""" frozen (immutable) data structures to support MultiIndexing These are used for: - .names (FrozenList) """ from __future__ import annotations from typing import ( Any, NoReturn, ) from pandas.core.base import PandasObject from pandas.io.formats.printing import pprint_thing class FrozenList(PandasObject, list): """ Container that doesn't allow setting item *but* because it's technically hashable, will be used for lookups, appropriately, etc. """ # Side note: This has to be of type list. Otherwise, # it messes up PyTables type checks. def union(self, other) -> FrozenList: """ Returns a FrozenList with other concatenated to the end of self. Parameters ---------- other : array-like The array-like whose elements we are concatenating. Returns ------- FrozenList The collection difference between self and other. """ if isinstance(other, tuple): other = list(other) return type(self)(super().__add__(other)) def difference(self, other) -> FrozenList: """ Returns a FrozenList with elements from other removed from self. Parameters ---------- other : array-like The array-like whose elements we are removing self. Returns ------- FrozenList The collection difference between self and other. """ other = set(other) temp = [x for x in self if x not in other] return type(self)(temp) # TODO: Consider deprecating these in favor of `union` (xref gh-15506) # error: Incompatible types in assignment (expression has type # "Callable[[FrozenList, Any], FrozenList]", base class "list" defined the # type as overloaded function) __add__ = __iadd__ = union # type: ignore[assignment] def __getitem__(self, n): if isinstance(n, slice): return type(self)(super().__getitem__(n)) return super().__getitem__(n) def __radd__(self, other): if isinstance(other, tuple): other = list(other) return type(self)(other + list(self)) def __eq__(self, other: Any) -> bool: if isinstance(other, (tuple, FrozenList)): other = list(other) return super().__eq__(other) __req__ = __eq__ def __mul__(self, other): return type(self)(super().__mul__(other)) __imul__ = __mul__ def __reduce__(self): return type(self), (list(self),) # error: Signature of "__hash__" incompatible with supertype "list" def __hash__(self) -> int: # type: ignore[override] return hash(tuple(self)) def _disabled(self, *args, **kwargs) -> NoReturn: """ This method will not function because object is immutable. """ raise TypeError(f"'{type(self).__name__}' does not support mutable operations.") def __str__(self) -> str: return pprint_thing(self, quote_strings=True, escape_chars=("\t", "\r", "\n")) def __repr__(self) -> str: return f"{type(self).__name__}({str(self)})" __setitem__ = __setslice__ = _disabled # type: ignore[assignment] __delitem__ = __delslice__ = _disabled pop = append = extend = _disabled remove = sort = insert = _disabled # type: ignore[assignment]