Returns true if this pattern does not contain any wildcards.
Returns the id of the index/triple vertex to which this pattern should be routed.
Returns the id of the index/triple vertex to which this pattern should be routed. Any variables (<0) should be converted to "unbound", which is represented by a wildcard.
Pattern of 3 expressions (subject, predicate object). They are represented as Int, but can be converted to Expression implicitly and for free (value class).