python-sly

Python implementation of the lex and yacc tools

SLY is a 100% Python implementation of the lex and yacc tools commonly used to write parsers and compilers. Parsing is based on the same LALR(1) algorithm used by many yacc tools. Here are a few notable features: * SLY provides very extensive error reporting and diagnostic information to assist in parser construction. The original implementation was developed for instructional purposes. As a result, the system tries to identify the most common types of errors made by novice users. * SLY provides full support for empty productions, error recovery, precedence specifiers, and moderately ambiguous grammars. * SLY uses various Python metaprogramming features to specify lexers and parsers. There are no generated files or extra steps involved. You simply write Python code and run it. * SLY can be used to build parsers for "real" programming languages. Although it is not ultra-fast due to its Python implementation, SLY can be used to parse grammars consisting of several hundred rules (as might be found for a language like C).