1.2.1031. Regex On Arrays¶
Avoid using a loop with arrays of regex or values. There are several PHP function which work directly on arrays, and much faster.
preg_grep() is able to extract all matching strings from an array, or non-matching strings. This usually saves a loop over the strings.
preg_filter() is able to extract all strings from an array, matching at least one regex in an array. This usually saves a double loop over the strings and the regex. The trick here is to provide ‘$0’ as replacement, leading preg_filter() to replace the found string by itself.
Finally, preg_replace_callback() an preg_replace_callback_array() are also able to apply an array of regex to an array of strings, and then, apply callbacks to the found values.
<?php
$regexs = ['/ab+c/', '/abd+/', '/abe+/'];
$strings = ['/abbbbc/', '/abd/', '/abeee/'];
// Directly extract all strings that match one regex
foreach($regexs as $regex) {
$results[] = preg_grep($regex, $strings);
}
// extract all matching regex, by string
foreach($strings as $string) {
$results[] = preg_filter($regexs, array_fill(0, count($regexs), '$0'), $string);
}
// very slow way to get all the strings that match a regex
foreach($regexs as $regex) {
foreach($strings as $string) {
if (preg_match($regex, $string)) {
$results[] = $string;
}
}
}
?>
See also preg_filter.
1.2.1031.1. Suggestions¶
Apply preg_match() to an array of string or regex, via preg_filter() or preg_grep().
Apply preg_match() to an array of string or regex, via preg_replace_callback() or preg_replace_callback_array().
1.2.1031.2. Specs¶
Short name |
Performances/RegexOnArrays |
Rulesets |
|
Exakat since |
1.8.4 |
PHP Version |
All |
Severity |
Minor |
Time To Fix |
Quick (30 mins) |
Precision |
Very high |
Features |
regex |
Available in |