Class Registry

markdown/util.py:273–409

A priority sorted registry. A `Registry` instance provides two public methods to alter the data of the registry: `register` and `deregister`. Use `register` to add items and `deregister` to remove items. See each method for specifics. When registering an item, a "name" and a "

class Registry(Generic[_T]):
    """
    A priority sorted registry.

    A `Registry` instance provides two public methods to alter the data of the
    registry: `register` and `deregister`. Use `register` to add items and
    `deregister` to remove items. See each method for specifics.

    When registering an item, a "name" and a "priority" must be provided. All
    items are automatically sorted by "priority" from highest to lowest. The
    "name" is used to remove ("deregister") and get items.

    A `Registry` instance it like a list (which maintains order) when reading
    data. You may iterate over the items, get an item and get a count (length)
    of all items. You may also check that the registry contains an item.

    When getting an item you may use either the index of the item or the
    string-based "name". For example:

        registry = Registry()
        registry.register(SomeItem(), 'itemname', 20)
        # Get the item by index
        item = registry[0]
        # Get the item by name
        item = registry['itemname']

    When checking that the registry contains an item, you may use either the
    string-based "name", or a reference to the actual item. For example:

        someitem = SomeItem()
        registry.register(someitem, 'itemname', 20)
        # Contains the name
        assert 'itemname' in registry
        # Contains the item instance
        assert someitem in registry

    The method `get_index_for_name` is also available to obtain the index of
    an item using that item's assigned "name".
    """

    def __init__(self):
        self._data: dict[str, _T] = {}
        self._priority: list[_PriorityItem] = []
        self._is_sorted = False

    def __contains__(self, item: str | _T) -> bool:
        if isinstance(item, str):
            # Check if an item exists by this name.
            return item in self._data.keys()
        # Check if this instance exists.
        return item in self._data.values()

    def __iter__(self) -> Iterator[_T]:
        self._sort()
        return iter([self._data[k] for k, p in self._priority])

    @overload
    def __getitem__(self, key: str | int) -> _T:  # pragma: no cover