Replace all occurences of char inside quotes on PHP

Question

How could I convert something like this:

\"hi (text here) and (other text)\" come (again)

To this:

\"hi \\(text here\\) and \\(         


        

Answer 1

Given the string

$str = '"hi (text here) and (other text)" come (again) "maybe (to)morrow?" (yes)';

Iterative method

 for ($i=$q=0,$res='' ; $i<strlen($str) ; $i++) {
   if ($str[$i] == '"') $q ^= 1;
   elseif ($q && ($str[$i]=='(' || $str[$i]==')')) $res .= '\\';
   $res .= $str[$i];
 }

 echo "$res\n";

But if you're a fan of recursion

 function rec($i, $n, $q) {
   global $str;
   if ($i >= $n) return '';
   $c = $str[$i];
   if ($c == '"') $q ^= 1;
   elseif ($q && ($c == '(' || $c == ')')) $c = '\\' . $c;
   return $c . rec($i+1, $n, $q);
 }

 echo rec(0, strlen($str), 0) . "\n";

Result:

"hi \(text here\) and \(other text\)" come (again) "maybe \(to\)morrow?" (yes)

Answer 2

This should do it for both single and double quotes:

$str = '"hi \(text here)" and (other text) come \'(again)\'';

$str = preg_replace_callback('`("|\').*?\1`', function ($matches) {
    return preg_replace('`(?<!\\\)[()]`', '\\\$0', $matches[0]);
}, $str);

echo $str;

output

"hi \(text here\)" and (other text) come '\(again\)'

It is for PHP >= 5.3. If you have a lower version (>=5) you have to replace the anonymous function in the callback with a separate function.

Answer 3

You can use preg_replace_callback for this;

// outputs: hi \(text here\) and \(other text\) come (again)
print preg_replace_callback('~"(.*?)"~', function($m) {
    return '"'. preg_replace('~([\(\)])~', '\\\$1', $m[1]) .'"';
}, '"hi (text here) and (other text)" come (again)');

What about already escaped strings;

// outputs: hi \(text here\) and \(other text\) come (again)
print preg_replace_callback('~"(.*?)"~', function($m) {
    return '"'. preg_replace('~(?:\\\?)([\(\)])~', '\\\$1', $m[1]) .'"';
}, '"hi \(text here\) and (other text)" come (again)');

Answer 4

Here's how you can do it with the preg_replace_callback() function.

$str = '"hi (text here) and (other text)" come (again)';
$escaped = preg_replace_callback('~(["\']).*?\1~','normalizeParens',$str);
// my original suggestion was '~(?<=").*?(?=")~' and I had to change it
// due to your 2nd edit in your question. But there's still a chance that
// both single and double quotes might exist in your string.

function normalizeParens($m) {
    return preg_replace('~(?<!\\\)[()]~','\\\$0',$m[0]);
    // replace parens without preceding backshashes
}
var_dump($str);
var_dump($escaped);