Java Compiler Compiler (JavaCC) is a parser generator for use with
Java 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, and more.

WWW: http://javacc.dev.java.net