rlex: a clear and simple alternative to GNU flex

rlex is a clear and simple alternative to GNU flex - a tool for generating lexer. with a clean and small codebase, rlex is easy to read, understand, and extend - great for learning and exploring how lexer work.

Usage

$ cd src && make
$ ./rlex
rlex 0.02 [gcc 12.2.0] [Jul 22 2025]. (c) 2025, ****. all rights reserved.
rlex: file name required

usage is: rlex [options] file
-f  for (f)ast. don't compress tables
-h  suppress (h)eader comment that describes state machine
-H  print the (H)eader only
-l  suppress #(l)ine directives in the output
-t  send output to standard output instead of lex.yy.c
-v  (v)erbose mode, print statistics
-V  more (V)erbose, print internal diagnostics as rlex runs

to build and run a simple word count tool (like Linux wc)

$ ./rlex ../test/wc.lex
$ gcc -o wc lex.yy.c ../lib/libl.a
$ ./wc lex.c

alternatively, run make test to build and test the wc example

$ make test
generating lex.yy.c from wc.lex
./rlex ../test/wc.lex
compiling lex.yy.c into executable wc
gcc -I../include -g -o wc lex.yy.c ../lib/libl.a
running wc test (word count on lex.c)
./wc lex.c
412     1417    11246   lex.c