Class Ruler

markdown_it/ruler.py:75–275

class Ruler(Generic[RuleFuncTv]):
    def __init__(self) -> None:
        # List of added rules.
        self.__rules__: list[Rule[RuleFuncTv]] = []
        # Cached rule chains.
        # First level - chain name, '' for default.
        # Second level - diginal anchor for fast filtering by charcodes.
        self.__cache__: dict[str, list[RuleFuncTv]] | None = None

    def __find__(self, name: str) -> int:
        """Find rule index by name"""
        for i, rule in enumerate(self.__rules__):
            if rule.name == name:
                return i
        return -1

    def __compile__(self) -> None:
        """Build rules lookup cache"""
        chains = {""}
        # collect unique names
        for rule in self.__rules__:
            if not rule.enabled:
                continue
            for name in rule.alt:
                chains.add(name)
        self.__cache__ = {}
        for chain in chains:
            self.__cache__[chain] = []
            for rule in self.__rules__:
                if not rule.enabled:
                    continue
                if chain and (chain not in rule.alt):
                    continue
                self.__cache__[chain].append(rule.fn)

    def at(
        self, ruleName: str, fn: RuleFuncTv, options: RuleOptionsType | None = None
    ) -> None:
        """Replace rule by name with new function & options.

        :param ruleName: rule name to replace.
        :param fn: new rule function.
        :param options: new rule options (not mandatory).
        :raises: KeyError if name not found
        """
        index = self.__find__(ruleName)
        options = options or {}
        if index == -1:
            raise KeyError(f"Parser rule not found: {ruleName}")
        self.__rules__[index].fn = fn
        self.__rules__[index].alt = options.get("alt", [])
        self.__cache__ = None

    def before(
        self,
        beforeName: str,
        ruleName: str,
        fn: RuleFuncTv,