regexp从字符串中删除空格，但不能在'或“之间

Question

How to remove all whitespaces from string but not between single or double qoutes?

for example, I have text:

$request = $requests[ $requestsCnt];
var_dump($request );
var_dump( getmypid());

$query = 'SELECT  FROM users';

$query2 = 'SELECT `*` FROM       
   `users`';

die;

$array = [ '    ' => 'bb']

I need to preserve whitespaces in $query and $query2 My regexp is \\s+(?![^'].*') , but in doesn't work with:

$query2 = 'SELECT `*` FROM       
`users`';

and

$array = [ '    ' => 'bb']

Answer 1

This regular expression will remove all horizontal whitespace (to preserve new lines) from a string (in this case, it seems to ve a PHP file):

\h+(?=([^']*'[^']*')*[^']*$)

**Details**

\h                     # Any whitespace except new lines, one or more times
(?=                    # Positive lookahead
([^']*'[^']*')*[^']*$  # Match anything in between single quotes
)

PHP example

<pre>
<?php
$s = '
$request = $requests[ $requestsCnt];
var_dump($request );
var_dump( getmypid());

$query = \'SELECT  FROM users\';

$query2 = \'SELECT `*` FROM       
`users`\';

die;

$array = [ \'    \' => \'bb\']';
$s = preg_replace("/\h+(?=([^']*'[^']*')*[^']*$)/i", "", $s);
echo nl2br($s); // <pre> and nl2br() to show formatted code

Demo