1) Introduction

1.1) BNF Converter

The BNF Converter is a compiler construction tool generating a compiler front-end from a labeled BNF grammar. It is currently able to generate representations for several languages. Given a labeled BNF grammar BNFC generates:

an abstract syntax implementation
an Alex, JLex or Flex lexer generator file
an Happy, CUP, or Bison parser generator file
a pretty printer
a LaTeX file containing a readable specification of the language

Further informations and sources can be found at:

http://www.cse.chalmers.se/research/group/Language-technology/BNFC/

Bnfc has to be installed in order to use bnfcCabal.

1.2) BnfcCabal

BnfcCabal is a cabal file creating tool for labeled BNF grammars of file extension *.cf. BnfcCabal runs bnfc on a given labeled grammar and automatically builds a cabal file containing all modules created by bnfc.

2) Installing BnfcCabal

BnfcCabal can be installed using

cabal install bnfcCabal

3) Using BnfcCabal

Before using BnfcCabal ensure the executable bnfc can be found in system PATH.

3.1) How to build a cabal file for your own grammar

Create a labeled grammar like mygrammar.cf
Launch bnfcCabal mygrammar.cf
Type cabal install in order to install the bnfc modules

3.2) Example: How to build the c grammar?

Grammar Examples/c.cf is already existing
Change to directory Examples
Type bnfcCabal c.cf to build a cabal file for c grammar
To install grammar type cabal install

See Section (3.3) how to use installed modules

3.3) Using installed modules

We use a grammar named mygrammar as a running example in this section. After running bnfcCabal mygrammar.cf the modules of a grammar mygrammar can be found as submodules of Language.Mygrammar. In order to use the parser of mygrammar some modules have to be imported:

import Language.Mygrammar.Parmygrammar
import Language.Mygrammar.Absmygrammar
import Language.Mygrammar.ErrM

Module ErrM contains a error monad to handle parse errors, whereas Absmygrammar contains the abstract syntax. The module Parmygrammar contains lexer and parse functions. The lexer function is always called myLexer, but the parsing function is named after the root of your grammar. Assume data type Myroot is the root of mygrammar. The function

(pMyroot . myLexer) :: String -> Err Root

is the correct parsing function for data type Myroot. Have a look at module Language.Mygrammar.ErrM to get an impression of the error monad.

4) To Do

[BUG] Module Main (in file Testmygrammar) is not being installled
check whether link to bnfc binary is correct (preConf-hook)

SantiMunin / BnfcCabal