string out from my database, containing double/triple/quadruple newlines, and putting it into a textarea, the newlines are reduced to only a single newline. 
Therefore: Is it possible to have the function exclude all output between <pre>, <textarea> and </pre>, </textarea>? 
Seeing this question, How to minify php html output without removing IE conditional comments?,  I think i need to use the preg_match, but I'm not sure how to implement it into this function. 
The function I'm using is
function sanitize_output($buffer) {
    $search = array(
        '/\>[^\S ]+/s',  // strip whitespaces after tags, except space
        '/[^\S ]+\</s',  // strip whitespaces before tags, except space
        '/(\s)+/s'       // shorten multiple whitespace sequences
    );

    $replace = array(
        '>',
        '<',
        '\\1'
    );

    $buffer = preg_replace($search, $replace, $buffer);

    return $buffer;
}

ob_start("sanitize_output");

And yeah I'm using both this sanitizer and GZIP to get the smallest size possible. 

A:

here is an implementation of the function mentioned in the comments:
function sanitize_output($buffer) {

    // Searching textarea and pre
    preg_match_all('#\<textarea.*\>.*\<\/textarea\>#Uis', $buffer, $foundTxt);
    preg_match_all('#\<pre.*\>.*\<\/pre\>#Uis', $buffer, $foundPre);

    // replacing both with <textarea>$index</textarea> / <pre>$index</pre>
    $buffer = str_replace($foundTxt[0], array_map(function($el){ return '<textarea>'.$el. '</textarea>'; }, array_keys($foundTxt[0])), $buffer);
    $buffer = str_replace($foundPre[0], array_map(function($el){ return '<pre>'.$el. '</pre>'; }, array_keys($foundPre[0])), $buffer);

    // your stuff
    $search = array(
        '/\>[^\S ]+/s',  // strip whitespaces after tags, except space
        '/[^\S ]+\</s',  // strip whitespaces before tags, except space
        '/(\s)+/s'       // shorten multiple whitespace sequences
    );

    $replace = array(
        '>',
        '<',
        '\\1'
    );

    $buffer = preg_replace($search, $replace, $buffer);

    // Replacing back with content
    $buffer = str_replace(array_map(function($el){ return '<textarea>'.$el. '</textarea>'; }, array_keys($foundTxt[0])), $foundTxt[0], $buffer);
    $buffer = str_replace(array_map(function($el){ return '<pre>'.$el. '</pre>'; }, array_keys($foundPre[0])), $foundPre[0], $buffer);

    return $buffer;
}

There is always room for optimation but that works

