feat: add N3Util.isQuad (#535)

* Add N3Util.isQuad

* feat: add IRI content to quad

---------

Co-authored-by: opl- <opl-@users.noreply.github.com>

Author: jeswr

src/N3Util.js

@@ -22,6 +22,11 @@ export function isVariable(term) {
   return !!term && term.termType === 'Variable';
 }
 
+// Tests whether the given term represents a quad
+export function isQuad(term) {
+  return !!term && term.termType === 'Quad';
+}
+
 // Tests whether the given term represents the default graph
 export function isDefaultGraph(term) {
   return !!term && term.termType === 'DefaultGraph';

test/N3Util-test.js

@@ -131,6 +131,45 @@ describe('Util', () => {
     });
   });
 
+  describe('isQuad', () => {
+    it('matches a quad', () => {
+      expect(Util.isQuad(quad(null, null, null, null))).toBe(true);
+    });
+
+    it('matches a quad with iri content', () => {
+      expect(Util.isQuad(quad(
+        namedNode('http://example.org/'),
+        namedNode('http://example.org/'),
+        namedNode('http://example.org/'),
+        namedNode('http://example.org/'),
+      ))).toBe(true);
+    });
+
+    it('does not match an IRI', () => {
+      expect(Util.isQuad(namedNode('http://example.org/'))).toBe(false);
+    });
+
+    it('does not match a literal', () => {
+      expect(Util.isQuad(literal('http://example.org/'))).toBe(false);
+    });
+
+    it('does not match a blank node', () => {
+      expect(Util.isQuad(blankNode('x'))).toBe(false);
+    });
+
+    it('does not match a variable', () => {
+      expect(Util.isQuad(variable('x'))).toBe(false);
+    });
+
+    it('does not match null', () => {
+      expect(Util.isQuad(null)).toBe(false);
+    });
+
+    it('does not match undefined', () => {
+      expect(Util.isQuad(undefined)).toBe(false);
+    });
+  });
+
   describe('isDefaultGraph', () => {
     it('does not match a blank node', () => {
       expect(Util.isDefaultGraph(blankNode('x'))).toBe(false);