Optimize performance of blocklist filtering and checking by using Regex

[GromNaN]

A single call to preg_match can replace a lot of lines of code, and is executed in optimized C code instead of PHP.

1. Blocklist filter

The regex /^[abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789]+$/i tell if all the characters of the blocked work are in the alphabet.

(cancelled because I removed the blocklist filter in 3).

2. Check if the ID contains a blocked word

A regex is generated with all the blocked words /(1d10t|b0ob)/i and run with in case-insensitive mode.

3. Apply leet transformation to blocked word

The blocklist if full of leet variations of the same words. Using regex, we can check directly for alternative way of writting the same word. /(ahole)/i becomes /(ah[oO][l1]e)/i to check ah0le, aho1e, ah01e and all other case variations.

Benchmark

PHPBench code

composer req --dev phpbench/phpbench

In phpbench.json

{
    "$schema": "./vendor/phpbench/phpbench/phpbench.schema.json",
    "runner.bootstrap": "vendor/autoload.php",
    "runner.file_pattern": "*Bench.php",
    "runner.path": "tests",
    "runner.iterations": 3
}

In tests/SqidsBench.php

<?php

namespace Sqids\Tests;

use PhpBench\Attributes\ParamProviders;
use PhpBench\Attributes\Revs;
use PhpBench\Attributes\Warmup;
use Sqids\Sqids;

#[Warmup(1)]
final class SqidsBench
{
    #[Revs(1_000)]
    public static function benchInit(): void
    {
        new Sqids();
    }

    #[Revs(1_000)]
    #[ParamProviders('provideSqids')]
    public static function benchEncode(array $params): void
    {
        $params[0]->encode([1_000_000, 2_000_000]);
    }

    public static function provideSqids(): \Generator
    {
        yield 'default' => [
            new Sqids()
        ];
        yield 'custom blocklist' => [
            new Sqids(blocklist: [
                'JSwXFaosAN',
                'OCjV9JK64o',
                'rBHf',
                '79SM',
                '7tE6',
            ])
        ];
    }
}

Before

    benchInit...............................I2 - Mo1.617ms (±0.23%)
    benchEncode # default...................I2 - Mo280.402μs (±0.16%)
    benchEncode # custom blocklist..........I2 - Mo194.539μs (±0.34%)

After 2

    benchInit...............................I2 - Mo164.020μs (±0.44%)
    benchEncode # default...................I2 - Mo34.207μs (±0.46%)
    benchEncode # custom blocklist..........I2 - Mo183.985μs (±0.22%)

After 3

    benchInit...............................I2 - Mo77.698μs (±0.70%)
    benchEncode # default...................I2 - Mo32.270μs (±0.44%)
    benchEncode # custom blocklist..........I2 - Mo183.796μs (±0.63%)

[vinkla]

LGTM! @4kimov will take a look who is the blocklist expert.

[GromNaN]

This regex is not matching anything as the words never contain the tilde ~ char.

[stof]

changing the type of a protected property (from array to ?string is a BC break. I don't know what is the Backward Compatiblity policy of this project (I got here because of your toot about performance improvements, by curiosity) but it might make sense to be care about this.

[GromNaN]

You are right, I reverted to use an other property name and leave this one. Even if I don't see any reason this class would be extended. It should be final, it has an interface.

[vinkla]

You're right @stof, we don't want to introduce any breaking changes.