YACC AND LEX

There are two traditional UNIX utilities named and that enable you to create compilers for computer languages that you design yourself. Mike Lesk developed the original version around 1975 at the AT&T Bell Labs. It can help you make lexical analysers, and its main job is to break up an input stream into usable elements, which are called tokens. Lexical analysers are naïve tools that do not deal with the true meaning of the tokens – this is the job of a parser such as or . The lexical analysis phase usually eliminates all blanks, because apart from helping you separate tokens they have no other use. The utility has been subsequently been completely replaced by .