Tool: ORO
Purpose: Regular expressions
Version covered: 2.0.8
Home page: http://jakarta.apache.org/oro/
License: The Apache Software License, Version 1.1
Tool: Jakarta regexp
Purpose: Regular expressions
Version covered: 1.3
Home page: http://jakarta.apache.org/regexp/
License: The Apache Software License, Version 1.1
Tool: Java regexp
Purpose: Regular expressions
Version covered: 1.4.1
Home page: N/A, included with Java
Further Reading:
Introduction to Automata Theory, Languages, and Computation , 2/e, by John E. Hopcroft, Rajeev Motwani, and Jeffrey D. Ullman, Addison-Wesley, 2001Contains lots of information about regular expressions and finite state machines.
The POSIX standards committee: http://www.pasc.org/.