Replace Preg_Replace() E Modifier With Preg_Replace_Callback

Replace preg_replace() e modifier with preg_replace_callback

In a regular expression, you can "capture" parts of the matched string with (brackets); in this case, you are capturing the (^|_) and ([a-z]) parts of the match. These are numbered starting at 1, so you have back-references 1 and 2. Match 0 is the whole matched string.

The /e modifier takes a replacement string, and substitutes backslash followed by a number (e.g. \1) with the appropriate back-reference - but because you're inside a string, you need to escape the backslash, so you get '\\1'. It then (effectively) runs eval to run the resulting string as though it was PHP code (which is why it's being deprecated, because it's easy to use eval in an insecure way).

The preg_replace_callback function instead takes a callback function and passes it an array containing the matched back-references. So where you would have written '\\1', you instead access element 1 of that parameter - e.g. if you have an anonymous function of the form function($matches) { ... }, the first back-reference is $matches[1] inside that function.

So a /e argument of

'do_stuff(\\1) . "and" . do_stuff(\\2)'

could become a callback of

function($m) { return do_stuff($m[1]) . "and" . do_stuff($m[2]); }

Or in your case

'strtoupper("\\2")'

could become

function($m) { return strtoupper($m[2]); }

Note that $m and $matches are not magic names, they're just the parameter name I gave when declaring my callback functions. Also, you don't have to pass an anonymous function, it could be a function name as a string, or something of the form array($object, $method), as with any callback in PHP, e.g.

function stuffy_callback($things) {
    return do_stuff($things[1]) . "and" . do_stuff($things[2]);
}
$foo = preg_replace_callback('/([a-z]+) and ([a-z]+)/', 'stuffy_callback', 'fish and chips');

As with any function, you can't access variables outside your callback (from the surrounding scope) by default. When using an anonymous function, you can use the use keyword to import the variables you need to access, as discussed in the PHP manual. e.g. if the old argument was

'do_stuff(\\1, $foo)'

then the new callback might look like

function($m) use ($foo) { return do_stuff($m[1], $foo); }

Gotchas

• Use of preg_replace_callback is instead of the /e modifier on the regex, so you need to remove that flag from your "pattern" argument. So a pattern like /blah(.*)blah/mei would become /blah(.*)blah/mi.
• The /e modifier used a variant of addslashes() internally on the arguments, so some replacements used stripslashes() to remove it; in most cases, you probably want to remove the call to stripslashes from your new callback.

Replace preg_replace through preg_replace_callback

You need to use $m[1] to access the second element in the $m array:

preg_replace_callback("/=([0-9A-F][0-9A-F])/", function($m) { return  
    chr(hexdec($m[1])); }, $line
);

See PHP demo.

Replacing preg_replace e modifier

Easily.

$str = preg_replace_callback('/&#(\d+);/', function($m) use ($lo) {
    return code2utf($m[1],$lo);
}, $str);

The important thing here is the use ($lo), as it allows you to "import" the $lo variable into your callback.

I've also cleaned up your regex - way too many backslashes ;)

Can't convert preg_replace() with modifier /e to preg_replace_callback()

Your problem is as you already know, that your variables are out of scope in your anonymous functions and since you don't know which one you will replace you can't pass them to the function, so you have to use the global keyword, e.g.

$uri = "module/page/{#page}";
$page = 3;

$uri_to_call = $uri_rule = preg_replace_callback("/\{\#([A-Za-z_]+)\}/", function($m){
    global ${$m[1]};
    return ${$m[1]};
});

PHP7 - The /e modifier is no longer supported, use preg_replace_callback instead

The error message is telling you to remove the e modifier that you've included in your new code.

/ (?<=^|[\x09\x20\x2D]). / e
^ ^------Pattern-------^ ^ ^ ---- Modifiers
|                        |
 -------Delimiters-------

You need to remove the modifier, so preg_replace_callback('/(?<=^|[\x09\x20\x2D])./e', ...) should be preg_replace_callback('/(?<=^|[\x09\x20\x2D])./' , ...).

As an aside, you aren't benefiting from using a foreach loop in your new code. The match will always be in the second item in the array. Here's an example without using a loop:

$inputString = 'foobazbar';

$result = preg_replace_callback('/^foo(.*)bar$/', function ($matches) {
     // $matches[0]: "foobazbar" 
     // $matches[1]: "baz" 
     return "foo" . strtoupper($matches[1]) . "bar";
}, $inputString);

// "fooBAZbar"
var_dump($result);

The /e modifier is deprecated, use preg_replace_callback instead of preg_replace()

You can't put the replacement function in fetch_full_ameinfo(), because it needs to refer to the $param1 and $param2 variables, which are local to this function.

This means it needs to use eval() in the current function (this is essentially what preg_replace() does internally when it processes the /e flag).

You need to change the replacement string that fetch_full_ameinfo() creates so that it uses a variable instead of \1, \2, etc. to refer to the capture groups, because the callback function receives the captured matches as an array. So replace the block beginning with if (!$findonly) with this:

if (!$findonly)
    {

        $ameinfo['find'][] = "~($result[findcode])~i";
        $ameinfo['replace'][] = 'ame_match_bbcode($param1, $param2, \'' . $result['ameid'] . '\', \'' . ame_slasher($result['title']) . '\', ' . $result['container'] . ', \'' . ame_slasher($result['replacecode']) . '\', \'$match[1]\', \'$match[2]\', \'$match[3]\', \'$match[4]\', \'$match[5]\', \'$match[6]\')';


    }
else
    {

        $ameinfo['find'][] = "~(\[url\]$result[findcode]\[/url\])~i";
        $ameinfo['find'][] = "~(\[url=\"?$result[findcode]\"?\](.*?)\[/url\])~i";
        $ameinfo['replace'][] = 'ame_match("$match[1]", "", ' . intval($result['extraction']) .', "' . ($result['embedregexp'] ? "~" . ame_slasher($result['embedregexp']) . "~sim" : "") . '", "' . ($result['validation'] ? "~" . ame_slasher($result['validation']) . "~sim" : "") . '",$ameinfo)';
        $ameinfo['replace'][] = 'ame_match("$match[1]", "$match[2]", ' . intval($result['extraction']) .', "' . ($result['embedregexp'] ? "~" . ame_slasher($result['embedregexp']) . "~sim" : "") . '", "' . ($result['validation'] ? "~" . ame_slasher($result['validation']) . "~sim" : "") . '", $ameinfo)';

    }

Then change your code to:

    $text = preg_replace_callback($ameinfo['find'], function($match) use (&$param1, &$param2, &$ameinfo) {
        return eval($ameinfo['replace']);
    }, ($param2 ? $param2 : $param1), 1);

Replace deprecated preg_replace /e with preg_replace_callback

You can use an anonymous function to pass the matches to your function:

$result = preg_replace_callback(
    "/\{([<>])([a-zA-Z0-9_]*)(\?{0,1})([a-zA-Z0-9_]*)\}(.*)\{\\1\/\\2\}/isU",
    function($m) { return CallFunction($m[1], $m[2], $m[3], $m[4], $m[5]); },
    $result
);

Apart from being faster, this will also properly handle double quotes in your string. Your current code using /e would convert a double quote " into \".

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