preg_replace_callback

(PHP 4 >= 4.0.5, PHP 5, PHP 7, PHP 8)

preg_replace_callback — Realiza una búsqueda y sustitución de una expresión regular usando una llamada de retorno

Descripción

preg_replace_callback(
    mixed $pattern,
    callable $callback,
    mixed $subject,
    int $limit = -1,
    int &$count = ?
): mixed

El comportamiento de esta función es casi idéntico al de preg_replace(), excepto por el hecho de que en vez del parámetro replacement, se debería especificar callback.

Parámetros

pattern

El patron de búsqueda. Puede ser tanto un cadena como un array de cadenas.

callback

Una llamada de retorno que será llamada y pasada a un array de elementos coincidentes en la cadena subject. La llamada de retorno debería devolver la cadena de sustitución. Esta es la firma de la llamada de retorno:

handler(array $matches): string

A menudo se necesitará la función de callback para usar preg_replace_callback() únicamente en un lugar. En este caso se puede usar una función anónima para declarar una llamada de retorno dentro de la llamada a preg_replace_callback(). Al hacerlo de este modo, se tiene toda la información de la llamada en un único lugar y no abarrota el espacio de nombres de funciones con un nombre de función de llamada de retorno que no se usa en ningún otro sitio.

Ejemplo #1 preg_replace_callback() y función anónima

<?php
/* un filtro de línea de comandos estilo unix para convertir letras
 * mayúsculas a minúsculas al principio de párrafos */
$fp = fopen("php://stdin", "r") or die("no se puede leer stdin");
while (!feof($fp)) {
    $línea = fgets($fp);
    $línea = preg_replace_callback(
        '|<p>\s*\w|',
        function ($coincidencias) {
            return strtolower($coincidencias[0]);
        },
        $línea
    );
    echo $línea;
}
fclose($fp);
?>

subject

La cadena o un array de cadenas a buscar y reemplazar.

limit

Las sustituciones máximas posibles por cada patrón en cada cadena subject. Por defecto -1 (sin límite).

count

Si se especifica, esta variable será rellenada con el número de sustituciones hechas.

Valores devueltos

preg_replace_callback() devuelve un array si el parámetro subject es un array, o, por el contrario una cadena. Si se producen errores, el valor devuleto es null

Si se encontraron coincidencias, el nuevo sujeto será devuelto, de lo contrario subject será devuelto sin cambios.

Historial de cambios

Versión	Descripción
5.1.0	Se añadió el parámetro `count`

Ejemplos

Ejemplo #2 Ejemplo de preg_replace_callback()

<?php
// este texto se usó en 2002
// queremos actualizarlo al 2003
$texto = "El Día de los Inocentes es el 28/12/2002\n";
$texto.= "Las últimas Navidades fueron el 24/12/2001\n";
// la función de llamada de retorno
function añoSiguiente($coincidencias)
{
  // como es usual: $coincidencias[0] es la coincidencia completa
  // $coincidencias[1] la coincidencia del primer sub-patrón
  // encerrado entre '(...)' y así sucesivamente
  return $coincidencias[1].($coincidencias[2]+1);
}
echo preg_replace_callback(
            "|(\d{2}/\d{2}/)(\d{4})|",
            "añoSiguiente",
            $texto);

?>

El resultado del ejemplo sería:

El Día de los Inocentes es el 28/12/2003
Las últimas Navidades fueron el 24/12/2002

Ejemplo #3 preg_replace_callback() usando una estructura recursiva para manejar el código BB encapsulado

<?php
$entrada = "nivel 1 [indent] nivel 2 [indent] nivel 3 [/indent] nivel 2 [/indent] nivel 1";

function analizarEtiquetasRecursivo($entrada)
{

    $regex = '#\[indent]((?:[^[]|\[(?!/?indent])|(?R))+)\[/indent]#';

    if (is_array($entrada)) {
        $entrada = '<div style="margin-left: 10px">'.$entrada[1].'</div>';
    }

    return preg_replace_callback($regex, 'analizarEtiquetasRecursivo', $entrada);
}

$salida = analizarEtiquetasRecursivo($entrada);

echo $salida;
?>

Ver también

Patrones de PCRE
preg_replace_callback_array() - Realizar una búsqueda y sustitución de expresión regular con retrollamadas
preg_quote() - Escapar caracteres en una expresión regular
preg_replace() - Realiza una búsqueda y sustitución de una expresión regular
preg_last_error() - Devuelve el código de error de la última ejecución de expresión regular de PCRE
Funciones anónimas

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User Contributed Notes 22 notes

down

104

Richard ¶

12 years ago

The easiest way to pass more than one parameters to the callback function is with the 'use' keyword. 



[This is better than using global, because it works even when we are already inside a function.]



In this example, the callback function is an anonymous function, which takes one argument, $match, supplied by preg_replace_callback().  The extra 

"use ($ten)" puts the $ten variable into scope for the function.



<?php

$string = "Some numbers: one: 1; two: 2; three: 3 end";

$ten = 10;

$newstring = preg_replace_callback(

    '/(\\d+)/',

    function($match) use ($ten) { return (($match[0] + $ten)); },

    $string

    );

echo $newstring;

#prints "Some numbers: one: 11; two: 12; three: 13 end";

?>

down

Sjon at hortensius dot net ¶

17 years ago

preg_replace_callback returns NULL when pcre.backtrack_limit is reached; this sometimes occurs faster then you might expect. No error is raised either; so don't forget to check for NULL yourself

down

Yuri ¶

12 years ago

If you want to call non-static function inside your class, you can do something like this. 

For PHP 5.2 use second argument like array($this, 'replace'):
<?php
class test_preg_callback{

  private function process($text){
    $reg = "/\{([0-9a-zA-Z\- ]+)\:([0-9a-zA-Z\- ]+):?\}/";
    return preg_replace_callback($reg, array($this, 'replace'), $text);
  }
  
  private function replace($matches){
    if (method_exists($this, $matches[1])){
      return @$this->$matches[1]($matches[2]);     
    }
  }  
}
?>

For PHP 5.3 use second argument like "self::replace":
<?php
class test_preg_callback{

  private function process($text){
    $reg = "/\{([0-9a-zA-Z\- ]+)\:([0-9a-zA-Z\- ]+):?\}/";
    return preg_replace_callback($reg, "self::replace", $text);
  }
  
  private function replace($matches){
    if (method_exists($this, $matches[1])){
      return @$this->$matches[1]($matches[2]);     
    }
  }  
}
?>

down

carlos dot ballesteros at softonic dot com ¶

15 years ago

A simple function to replace a list of complete words or terms in a string (for PHP 5.3 or above because of the closure):

<?php
function replace_words($list, $line, $callback) {
    return preg_replace_callback(
        '/(^|[^\\w\\-])(' . implode('|', array_map('preg_quote', $list)) . ')($|[^\\w\\-])/mi',
        function($v) use ($callback) { return $v[1] . $callback($v[2]) . $v[3]; },
        $line
    );
}
?>

Example of usage:
<?php
$list = array('php', 'apache web server');
$str = "php and the apache web server work fine together. php-gtk, for example, won't match. apache web servers shouldn't too.";

echo replace_words($list, $str, function($v) {
    return "<strong>{$v}</strong>";
});
?>

down

Drake ¶

14 years ago

The good version of the class PhpHex2Str
<?php
class PhpHex2Str
{
    private $strings;

    private static function x_hex2str($hex) {
        $hex = substr($hex[0], 1);
        $str = '';
        for($i=0;$i < strlen($hex);$i+=2) {
            $str.=chr(hexdec(substr($hex,$i,2)));
        }
        return $str;
    }

    public function decode($strings = null) {
        $this->strings = (string) $strings;
        return preg_replace_callback('#\%[a-zA-Z0-9]{2}#', 'PhpHex2Str::x_hex2str', $this->strings);
    }
}

// Exemple
$obj = new PhpHex2Str;

$strings = $obj->decode($strings);
var_dump($strings);
?>

down

matt at mattsoft dot net ¶

18 years ago

it is much better on preformance and better practice to use the preg_replace_callback function instead of preg_replace with the e modifier.

function a($text){return($text);}

// 2.76 seconds to run 50000 times
preg_replace("/\{(.*?)\}/e","a('\\1','\\2','\\3',\$b)",$a);

// 0.97 seconds to run 50000 times
preg_replace_callback("/\{(.*?)\}/s","a",$a);

down

Fredow ¶

9 years ago

<?php

// Nice little function that convert a string to uppercase by keeping the HTMLentities intact.

public static function strtoupper_entities($str) {



    $patternMajEntities = '/(\&([A-Z])(ACUTE|CEDIL|CARON|CIRC|GRAVE|ORN|RING|SLASH|TH|TILDE|UML)\;)+/';

    $str = preg_replace_callback ($patternMajEntities, 

        function ($matches) {

            return "&" . $matches[2] . strtolower($matches[3]) . ";";

        }, strtoupper($str));

    

    return $str;

}

down

T-Soloveychik at ya dot ru ¶

11 years ago

Text lines numeration:
<?PHP
// Multieline text:
    $Text = "
Some 
Multieline
text
for
numeration";

// For count:
    $GLOBALS["LineNUMBER"] = 1;

// Replace linestart on number:
    PRINT preg_replace_callback("/^/m",function ()
        {
            return $GLOBALS["LineNUMBER"]++."  ";
        },
        $Text);

?>

1
2 Some
3 Multieline
4 text
5 for
6 numeration

down

development at HashNotAdam dot com ¶

12 years ago

From PHP 5.3 you can use an anonymous function to pass local variables into the callback.



<?php



public function replace_variables( $subject, $otherVars ) {

    $linkPatterns = array(

        '/(<a .*)href=(")([^"]*)"([^>]*)>/U',

        "/(<a .*)href=(')([^']*)'([^>]*)>/U"

    );



    $callback = function( $matches ) use ( $otherVars ) {

        $this->replace_callback($matches, $otherVars);

    };



    return preg_replace_callback($this->patterns, $callback, $subject);

}



public function replace_callback($matches, $otherVars) {

    return $matches[1] . $otherVars['myVar'];

}

?>

down

kkatpki ¶

11 years ago

Note that, as of PHP 5.3, it seems that named subpatterns are now included in the matches array by their named key as well as their numerical key.

To build off of Chris' previous example, as of PHP 5.3, you *can* do

<?php

preg_replace_callback('/(?<char>[a-z])/', 'callback', 'word');

function callback($matches) {
    var_dump($matches);
}

?>

and expect to get $matches['char'] in your function. * BUT ONLY AS OF PHP 5.3 *

Please be mindful of this if you intend to support PHP 5.2.

down

Florian Arndt ¶

12 years ago

This small class allows PHP users to read JSON files with include statements in them. For instance the include {{{ "relative/to/including.json" }}} is replaced by the content of the json file located at "relative/to/including.json".

<?php
    /**
     * Handles JSON files with includes
     * Purpose: handle bigger JSON files by featuring "includes"
     * 
     * @author Florian Arndt
     */
    class JWI {
        /**
         * Parses a JSON file and returns its contents
         * @param String $filename
         */
        static function read($filename) {
            if(!file_exists($filename))
                throw new Exception('<b>JWI Error: JSON file <tt>'.$filename.'</tt> not found!</b>');
            $content = join('', file($filename));
            $dir = dirname($filename);
            /**
             * replace
             *   include statements
             * with
             *   content of the file to include
             * recursively
             */
            $content = preg_replace_callback(
                '/{{{\s*"\s*(.+)\s*"\s*}}}/', // >include file< - pattern
                create_function(
                    '$matches', // callback parameter
                    sprintf(
                        '$fn = "%s/".$matches[1];'.
                        'return JWI::read($fn);',
                        realpath(dirname($filename))
                    )
                ),
                $content
            );
            return $content;
        }
    }

down

chris at ocproducts dot com ¶

14 years ago

The pcre.backtrack_limit option (added in PHP 5.2) can trigger a NULL return, with no errors. The default pcre.backtrack_limit value is 100000. If you have a match that exceeds about half this limit it triggers a NULL response.
e.g. My limit was at 100000 but 500500 triggered a NULL response. I'm not running unicode but I *guess* PCRE runs in utf-16.

down

Anonymous ¶

14 years ago

Created this to fetch the link and name of an anchor tag. I use this when cleaning an HTML email to text. Using regex for HTML is not recommended but for this purpose I see no issue with it. This is not designed to work for nested anchors.

A note to keep in mind:
I was primarily concerned with valid HTML so if attributes do no use ' or " to contain the values then this will need to be tweaked.
If you can edit this to work better, please let me know.
<?php
/**
 * Replaces anchor tags with text
 * - Will search string and replace all anchor tags with text (case insensitive)
 * 
 * How it works:
 * - Searches string for an anchor tag, checks to make sure it matches the criteria
 *         Anchor search criteria:
 *             - 1 - <a (must have the start of the anchor tag )
 *             - 2 - Can have any number of spaces or other attributes before and after the href attribute
 *             - 3 - Must close the anchor tag
 * 
 * - Once the check has passed it will then replace the anchor tag with the string replacement
 * - The string replacement can be customized
 * 
 * Know issue:
 * - This will not work for anchors that do not use a ' or " to contain the attributes. 
 *         (i.e.- <a href=http: //php.net>PHP.net</a> will not be replaced)
 */
function replaceAnchorsWithText($data) {
    /**
     * Had to modify $regex so it could post to the site... so I broke it into 6 parts.
     */
    $regex  = '/(<a\s*'; // Start of anchor tag
    $regex .= '(.*?)\s*'; // Any attributes or spaces that may or may not exist
    $regex .= 'href=[\'"]+?\s*(?P<link>\S+)\s*[\'"]+?'; // Grab the link
    $regex .= '\s*(.*?)\s*>\s*'; // Any attributes or spaces that may or may not exist before closing tag 
    $regex .= '(?P<name>\S+)'; // Grab the name
    $regex .= '\s*<\/a>)/i'; // Any number of spaces between the closing anchor tag (case insensitive)
    
    if (is_array($data)) {
        // This is what will replace the link (modify to you liking)
        $data = "{$data['name']}({$data['link']})";
    }
    return preg_replace_callback($regex, 'replaceAnchorsWithText', $data);
}

$input  = 'Test 1: <a href="http: //php.net1">PHP.NET1</a>.<br />';
$input .= 'Test 2: <A name="test" HREF=\'HTTP: //PHP.NET2\' target="_blank">PHP.NET2</A>.<BR />';
$input .= 'Test 3: <a hRef=http: //php.net3>php.net3</a><br />';
$input .= 'This last line had nothing to do with any of this';

echo replaceAnchorsWithText($input).'<hr/>';
?>
Will output:
Test 1: PHP.NET1(http: //php.net1).
Test 2: PHP.NET2(HTTP: //PHP.NET2).
Test 3: php.net3 (is still an anchor)
This last line had nothing to do with any of this

down

Evgeny ¶

1 year ago

Please note! if you have defined namespace,
the usage format must me changed:

echo preg_replace_callback(
            "|(\d{2}/\d{2}/)(\d{4})|",
            __NAMESPACE__ . '\\next_year',
            $text);

down

steven at nevvix dot com ¶

6 years ago

<?php
$format = <<<SQL
CREATE DATABASE IF NOT EXISTS :database;
GRANT ALL PRIVILEGES ON :database_name.* TO ':user'@':host';
SET PASSWORD = PASSWORD(':pass');
SQL;
$args = ["database"=>"people", "user"=>"staff", "pass"=>"pass123", "host"=>"localhost"];

preg_replace_callback("/:(\w+)/", function ($matches) use ($args) {
    return @$args[$matches[1]] ?: $matches[0];
}, $format);

/*
Result:

CREATE DATABASE IF NOT EXISTS people;
GRANT ALL PRIVILEGES ON :database_name.* TO 'staff'@'localhost';
SET PASSWORD = PASSWORD('pass123');

The `:database_name` placeholder doesn't exist as a matching key in `$args` so it's returned as is.
This way you know you need to correct the array by adding the "database_name" item.
*/

down

-2

2962051004 at qq dot com ¶

6 years ago

<?php

/**
 * 将中文转为Html实体
 * Turning Chinese into Html entity
 * Author QiangGe
 * Mail 2962051004@qq.com
 *
*/

$str = <<<EOT
你好 world
EOT;

function ChineseToEntity($str) {
 return preg_replace_callback(
        '/[\x{4e00}-\x{9fa5}]/u', // utf-8 
        // '/[\x7f-\xff]+/', // if gb2312
        function ($matches) {
            $json = json_encode(array($matches[0]));
            preg_match('/\[\"(.*)\"\]/', $json, $arr);
            /*
             * 通过json_encode函数将中文转为unicode
             * 然后用正则取出unicode
             * Turn the Chinese into Unicode through the json_encode function, then extract Unicode from regular.
             * I think this idea is seamless.
            */
            return '&#x'. str_replace('\\u', '', $arr[1]). ';';
        }, $str
   );
}

echo ChineseToEntity($str);
// &#x4f60;&#x597d; world

down

-1

Drake ¶

14 years ago

Decode Hexa to Strings =)
<?php
class PhpHex2Str
{
    private $strings;

    private function x_hex2str($hex) {
        $hex = substr($hex[0], 1);
        $str = '';
        for($i=0;$i < strlen($hex);$i+=2) {
            $str.=chr(hexdec(substr($hex,$i,2)));
        }
        return $str;
    }

    public function decode($strings = null) {
        $this->strings = (string) $strings;
        return preg_replace_callback('#\%[a-zA-Z0-9]{2}#', 'x_hex2str', $this->strings);
    }
}

// Example
$strings = 'a %20 b%0A h %27 h %23';

$obj = new PhpHex2Str;
$strings = $obj->decode($strings);
var_dump($strings);
?>

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-2

Anteaus ¶

9 years ago

Be aware that as of php5.4 you MUST NOT pass variables by reference, as in  '[, int &$count ]' - if you do it will result in a fatal error. 
I think the writer is trying to say that the function accepts the parameter by reference, but that is not how it reads. -Manual needs updating/clarifying ?

down

-3

alex dot cs00 at yahoo dot ca ¶

14 years ago

Don't use this function to fetch BBCode, as explained. If you have some text that runs over 5000 chars (average), it will run out of its limit and makes you download the PHP page. 



According to this, you should instead use something more advanced yet complex. You will need a function called "str_replace_once()" (search for it), one called "countWord()", the famous "after()", "before()", "between()". 



str_replace_once does same as str_replace, but only replace first occurence. As for countWord, I guess you know how to count the number of a word occurence. As for after, before and between, this is a function that you may find easily somewhere on the site by a user. Else, you can do it. 



The following function is able to do all blocks, supposing [code] and [/code], you might wish things between parents dont get parsed, including [code] if inside of another [code]. 



<?php

function prepareCode($code, $op, $end)

{

    $ix = 0;

    $iy = 0;

    $nbr_Op = countWord($op, $code);

    while($ix < $nbr_Op)

    {

        if(in_string($op, before($end, $code), false))

        {

            // The following piece of code replace the default [tag] by [tag:#]

            $code = str_replace_once($op, substr($op, 0, -1).':'.$ix.']', $code); 

            $iy++;

        }

        elseif(in_string($end, before($op, $code), false))

        {

            $iy = $iy-1;

            $code = str_replace_once($end, substr($end, 0, -1).':'.($ix-1).']', $code);

            $ix = $ix-2;

        }

        $ix++;

    }

    while(in_string($end, $code))

    {

        $code = str_replace_once($end, substr($end, 0, -1).':'.($iy-1).']', $code);

        $iy=$iy-1;

    }



    $code = preg_replace('#\\'.substr($end, 0, 1).':-[0-9]\]#i', '', $code);

    if(in_string(substr($op, 0, -1).':0]', $code) && !in_string(substr($end, 0, -1).':0]', $code))

    {

        $code .= substr($end, 0, -1).":0]";

    }

    return $code;

}

?>



$code returns the whole text semi-formated. You only need to use it as :

$code = prepareCode($code="Your text", $op="[tag]" , $end="[/tag]");

Then just replace the parent tags :

str_replace("[tag:0]", "<tag>", $code);

str_replace("[/tag:0]", "</tag>", $code);

So at the end something like :

[

down

-1

jobowo ¶

2 years ago

Note that when using the 'Use ($variable)' with preg_replace_callback, if you wish the value to be altered by the anonymous function, you must pass the value in by reference. eg preg_replace_callback($pattern, function($matches) use (&$alterThis) { $alterThis+=$something;},$string);

down

-5

Underdog ¶

10 years ago

For the callback I advise only to use a permanent or anonymous function. 

Depending on the usage you may encounter memory issues when using create_function for the callback possibly due to attempts at being compatible with PHP 5.2 or prior. Some servers  refuse to update their PHP  for whatever reason.

Please peruse the create_function documentation for more details regarding its memory usage.

Regards.

down

-3

tgage at nobigfoot dot com ¶

6 years ago

To use variable from the parent scope of the anonymous callback function passed to preg_replace_callback(), utilize the use() parameter.

$var1 = "one";
$var2 = "two";
$line = preg_replace_callback('/^.*$/',
            function( $matches ) use ( $var1, $var2 ) {
                return( $var1 . " " . $var2 );
            }, $line);

Will replace the entire string with the concatenated values or $var1 and $var2 ("one two") from the parent scope.

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