{-  Copyright 2010 Dominique Devriese

    This file is part of the grammar-combinators library.

    The grammar-combinators library is free software: you can
    redistribute it and/or modify it under the terms of the GNU
    Lesser General Public License as published by the Free
    Software Foundation, either version 3 of the License, or (at
    your option) any later version.

    Foobar is distributed in the hope that it will be useful, but
    WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
    GNU Lesser General Public License for more details.

    You should have received a copy of the GNU Lesser General
    Public License along with Foobar. If not, see
    <http://www.gnu.org/licenses/>.
-}
{-# LANGUAGE FlexibleContexts #-}
{-# LANGUAGE NoMonomorphismRestriction #-}
{-# LANGUAGE TypeFamilies #-}

import Text.GrammarCombinators.Parser.RecursiveDescent
import Text.GrammarCombinators.Parser.Packrat
import Text.GrammarCombinators.Base

import Generics.MultiRec.FoldAlg

import Text.GrammarCombinators.Test.Grammar

data family NodeResult ix
data instance NodeResult AdditiveExpr = NRA (IO ())
data instance NodeResult MultiplicativeExpr = NRM (IO ())
data instance NodeResult PrimaryExpr = NRP (IO ())
data instance NodeResult Decimal = NRD (IO ())

printOpEx :: Char -> IO () -> IO () -> IO ()
printOpEx op a b = do putChar '('; a; putChar op; b; putChar ')'

printAlg :: Algebra ASTNode NodeResult
printAlg = const ( (\(NRM a) (NRA b) -> NRA $ printOpEx '+' a b)
                 & (\(NRM a) -> NRA a)
                 & (\(NRP a) (NRM b) -> NRM $ printOpEx '*' a b)
                 & (\(NRP a) -> NRM a)
                 & (\(NRA a) -> NRP a)
                 & (\(NRD a) -> NRP a)
                 & (\c -> NRD $ putChar '(' >> putChar c >> putChar ')'))

printer = alg . printAlg

printgram :: ProcessingContextFreeGrammar ASTNode Char NodeResult
printgram = applyProcessor grammar printer 

test1 = "((2+1)*2)+3*4"
prTest1 = parsePackrat printgram AdditiveExpr test1
prTest1Result = case prTest1 of Parsed (NRA r) _ -> r

rdTest1 = parseRecDec printgram AdditiveExpr test1
rdTest1Result = case rdTest1 of Just (NRA r) -> r