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| from typing import Iterable, List, Optional | |
| class Order: | |
| """ | |
| A list-like structure to specify the order of items in a dictionary. | |
| The main characteristics are: | |
| - Append and insert only. Cannot remove elements. This is not strictly required | |
| by the use-case but probably good practice. | |
| - Elements must be unique. Inserting an element which is already in the list | |
| will throw an error. | |
| Primarily useful for specifying the order in which UI elements | |
| should be shown in Wave. | |
| """ | |
| def __init__(self, keys: Optional[List[str]] = None): | |
| if keys is not None: | |
| self._list = list(keys) | |
| else: | |
| self._list = list() | |
| def _unique_guard(self, *keys: str) -> None: | |
| for key in keys: | |
| if key in self._list: | |
| raise ValueError(f"`{key}` is already in the list!") | |
| def append(self, key: str) -> None: | |
| """ | |
| Append a key at the end of the list: | |
| Args: | |
| key: String to append. | |
| Raises: | |
| - `ValueError` if the key is already in the list. | |
| """ | |
| self._unique_guard(key) | |
| self._list.append(key) | |
| def extend(self, keys: Iterable[str]) -> None: | |
| """ | |
| Extend the list by multiple keys. | |
| Args: | |
| keys: Iterable of keys. | |
| Raises: | |
| - `ValueError` if one or more key is already in the list. | |
| """ | |
| self._unique_guard(*keys) | |
| self._list.extend(keys) | |
| def insert( | |
| self, *keys: str, before: Optional[str] = None, after: Optional[str] = None | |
| ) -> None: | |
| """ | |
| Insert one or more keys. Either `before` or `after`, but not both, must be set | |
| to determine position. | |
| Args: | |
| keys: One more keys to insert. | |
| after: A key immediately after which the `keys` will be inserted. | |
| before: A key immediately before which the `keys` are inserted. | |
| Raises: | |
| - `ValueError` if one or more key is already in the list. | |
| - `ValueError` if `before` / `after` does not exist in the list. | |
| - `ValueError` if an invalid combination of arguments is set. | |
| """ | |
| self._unique_guard(*keys) | |
| if before is None and after is None: | |
| raise ValueError("Either `before` or `after` must be set.") | |
| if before and after: | |
| raise ValueError("Can't set `before` and `after` at the same time.") | |
| if before is not None: | |
| for key in keys: | |
| self._list.insert(self._list.index(before), key) | |
| if after is not None: | |
| for key in keys: | |
| self._list.insert(self._list.index(after) + 1, key) | |
| def __getitem__(self, idx): | |
| return self._list[idx] | |
| def __len__(self) -> int: | |
| return len(self._list) | |
| def __iter__(self): | |
| return iter(self._list) | |