Lemon

The Lemon program is an LALR(1) parser generator. It takes a context free
grammar and converts it into a subroutine that will parse a file using that
grammar.

Lemon is similar to the much more famous programs "YACC" and "BISON". But lemon
is not compatible with either yacc or bison. There are several important
differences: 

  o Lemon using a different grammar syntax which is less prone to programming
errors.

  o The parser generated by Lemon is both re-entrant and thread-safe.

  o Lemon includes the concept of a non-terminal destructor, which makes it much
easier to write a parser that does not leak memory.

The complete source code to the lemon parser generator is contained in two
files. The file lemon.c is the parser generator program itself. A separate file
lempar.c is the template for the parser subroutine that lemon generates.
Documentation on lemon is also available.

Both the source code to lemon itself and the code that lemon generates are in
the public domain. 

To see an example of how to use lemon, see the source code to the SQLite
database engine. Lemon is maintained as part of the SQLite project.