"""Types related to translation fetching."""
import typing as _t
from dataclasses import dataclass as _dataclass
from .. import types as _tt
from ..offline import types as _ot
[docs]
@_dataclass(frozen=True)
class IdsToFetch(_t.Generic[_tt.SourceType, _tt.IdType]):
"""A source and the IDs to fetch from it."""
source: _tt.SourceType
"""Where to fetch from."""
ids: set[_tt.IdType]
"""Unique IDs to fetch translations for."""
[docs]
@_dataclass(frozen=True)
class FetchInstruction(_t.Generic[_tt.SourceType, _tt.IdType]):
"""Instructions passed from an ``AbstractFetcher`` to an implementation."""
source: _tt.SourceType
"""Where to fetch from."""
placeholders: _ot.PlaceholdersTuple
"""All desired placeholders in preferred order."""
required: set[str]
"""Placeholders that must be included in the response."""
placeholder_attributes: _ot.PlaceholderAttributes
"""See :attr:`.Format.placeholder_attributes` for details."""
ids: set[_tt.IdType] | None
"""Unique IDs to fetch translations for."""
task_id: int
"""Used for logging purposes."""
enable_uuid_heuristics: bool
"""Improves matching when :py:class:`~uuid.UUID`-like IDs are in use.
Implementations which have no UUID heuristics may silently ignore this flag.
"""
@property
def fetch_all(self) -> bool:
"""If ``True``, retrieve all available data."""
return self.ids is None
[docs]
@_dataclass(frozen=True)
class PartialCacheHit(_t.Generic[_tt.SourceType, _tt.IdType]):
"""Partial result of :meth:`.CacheAccess.load`: cached rows plus the IDs the cache vouches for.
.. attention::
Not supported for :attr:`.FetchInstruction.fetch_all` instructions.
Returning this -- instead of a full :class:`.PlaceholderTranslations` (complete hit) or ``None`` (miss) -- tells the
:class:`.AbstractFetcher` to fetch only the *missing* IDs and merge them with `translations`.
"""
translations: _ot.PlaceholderTranslations[_tt.SourceType]
"""Cached :class:`.PlaceholderTranslations`, scoped to the requested IDs.
May be empty (length of :attr:`.PlaceholderTranslations.records` is 0) to enforce layout; see :attr:`placeholders`.
"""
covered: set[_tt.IdType] | None = None
"""Requested IDs the cache is satisfying.
Defaults to the IDs present in :attr:`translations` (extracted by the fetcher); set this only to *additionally*
vouch for IDs that have no row, e.g. known-missing IDs for negative caching.
"""
@property
def placeholders(self) -> _ot.PlaceholdersTuple:
"""Layout to fetch the missing IDs with; a thin alias of ``translations.placeholders``.
.. hint::
Use the :attr:`.CacheAccess.parent` to access e.g. available placeholders.
The fetcher fetches the complement using at least these placeholders, so a cache keeps its stored layout
cohesive (avoiding a per-request layout split) simply by returning that layout here -- even when `translations`
has no rows.
"""
return self.translations.placeholders
FetchOperation = _t.Literal["FETCH", "FETCH_ALL"]
"""Key operation types for fetching."""
Operation = _t.Literal["INITIALIZE_SOURCES"] | FetchOperation
"""Key operation types for fetchers."""
