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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 Compact ( generate )
> where
> import Atom
> import Haskell
> import Grammar hiding ( prec )
> import qualified Grammar as G
> import Convert
> import LR0 hiding ( fromList )
> import Lookahead
> import Case
> import qualified OrdUniqListSet as Set
> import OrdUniqListSet ( Set )
> import qualified SearchTree as ST
> import Options
> import Base
> import Generate
> import MergeSort
> import Data.Char
> import System.IO
> import Data.Maybe
> import Prelude hiding ( lookup )
%-------------------------------= --------------------------------------------
\subsection{Helper functions}
%-------------------------------= --------------------------------------------
> back :: RevList Edge -> State
> back Nil = impossible "Compact.back"
> back (Nil :> (s, _ ,_)) = s
> back (st :> _) = back st
> {-
NEU: für die optimierten Reduktionen.
> ntArgsOf v ctx = args (pattern v)
> where
> args (Case e [(p, e')]) = Case e [(p, args e')]
> args e = ctx (map fst (quotesOf e))
> -}
Extract reductions.
> extract :: Branch -> [Action]
> extract (Shift1 _e) = []
> extract (ReduceN rs) = rs
> extract (ShiftReduce _e b) = extract b
> extract (ReduceReduce rs) = rs
> extract (TokenCase es bs _la) = concat [ extract b | b <- map snd es ++ bs ]
> reductions :: [Branch] -> [[(Int, Action)]]
> reductions bs = groupBy equ1 (mergeSortBy leq1 rs)
> where rs = [ (pnumber r, r) | b <- bs, r <- extract b ]
> safeLookup :: (Show a, Ord a) => ST.FM a v -> a -> v
> safeLookup fm a = fromMaybe (error ("not found: " ++ show a)) (ST.lookup fm a)
Key of a symbol (we cannot use equality below, because terminals with
different modifiers are distinguished).
> data Tree a = Node a [Tree a]
> deriving (Eq, Ord, Show)
> key :: Symbol -> Tree Int
> key (Terminal { number = n}) = Node n []
> key (Nonterminal { number = n, arguments = vs})
> = Node n (map key vs)
%-------------------------------= --------------------------------------------
\subsection{Generate Haskell code}
%-------------------------------= --------------------------------------------
> generate :: [Flag] -> Grammar -> [(Symbol, State)]
> -> Set Symbol -> GotoTable -> BranchTable -> IO [Decl]
> generate opts grammar entries reachable edges table
> = do verb "* Generating Haskell code ... (--code=compact)"
> -- print (symbols grammar)
>-- print reachable
> let sgs = length [ n | (n, b) <- ST.toList singleGotoFM, b ]
> verb (" " ++ show sgs ++ " singleton gotos (of "
> ++ show (ST.length singleGotoFM) ++ ")")
> let sss = length [ s | (s, b) <- ST.toList shiftOnlyFM, b ]
> verb (" " ++ show sss ++ " `stateless' states (of "
> ++ show (ST.length shiftOnlyFM) ++ ")")
> return decls
> where
> verb = verbose opts
The stack data type. The generation of the stack data type relies on
the fact that terminals and nonterminals are numbered consecutively.
> decls = [ DataDecl stack_tcon (
> (unCon empty_con, [])
> : [ (unCon (wrap_con ("T_" ++ s)), state_tcon : stack_tcon : ts)
> | (ts, s) <- stTypes ]
> ++ if optimize then
> [ (unCon (wrap_con ("T'_" ++ s)), stack_tcon : ts)
> | (ts, s) <- stTypes ]
> else
> []) ]
> ++ (if ghcFlag then
> []
> else
> let constrs = [ (unCon (s_con s), [])
> | (s, _) <- ST.toList table
> , not (stateless s) ]
> in [ Empty
> , DataDecl state_tcon (if null constrs then
> [(unCon (wrap_con "Void"), [])]
> else constrs) ])
The data type of nonterminals. This is needed if there are multiple
entry points into the parser (that is, multiple start symbols).
> ++ [ Empty
> , DataDecl nonterminal_tcon
> [ (unCon (ntName n), typesOf n) | (n, _) <- entries ] ]
> ++ [ Empty ]
The parsers for the start symbols.
> ++ concat [ Empty
> : [ Sig [unVar (globalNTName n)]
> ([ x_tcon | not lexFlag ] <->> result_tcon <$> [Tuple (typesOf n)])
> | sigFlag ]
> ++ [funbind (globalNTName n <$> [tr_var | not lexFlag])
> (next_n s (empty_con) False <>>=>
> Fun [ntName n <$> genVars n]
> (hsReturn <$> [Tuple (genVars n)]))]
> | (n, s) <- entries ]
The |parse_i| functions.
> ++ concat [ Empty
>-- : AComment [" state" ++ (if stateless s then "*" else "") ++ " " ++ show (snumber s) ++ reportConflicts cases ++ " "]
Problems with supplying the type signatures: for parsers with a
monadic lexer we don't know the type (for instance, `|Lex a|' or
`|Lex m a|' which requires a constraint on `|m|').
> : genParse_n s cases
> | (s, cases) <- ST.toList table ]
The |reduce| functions.
> ++ concat [ Empty
> : [ funbind (reduce_var p <$>
> ([x_var] ++ [ s_var | epsilon && not (stateless (let (s, _, _) = goto r' in s)) ] ++ [genStack2 (stack r')]))
> (reduceRHS' r')
> | r' <- collapse (map snd prs) ]
> ++ if epsilon || not backtrFlag then
> []
> else
> funbind (reduce_var p <$>
> ([x_var, st_var]))
> (notpossible st_var x_var) : []
> | prs <- reductions (map snd (ST.toList table))
> , let (p, r) = head prs, let epsilon = stack r == Nil ]
The |goto| functions.
> ++ concat [ Empty
> : [ funbind (goto_var v <$> [s_con s])
> (parse_var s')
> | e@(s, v', s') <- edges, v' == v ]
> | v <- Set.toList reachable, not (singleGoto v) ]
The |impossible| function (final failure).
> ++ [ Empty
> , funbind (notpossible st_var x_var) (
> hsFail <$> [stringLiteral "\"The `impossible' happened.\""])]
Options and settings.
> 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
> optimize = Optimize `elem` opts
Group the symbols by type.
> symbolsByType = groupBy equ2 (mergeSortBy leq2 [ (v, typesOf v) | v <- symbols grammar ])
> stTypes = zip (map (snd . head) symbolsByType) (map show [(1 :: Int) ..])
> stFM = ST.fromList [ (key v, show i)
> | (i, sx) <- zip [(1 :: Int) ..] symbolsByType, (v, _) <- sx ]
> lookupStFM v = safeLookup stFM (key v)
Determine states with no nonterminal transition.
> shiftOnlyFM = ST.fromList [ (snumber s, and [ singleGoto v
> | (s1, v, s2) <- edges
> , s1 == s, nonterminal v ])
> | (s, _) <- ST.toList table ]
> stateless s = optimize && safeLookup shiftOnlyFM (snumber s)
Determine singleton gotos.
> singleGotoFM = ST.fromList [ (n, length [ e | e@(s, v, s') <- edges, v == n ] <= 1)
> | n <- Set.toList reachable ]
> singleGoto v = optimize && safeLookup singleGotoFM v
Generate parser.
> genParse_n _s (ReduceN as)
> = reduces as Nothing
> genParse_n s (TokenCase es bs la)
> = concat [ topLevel s e (Just t) | (t, e) <- es ]
> ++ catchall s bs la
> genParse_n _ _ = impossible "Compact.genParse_n"
>
> topLevel _s (Shift1 e) _ = [shift e False]
> topLevel _s (ReduceN rs) t= reduces rs t
> topLevel _s (ShiftReduce e b) _
> = [shift e backtrFlag <||> caseexpr b]
> topLevel s b t = [funbind (parse_n s st_var (genAnoPat t)) (caseexpr b)]
>
> caseexpr (Shift1 e) = shiftRHS e -- this must be an error-correcting transition
> caseexpr (ReduceN rs)
> | equal (map pnumber rs)= reduceRHS (head rs) True
> | otherwise = switch st_var ([ (genStack1 (stack r), reduceRHS r False) | r <- rs ]
> ++ [ (anon, notpossible st_var x_var) | backtrFlag ])
> caseexpr (ReduceReduce rs)= foldr1 (<|>) [ switch st_var ([ (genStack1 (stack r), reduceRHS r False)]
> ++ [(anon, frown (Set.empty))]) | r <- rs ] -- TODO: pass set of expected tokens
> caseexpr (TokenCase es bs la)
> = switch tr_var ([ ( genNewPat x False, caseexpr t)
> | (x, t) <- es ]
> ++ [(anon, catchallRHS bs la)])
> caseexpr _ = impossible "Compact.caseexpr"
Code for shift actions. NB `|insert|' shift actions (which are akin to
epsilon transitions) must be treated specially (no input is consumed).
> shift e@(s, t, _) flag = funbind (parse_n s st_var (genNewPat t flag)) (shiftRHS e)
>
> shiftRHS e@(s, t, s') = trace
> (hsPutStrLn <$>
> [stringLiteral ("\"shift " ++ smangle s ++ " (\"")
> <++> hsShow <$> [fresh t]
> <++> stringLiteral ("\") " ++ smangle s' ++ "\"")])
> (next_n s' (con_s_s e st_var (genVars t)) (modifier t == Insert))
>
> next_n s st errCorr
> | errCorr = parse_n s st x_var
> | lexFlag = hsGet <>>=> Fun [t'_var] (parse_n s st t'_var)
> | otherwise = parse_n s st tr_var
Generate input pattern for shift action (the as patterns are only
needed if the rhs includes reductions).
> genNewPat v flag
> | lexFlag = asPat' t_var (fresh v)
> | isNewEOF (pattern v)= asPat' ts_var (asPat tr_var hsNil)
> | otherwise = asPat' ts_var (fresh v <:> tr_var)
> where asPat' x p
> | flag = asPat x p
> | otherwise = p
Code for reduce actions.
> reduces rs x
> | equal (map pnumber rs)= [ reduce (head rs) x True ]
> | otherwise = [ reduce r x False | r <- rs ]
>
> reduce r x True = funbind (parse_n (current r) st_var (genAnoPat x))
> (reduceRHS r True)
> reduce r x False = funbind (parse_n (current r) (genStack1 (stack r)) (genAnoPat x))
> (reduceRHS r False)
>
> reduceRHS (Reduce st (s, _, _) _ _ i) True
> = reduce_var i <$>
> ([x_var] ++ [ s_con s | st == Nil && not (stateless s) ] ++ [st_var])
> reduceRHS (Reduce _ e@(_, v, s') _ _ i) False
> | isStart v = trace
> (hsPutStrLn <$> [stringLiteral "\"accept\""])
> (evaluate (argsOf v) (\ args -> hsReturn <$> [ntName v <$> args]))
> | otherwise = trace traceReduce
> (evaluate (argsOf v) (\args ->
> proceed_n s' (con_s_s e st_var args)))
> where
> traceReduce = hsPutStrLn <$> [stringLiteral ("\"reduce by " ++ show i ++ "\"")]
>
> proceed_n s st' = parse_n s st' x_var
>
> reduceRHS _ _ = impossible "Compact.reduceRHS"
Separate reduce action.
> reduceRHS' (Reduce _ (s, v, s') _ _ i)
> | isStart v = trace
> (hsPutStrLn <$> [stringLiteral "\"accept\""])
> (evaluate (argsOf v) (\ args -> hsReturn <$> [ntName v <$> args]))
> | otherwise = trace traceReduce
> (evaluate (argsOf v) (\ args ->
> proceed_n (x st_var args)))
> where
> traceReduce = hsPutStrLn <$> [stringLiteral ("\"reduce by " ++ show i ++ "\"")]
>
> x st vs
> | stateless s = if null vs then st else st_con v <$> (st : vs)
> | otherwise = sts_con v <$> (s_var : st : vs)
>
> proceed_n st'
> | singleGoto v = parse_n s' st' x_var
> | otherwise = goto_var v <$> [s_var, x_var, st']
>
> reduceRHS' _ = impossible "Compact.reduceRHS"
Generate input pattern for reduce action with anonymous variables (to
avoid name capture).
> genAnoPat Nothing = x_var
> genAnoPat (Just v)
> | lexFlag = asPat t_var (anonymous v)
> | isNewEOF (pattern v)= asPat ts_var (asPat tr_var hsNil)
> | otherwise = asPat ts_var (anonymous v <:> tr_var)
Tracing.
> trace tr e
> | trFlag = tr <>>> e
> | otherwise = e
The error case; if we have any |Insert| transitions we use these.
> catchall s bs la = [ funbind (parse_n s st_var x_var) (catchallRHS bs la) ]
>
> catchallRHS bs la = if null bs then frown la else foldr1 (<|>) (map caseexpr bs)
>
> frown la
> | expFlag = hsFrown <$> [expected la, x_var]
> | otherwise = hsFrown <$> [x_var]
>
> x_var = if lexFlag then t_var else ts_var
>
> x_tcon = if lexFlag then terminal_tcon else List [terminal_tcon]
Generate stack pattern for reduce action, if flag is |True| then
ignore intermediate states (for shift-only states we use the |St_|
constructors rather than the |StS_| constructors).
> genStack1 Nil = st_var
> genStack1 (st :> e@(_, v, _))
> = con_s_s e (genStack1 st) (argsOf v)
>
> genStack2 Nil = st_var
> genStack2 (st :> e@(s, v, _))
> | stateless s = con_s_s e (genStack2 st) (argsOf v)
> | otherwise = sts_con v <$> ((if st == Nil then s_var else anon): genStack2 st : argsOf v)
Stack constructors.
> con_s_s (s, v, _s') st vs
> | stateless s = if null vs then st else st_con v <$> (st : vs)
> | otherwise = sts_con v <$> (s_con s : st : vs)
Collapse reductions.
> collapse rs = map (fst . head) gs
> where char r = (r, [ stateless s | (s, _, _) <- list (stack r) ])
> gs = groupBy equ2 (mergeSortBy leq2 (map char rs))
Possibly use GHC extensions, that is, unboxed types.
> ghcFlag = GHC `elem` opts
>
> state_tcon | ghcFlag = con "Int#"
> | otherwise = wrap_con "State"
>
> s_con s | ghcFlag = stringLiteral (smangle s ++ "#")
> | otherwise = wrap_con ("S_" ++ smangle s)
Possibly generate a backtracking parser.
> FunBind lhs rhs <||> alt = FunBind lhs (rhs <|> alt)
> _ <||> _ = impossible "Compact.<||>"
>
> e1 <|> e2
> | backtrFlag = Infix e1 (ident "`mplus`") e2
> | otherwise = e1
Names.
>
> sts_con v = wrap_con ("T_" ++ lookupStFM v)
> st_con v = wrap_con ("T'_" ++ lookupStFM v)
>
> parse_n i st ts = parse_var i <$> [ts, st]
> notpossible st ts = impossible_var <$> [ts, st]
> parse_var i = wrap_var ("parse_" ++ smangle i)
> goto_var v = wrap_var ("goto_" ++ vmangle 1 v)
> reduce_var i = wrap_var ("reduce_" ++ show i)
> impossible_var = wrap_var "impossible"
> stack_tcon = wrap_con "Stack"
> empty_con = wrap_con "Empty"
> nonterminal_tcon = wrap_con "Nonterminal"
> st_var = wrap_var "st"
> ts_var = wrap_var "ts"
> tr_var = wrap_var "tr"
> t_var = wrap_var "t"
> t'_var = wrap_var "t'"
> s_var = wrap_var "s"
> 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)
|
