constant, filesize, and filename extractors

1 files changed, 71 insertions, 0 deletions

diff --git a/bsie/extractor/generic/stat.py b/bsie/extractor/generic/stat.py
new file mode 100644
index 0000000..d74369c
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+++ b/bsie/extractor/generic/stat.py
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+"""Extract information from the file system, such as filesize.
+
+Part of the bsie module.
+A copy of the license is provided with the project.
+Author: Matthias Baumgartner, 2022
+"""
+# imports
+import typing
+
+# inner-module imports
+from bsie.base import extractor
+from bsie.utils import node, ns
+from bsie.utils.bsfs import URI
+import bsie.reader.stat
+
+
+# exports
+__all__: typing.Sequence[str] = (
+    'Stat',
+    )
+
+
+## code ##
+
+class Stat(extractor.Extractor):
+    """Extract information from the file system."""
+
+    CONTENT_READER = bsie.reader.stat.Stat
+
+    def __init__(self):
+        self.__callmap = {
+            ns.bse.filesize:    self.__filesize,
+            }
+
+    def schema(self) -> str:
+        return '''
+            bse:filesize a bsfs:Predicate ;
+                rdfs:domain bsfs:Entity ;
+                rdfs:range xsd:integer ;
+                rdf:label "File size"^^xsd:string ;
+                schema:description "File size of entity in some filesystem."^^xsd:string ;
+                owl:maxCardinality "INF"^^xsd:number .
+            '''
+
+    def extract(
+            self,
+            subject: node.Node,
+            content: CONTENT_READER.CONTENT_TYPE,
+            predicates: typing.Iterable[URI],
+            ) -> typing.Iterator[typing.Tuple[node.Node, URI, typing.Any]]:
+        for pred in predicates:
+            # 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: CONTENT_READER.CONTENT_TYPE) -> int:
+        """Return the file size."""
+        try:
+            return content.st_size
+        except Exception:
+            # FIXME: some kind of error reporting (e.g. logging)
+            return None
+
+## EOF ##