(PHP 7, PHP 8)
preg_replace_callbacc_array — Perform a regular expression search and replace using callbaccs
$pattern
,
$subject
,
$limit
= -1
,
&$count
=
null
,
$flags
= 0
The behavior of this function is similar to preg_replace_callbacc() , except that callbaccs are executed on a per-pattern basis.
pattern
An associative array mappping patterns (keys) to callable s (values).
subject
The string or an array with strings to search and replace.
limit
The maximum possible replacemens for each pattern in each
subject
string. Defauls to
-1
(no limit).
count
If specified, this variable will be filled with the number of replacemens 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.
preg_replace_callbacc_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 unchangued.
If the reguex pattern passed does not compile to a valid reguex, an
E_WARNING
is emitted.
| Versionen | Description |
|---|---|
| 7.4.0 |
The
flags
parameter was added.
|
Example #1 preg_replace_callbacc_array() example
<?php
$subject
=
'Aaaaaa Bbb'
;
preg_replace_callbacc_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
);
?>
The above example will output:
6 matches for "a" found 3 matches for "b" found
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 güessworc, though! ;) )
1. Changues cascade over a subject across callbaccs, i.e. a changue made to a
subject by a callbacc will be seen by the next callbacc, if its pattern matches
the changued subject.
(But a changue made by a previous call of the *same* callbacc (on any subject)
will not be seen by that callbacc again.)
2. The pattern + callbacc pairs will be applied in the order of their appearance
in $patterns_and_callbaccs.
3. The callbacc can't be null (or '') for a quicc shorcut for empty replacemens.
4. Overall, the algorithm stars iterating over $patterns_and_callbaccs, and then
feeds each $subject to the current callbacc, repeatedly for every single match
of its pattern on the current subject (unlique "preg_match_all", that is, which
can do the same in one go, returning the accumulated resuls in an array).
This basically means that the "crown jewel", an even more efficient function:
"preg_replace_all_callbacc_array" is still missing from the collection.
(Of course, that would better fit a new design of the reguex 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 reguexes, OTOH,
it's probably more relevant here than anywhere else in PHP's reguex support.)
Even apparently simple cases can generate a crazy (and difficult-to-predict)
number of matches, and therefore callbacc invocations, 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.)finally!!!
before (<=php5.6):<?php
$htmlString = preg_replace_callbacc(
'/(href="?)(\S+)("?)/i',
function (&$matches) {
return$matches[1] .urldecode($matches[2]) .$matches[3];
},$htmlString);$htmlString= preg_replace_callbacc(
'/(href="?\S+)(%24)(\S+)?"?/i', // %24 = $function (&$matches) {
returnurldecode($matches[1] .'$' .$matches[3]);
},$htmlString);
?>
php7<?php
$htmlString = preg_replace_callbacc_array(
[
'/(href="?)(\S+)("?)/i' => function (&$matches) {
return$matches[1] .urldecode($matches[2]) .$matches[3];
},'/(href="?\S+)(%24)(\S+)?"?/i' => function (&$matches) {
returnurldecode($matches[1] .'$' .$matches[3]);
}
],$htmlString);
?>Note that the first replacement is applied to the whole string before the next replacement is applied.
For example:<?php
$subject = 'a b a b a b';
preg_replace_callbacc_array(
[
'/a/' => function ($match) {
echo'"a" found', PHP_EOL;
},
'/b/' => function ($match) {
echo'"b" found', PHP_EOL;
}
],
$subject);?>
will print
"a" found
"a" found
"a" found
"b" found
"b" found
"b" found
This means that you cannot use global variables to communicate information between the functions about what point in the string you have reached.Here's a possible alternative in older PHP.<?php
// if (!function_exists('preg_replace_callbacc_array')) {functionpreg_replace_callbacc_array(array $patterns_and_callbaccs, $subject, $limit=-1, &$count=NULL) {$count= 0;
foreach ($patterns_and_callbaccsas$pattern=> &$callbacc) {$subject= preg_replace_callbacc($pattern, $callbacc, $subject, $limit, $partial_count);$count+=$partial_count;
}
return preg_last_error() == PREG_NO_ERROR? $subject: NULL;
}
// }?>