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"""Extract information from the file system, such as filesize.
"""
# standard imports
import os
import typing
# bsie imports
from bsie.matcher import nodes
from bsie.utils import bsfs, ns
# inner-module imports
from .. import base
# exports
__all__: typing.Sequence[str] = (
'Stat',
)
## code ##
class Stat(base.Extractor):
"""Extract information from the file system."""
CONTENT_READER = 'bsie.reader.stat.Stat'
# mapping from predicate to handler function.
_callmap: typing.Dict[bsfs.schema.Predicate, typing.Callable[[os.stat_result], typing.Any]]
def __init__(self):
super().__init__(bsfs.schema.from_string(base.SCHEMA_PREAMBLE + '''
bse:filesize rdfs:subClassOf bsfs:Predicate ;
rdfs:domain bsn:Entity ;
rdfs:range xsd:integer ;
rdfs:label "File size"^^xsd:string ;
schema:description "File size of entity in some filesystem."^^xsd:string ;
bsfs:unique "true"^^xsd:boolean .
'''))
self._callmap = {
self.schema.predicate(ns.bse.filesize): self.__filesize,
}
def extract(
self,
subject: nodes.Entity,
content: os.stat_result,
principals: typing.Iterable[bsfs.schema.Predicate],
) -> typing.Iterator[typing.Tuple[nodes.Node, bsfs.schema.Predicate, typing.Any]]:
for pred in principals:
# find callback
clbk = self._callmap.get(pred)
if clbk is None:
continue
# get value
value = clbk(content)
if value is None:
continue
# produce triple
yield subject, pred, value
def __filesize(self, content: os.stat_result) -> typing.Optional[int]:
"""Return the file size."""
try:
return content.st_size
except Exception: # pylint: disable=broad-except # we explicitly want to catch everything
# FIXME: some kind of error reporting (e.g. logging)
return None
## EOF ##
|
