PLY (Python Lex-Yacc)

PLY is a parsing tool written purely in Python. It is basically a re-implementation of Lex and Yacc originally in C-language. It was written by David Beazley. Unlike Lex and Yacc in C which uses LALR parsing technique, PLY uses LR parsing which can incorporate large grammars easily. PLY also has extensive debugging and error reporting facilities.