70 lines
1.8 KiB
Python
70 lines
1.8 KiB
Python
"""Provides an immutable sequence view class."""
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from __future__ import annotations
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from sys import maxsize
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from typing import TYPE_CHECKING, Generic, Iterator, Sequence, TypeVar, overload
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T = TypeVar("T")
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class ImmutableSequenceView(Generic[T]):
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"""Class to wrap a sequence of some sort, but not allow modification."""
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def __init__(self, wrap: Sequence[T]) -> None:
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"""Initialise the immutable sequence.
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Args:
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wrap: The sequence being wrapped.
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"""
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self._wrap = wrap
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if TYPE_CHECKING:
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@overload
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def __getitem__(self, index: int) -> T: ...
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@overload
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def __getitem__(self, index: slice) -> ImmutableSequenceView[T]: ...
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def __getitem__(self, index: int | slice) -> T | ImmutableSequenceView[T]:
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return (
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self._wrap[index]
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if isinstance(index, int)
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else ImmutableSequenceView[T](self._wrap[index])
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)
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def __iter__(self) -> Iterator[T]:
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return iter(self._wrap)
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def __len__(self) -> int:
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return len(self._wrap)
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def __length_hint__(self) -> int:
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return len(self)
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def __bool__(self) -> bool:
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return bool(self._wrap)
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def __contains__(self, item: T) -> bool:
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return item in self._wrap
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def index(self, item: T, start: int = 0, stop: int = maxsize) -> int:
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"""Return the index of the given item.
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Args:
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item: The item to find in the sequence.
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start: Optional start location.
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stop: Optional stop location.
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Returns:
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The index of the item in the sequence.
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Raises:
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ValueError: If the item is not in the sequence.
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"""
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return self._wrap.index(item, start, stop)
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def __reversed__(self) -> Iterator[T]:
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return reversed(self._wrap)
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