preg_replace_callback_array

(PHP 7, PHP 8)

preg_replace_callback_array — Perform a regular expression search and replace using callbacks

Beschreibung

preg_replace_callback_array(
    array $pattern,
    string|array $subject,
    int $limit = -1,
    int &$count = null,
    int $flags = 0
): string|array|null

The behavior of this function is similar to preg_replace_callback(), except that callbacks are executed on a per-pattern basis.

Parameter-Liste

pattern: An associative array mapping patterns (keys) to callables (values).
subject: The string or an array with strings to search and replace.
limit: The maximum possible replacements for each pattern in each subject string. Defaults to -1 (no limit).
count: If specified, this variable will be filled with the number of replacements done.
flags: flags can be a combination of the PREG_OFFSET_CAPTURE and PREG_UNMATCHED_AS_NULL flags, which influence the format of the matches array. See the description in preg_match() for more details.

Rückgabewerte

preg_replace_callback_array() returns an array if the subject parameter is an array, or a string otherwise. On errors the return value is null

If matches are found, the new subject will be returned, otherwise subject will be returned unchanged.

Fehler/Exceptions

Wenn das übergebene Regex-Muster nicht zu einem gültigen Regex kompiliert werden kann, wird ein Fehler der Stufe E_WARNING ausgegeben.

Changelog

Version	Beschreibung
7.4.0	The `flags` parameter was added.

Beispiele

Beispiel #1 preg_replace_callback_array() example

<?php
$subject = 'Aaaaaa Bbb';

preg_replace_callback_array(
    [
        '~[a]+~i' => function ($match) {
            echo strlen($match[0]), ' matches for "a" found', PHP_EOL;
        },
        '~[b]+~i' => function ($match) {
            echo strlen($match[0]), ' matches for "b" found', PHP_EOL;
        }
    ],
    $subject
);
?>

Das oben gezeigte Beispiel erzeugt folgende Ausgabe:

6 matches for "a" found
3 matches for "b" found

Siehe auch

PCRE Patterns
preg_replace_callback() - Sucht und ersetzt mit regulären Ausdrücken unter Verwendung eines Callbacks
preg_quote() - Maskiert Zeichen regulärer Ausdrücke
preg_replace() - Sucht und ersetzt mit regulären Ausdrücken
preg_last_error() - Liefert den Fehlercode der letzten PCRE-RegEx-Auswertung
Anonymous functions

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User Contributed Notes 3 notes

down

Sz. ¶

6 years ago


Based on some tests, I found these important traits of the function. (These would
be nice to see documented as part of its spec, e.g. for confirmation. Without that,
this is just experimental curiosity. Still better than guesswork, though! ;) )

1. Changes cascade over a subject across callbacks, i.e. a change made to a
   subject by a callback will be seen by the next callback, if its pattern matches
   the changed subject.
   (But a change made by a previous call of the *same* callback (on any subject)
   will not be seen by that callback again.)

2. The pattern + callback pairs will be applied in the order of their appearance
   in $patterns_and_callbacks.

3. The callback can't be null (or '') for a quick shortcut for empty replacements.

4. Overall, the algorithm starts iterating over $patterns_and_callbacks, and then
   feeds each $subject to the current callback, repeatedly for every single match
   of its pattern on the current subject (unlike "preg_match_all", that is, which
   can do the same in one go, returning the accumulated results in an array).

   This basically means that the "crown jewel", an even more efficient function:
   "preg_replace_all_callback_array" is still missing from the collection.

   (Of course, that would better fit a new design of the regex API, where one
   API could flexibly handle various different modes via some $flags = [] array.)

5. (This last one is not specific to this function, but inherent to regexes, OTOH,
   it's probably more relevant here than anywhere else in PHP's regex support.)

   Even apparently simple cases can generate a crazy (and difficult-to-predict)
   number of matches, and therefore callback invokations, so remember the set
   $limit, where affordable. But, of course, try to sharpen your patterns first!

   E.g. use ^...$ anchoring to avoid unintended extra calls on matching substrings
   of a subject, (I.e. '/.*/', without anchoring, would match twice: once for the
   whole subject, and then for a trailing empty substring -- but I'm not quite sure
   this should actually be correct behavior, though.)

down

drevilkuko at gmail dot com ¶

9 years ago


finally!!!

before (<=php5.6):

<?php
        $htmlString = preg_replace_callback(
            '/(href="?)(\S+)("?)/i',
            function (&$matches) {
                return $matches[1] . urldecode($matches[2]) . $matches[3];
            },
            $htmlString
        );

        $htmlString = preg_replace_callback(
            '/(href="?\S+)(%24)(\S+)?"?/i', // %24 = $
            function (&$matches) {
                return urldecode($matches[1] . '$' . $matches[3]);
            },
            $htmlString
        );
?>

php7

<?php

        $htmlString = preg_replace_callback_array(
            [
                '/(href="?)(\S+)("?)/i' => function (&$matches) {
                    return $matches[1] . urldecode($matches[2]) . $matches[3];
                },
                '/(href="?\S+)(%24)(\S+)?"?/i' => function (&$matches) {
                    return urldecode($matches[1] . '$' . $matches[3]);
                }
            ],
            $htmlString
        );
?>

down

-4

jfcherng at NOSPAM dot gmail dot com ¶

8 years ago


Here's a possible alternative in older PHP.

<?php

// if (!function_exists('preg_replace_callback_array')) {

function preg_replace_callback_array (array $patterns_and_callbacks, $subject, $limit=-1, &$count=NULL) {
    $count = 0;
    foreach ($patterns_and_callbacks as $pattern => &$callback) {
        $subject = preg_replace_callback($pattern, $callback, $subject, $limit, $partial_count);
        $count += $partial_count;
    }
    return preg_last_error() == PREG_NO_ERROR ? $subject : NULL;
}

// }

?>

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