Last updated: Fri, 24 Jul 2009

preg_replace_callback

(PHP 4 >= 4.0.5, PHP 5)

preg_replace_callback — 콜백을 이용한 정규 표현식 검색과 치환을 수행

설명

mixed preg_replace_callback ( mixed $pattern , callback $callback , mixed $subject [, int $limit [, int &$count ]] )

이 함수의 작동은 replacement 대신 callback 을 지정하는 것을 제외하면, preg_replace()와 거의 동일합니다.

인수

pattern

검색할 패턴. 문자열이나 문자열을 가진 배열일 수 있습니다.

callback

string 문자열에서 매치한 요소의 배열이 넘겨져서 호출될 콜백. 콜백은 치환할 문자열을 반환해야 합니다.

종종 단 한번만 preg_replace_callback()에만 사용할 callback 함수가 필요합니다. 이러한 경우에 preg_replace_callback() 호출 안에서 create_function()을 사용해서 익명 함수를 선언할 수 있습니다. 이 방법으로 호출에 필요한 모든 정보를 한 군데 위치하게 할 수 있고, 다른 곳에서 사용하지 않는 콜백 함수의 이름으로 함수 이름공간을 어지럽히는 일을 막을 수 있습니다.

Example #1 preg_replace_callback()과 create_function()


/* 유닉스 형식 명령줄 필터로
 * 문단의 첫 대문자를 소문자로 바꿉니다. */
$fp = fopen("php://stdin", "r") or die("stdin을 읽을 수 없습니다");
while (!feof($fp)) {
    $line = fgets($fp);
    $line = preg_replace_callback(
        '|<p>\s*\w|',
        create_function(
             // 여기에서 홑따옴표가 중요합니다.
             // 혹은 모든 $를 \$로 회피해야 합니다.
             '$matches',
             'return strtolower($matches[0]);'
        ),
        $line
    );
    echo $line;
}
fclose($fp);
?>

subject

검색 치환할 문자열이나 문자열로 이루어진 배열.

limit

각 subject 문자열에 대한 각 패턴의 최대 가능 치환수. 기본값은 -1. (무제한)

count

지정하면, 이 변수는 치환을 마친 수로 채워집니다.

반환값

preg_replace_callback()은 subject 인수에 따라 배열이나 문자열을 반환합니다.

매치가 발견되면 새 subject가 반환되고, 그렇지 않으면 변경되지 않은 subject 가 반환됩니다.

변경점

버전	설명
5.1.0	`count` 인수 추가

예제

Example #2 preg_replace_callback() 예제


<?php
// 이 문장은 2002년에 사용되었습니다.
// 2003년에 적합하게 업데이트합니다.
$text = "April fools day is 04/01/2002\n";
$text.= "Last christmas was 12/24/2001\n";

// 콜백 함수
function next_year($matches)
{
  // 보통: $matches[0]는 전채 매치입니다.
  // $matches[1]은 첫번째 '(...)'에 들어있는
  // 서브 패턴 매치로 이어집니다.
  return $matches[1].($matches[2]+1);
}

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

?>

위 예제의 출력:

April fools day is 04/01/2003
Last christmas was 12/24/2002

Example #3 BB 코드를 다루기 위해 재귀 구조를 사용하는 preg_replace_callback()


<?php
$input = "plain [indent] deep [indent] deeper [/indent] deep [/indent] plain";

function parseTagsRecursive($input)
{

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

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

    return preg_replace_callback($regex, 'parseTagRecursive', $input);
}

$output = parseTagsRecursive($input);

echo $output;
?>

참고

preg_replace() - 정규 표현식 검색과 치환을 수행
create_function() - Create an anonymous (lambda-style) function
callback형에 대한 정보

preg_replace

preg_quote

Last updated: Fri, 24 Jul 2009

add a note User Contributed Notes
preg_replace_callback

Matt
14-Sep-2009 04:24


If you're looking to show only the first digit and last four digits of a credit card number (4xxxxxxxxxxxx2331) use something like this:

preg_replace_callback('/((.)(.*))?(.{4})/', create_function('$x', 'return $x[2].str_repeat("x", strlen($x[3])).$x[4];'), '$CCNUMBER')

ixiter at gmail dot com
29-Jul-2009 02:06


When you use preg_replace_callback in a class and have the callback function as a private method of that class, you need to set the callback function name like className::CallBack.


self::CallBack does not work and returns an error:


"Cannot call method self::CallBack() or method does not exist"!





<?php


class myClass{


    public function parsetext($text){


        // parses text and sets literals A - C to lower case


        // this works 


        return preg_replace_callback('|([a-c])|i', 'myClass::preg_tolower', $text);


    }


    public function parsefail($text){


        // parses text and sets literals A - C to lower case


        // this fails


        return preg_replace_callback('|([a-c])|i', 'self::preg_tolower', $text);


    }


    


    private static function preg_tolower($matches){


        return strtolower($matches[1]);


    }


}





$parser = new myClass;


echo $parser->parsetext('ABCDEFGH');


// echoes abcDEFGH





echo $parser->parsefail('ABCDEFGH');


// throws the error


?>

carlos dot ballesteros at softonic dot com
02-Jul-2009 03:02


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>";

});

?>

chris AT cmbuckley DOT co DOT uk
09-Jun-2009 02:44


This function does not support named subpatterns, so you can't 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.

mariush
12-May-2009 08:17


If you're planning to use preg_replace_callback inside a class, you need to use the array() function:





<?php


class MyClass


{





  function preg_callback_url($matches)


  {


    //var_dump($matches);


    $url = $matches[1].$matches[2];


    $text = '';


    $pos = strpos($url,' ');


    if ($pos!==FALSE) {


      $text = trim(substr($url,$pos+1));


      $url = substr($url,0,$pos);


    }


    return '<a href="'.$url.'" rel="nofollow">'.(($text!='') ? $text : $url).'</a>';


  }





  function ParseText($text)


  {


    return preg_replace_callback('/\[(http|https|ftp)(.*?)\]/iS',array( &$this, 'preg_callback_url'), $text);


  }





}


?>

james dot records at gmail dot com
26-Apr-2009 07:22


This is what i use to read log files and do dns lookups on the ip's from the file.





<?php


function resolve_logs($arr) {


        return gethostbyaddr($arr[0]);


}





$logent=file('yourlogfile');





$ipaddr = '/\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}/';


$logent = preg_replace_callback($ipaddr, resolve_logs, $logent);


?>

long2hu3 ATT yahoo DOTT com
02-Apr-2009 07:25


When you access variables from outside in a callback function, use the $global keyword:



<?php



// global # 1:

global $x;



$x = 0;

$str = '&Bla bla. &#x25ba;';



$find = '/(\&)([^#])/';



// global # 2:

$replace = create_function('$f',

    'global $x; $x ++; return $f[2];';



$str2 = preg_replace_callback($find, $replace, $str);



// $x == 1

// $str2 == 'Bla bla. &#x25ba;'

// without global, $x would be 0



?>

tijn at q-go dot com
06-Jan-2009 10:01


To access a local variable within a callback, use currying (delayed argument binding). For example

<?php

function curry($func, $arity) {

    return create_function('', "

        \$args = func_get_args();

        if(count(\$args) >= $arity)

            return call_user_func_array('$func', \$args);

        \$args = var_export(\$args, 1);

        return create_function('','

            \$a = func_get_args();

            \$z = ' . \$args . ';

            \$a = array_merge(\$z,\$a);

            return call_user_func_array(\'$func\', \$a);

        ');

    ");

}



function on_match($transformation, $matches)

{

    return $transformation[strtolower($matches[1])];

}



$transform = array('a' => 'Well,', 'd'=>'whatever', 'b'=>' ');



$callback = curry(on_match, 2);

echo preg_replace_callback('/([a-z])/i', $callback($transform), 'Abcd');



echo "\n";

?>



outputs:



"Well, whatever"



The magic lies in this curry function I found here: http://www.sitepoint.com/forums/showthread.php?threadid=336758

tijn at q-go dot com
05-Jan-2009 04:48


To access a local variable within a callback, use currying (delayed argument binding). For example

<?php

function curry($func, $arity) {

    return create_function('', "

        \$args = func_get_args();

        if(count(\$args) >= $arity)

            return call_user_func_array('$func', \$args);

        \$args = var_export(\$args, 1);

        return create_function('','

            \$a = func_get_args();

            \$z = ' . \$args . ';

            \$a = array_merge(\$z,\$a);

            return call_user_func_array(\'$func\', \$a);

        ');

    ");

}



function on_match($transformation, $matches)

{

    return $transformation[strtolower($matches[1])];

}



$transform = array('a' => 'Well,', 'd'=>'whatever', 'b'=>' ');



$callback = curry(on_match, 2);

echo preg_replace_callback('/([a-z])/i', $callback($transform), 'Abcd');



echo "\n";

?>



outputs:



"Well, whatever"



The magic lies in this curry function I found here: http://www.sitepoint.com/forums/showthread.php?threadid=336758

nicolaspar at gmail dot com
20-Dec-2008 02:33


To spend more than one parameter can do the following (note the "e" parameter in preg_replace function)

<?

$array = array(

1=>'ONE',

2=>'TWO',

3=>'Three'

);



function search(&$array, $str, $foo, $bar){

    return ( empty($array[$str]) ? '['.$foo.'-'.$bar.']' : $array[$str] );

}



function keys(&$array, $str,$foo,$bar){

    return preg_replace('/\[(.*?)\]/e',"search(\$array,$1,\$foo,\$bar)",$str);

}



$str = "One [1] Two [2] Three [3], Other parameter [22]";



echo keys($array, $str,'Foo','Bar');

?>

Nice

harrrrpo at gmail dot com
19-Sep-2008 07:59


The last example -nested BBCode- has a problem and won't work

it should be

<?php

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

?>

([ should be escaped to be \[)



--

a nicer regex i used in a BBCode parser  (BBEngine http://www.phpclasses.org/browse/package/4829.html)

This one Captures Tag Arguments ,Empty tags and 

also uses ?> for performance , wrapped in a simple function for templating (ofcourse it's one line but note's line size is limited :) )

<?php

     /**

     * A Template for the recursive tags matcher RE

     * it generates it for a given tag ,open bracket and closing one

     * $O & $C must be pre-escaped from #'s

     * @param String $tag Tag to be parsed recursively

     * @param String $O   Opeening brackets of tag

     * @param String $C   Closing brackets of tag

     */

    public function Recursive_RE_Generator($tag,$O,$C)

    {

       $re="#{$O}({$tag}.*?){$C}((?>{$O}(?!/?{$tag}[^{$O}]*?{$C})|

[^{$O}]|(?R))*){$O}/{$tag}{$C}#is";

        return $re;

    }

?>

nene at triin dot net
20-May-2008 10:14


The first example is bad, because it creates function for every line it processes. When the file has many lines, you could easily run out of memory. The code should be changed so, that create_function() is used outside of loop.

Sjon at hortensius dot net
24-Jun-2007 11:56


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

matt at mattsoft dot net
26-Apr-2006 09:16


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);

add a note

preg_replace

preg_quote

Last updated: Fri, 24 Jul 2009