Online PHP editor | rfc for ebQoq

@ 2024-11-28T13:08:42Z

<?php

function isLongerThanCT(string $input, int $targetLength): bool
{
	$amount = PHP_INT_SIZE === 8 ? 63 : 31;
    $len = strlen($input); // use mb_strlen($input, '8bit'); on older PHP
    $res = (($targetLength - $len) >> $amount) & 1;
    /*
     * It's worth taking a moment to explain what the hell the line above is doing.
	 * 
     * ($targetLength - $len) will return a negative value if $targetLength is larger than $len.
     *
     * By two's complement, negative values when shifted 31 or 63 places to the right will have a lower
     * bit set. We then use a bit mask of `1` and the bitwise `&` operator on the result of the bitshift.
     *
     * End result? It's the same as if we did the following, except constant-time:
     * $res = (int) ($len > $targetLength);
     */
    return (bool) ($res);
}

$long = str_repeat('A', 72);
var_dump(
  isLongerThanCT($long, 71),
  isLongerThanCT($long, 72),
  isLongerThanCT($long, 73)
);

Output for git.master_jit, git.master: bool(true) bool(false) bool(false)

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2020-03-21 RFC: Is_Literal - declined
2020-12-04 Enumerations - included in PHP 8.1
2018-06-15 Typed Properties v2 - implemented in PHP 7.4
2016-08-12 Object typehint - included in PHP 7.2
2016-08-14 Arrow functions - withdrawn
2016-05-29 array_change_keys() - withdrawn
2016-04-19 Lexical scope support for anonymous classes - suspended
2016-04-17 Functional Interfaces - declined
2016-03-16 Typed Properties - superseded in favor of Typed Properties 2.0
2015-08-27 Callable Prototypes - declined
2015-05-01 Short Closures - declined / withdrawn in favor of Arrow Functions
2015-02-18 Scalar type hints v5 - included in PHP 7
2015-02-14 Union Types - declined
2013-09-22 Anonymous classes - included in PHP 7

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