I was using treetop to do some parsing the other day and it got me thinking. Treetop is a parsing DSL for ruby based on the idea of a parsing expression grammar. This could get dangerous. lex and yacc (flex and bison) If you open up the ruby source code, you'll probably find a file named parse.y. This is probably used by bison to generate a parser. The parser is (probably) used in conjuction with flex to deal with parsing things. A thing could b…