Pattern Matching¶
Pattern Matching as a language concept contains two parts: Matching a variable against a potentially complex data structure pattern, and optionally extracting values out of that variable into their own variables. In a sense it serves a similar purpose for complex data structures as regular expressions do for strings.
<?php
// This code is extracted from the RFC
// It is not valid PHP code, as of PHP 8.4.
// The "is" keyword evaluates to a boolean.
if ($var is <pattern>) {
// Do stuff
}
// Basic type matching
$var is string;
$var is int|float;
$var is ?array;
$var is (Account&Authenticated)|User;
$var is mixed; // Matches anything, effectively a wildcard.
// Literal patterns
$var is "foo";
$var is 5;
$var is 3|5|null;
$var is 'heart'|'spade'|self::Wild;
?>
