Extension points

phil/slug-bundle

What an application configures, decorates or relies on. The types are phil/slug's.

Configuration

Option	What it extends
`sluggers`	One slugger per name, each with its `locale`, `max_length` and `leading_words` — see Configuration
`default`	Which named slugger `Phil\Slug\Slugger` is
`history`	The history of former slugs, its connection and its clock — see History of former slugs

Service	How an application relies on it
`phil_slug.slugger.<name>`	Decorated by the application, with `#[AsDecorator]` or `decorates:`: the decorator takes the place of the slugger in `Sluggers`, through the aliases and in Twig — see Services
`Phil\Slug\Slugger`	Autowired: the default slugger
`Phil\Slug\Slugger $<name>Slugger`	Autowired by argument name: the slugger of that name
`Phil\Slug\Sluggers`	Injected wherever the slugger is chosen at run time; public
`Phil\SlugBundle\Application\Contract\SlugHistory`	Autowired when the history is enabled: recorded by the code that changes a slug, read by a redirect provider or a controller
`phil_slug.history`	The Doctrine history; an application replaces it by aliasing `SlugHistory` to its own implementation

A bundle that takes a slugger by service id is given phil_slug.slugger.<name>.

An implementation other than the Doctrine one keeps the contract's invariants:

a scope and a subject are checked with SlugHistoryKeys before anything is stored or read;
recording a change makes the new slug stop being a former slug of the scope, whichever subject had it, points every former slug of the subject to the new slug, and writes the old slug as a former slug of the subject, all at once;
recording a slug as its own former slug changes nothing;
formerSlugs() never yields a chain: each value is a current slug;
it keeps nothing between two calls, or is tagged kernel.reset.

The phil_slug filter takes a slugger's name; it uses the same services, decorators included.