1. A token stitcher for determining whether an input string of characters matches a regular expression comprising a number of sub-expressions, the token stitcher comprising: a flag bank storing a number of flags, where each flag identifies one or more of the sub-expressions that match the input string; and a token stitcher engine configured to implement an unbounded sub-expression without utilizing resources of a deterministic finite state automaton (DFA) engine or a non-deterministic finite state automaton (NFA) engine and to identify one or lore programs stored in a program memory that are associated with a new token received by the token stitcher, wherein a particular program in the program memory is configured to indicate a match when a particular set of flags in the flag bank are asserted, and wherein the flag bank is configured to discard one or more flags upon satisfaction of a predetermined condition and wherein the token stitcher is implemented by at least one processor-based computing device.