frontend-for-free 0.3

Statically generating standablone regex-based lexers and highly optimized LL(k) parsers

Frontend-For-Free

A bootstrap of RBNF.hs for generating standalone parsers targeting multiple programming languages, where the generated code needs no runtime system.

Installation

Binary files

You can install binary files via The Haskell Tool Stack.

sh> stack install .

Otherwise, so far Windows binary files are released on GitHub.

Download it from Releases, add fff-lex and fff-pgen to your PATH.

Python Wrapper

frontend-for-free now supports Python only:

pip install frontend-for-free or install it from GitHub.

Usage

sh> fff <xxx>.rbnf --trace # note that you should also provide a <xxx>.rlex
sh> ls | grep <xxx>
<xxx>_parser.py <xxx>_lex.py

See examples at runtest.

What is Frontend-For-Free?

A framework for generating context-free parsers with following properties:

• cross-language
• distributed with a lexer generator, but feel free to use your own lexers.
• LL(k) capability
• efficient left recursions
• standalone No 3rd party library is introduced, while the generator requires Python3.6+ with a few dependencies.
• defined with a most intuitive and expressive BNF derivative

  • action/rewrite:

    pair := a b { ($1, $2) }

  • parameterised polymorphisms for productions:

    nonEmpty[A] := A { [$1] } | hd=A tl=nonEmpty[A] { append(hd, tl) }

    where append shall be provided by the user code.

Currently,

• the parser generator support for a programming language is hard coded in src/RBNF/BackEnds/<LanguageName>.hs.
• the lexer generator support for a programming language is hard coded in ffflex.py.