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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 GVStack ( generate )
> where
> import Atom
> import Haskell
> import Grammar hiding ( prec )
> import qualified Grammar as G
> import LR0 hiding ( fromList )
> import Case
> import qualified OrdUniqListSet as Set
> import qualified SearchTree as ST
> import Options
> import Base
> import Generate
> import System.IO
> import Control.Monad
> import Data.Char
> import Data.List ( maximumBy )
> import Prelude hiding ( lookup )
%-------------------------------= --------------------------------------------
\subsection{Helper functions}
%-------------------------------= --------------------------------------------
> cmpLength :: RevList a -> RevList a -> Ordering
> cmpLength x y = compare (revLength x) (revLength y)
%-------------------------------= --------------------------------------------
\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=gvstack)"
> when backtrFlag (warning "--backtrack is not supported")
> when (k > 1) (warning "--lookahead=k with k > 1 is not supported")
> when trFlag (warning "--trace is not supported")
> return decls
> where
> verb = verbose opts
The data type of nonterminals.
> decls = [ Empty
> , DataDecl nonterminal_tcon
> [ (unCon (ntName n), typesOf n) | n <- nonterminals grammar ]
> , Empty
> , TypeDecl parser_tcon ([if lexFlag then terminal_tcon else List [terminal_tcon]]
> <->> (result_tcon <$> [nonterminal_tcon]))
> , Empty
> , TypeDecl (vstack_tcon <$> [vs_var, v_var])
> (Tuple [Tuple [vs_var, [nonterminal_tcon] <->> parser_tcon], v_var])
> , Empty ]
The parsers for the start symbols.
> ++ [ funbind (globalNTName n <$> [tr_var | not lexFlag])
> (next_n s [Tuple []] <>>=>
> Fun [ntName n <$> (genVars n)]
> (hsReturn <$> [Tuple (genVars n)]))
> | (n, s) <- entries ]
The |state_i| functions.
> ++ concat [ Empty
>-- : AComment [" state " ++ show (snumber s) ++ reportConflicts cases ++ " "]
> : genState_n s cases
> | (s, cases) <- ST.toList table ]
The |reduce| functions. BUG: if a symbol is unreachable then
reductions must not be generated (cf `Dead.g')
> ++ concat [ [ Empty ]
> ++ [ AComment ["# NOINLINE " ++ string (unVar red) ++ " #"] | noinline ]
> ++ [ let cont = if isStart (rlhs r) then accept_var else g_var in
> funbind (red <$> [genStack (revList (rrhs r)), x_var])
> (evaluate (argsOf (rlhs r))
> (\ args -> cont <$> [ntName (rlhs r) <$> args, x_var])) ]
> | r <- productions grammar, let red = reduce_var (rnumber r) ]
The |impossible| function (final failure).
> ++ [ Empty
> , funbind (state_var <$> [action_var, goto_var, vs_var, x_var])
> (local [ funbind gs_var (Tuple [vs_var, g_var])
> , funbind (g_var <$> [v_var]) (goto_var <$> [v_var, gs_var])]
> (action_var <$> [if lexFlag then t_var
> else hsHead <$> [ts_var], gs_var, x_var]))
> , Empty
> , funbind (shift_var <$> [state_var, v_var, vs_var, x_var])
> (if lexFlag then
> hsGet <>>=> (state_var <$> [Tuple [vs_var, v_var]])
> else
> state_var <$> [Tuple [vs_var, v_var], hsTail <$> [ts_var]])
> , Empty
> , funbind (shift'_var <$> [state_var, v_var, vs_var, x_var])
> (if lexFlag then
> state_var <$> [Tuple [vs_var, v_var], t_var]
> else
> state_var <$> [Tuple [vs_var, v_var], ts_var])
> , Empty
> , funbind (accept_var <$> [v_var, anon]) (hsReturn <$> [v_var])
> , Empty
> , funbind (goto_var <$> [state_var, v_var, vs_var])
> (state_var <$> [Tuple [vs_var, v_var]])
> , Empty
> , funbind (error_var <$> ([ la_var | expFlag ] ++ [gs_var, x_var]))
> (hsFrown <$> ([ la_var | expFlag ] ++ [x_var]))
> , Empty
> , funbind (notpossible x_var) (
> hsFail <$> [stringLiteral "\"The `impossible' happened.\""])]
Options and settings.
> k = lookahead opts
> trFlag = Trace `elem` opts
> lexFlag = Lexer `elem` opts
> expFlag = Expected `elem` opts
> backtrFlag = Backtrack `elem` opts
> noinline = Noinline `elem` opts
>
> genState_n s cases
> = [ Sig [unVar (state_n s)]
> ([stack_type (maximumBy cmpLength [ istack i | i <- Set.toList q ])] <->> parser_tcon)
> , funbind (state_n s)
> (state_var <$> [action_n s, if null gotos then hsUndefined else goto_n s])
> , Empty
> , funbind (action_n s <$> [t_var]) (genBody cases) ]
> ++ [ Empty | not (null gotos)]
> ++ gotos
> ++ [Empty]
> where
> q :\/ _q' = items s
>
> gotos = [ funbind (goto_n s <$> [ntName v <$> genVars v])
> (goto_var <$> [state_n s2, Tuple (genVars v)])
> | (s1, v, s2) <- edges, s1 == s, nonterminal v ]
> genBody (ReduceN rs)
> | equal (map pnumber rs)
> = reduce_n (head rs)
> | otherwise = error "not LALR" -- TODO: Is this correct? One could use additional lookahead.
> genBody (TokenCase es bs la)
> = switch t_var ([ (fresh t, genExpr e (genVars t))
> | (t, e) <- es ]
> ++ [(anon, if null bs then
> frown la
> else
> genExpr (head bs) [])])
> genBody _ = impossible "GVStack.genBody"
>
> genExpr (Shift1 (_, t, s')) vs
> = shift <$> [state_n s', Tuple vs]
> where shift = if modifier t == Insert then shift'_var else shift_var
> genExpr (ReduceN rs) _vs
> | equal (map pnumber rs)
> = reduce_n (head rs)
> | otherwise = error "not LALR"
> genExpr (ShiftReduce e _b) vs
> = genExpr (Shift1 e) vs -- select shift (for the moment)
> genExpr (ReduceReduce rs) vs
> = genExpr (ReduceN [head rs]) vs
> genExpr _ _ = impossible "GVStack.genExpr"
>
> genStack Nil = Tuple [anon, g_var]
> genStack (st :> v) = Tuple [Tuple [genStack st, Tuple (argsOf v)], anon]
>
> stack_type Nil = vs_var
> stack_type (st :> v) = vstack_tcon <$> [stack_type st, Tuple (typesOf v)]
>
> next_n s ks
> | lexFlag = hsGet <>>=> state_n' s ks
> | otherwise = state_n' s ks <$> [tr_var]
> where state_n' i ks' = state_n i <$> ks' -- HACK to fit the type
>
>-- catchall' la rhss = if null rhss then frown la else foldr1 (<|>) rhss
>
> frown la
> | expFlag = error_var <$> [expected la]
> | otherwise = error_var
>
> x_var = if lexFlag then t_var else ts_var
Possibly generate a backtracking parser.
> {-
> FunBind lhs rhs <||> alt = FunBind lhs (rhs <|> alt)
>
> e1 <|> e2
> | backtrFlag = Infix e1 "`mplus`" e2
> | otherwise = e1
> -}
Helper functions.
Names.
> state_n i = wrap_var ("state_" ++ smangle i)
> action_n i = wrap_var ("action_" ++ smangle i)
> goto_n i = wrap_var ("goto_" ++ smangle i)
> reduce_n a = wrap_var ("reduce_" ++ pmangle a)
> notpossible ts = impossible_var <$> [ts]
> state_var = wrap_var "state"
> shift_var = wrap_var "shift"
> shift'_var = wrap_var "shift'"
> action_var = wrap_var "action"
> goto_var = wrap_var "goto"
> accept_var = wrap_var "accept"
> error_var = wrap_var "error"
> reduce_var i = wrap_var ("reduce_" ++ show i)
> impossible_var = wrap_var "impossible"
> ts_var = wrap_var "ts"
> tr_var = wrap_var "tr"
> t_var = wrap_var "t"
> g_var = wrap_var "g"
> gs_var = wrap_var "gs"
> v_var = wrap_var "v"
> vs_var = wrap_var "vs"
> la_var = wrap_var "la"
> parser_tcon = wrap_con "Parser"
> vstack_tcon = wrap_con "VStack"
> nonterminal_tcon = wrap_con "Nonterminal"
> globalNTName v = var (string (name v))
> ntName v = wrap_con (rename (name v))
> rename i
> | isPrimed i = string i ++ "'" -- NB. A prime for the new start symbols.
> | otherwise = string i
> wrap s = prefix opts ++ s ++ suffix opts
> wrap_var s = var (wrap s)
> wrap_con s = con (wrap s)
|
