84 lines
3.1 KiB
Python
Executable File
84 lines
3.1 KiB
Python
Executable File
# Copyright 2008-2020 pydicom authors. See LICENSE file for details.
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"""Define the Sequence class, which contains a sequence DataElement's items.
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Sequence is a list of pydicom Dataset objects.
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"""
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from typing import cast, Any, TypeVar
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from collections.abc import Iterable
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from pydicom.dataset import Dataset
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from pydicom.multival import ConstrainedList
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# Python 3.11 adds typing.Self, until then...
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Self = TypeVar("Self", bound="Sequence")
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class Sequence(ConstrainedList[Dataset]):
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"""Class to hold multiple :class:`~pydicom.dataset.Dataset` in a :class:`list`."""
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def __init__(self, iterable: Iterable[Dataset] | None = None) -> None:
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"""Initialize a list of :class:`~pydicom.dataset.Dataset`.
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Parameters
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----------
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iterable : Iterable[Dataset] | None
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An iterable object (e.g. :class:`list`, :class:`tuple`) containing
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:class:`~pydicom.dataset.Dataset`. If not used then an empty
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:class:`Sequence` is generated.
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"""
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# We add this extra check to throw a relevant error. Without it, the
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# error will be simply that a Sequence must contain Datasets (since a
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# Dataset IS iterable). This error, however, doesn't inform the user
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# that the actual issue is that their Dataset needs to be INSIDE an
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# iterable object
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if isinstance(iterable, Dataset):
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raise TypeError("The Sequence constructor requires an iterable")
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# If True, SQ element uses an undefined length of 0xFFFFFFFF
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self.is_undefined_length: bool
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super().__init__(iterable)
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def extend(self, val: Iterable[Dataset]) -> None:
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"""Extend the :class:`~pydicom.sequence.Sequence` using an iterable
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of :class:`~pydicom.dataset.Dataset` instances.
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"""
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if isinstance(val, Dataset):
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raise TypeError("An iterable of 'Dataset' is required")
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super().extend(val)
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def __iadd__(self: Self, other: Iterable[Dataset]) -> Self:
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"""Implement Sequence() += [Dataset()]."""
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if isinstance(other, Dataset):
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raise TypeError("An iterable of 'Dataset' is required")
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return super().__iadd__(other)
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def __setitem__(self, index: slice | int, val: Iterable[Dataset] | Dataset) -> None:
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"""Add item(s) to the Sequence at `index`."""
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if isinstance(index, slice):
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if isinstance(val, Dataset):
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raise TypeError("Can only assign an iterable of 'Dataset'")
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super().__setitem__(index, val)
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else:
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super().__setitem__(index, cast(Dataset, val))
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def __str__(self) -> str:
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"""String description of the Sequence."""
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return f"[{''.join([str(x) for x in self])}]"
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def __repr__(self) -> str:
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"""String representation of the Sequence."""
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return f"<{self.__class__.__name__}, length {len(self)}>"
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@staticmethod
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def _validate(item: Any) -> Dataset:
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"""Check that `item` is a :class:`~pydicom.dataset.Dataset` instance."""
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if isinstance(item, Dataset):
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return item
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raise TypeError("Sequence contents must be 'Dataset' instances.")
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