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