reflex

reflex is a variant of flex, a tool for generating scanners (programs which recognize lexical patterns in text).

It reads the given input files for a description of a scanner to generate. The description is in the form of pairs of regular expressions and C code, called rules. Reflex generates as output a C source file, lex.yy.c, which defines a routine yylex(). When this routine is called, it analyzes its input for occurrences of the regular expressions. Whenever it finds one, it executes the corresponding C code.