Implement Text Editor with Undo/Redo

Implement a TextDocument class that supports basic text manipulation (inserting and deleting characters from the end) along with full undo/redo functionality.

Provided Skeleton

class Operation:
    pass

class InsertAtEndOperation(Operation):
    def __init__(self, chars_to_insert: str):
        self.chars_to_insert = chars_to_insert

class DeleteFromEndOperation(Operation):
    def __init__(self, num_chars_to_delete: int):
        self.num_chars_to_delete = num_chars_to_delete

class TextDocument:
    def __init__(self) -> None:
        pass

    def apply_operation(self, op: Operation) -> None:
        pass

    def get_current_content(self) -> str:
        return self.doc # Assuming 'doc' is the internal representation

    def undo_last(self) -> None:
        pass

    def redo_last(self) -> None:
        pass

Requirements

• apply_operation(self, op: Operation):
  • Must support appending chars_to_insert to the end of the document.
  • Must support deleting up to num_chars_to_delete characters from the end of the document. If fewer characters exist than requested, delete all available characters without error.
• get_current_content(): Returns the current string content of the document. The document starts empty.
• undo_last(): Reverts the most recently applied operation.
• redo_last(): Reapplies the most recently undone operation.
• History Management: After any successful apply_operation, the entire redo history must be cleared.
• Performance: Ensure each operation (apply_operation, undo_last, redo_last) runs in time proportional to the size of the change (e.g., length of inserted string, number of deleted characters), specifically avoiding copying the entire document per step.
• Discussion: Be prepared to discuss:
  • The chosen internal data structures (e.g., stacks, chunked buffers).
  • How inverse operations are computed and stored.
  • Time and space complexity of each method.
  • Key edge cases (e.g., deleting more characters than available, performing multiple undos/redos, applying new operations after undos).