3 files changed, 29 insertions, 0 deletions
diff --git a/bsfs/triple_store/base.py b/bsfs/triple_store/base.py
index 6561262..28ebb86 100644
--- a/bsfs/triple_store/base.py
+++ b/bsfs/triple_store/base.py
@@ -109,6 +109,14 @@ class TripleStoreBase(abc.ABC):
         """
 
     @abc.abstractmethod
+    def get(
+            self,
+            node_type: bsc.Node,
+            query: ast.filter.FilterExpression,
+            ) -> typing.Iterator[URI]:
+        """Return guids of nodes of type *node_type* that match the *query*."""
+
+    @abc.abstractmethod
     def exists(
             self,
             node_type: _schema.Node,
diff --git a/bsfs/triple_store/sparql/__init__.py b/bsfs/triple_store/sparql/__init__.py
new file mode 100644
index 0000000..285334a
--- /dev/null
+++ b/bsfs/triple_store/sparql/__init__.py
@@ -0,0 +1,18 @@
+"""
+
+Part of the BlackStar filesystem (bsfs) module.
+A copy of the license is provided with the project.
+Author: Matthias Baumgartner, 2022
+"""
+# imports
+import typing
+
+# inner-module imports
+from .sparql import SparqlStore
+
+# exports
+__all__: typing.Sequence[str] = (
+    'SparqlStore',
+    )
+
+## EOF ##
diff --git a/bsfs/triple_store/sparql.py b/bsfs/triple_store/sparql/sparql.py
index 7516dff..fff540a 100644
--- a/bsfs/triple_store/sparql.py
+++ b/bsfs/triple_store/sparql/sparql.py
@@ -11,6 +11,7 @@ import rdflib
 
 # bsfs imports
 from bsfs import schema as bsc
+from bsfs.query import ast
 from bsfs.utils import errors, URI
 
 # inner-module imports
@@ -152,6 +153,8 @@ class SparqlStore(base.TripleStoreBase):
         # migrate schema
         self._schema = schema
 
+    def get(self, node_type: bsc.Node, query: ast.filter.FilterExpression) -> typing.Iterator[URI]:
+        raise NotImplementedError()
 
     def _has_type(self, subject: URI, node_type: bsc.Node) -> bool:
         """Return True if *subject* is a node of class *node_type* or a subclass thereof."""