1. A method of incrementally updating a suffix tree comprising: providing an initial suffix tree based on a first sequence of symbols drawn from an alphabet, the suffix tree comprising existing nodes representing respective subsequences occurring in the first sequence of symbols, the existing nodes being associated with information relating to membership of the subsequences in at least one class of repeat subsequences; receiving a second sequence of symbols drawn from the alphabet; based on the second sequence of symbols, updating the initial suffix tree to form an updated suffix tree, the updating including adding new nodes representing subsequences occurring in the second sequence of symbols that are not represented by the existing nodes; ordering the subsequences represented by the new nodes in a new node data structure based on at least one of a length of the respective subsequence and a depth of the new node in the updated suffix tree; and processing the new node data structure, the processing including updating the information relating to the at least one class of repeat subsequences associated with at least some of the nodes in the updated suffix tree, and wherein at least one of the providing, receiving adding, ordering, and processing is performed with a computer processor.