fix: make sure filter works when encountering unseen named graphs (#498)

Author: jeswr

src/N3Store.js

@@ -1134,27 +1134,28 @@ class DatasetCoreAndReadableStream extends Readable {
 
       const graphs = n3Store._getGraphs(graph);
       for (const graphKey in graphs) {
-        let subjects, predicates, objects;
-
-        if (!subjectId && predicateId) {
-          if (predicates = indexMatch(graphs[graphKey].predicates, [predicateId, objectId, subjectId])) {
-            subjects = indexMatch(graphs[graphKey].subjects, [subjectId, predicateId, objectId]);
-            objects = indexMatch(graphs[graphKey].objects, [objectId, subjectId, predicateId]);
+        let subjects, predicates, objects, content;
+        if (content = graphs[graphKey]) {
+          if (!subjectId && predicateId) {
+            if (predicates = indexMatch(content.predicates, [predicateId, objectId, subjectId])) {
+              subjects = indexMatch(content.subjects, [subjectId, predicateId, objectId]);
+              objects = indexMatch(content.objects, [objectId, subjectId, predicateId]);
+            }
           }
-        }
-        else if (objectId) {
-          if (objects = indexMatch(graphs[graphKey].objects, [objectId, subjectId, predicateId])) {
-            subjects = indexMatch(graphs[graphKey].subjects, [subjectId, predicateId, objectId]);
-            predicates = indexMatch(graphs[graphKey].predicates, [predicateId, objectId, subjectId]);
+          else if (objectId) {
+            if (objects = indexMatch(content.objects, [objectId, subjectId, predicateId])) {
+              subjects = indexMatch(content.subjects, [subjectId, predicateId, objectId]);
+              predicates = indexMatch(content.predicates, [predicateId, objectId, subjectId]);
+            }
+          }
+          else if (subjects = indexMatch(content.subjects, [subjectId, predicateId, objectId])) {
+            predicates = indexMatch(content.predicates, [predicateId, objectId, subjectId]);
+            objects = indexMatch(content.objects, [objectId, subjectId, predicateId]);
           }
-        }
-        else if (subjects = indexMatch(graphs[graphKey].subjects, [subjectId, predicateId, objectId])) {
-          predicates = indexMatch(graphs[graphKey].predicates, [predicateId, objectId, subjectId]);
-          objects = indexMatch(graphs[graphKey].objects, [objectId, subjectId, predicateId]);
-        }
 
-        if (subjects)
-          newStore._graphs[graphKey] = { subjects, predicates, objects };
+          if (subjects)
+            newStore._graphs[graphKey] = { subjects, predicates, objects };
+        }
       }
       newStore._size = null;
     }

test/N3Store-test.js

@@ -150,6 +150,17 @@ describe('Store', () => {
 
     it('should have size 5', () => {
       expect(store.size).toEqual(5);
+
+      expect(store.match(namedNode('s2'), namedNode('p2'), namedNode('o2'), namedNode('g1')).size).toEqual(1);
+      expect(store.match(null, namedNode('p2'), namedNode('o2'), namedNode('g1')).size).toEqual(1);
+      expect(store.match(namedNode('s2'), null, namedNode('o2'), namedNode('g1')).size).toEqual(1);
+      expect(store.match(namedNode('s2'), namedNode('p2'), null, namedNode('g1')).size).toEqual(1);
+      expect(store.match(namedNode('s2'), namedNode('p2'), namedNode('o2'), null).size).toEqual(1);
+
+      expect(store.match(namedNode('s2'), namedNode('p2'), namedNode('o2'), namedNode('g2')).size).toEqual(0);
+      expect(store.match(null, namedNode('p2'), namedNode('o2'), namedNode('g2')).size).toEqual(0);
+      expect(store.match(namedNode('s2'), null, namedNode('o2'), namedNode('g2')).size).toEqual(0);
+      expect(store.match(namedNode('s2'), namedNode('p2'), null, namedNode('g2')).size).toEqual(0);
     });
 
     describe('adding a triple that already exists', () => {