value_bool operator() (value_unicode_string const& ustr) const
{
return !ustr.isEmpty();
}
// back compatibility shim to equate empty string with null for != test
// https://github.com/mapnik/mapnik/issues/1859
// TODO - consider removing entire specialization at Mapnik 3.1.x
static bool apply(value_null, value_unicode_string const& rhs)
{
if (rhs.isEmpty()) return false;
return true;
}