Represents a comparator for pairs of token sequences.
.Dataa function that calls the elementwise method for this class,
with arguments x, y and ....
symmetrica logical of length 1. If TRUE, the comparator is symmetric
in its arguments---i.e. comparator(x, y) is identical to
comparator(y, x).
distancea logical of length 1. If TRUE, the comparator produces
distances and satisfies comparator(x, x) = 0. The comparator may not
satisfy all of the properties of a distance metric.
similaritya logical of length 1. If TRUE, the comparator produces
similarity scores.
tri_inequala logical of length 1. If TRUE, the comparator satisfies
the triangle inequality. This is only possible (but not guaranteed) if
distance = TRUE and symmetric = TRUE.
ordereda logical of length 1. If TRUE, the comparator treats token sequences as ordered, otherwise they are treated as unordered.