perf(laravel): memoize the Symfony RouteCollection in Router

[soyuka]

Q	A
Branch?	4.3
Bug fix?	yes
New feature?	no
Deprecations?	no
Issues	Closes #8337
License	MIT

Problem

ApiPlatform\Laravel\Routing\Router::generate() calls getRouteCollection(), which rebuilds the entire Symfony RouteCollection on every call via Illuminate\Routing\AbstractRouteCollection::toSymfonyRouteCollection() — converting the whole Laravel route table each time, with no memoization.

generate() runs once per IRI during normalization (once per relation/sub-resource reference). A single response with several relations triggers the full route-table conversion repeatedly — ~65 times for a resource with ~8 relations in the reporter's Xdebug profiling. php artisan route:cache doesn't help; this conversion happens after Laravel's own route loading.

Fix

Routes are static within a request and Router is registered as a per-request singleton (ApiPlatformProvider), so the built RouteCollection is safely cached on the instance:

public function getRouteCollection(): RouteCollection
{
    if (null !== $this->routeCollection) {
        return $this->routeCollection;
    }

    $routes = $this->router->getRoutes();

    return $this->routeCollection = $routes->toSymfonyRouteCollection();
}

Only the RouteCollection is memoized, not the UrlGenerator — the generator depends on $this->context (mutable via setContext()), while the collection is context-independent and is the expensive part. Memoizing the generator would risk a stale-context bug.

IriConverter and SkolemIriConverter inject the concrete Router directly, so the fix lands in Router itself rather than in a decorator of the interface binding.

SkolemIriConverter typing

As noted in the issue, SkolemIriConverter hard-typed the final concrete Router in its constructor, blocking any userland wrapper (a replacement must stay instanceof Router, impossible for a final class). It only uses $this->router->generate(), so its constructor now type-hints Symfony\Component\Routing\RouterInterface (matching IriConverter), removing the dependency on the concrete class.

Tests

Added Tests/Unit/Routing/RouterTest.php asserting toSymfonyRouteCollection() is invoked once across multiple getRouteCollection() calls and that the same instance is returned. Functional suites (JsonLdTest, JsonApiTest) pass unchanged.