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| 3.0 Introduction |
3.6 LEX, A Lexical Analyzer Generator
This section describes LEX, a lexical analyzer generator, written by Lesk and Schmidt at Bell Labs in 1975 for the UNIX operating system. It now exists for many operating systems, and versions can be obtained for almost any system including microcomputers. The discussion here is for illustration and should not be considered sufficient to use LEX.
LEX produces a scanner which is a C program (there are versions which produce other languages) that can be compiled and linked with other compiler modules. Other LEX-like tools exist which generate lexical analyzers in Pascal, Ada, C++, etc.
LEX accepts regular expressions and allows actions, code to executed, to be associated with each regular expression. At scan time, when an input string matches one of the defined regular expressions, the action code is executed.
