[COMMONSRDF-56] JSON-LD Literals wrongly compare equal

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 0.3.0
• Component/s: jsonld-java
• Assignee: Stian Soiland-Reyes
• Reporter: Stian Soiland-Reyes
• Created: 08/Feb/17 19:17
• Updated: 08/Feb/17 22:41
• Resolved: 08/Feb/17 22:39

Description

There's a bug in JSON-LD Java in Node.compareTo() for Literals, namely, they don't compare the values of the literal, language or datatype, which in Commons RDF can wrongly match a literal, say in dataset.stream() or in Literal.equals():

    JsonLdRDF rdf = new JsonLdRDF();
    JsonLdLiteral lit1 = rdf.createLiteral("Hello");
    JsonLdLiteral lit2 = rdf.createLiteral("Hello there");
    assertNotEquals(lit1, lit2);

The above will fail because JsonLdLiteralImpl.equals does a short JsonLdLiteral-specific call to the deeper .compareTo:

        if (obj instanceof JsonLdLiteral) {
            final JsonLdLiteral other = (JsonLdLiteral) obj;
            return asJsonLdNode().compareTo(other.asJsonLdNode()) == 0;
        }

Similarly, using .contains or .stream matching a literal object backed by a JSON-LD Graph or Dataset will wrongly match any literal:

        JsonLdDataset dataset = rdf.createDataset();
        JsonLdIRI s = rdf.createIRI("http://example.com/s");
        JsonLdIRI p = rdf.createIRI("http://example.com/p");
        JsonLdLiteral lit1 = rdf.createLiteral("Hello");
        JsonLdLiteral lit2 = rdf.createLiteral("Other");
        
        dataset.add(null, s, p, lit1);
        assertTrue(dataset.contains(Optional.empty(), s, p, lit2));
        assertFalse(dataset.contains(Optional.empty(), s, p, lit2));