node.py

from typing import Any

class Node:
    """
    Represents a node in a hierarchical document/tree structure.
    Each node has a unique identifier (id) and a parent node (parent), both integers.
    """

    __slots__ = ('id', 'parent')  # Memory optimization and faster attribute access

    id: int
    parent: int

    def __init__(self, id: int, parent: int) -> None:
        """
        Initialize a Node instance with id and parent.

        Raises:
            ValueError: If id or parent are not integers, or if parent is invalid.
        """
        if not isinstance(id, int) or not isinstance(parent, int):
            raise ValueError("Both id and parent must be integers.")
        if parent == id:
            raise ValueError("A node cannot be its own parent.")
        if parent > id:
            raise ValueError("Parent id cannot be greater than node id.")
        self.id = id
        self.parent = parent

    def __repr__(self) -> str:
        """
        Return the string representation of the Node that allows recreation using eval().
        Example: Node(2, 1)
        """
        return f"Node({self.id}, {self.parent})"

    def __eq__(self, other: Any) -> bool:
        """
        Compare Node equality based on id and parent.
        """
        if not isinstance(other, Node):
            return NotImplemented
        return self.id == other.id and self.parent == other.parent

    def __hash__(self) -> int:
        """
        Provide a hash function to allow using Node in sets or as dict keys.
        """
        return hash((self.id, self.parent))