Add virtualgraph code

src/app/virtual.py

@@ -0,0 +1,59 @@
+# A Virtual GRAPH that dynamically fills up based on queries performed
+import sys, sqlite3, io
+from tree_sitter import Language, Parser
+import pyoxigraph as px
+
+if sys.platform == "darwin":
+    SPARQL = Language("/usr/local/lib/sparql.dylib", "sparql")
+else:
+    SPARQL = Language("/usr/local/lib/sparql.so", "sparql")
+
+PARSER = Parser()
+PARSER.set_language(SPARQL)
+
+
+class VirtualGraph:
+    def get_triples_from_fts(self, iris: list[str]):
+        db = sqlite3.connect(self.FTS_FILEPATH)
+        db.enable_load_extension(True)
+        if sys.platform == "darwin":
+            db.load_extension("/usr/local/lib/fts5stemmer.dylib")
+            db.load_extension("/usr/local/lib/spellfix.dylib")
+        else:
+            db.load_extension("/usr/local/lib/spellfix")
+            db.load_extension("/usr/local/lib/fts5stemmer")
+
+        try:
+            vals = ", ".join([f"'{i.strip('<>')}'" for i in iris])
+            SQL = f"SELECT subject, predicate, txt FROM literal_index WHERE subject in ({vals}) LIMIT 10000"
+            return [
+                f"<{subject}> <{predicate}> {txt} ."
+                for subject, predicate, txt in db.execute(SQL)
+            ]
+        except sqlite3.OperationalError:
+            return []
+
+    def quads_for_pattern(self, subject, predicate, obj):
+        raise NotImplementedError()
+
+    def __len__(self):
+        return len(self.store)
+
+    def __init__(self, FTS_FILEPATH):
+        self.store = px.Store()
+        self.FTS_FILEPATH = FTS_FILEPATH
+
+    def query(self, query: str):
+        cst = PARSER.parse(query.encode("utf8"))
+        iris = [
+            n.text.decode("utf8")
+            for n, name in SPARQL.query("(iri_reference) @aniri").captures(
+                cst.root_node
+            )
+        ]
+        triples = self.get_triples_from_fts(iris)
+        if len(triples) > 0:
+            self.store.bulk_load(
+                io.StringIO("\n".join(triples)), "application/n-triples"
+            )
+        return self.store.query(query)