javacc - 5.0-8 main

Java Compiler-Compiler (JavaCC) is (according to sun)
"the most popular parser generator" for use with Java [tm]
applications.
.
A parser generator is a tool that reads a grammar specification
and converts it to a Java program that can recognize matches to
the grammar. In addition to the parser generator itself, JavaCC
provides other standard capabilities related to parser
generation such as tree building (via a tool called JJTree
included with JavaCC), actions, debugging, etc.