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|
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% %
% Frown --- An LALR(k) parser generator for Haskell 98 %
% Copyright (C) 2001-2005 Ralf Hinze %
% %
% This program is free software; you can redistribute it and/or modify %
% it under the terms of the GNU General Public License (version 2) as %
% published by the Free Software Foundation. %
% %
% This program 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 General Public License for more details. %
% %
% You should have received a copy of the GNU General Public License %
% along with this program; see the file COPYING. If not, write to %
% the Free Software Foundation, Inc., 59 Temple Place - Suite 330, %
% Boston, MA 02111-1307, USA. %
% %
% Contact information %
% Email: Ralf Hinze <ralf@cs.uni-bonn.de> %
% Homepage: http://www.informatik.uni-bonn.de/~ralf/ %
% Paper mail: Dr. Ralf Hinze %
% Institut für Informatik III %
% Universität Bonn %
% Römerstraße 164 %
% 53117 Bonn, Germany %
% %
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%-------------------------------= --------------------------------------------
\section{|Generate.lhs|}
%-------------------------------= --------------------------------------------
> module Stackless ( generate )
> where
> import Atom
> import Haskell
> import Grammar hiding ( prec )
> import qualified Grammar as G
> import Convert
> import LR0 hiding ( fromList )
> import Case
> import qualified OrdUniqListSet as Set
> import qualified SearchTree as ST
> import Options
> import Base
> import Generate
> import MergeSort
> import Data.Char
> import Data.Maybe
> import System.IO
> import Control.Monad
> import Prelude hiding ( lookup )
Characteristics.
%
\begin{description}
\item[required] --
\item[unsupported] |--backtrack| and |--lookahead=k|??
\end{description}
%-------------------------------= --------------------------------------------
\subsection{Helper functions}
%-------------------------------= --------------------------------------------
> safeLookup :: (Show a, Ord a) => ST.FM a v -> a -> v
> safeLookup fm a = fromMaybe (error ("not found: " ++ show a)) (ST.lookup fm a)
> data Branch' = Shift1' Symbol State
> | ReduceN' [Int]
> | ShiftReduce' Symbol State Branch'
> | ReduceReduce' [Int] -- reduce/reduce conflict
> | TokenCase' [(Symbol, Branch')] [Branch']
> deriving (Eq, Ord, Show)
> branch' :: Branch -> Branch'
> branch' (Shift1 (_s, v, s')) = Shift1' v s'
> branch' (ReduceN as) = ReduceN' (map pnumber as)
> branch' (ShiftReduce (_s, v, s') b)
> = ShiftReduce' v s' (branch' b)
> branch' (ReduceReduce as) = ReduceReduce' (map pnumber as)
> branch' (TokenCase es bs _la) = TokenCase' [ (v, branch' b) | (v, b) <- es ] [ branch' b | b <- bs ]
codeLeq (_s1, b1) (_s2, b2) = branch' b1 <= branch' b2
codeEqu (_s1, b1) (_s2, b2) = branch' b1 == branch' b2
> codeLeq (s1, _b1) (s2, _b2) = rests s1 <= rests s2
> codeEqu (s1, _b1) (s2, _b2) = rests s1 == rests s2
> rests s = mergeSort (map iinput (toList (items s)))
%-------------------------------= --------------------------------------------
\subsection{Generate Haskell code}
%-------------------------------= --------------------------------------------
> generate :: [Flag] -> Grammar -> [(Symbol, State)] -> GotoTable -> BranchTable -> IO [Decl]
> generate opts grammar entries edges table
> = do verb "* Generating Haskell code ... (--code=stackless)"
> when backtrFlag (warning "--backtrack is not supported")
> when trFlag (warning "--trace is not supported")
> verb (" identical states: " ++ show [ map (snumber . fst) g | g <- groupedTable, length g > 1 ])
> return decls
> where
> verb = verbose opts
The data type of nonterminals (this type is only required if we
generate monomorphic type signatures).
> decls = (if sigFlag then
> [ TypeDecl parser_type ([x_tcon] <->>
> result_tcon <$> [if Signature False `elem` opts then nonterminal_tcon else t_var])
> , Empty ]
> ++ (if Signature False `elem` opts then
> [ DataDecl nonterminal_tcon
> [ (unCon (ntName n), typesOf n) | (n, _) <- entries ]
> , Empty ]
> else
> [])
> else
> [])
The parsers for the start symbols.
> ++ [ funbind (globalNTName n <$> [tr_var | not lexFlag])
> (if Signature False `elem` opts then
> (next_n s [Fun (genVars n ++ [anon])
> (hsReturn <$> [ntName n <$> genVars n])]) <>>=>
> Fun [ntName n <$> genVars n]
> (hsReturn <$> [Tuple (genVars n)])
> else
> (next_n s [Fun (genVars n ++ [anon])
> (hsReturn <$> [Tuple (genVars n)])]))
> | (n, s) <- entries ]
The |state_i| functions.
> ++ concat [ Empty
>-- : AComment ["state " ++ show (snumber s) ++ reportConflicts cases ++ " "]
> : genState_n s cases
> | (s, cases) <- ST.toList table, not (isIdState s) ]
>-- | (s, cases) <- mergeSort (map head groupedTable), not (isIdState s) ]
The |reduce| functions. BUG: if a symbol is unreachable then
reductions must not be generated (cf `Dead.g')
> ++ concat [ [ Empty ]
> ++ [ AComment ["# NOINLINE " ++ string (unVar red) ++ " #"] | noinline ]
> ++ [ Sig [unVar red] (((typesOf (rlhs r) <->> parser_type)
> : concat [ typesOf v | v <- rrhs r ]) <->> parser_type)
> | sigFlag ]
> ++ [funbind (red <$> ([g_var] ++ concat [ argsOf v | v <- rrhs r ] ++ [ts_var]))
> (evaluate (argsOf (rlhs r)) (\ args -> g_var <$> (args ++ [ts_var])))]
> | r <- productions grammar
> , not (isPrimed (name (rlhs r)))
> , let red = reduce_var (rnumber r) ]
The |impossible| function (final failure).
>-- ++ [ Empty
>-- , funbind (notpossible x_var) (
>-- hsFail <$> [stringLiteral "\"The `impossible' happened.\""])]
Options and settings.
> k = lookahead opts
> trFlag = Trace `elem` opts
> lexFlag = Lexer `elem` opts
> expFlag = Expected `elem` opts
> backtrFlag = Backtrack `elem` opts
> sigFlag = Signature False `elem` opts || Signature True `elem` opts
> noinline = Noinline `elem` opts
> optimize = Optimize `elem` opts
>
> x_var = if lexFlag then t_var else ts_var
> x_tcon = if lexFlag then terminal_tcon else List [terminal_tcon]
`Identity' states.
> idStates = ST.fromList [ (s, isId cases) | (s, cases) <- ST.toList table ]
> isIdState s = optimize && safeLookup idStates s
> isId (ReduceN as) = equal (map pnumber as) && stack (head as) /= Nil
> isId _ = False
Note that only kernel items may be `Identity' states (eps productions
are predict items).
`Code-identical' states. TODO: consider also lookahead information.
TODO: order continuation arguments by `|iinput|'.
> groupedTable = groupBy codeEqu (mergeSortBy codeLeq (ST.toList table))
> codeEquState = ST.fromList [ (s, fst (head g)) | g <- groupedTable, (s, _) <- g ]
> state_n s ks
> | isIdState s = head ks
> | otherwise = state_var s <$> ks
>-- | otherwise = state_var (safeLookup codeEquState s) <$> ks
Generate code.
> genState_n s cases
> = [ Sig [unVar (state_var s)] ([ k_type i | i <- Set.toList q ] <->> parser_type)
> | sigFlag]
> ++ [ funbind (state_n s [ k_var i | i <- Set.toList q ] <$> [x_var])
> (local [ funbind (goto_var v <$> (genVars v)) --(argsOf v))
> (state_n s2 [ kernel i <$> (genVars v) | i <- itemsOf v ])
> | (s1, v, s2) <- edges, s1 == s, nonterminal v ]
> (genBody cases))]
> where
> q :\/ _q' = items s
>
> k_type i = concat [ typesOf v | v <- iinput i ] <->> parser_type
>
> genBody (ReduceN as)
> | equal (map pnumber as)
> = kernel' (head as) <$> [x_var]
> | otherwise = error ("the grammar is not LALR(" ++ show k ++ ")")
> genBody (TokenCase es bs la)
> = switch x_var ([ (genPat t, genExpr e (genVars t))
> | (t, e) <- es ]
> ++ [(anon, if null bs then
> frown la
> else
> genExpr (head bs) [])])
> genBody _ = impossible "Stackless.genBody"
>
> itemsOf v = [ item | item@(Item i n l (v' : r) a) <- LR0.toList (items s), v' == v ]
>
> kernel i
> | i `Set.elem` q = k_var i
> | otherwise = reduce_var (inumber i) <$> [goto_var (ilhs i)]
>
> kernel' a
> | stack a /= Nil = k_var' a
> | otherwise = reduce_var (pnumber a) <$> [let (_, n, _) = goto a in goto_var n]
>
> genExpr (Shift1 (_s, t, s')) vs
> | modifier t == Insert
> = state_n s' [ kernel i | i <- itemsOf t ] <$> [x_var] -- NB `|t|' must not have semantic values
> | otherwise = next_n s' [ kernel i <$> vs | i <- itemsOf t ]
> genExpr (ReduceN rs) _vs
> | equal (map pnumber rs)
> = kernel' (head rs) <$> [x_var]
> | otherwise = error ("the grammar is not LALR(" ++ show k ++ ")")
> genExpr (ShiftReduce e _b) vs
> = genExpr (Shift1 e) vs -- select shift (for the moment)
> genExpr (ReduceReduce rs) vs
> = genExpr (ReduceN [head rs]) vs
> genExpr (TokenCase [] bs la) _vs -- HACK: for empty `case' that simulates `fail'
> = if null bs then
> frown la
> else
> genExpr (head bs) []
> genExpr (TokenCase es bs la) _vs -- does not work with a monadic lexer
> = switch tr_var ([ (genPat t, genExpr e [])
> | (t, e) <- es ]
> ++ [(anon, if null bs then
> frown la
> else
> genExpr (head bs) [])])
> --impossible "Stackless.genExpr"
>
> genPat v
> | lexFlag = fresh v
> | isNewEOF (pattern v)= asPat tr_var hsNil
> | otherwise = fresh v <:> tr_var
>
> next_n s ks
> | lexFlag = hsGet <>>=> state_n s ks
> | otherwise = state_n s ks <$> [tr_var]
>
> frown la
> | expFlag = hsFrown <$> [expected la, x_var]
> | otherwise = hsFrown <$> [x_var]
Possibly generate a backtracking parser.
> {-
> FunBind lhs rhs <||> alt = FunBind lhs (rhs <|> alt)
>
> e1 <|> e2
> | backtrFlag = Infix e1 "`mplus`" e2
> | otherwise = e1
> -}
Helper functions.
Names.
>-- notpossible ts = impossible_var <$> [ts]
> state_var s = wrap_var ("state_" ++ smangle s)
> k_var i = wrap_var ("k_" ++ imangle i ++ "_" ++ show (length (list (istack i))))
> k_var' a = wrap_var ("k_" ++ show (pnumber a) ++ "_" ++ show (length (list (stack a))))
> goto_var v = wrap_var ("goto_" ++ vmangle 1 v)
> reduce_var i = wrap_var ("reduce_" ++ show i)
> ts_var = wrap_var "ts"
> tr_var = wrap_var "tr"
> t_var = wrap_var "t"
> g_var = wrap_var "g"
> nonterminal_tcon = wrap_con "Nonterminal"
>-- impossible_var = wrap_var "impossible"
> parser_tcon = wrap_con "Parser"
> parser_type
> | Signature False `elem` opts
> = parser_tcon
> | otherwise = parser_tcon <$> [t_var]
> globalNTName v = var (string (name v))
> ntName v = wrap_con (string (name v))
> wrap s = prefix opts ++ s ++ suffix opts
> wrap_var s = var (wrap s)
> wrap_con s = con (wrap s)
|
