% % (c) The University of Glasgow 2001-2006 % \begin{code}

    module PprExternalCore () where

    import Encoding
    import ExternalCore

    import Pretty
    import Data.Char
    import Data.Ratio

    instance Show Module where
      showsPrec _ m = shows (pmodule m)

    instance Show Tdef where
      showsPrec _ t = shows (ptdef t)

    instance Show Cdef where
      showsPrec _ c = shows (pcdef c)

    instance Show Vdefg where
      showsPrec _ v = shows (pvdefg v)

    instance Show Exp where
      showsPrec _ e = shows (pexp e)

    instance Show Alt where
      showsPrec _ a = shows (palt a)

    instance Show Ty where
      showsPrec _ t = shows (pty t)

    instance Show Kind where
      showsPrec _ k = shows (pkind k)

    instance Show Lit where
      showsPrec _ l = shows (plit l)

    indent :: Doc -> Doc
    indent = nest 2

    pmodule :: Module -> Doc
    pmodule (Module mname tdefs vdefgs) =
      (text "%module" <+> text mname)
        $$ indent ((vcat (map ((<> char ';') . ptdef) tdefs))
    	       $$ (vcat (map ((<> char ';') . pvdefg) vdefgs)))

    ptdef :: Tdef -> Doc
    ptdef (Data tcon tbinds cdefs) =
      (text "%data" <+> pqname tcon <+> (hsep (map ptbind tbinds)) <+> char '=')
      $$ indent (braces ((vcat (punctuate (char ';') (map pcdef cdefs)))))

    ptdef (Newtype tcon coercion tbinds rep) =
      text "%newtype" <+> pqname tcon <+> pqname coercion
       <+> (hsep (map ptbind tbinds)) $$ indent repclause
           where repclause = char '=' <+> pty rep

    pcdef :: Cdef -> Doc
    pcdef (Constr dcon tbinds tys)  =
      (pqname dcon) <+> (sep [hsep (map pattbind tbinds),sep (map paty tys)])
    pcdef (GadtConstr dcon ty)  =
      (pqname dcon) <+> text "::" <+> pty ty

    pname :: Id -> Doc
    pname id = text (zEncodeString id)

    pqname :: Qual Id -> Doc
    pqname ("",id) = pname id
    pqname (m,id)  = text m <> char '.' <> pname id

    ptbind, pattbind :: Tbind -> Doc
    ptbind (t,Klifted) = pname t
    ptbind (t,k) = parens (pname t <> text "::" <> pkind k)

    pattbind (t,k) = char '@' <> ptbind (t,k)

    pakind, pkind :: Kind -> Doc
    pakind (Klifted) = char '*'
    pakind (Kunlifted) = char '#'
    pakind (Kopen) = char '?'
    pakind k = parens (pkind k)

    pkind (Karrow k1 k2) = parens (pakind k1 <> text "->" <> pkind k2)
    pkind (Keq t1 t2) = parens (parens (pty t1) <+> text ":=:" <+>
                                parens (pty t2))
    pkind k = pakind k

    paty, pbty, pty :: Ty -> Doc
    paty (Tvar n) = pname n
    paty (Tcon c) = pqname c
    paty t = parens (pty t)

    pbty (Tapp(Tapp(Tcon tc) t1) t2) | tc == tcArrow = parens(fsep [pbty t1, text "->",pty t2])
    pbty (Tapp t1 t2) = parens $ pappty t1 [t2]
    pbty t = paty t

    pty (Tapp(Tapp(Tcon tc) t1) t2) | tc == tcArrow = fsep [pbty t1, text "->",pty t2]
    pty (Tforall tb t) = text "%forall" <+> pforall [tb] t
    pty (TransCoercion t1 t2) =
      sep [text "%trans", paty t1, paty t2]
    pty (SymCoercion t) =
      sep [text "%sym", paty t]
    pty (UnsafeCoercion t1 t2) =
      sep [text "%unsafe", paty t1, paty t2]
    pty (LeftCoercion t) =
      sep [text "%left", paty t]
    pty (RightCoercion t) =
      sep [text "%right", paty t]
    pty (InstCoercion t1 t2) =
      sep [text "%inst", paty t1, paty t2]
    pty t = pbty t

    pappty :: Ty -> [Ty] -> Doc
    pappty (Tapp t1 t2) ts = pappty t1 (t2:ts)
    pappty t ts = sep (map paty (t:ts))

    pforall :: [Tbind] -> Ty -> Doc
    pforall tbs (Tforall tb t) = pforall (tbs ++ [tb]) t
    pforall tbs t = hsep (map ptbind tbs) <+> char '.' <+> pty t

    pvdefg :: Vdefg -> Doc
    pvdefg (Rec vdefs) = text "%rec" $$ braces (indent (vcat (punctuate (char ';') (map pvdef vdefs))))
    pvdefg (Nonrec vdef) = pvdef vdef

    pvdef :: Vdef -> Doc
    -- TODO: Think about whether %local annotations are actually needed.
    -- Right now, the local flag is never used, because the Core doc doesn't
    -- explain the meaning of %local.
    pvdef (_l,v,t,e) = sep [(pqname v <+> text "::" <+> pty t <+> char '='),
    		    indent (pexp e)]

    paexp, pfexp, pexp :: Exp -> Doc
    paexp (Var x) = pqname x
    paexp (Dcon x) = pqname x
    paexp (Lit l) = plit l
    paexp e = parens(pexp e)

    plamexp :: [Bind] -> Exp -> Doc
    plamexp bs (Lam b e) = plamexp (bs ++ [b]) e
    plamexp bs e = sep [sep (map pbind bs) <+> text "->",
    		    indent (pexp e)]

    pbind :: Bind -> Doc
    pbind (Tb tb) = char '@' <+> ptbind tb
    pbind (Vb vb) = pvbind vb

    pfexp (App e1 e2) = pappexp e1 [Left e2]
    pfexp (Appt e t) = pappexp e [Right t]
    pfexp e = paexp e

    pappexp :: Exp -> [Either Exp Ty] -> Doc
    pappexp (App e1 e2) as = pappexp e1 (Left e2:as)
    pappexp (Appt e t) as = pappexp e (Right t:as)
    pappexp e as = fsep (paexp e : map pa as)
               where pa (Left e) = paexp e
    		 pa (Right t) = char '@' <+> paty t

    pexp (Lam b e) = char '\\' <+> plamexp [b] e
    pexp (Let vd e) = (text "%let" <+> pvdefg vd) $$ (text "%in" <+> pexp e)
    pexp (Case e vb ty alts) = sep [text "%case" <+> paty ty <+> paexp e,
    			     text "%of" <+> pvbind vb]
    			$$ (indent (braces (vcat (punctuate (char ';') (map palt alts)))))
    pexp (Cast e co) = (text "%cast" <+> parens (pexp e)) $$ paty co
    pexp (Note s e) = (text "%note" <+> pstring s) $$ pexp e
    pexp (External n cc t) = (text "%external" <+> text cc <+> pstring n) $$ paty t
    pexp (DynExternal cc t) = (text "%dynexternal" <+> text cc) $$ paty t
    pexp (Label n) = (text "%label" <+> pstring n)
    pexp e = pfexp e

    pvbind :: Vbind -> Doc
    pvbind (x,t) = parens(pname x <> text "::" <> pty t)

    palt :: Alt -> Doc
    palt (Acon c tbs vbs e) =
    	sep [pqname c,
    	     sep (map pattbind tbs),
    	     sep (map pvbind vbs) <+> text "->"]
            $$ indent (pexp e)
    palt (Alit l e) =
    	(plit l <+>  text "->")
    	$$ indent (pexp e)
    palt (Adefault e) =
    	(text "%_ ->")
    	$$ indent (pexp e)

    plit :: Lit -> Doc
    plit (Lint i t) = parens (integer i <> text "::" <> pty t)
    -- we use (text (show (numerator r))) (and the same for denominator)
    -- because "(rational r)" was printing out things like "2.0e-2" (which
    -- isn't External Core), and (text (show r)) was printing out things
    -- like "((-1)/5)" which isn't either (it should be "(-1/5)").
    plit (Lrational r t) = parens (text (show (numerator r)) <+> char '%'
       <+> text (show (denominator r)) <>  text "::" <> pty t)
    plit (Lchar c t) = parens (text ("\'" ++ escape [c] ++ "\'") <> text "::" <> pty t)
    plit (Lstring s t) = parens (pstring s <> text "::" <> pty t)

    pstring :: String -> Doc
    pstring s = doubleQuotes(text (escape s))

    escape :: String -> String
    escape s = foldr f [] (map ord s)
        where
         f cv rest
    	| cv > 0xFF = '\\':'x':hs ++ rest
    	| (cv < 0x20 || cv > 0x7e || cv == 0x22 || cv == 0x27 || cv == 0x5c) =
    	 '\\':'x':h1:h0:rest
               where (q1,r1) = quotRem cv 16
    		 h1 = intToDigit q1
                     h0 = intToDigit r1
    		 hs = dropWhile (=='0') $ reverse $ mkHex cv
    		 mkHex 0 = ""
    		 mkHex cv = intToDigit r : mkHex q
    		    where (q,r) = quotRem cv 16
         f cv rest = (chr cv):rest

\end{code}