Processing Text with State Machines

Using state machines or finite automatons is a great technique for processing text. This article provides a rough framework for tackling string processing problems. It is easy to write programs that use FAs without going deep into the theory. The program goes through a set of states as it processes the input. Behaviour of the program on the next input token is defined by its current state. The FA "accepts" or "rejects" an input string based on its final state. An FA can be used to extract all the page links of a sitemap.