Source code for httk.optimade.backend.partial

"""Markers for property values transmitted via the partial data protocol.

A field extractor may return a :class:`PartialValue` in place of a concrete
value when the value is too large to include inline, or when its list axes are
sliceable. The endpoint layer turns it into ``null`` plus
``meta.partial_data_links`` (only the endpoint knows the base URL), slices it
inline when a ``dimension_slices`` query parameter is supplied, or streams it
via the JSON Lines partial data endpoint.
"""

from collections.abc import Callable
from dataclasses import dataclass
from typing import Any


@dataclass(frozen=True)


class PartialDimension:
    """One list axis of a :class:`PartialValue`.

    ``length`` is the number of items along the axis (``None`` when unknown or
    entry-dependent and not declared). ``sliceable`` indicates whether the
    server can honour a slice request for this axis.
    """



    name: str



    length: int | None = None



    sliceable: bool = False




@dataclass(frozen=True)


class PartialValue:
    """A property value provided lazily, one slice at a time.

    ``fetch`` takes a tuple of Python slices (one per dimension, with the usual
    *exclusive* stop) and returns the corresponding nested lists.
    """



    dimensions: tuple[PartialDimension, ...]



    fetch: Callable[[tuple[slice, ...]], Any]