re2c is a preprocessor that generates C-based recognizers from regular
expressions.  The input to re2c consists of C/C++ source interleaved
with comments of the form /*!re2c ...  */ which contain scanner
specifications.  In the output these comments are replaced with code
that, when executed, will find the next input token and then execute
some user-supplied token-specific code.

Homepage:
https://re2c.org/
