[GTALUG] Online Course for Lex/Yacc?

Every now and then, I come across situation where an ideal solution would have been a custom parser/interpreter, either to parse data format or to write my own sets of commands. In each case, I don't know enough to write it (I'm not Comp Sci) or don't have time. So, I end up resorting to shell, awk, python, etc. Now, I want to take some course on Lex/Yacc, finally! What online course do you recommend? -- William Park <opengeometry@yahoo.ca>