1. A system for scalable, rule-based processing, the system comprising: an automaton builder configured to construct a plurality of automatons corresponding to a plurality of trigger rules and a plurality of word lists that are employed by the trigger rules; and a rule evaluator configured to evaluate any of the trigger rules with respect to at least one input document by selecting any of the automatons to evaluate a given one of the trigger rules, parsing the input document using the selected automatons, determining whether conditions of the given trigger rule are met, and identifying any actions that are associated with the given trigger rule.