Memento Pattern in Python: Save and Restore Object State

class TextEditor:
    def __init__(self, text="", cursor_pos=0):
        self.text = text
        self.cursor_pos = cursor_pos

    def type_text(self, new_text):
        self.text += new_text
        self.cursor_pos += len(new_text)

    def move_cursor(self, pos):
        self.cursor_pos = max(0, min(pos, len(self.text)))

    def create_memento(self):
        return EditorMemento(self.text, self.cursor_pos)

    def restore_from_memento(self, memento):
        self.text = memento.text
        self.cursor_pos = memento.cursor_pos

    def __str__(self):
        return f"Text: '{self.text}' | Cursor: {self.cursor_pos}"


class EditorMemento:
    def __init__(self, text, cursor_pos):
        self.text = text
        self.cursor_pos = cursor_pos


class History:
    def __init__(self, editor):
        self.editor = editor
        self.states = []

    def backup(self):
        self.states.append(self.editor.create_memento())

    def undo(self):
        if self.states:
            memento = self.states.pop()
            self.editor.restore_from_memento(memento)
        else:
            print("No states to undo")


if __name__ == "__main__":
    editor = TextEditor()
    history = History(editor)

    editor.type_text("Hello")
    history.backup()
    editor.type_text(" World")
    print(editor)

    history.undo()
    print(f"After undo: {editor}")