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preg_replace_callback — Sucht und ersetzt einen regulären Ausdruck unter Verwendung eines Callbacks
Abgesehen von der Tatsache, dass statt des Parameters replacement ein callback angegeben werden soll, ist das Verhalten dieser Funktion identisch zu preg_replace().
Der Ausdruck, nach dem gesucht werden soll. Es kann entweder eine Zeichenkette oder ein Array mit Zeichenketten sein.
Ein Callback, dem ein Array von Übereinstimmungen mit subject übergeben wird. Der Callback sollte die Ersetzungs-Zeichenkette liefern.
Häufig werden Sie die callback-Funktion für preg_replace_callback() nur an einer Stelle benötigen. In diesem Fall können Sie eine Anonyme Funktion (seit PHP 5.3.0) oder create_function() verwenden, um innerhalb des Aufrufs von preg_replace_callback() eine anonyme Funktion als Callback zu deklarieren. Auf diese Weise haben Sie alle Informationen für den Aufruf an einer Stelle und stopfen den Namensraum für Funktionen nicht mit Namen für Callback-Funktionen voll, die sonst nirgends verwendet werden.
Beispiel #1 preg_replace_callback() und create_function()
<?php
// ein Kommandozeilen-Filter im Unix-Stil zum Umwandeln von Groß- in
// Kleinschreibung am Beginn eines Abschnitts
$fp = fopen("php://stdin", "r") or die("kann stdin nicht lesen");
while (!feof($fp)) {
$zeile = fgets($fp);
$zeile = preg_replace_callback(
'|<p>\s*\w|',
create_function(
// hier sind entweder einfache Anführungszeichen nötig
// oder alternativ die Maskierung aller $ als \$
'$treffer',
'return strtolower($treffer[0]);'
),
$zeile
);
echo $zeile;
}
fclose($fp);
?>
Die Zeichenkette oder ein Array mit Zeichenketten zum Suchen und Ersetzen.
Die Höchstzahl der Ersetzungen für jedes Suchmuster in jeder subject. Standardmäßig -1 (unbegrenzt).
Falls angegeben, wird dieser Variable die Anzahl vorgenommener Ersetzungen zugewiesen.
Falls subject ein Array ist, gibt preg_replace_callback() ein Array zurück und andernfalls eine Zeichenkette. Bei einem Fehler ist der Rückgabewert NULL.
Falls Übereinstimmungen gefunden werden, wird die neue Zeichenkette zurückgegeben und andernfalls die unveränderte Zeichenkette subject
| Version | Beschreibung |
|---|---|
| 5.1.0 | Den Parameter count hinzugefügt |
Beispiel #2 preg_replace_callback() Beispiel
<?php
// dieser Text wurde 2002 verwendet
// wir wollen ihn für 2003 aktualisieren
$text = "Aprilscherze gibts am 01.04.2002\n";
$text.= "Das letzte Weihnachten war am 24.12.2001\n";
// die Callback-Funktion
function naechstes_jahr($treffer)
{
// wie üblich: $treffer[0] ist die Übereinstimmung mit dem
// kompletten Suchmuster, $treffer[1] die Übereinstimmung mit
// dem ersten eingeklammerten Teilsuchmuster und so weiter
return $treffer[1].($treffer[2]+1);
}
echo preg_replace_callback(
"|(\d{2}\.\d{2}\.)(\d{4})|",
"naechstes_jahr",
$text);
?>
Das oben gezeigte Beispiel erzeugt folgende Ausgabe:
Aprilscherze gibts am 01.04.2003 Das letzte Weihnachten war am 24.12.2002
Beispiel #3 preg_replace_callback() unter Verwendung einer rekursiven Struktur um gekapselten BB-Code zu verarbeiten
<?php
$eingabe = "plain [indent] deep [indent] deeper [/indent] deep [/indent] plain";
function parseTagsRecursive($eingabe)
{
$regex = '#\[indent]((?:[^[]|\[(?!/?indent])|(?R))+)\[/indent]#';
if (is_array($eingabe)) {
$eingabe = '<div style="margin-left: 10px">'.$eingabe[1].'</div>';
}
return preg_replace_callback($regex, 'parseTagsRecursive', $eingabe);
}
$ausgabe = parseTagsRecursive($eingabe);
echo $ausgabe;
?>
I needed a simple code to tidy up a string. It simply had to upper-case letters after dot. Simple code to do so:
<?php
$string = preg_replace_callback(
'|(?:\.)(?:\s*)(\w{1})|Ui',
create_function('$matches', 'return ". ".strtoupper($matches[1]);'), ucfirst($string)
);
?>
<?php
$string = 'lorem ipsum dolor sit amet, consectetur adipiscing elit. sed ullamcorper diam eu lorem varius nec porta elit iaculis.';
echo preg_replace_callback(
'|(?:\.)(?:\s*)(\w{1})|Ui',
create_function('$matches', 'return ". ".strtoupper($matches[1]);'), ucfirst($string)
);
?>
Will output: Lorem ipsum dolor sit amet, consectetur adipiscing elit. Sed ullamcorper diam eu lorem varius nec porta elit iaculis.
<?php
$string = 'lorem ipsum dolor sit amet, consectetur adipiscing elit. sed ullamcorper diam eu lorem varius nec porta elit iaculis.';
echo preg_replace_callback(
'|(?:\.)(?:\s*)(\w{1})|Ui',
create_function('$matches', 'return ". ".strtoupper($matches[1]);'), ucfirst($string)
);
?>
Will output: Lorem ipsum dolor sit amet, consectetur adipiscing elit. Sed ullamcorper diam eu lorem varius nec porta elit iaculis.
Nothing fancy, but useful :)
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>", $code);
So at the end something like :
[
The pcre.backtrack_limit option (added in PHP 5.2) can trigger a NULL return, with no errors. The default pcre.backtrack_limit value is 100000. If you have a match that exceeds about half this limit it triggers a NULL response.
e.g. My limit was at 100000 but 500500 triggered a NULL response. I'm not running unicode but I *guess* PCRE runs in utf-16.
Created this to fetch the link and name of an anchor tag. I use this when cleaning an HTML email to text. Using regex for HTML is not recommended but for this purpose I see no issue with it. This is not designed to work for nested anchors.
A note to keep in mind:
I was primarily concerned with valid HTML so if attributes do no use ' or " to contain the values then this will need to be tweaked.
If you can edit this to work better, please let me know.
<?php
/**
* Replaces anchor tags with text
* - Will search string and replace all anchor tags with text (case insensitive)
*
* How it works:
* - Searches string for an anchor tag, checks to make sure it matches the criteria
* Anchor search criteria:
* - 1 - <a (must have the start of the anchor tag )
* - 2 - Can have any number of spaces or other attributes before and after the href attribute
* - 3 - Must close the anchor tag
*
* - Once the check has passed it will then replace the anchor tag with the string replacement
* - The string replacement can be customized
*
* Know issue:
* - This will not work for anchors that do not use a ' or " to contain the attributes.
* (i.e.- <a href=http: //php.net>PHP.net</a> will not be replaced)
*/
function replaceAnchorsWithText($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
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);
?>
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($strings);
?>
If you're looking to show only the first digit and last four digits of a credit card number (4xxxxxxxxxxxx2331) use something like this:
preg_replace_callback('/((.)(.*))?(.{4})/', create_function('$x', 'return $x[2].str_repeat("x", strlen($x[3])).$x[4];'), '$CCNUMBER')
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 $parser->parsefail('ABCDEFGH');
// throws the error
?>
A simple function to replace a list of complete words or terms in a string (for PHP 5.3 or above because of the closure):
<?php
function replace_words($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>{$v}</strong>";
});
?>
This function does not support named subpatterns, so you can't do
<?php
preg_replace_callback('/(?<char>[a-z])/', 'callback', 'word');
function callback($matches) {
var_dump($matches);
}
?>
and expect to get $matches['char'] in your function.
If you're planning to use preg_replace_callback inside a class, you need to use the array() function:
<?php
class MyClass
{
function preg_callback_url($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'), $text);
}
}
?>
This is what i use to read log files and do dns lookups on the ip's from the file.
<?php
function resolve_logs($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);
?>
When you access variables from outside in a callback function, use the $global keyword:
<?php
// global # 1:
global $x;
$x = 0;
$str = '&Bla bla. ►';
$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. ►'
// without global, $x would be 0
?>
To access a local variable within a callback, use currying (delayed argument binding). For example
<?php
function curry($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
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
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, $str,'Foo','Bar');
?>
Nice
The first example is bad, because it creates function for every line it processes. When the file has many lines, you could easily run out of memory. The code should be changed so, that create_function() is used outside of loop.
preg_replace_callback returns NULL when pcre.backtrack_limit is reached; this sometimes occurs faster then you might expect. No error is raised either; so don't forget to check for NULL yourself
it is much better on preformance and better practice to use the preg_replace_callback function instead of preg_replace with the e modifier.
function a($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);
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