Unable to parse queries containing FILTER NOT EXISTS

[jimjonesbr]

Hi :)

rasqal_query_prepare is returning an error if the query contains a FILTER NOT EXISTS, e.g.

SELECT ?s WHERE { ?s ?p ?o . FILTER NOT EXISTS { ?s ?p2 ?o2 } }

returns

WARNING: Rasqal error: syntax error, unexpected NOT (at line 1, column -1)

This is the code:

static void rasqal_log_handler(void *user_data, raptor_log_message *message)
{
    elog(WARNING, "Rasqal error: %s (at line %d, column %d)",
         message->text, message->locator->line, message->locator->column);
}

static bool is_valid_sparql_query(const char *sparql_string)
{
    bool is_valid = false;
    int prepare_result;
    rasqal_world *world = rasqal_new_world();
    rasqal_query *query = NULL;

    if (!world)
        return false;

    rasqal_world_set_log_handler(world, NULL, rasqal_log_handler);
    rasqal_world_set_warning_level(world, 0);

    if (rasqal_world_open(world) != 0)
    {
        elog(WARNING, "Failed to open Rasqal world");
        rasqal_free_world(world);
        return false;
    }

    query = rasqal_new_query(world, "sparql", NULL);
    if (!query)
    {
        elog(WARNING, "Failed to create Rasqal query");
        rasqal_free_world(world);
        return false;
    }

    prepare_result = rasqal_query_prepare(query, (const unsigned char *)sparql_string, NULL);
    if (prepare_result == 0)
        is_valid = true;
    else
        elog(WARNING, "SPARQL query preparation failed. Return code: %d", prepare_result);

    rasqal_free_query(query);
    rasqal_free_world(world);

    return is_valid;
}

Am I missing something here?
Thanks in advance!

Best, Jim