Class SyntaxTreeNode

markdown_it/tree.py:23–333

A Markdown syntax tree node. A class that can be used to construct a tree representation of a linear `markdown-it-py` token stream. Each node in the tree represents either: - root of the Markdown document - a single unnested `Token` - a `Token` "_open" and "_close" to

class SyntaxTreeNode:
    """A Markdown syntax tree node.

    A class that can be used to construct a tree representation of a linear
    `markdown-it-py` token stream.

    Each node in the tree represents either:
      - root of the Markdown document
      - a single unnested `Token`
      - a `Token` "_open" and "_close" token pair, and the tokens nested in
          between
    """

    def __init__(
        self, tokens: Sequence[Token] = (), *, create_root: bool = True
    ) -> None:
        """Initialize a `SyntaxTreeNode` from a token stream.

        If `create_root` is True, create a root node for the document.
        """
        # Only nodes representing an unnested token have self.token
        self.token: Token | None = None

        # Only containers have nester tokens
        self.nester_tokens: _NesterTokens | None = None

        # Root node does not have self.parent
        self._parent: Any = None

        # Empty list unless a non-empty container, or unnested token that has
        # children (i.e. inline or img)
        self._children: list[Any] = []

        if create_root:
            self._set_children_from_tokens(tokens)
            return

        if not tokens:
            raise ValueError(
                "Can only create root from empty token sequence."
                " Set `create_root=True`."
            )
        elif len(tokens) == 1:
            inline_token = tokens[0]
            if inline_token.nesting:
                raise ValueError(
                    "Unequal nesting level at the start and end of token stream."
                )
            self.token = inline_token
            if inline_token.children:
                self._set_children_from_tokens(inline_token.children)
        else:
            self.nester_tokens = _NesterTokens(tokens[0], tokens[-1])
            self._set_children_from_tokens(tokens[1:-1])

    def __repr__(self) -> str:
        return f"{type(self).__name__}({self.type})"