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masque/masque/library/device_library.py

111 lines
3.2 KiB
Python

"""
DeviceLibrary class for managing unique name->device mappings and
deferred loading or creation.
"""
from typing import Dict, Callable, TypeVar, TYPE_CHECKING
from typing import Any, Tuple, Union, Iterator
import logging
from pprint import pformat
from ..error import DeviceLibraryError
if TYPE_CHECKING:
from ..builder import Device
logger = logging.getLogger(__name__)
L = TypeVar('L', bound='DeviceLibrary')
class DeviceLibrary:
"""
This class maps names to functions which generate or load the
relevant `Device` object.
This class largely functions the same way as `Library`, but
operates on `Device`s rather than `Patterns` and thus has no
need for distinctions between primary/secondary devices (as
there is no inter-`Device` hierarchy).
Each device is cached the first time it is used. The cache can
be disabled by setting the `enable_cache` attribute to `False`.
"""
generators: Dict[str, Callable[[], 'Device']]
cache: Dict[Union[str, Tuple[str, str]], 'Device']
enable_cache: bool = True
def __init__(self) -> None:
self.generators = {}
self.cache = {}
def __setitem__(self, key: str, value: Callable[[], 'Device']) -> None:
self.generators[key] = value
if key in self.cache:
del self.cache[key]
def __delitem__(self, key: str) -> None:
del self.generators[key]
if key in self.cache:
del self.cache[key]
def __getitem__(self, key: str) -> 'Device':
if self.enable_cache and key in self.cache:
logger.debug(f'found {key} in cache')
return self.cache[key]
logger.debug(f'loading {key}')
dev = self.generators[key]()
self.cache[key] = dev
return dev
def __iter__(self) -> Iterator[str]:
return iter(self.keys())
def __contains__(self, key: str) -> bool:
return key in self.generators
def keys(self) -> Iterator[str]:
return iter(self.generators.keys())
def values(self) -> Iterator['Device']:
return iter(self[key] for key in self.keys())
def items(self) -> Iterator[Tuple[str, 'Device']]:
return iter((key, self[key]) for key in self.keys())
def __repr__(self) -> str:
return '<DeviceLibrary with keys ' + repr(list(self.generators.keys())) + '>'
def set_const(self, const: 'Device') -> None:
"""
Convenience function to avoid having to manually wrap
already-generated Device objects into callables.
Args:
const: Pre-generated device object
"""
self.generators[const.pattern.name] = lambda: const
def add(self: L, other: L) -> L:
"""
Add keys from another library into this one.
There must be no conflicting keys.
Args:
other: The library to insert keys from
Returns:
self
"""
conflicts = [key for key in other.generators
if key in self.generators]
if conflicts:
raise LibraryError('Duplicate keys encountered in library merge: ' + pformat(conflicts))
self.generators.update(other.generators)
self.cache.update(other.cache)
return self