[Translator] Cache the RegExp compiled by strtr()

[Kocal]

Q	A
Bug fix?	no
New feature?	no
Deprecations?	no
Documentation?	no
Issues	-
License	MIT

strtr() built and compiled a new RegExp on every call, and it is called once per trans() with parameters. The pattern only depends on the parameter names, which come from a fixed set in the source code.

Cache the compiled RegExp by pattern and hoist the escaping regex out of the mapping callback.

200k trans() calls: ~226 ms -> ~195 ms with parameters, ~214 ms -> ~189 ms with plural forms.

Browser-side JavaScript, so there is no Blackfire profile for this one. Benchmarked on node 22, after pnpm --filter @symfony/ux-translator run build, from the repository root with node bench.mjs:

import { createTranslator } from './src/Translator/assets/dist/translator_controller.js';

const messages = {
    'app.greeting': { id: 'app.greeting', translations: { messages: { en: 'Hello %name%, you have %count% new messages' } } },
    'app.plural': { id: 'app.plural', translations: { messages: { en: '{0} No apples|one: One apple|more: %count% apples' } } },
};

const translator = createTranslator({ messages, locale: 'en' });
const n = 200000;

let start = process.hrtime.bigint();
for (let i = 0; i < n; i++) {
    translator.trans('app.greeting', { '%name%': 'Hugo', '%count%': i });
}
console.log(`simple  ${n} trans() -> ${Number(process.hrtime.bigint() - start) / 1e6} ms`);

start = process.hrtime.bigint();
for (let i = 0; i < n; i++) {
    translator.trans('app.plural', { '%count%': i % 7 });
}
console.log(`plural  ${n} trans() -> ${Number(process.hrtime.bigint() - start) / 1e6} ms`);

Analysis, implementation and benchmarks by Claude Opus 5.

[github-actions]

📊 Packages dist files size difference

Thanks for the PR! Here is the difference in size of the packages dist files between the base branch and the PR.
Please review the changes and make sure they are expected.

File	Before (Size / Gzip)	After (Size / Gzip)
Translator
translator_controller.js	7.17 kB / 2.19 kB	7.39 kB+3% 📈 / 2.29 kB+5% 📈