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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{|Standard.lhs|}
%-------------------------------= --------------------------------------------
> module Standard ( 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 qualified SearchTree as ST
> import Options
> import Base
> import Generate
> import Data.Char
> import System.IO
> import Data.Maybe
> import Prelude hiding ( lookup )
Characteristics.
%
\begin{description}
\item[required] --
\item[unsupported] --
\end{description}
%
Possible optimization: transitions |s_i >- t -> s_j| such that |s_i|
has only shifts and |t| has no semantic values can be omitted.
%-------------------------------= --------------------------------------------
\subsection{Helper functions}
%-------------------------------= --------------------------------------------
> {-
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))
> -}
%-------------------------------= --------------------------------------------
\subsection{Generate Haskell code}
%-------------------------------= --------------------------------------------
> generate :: [Flag] -> [(Symbol, State)] -> GotoTable -> BranchTable -> IO [Decl]
> generate opts entries edges table
> = do verb "* Generating Haskell code ... (--code=standard)"
> return decls
> where
> verb = verbose opts
The stack data type.
> decls = [ DataDecl stack_tcon (
> (unCon empty_con, [])
> : [ (unCon (con_s_s e), stack_tcon : typesOf v)
> | e@(s, v, s') <- edges ]) ]
The data type of nonterminals. This data type is required 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 ] ]
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 " ++ show (snumber s) ++ reportConflicts cases ++ " "] ]
> ++ [ Sig [unVar (parse_var s)]
> ([x_tcon, stack_tcon] <->> result_tcon <$> [nonterminal_tcon])
> | sigFlag ]
>--OLD Sig [unVar (parse_var s)] (Con "Monad" <$> [Var "m"] <=>>
>--OLD ([x_tcon, stack_tcon] <->> Var "m" <$> [nonterminal_tcon]))
Problems with supplying the type signatures: for parsers with a
monadic lexer we don't know the type (for instance, `|Lex a|' or
`|Lex m a|' which requires a constraint on `|m|').
> ++ genParse_n s cases
> | (s, cases) <- ST.toList table ]
The |impossible| function (final failure).
> ++ (if backtrFlag then
> [ Empty ]
> ++ [ Sig [unVar impossible_var]
> ([x_tcon] <->> result_tcon <$> [nonterminal_tcon])
> | sigFlag ]
> ++ [ funbind (notpossible x_var) (
> hsFail <$> [stringLiteral "\"The `impossible' happened.\""])]
> else
> [])
Options and settings.
> trFlag = Trace `elem` opts
> lexFlag = Lexer `elem` opts
> expFlag = Expected `elem` opts
> backtrFlag = Backtrack `elem` opts
> sigFlag = Signature False `elem` opts || Signature True `elem` opts
>
> x_var = if lexFlag then t_var else ts_var
> x_tcon = if lexFlag then terminal_tcon else List [terminal_tcon]
Generate code.
> genParse_n s (ReduceN as)
> = reduces as Nothing ++ [ impossibleCase s | backtrFlag ]
> genParse_n s (TokenCase es bs la)
> = concat [ topLevel s e (Just t) | (t, e) <- es ]
> ++ catchall s bs la
> genParse_n _ _ = impossible "Standard.genParse_n"
>
> topLevel _s (Shift1 e) _ = [shift e False]
> topLevel _s (ReduceN rs) t= reduces rs t
> topLevel _s (ShiftReduce e b) _
> = [shift e backtrFlag <||> caseexpr b]
> topLevel s b t = [funbind (parse_n s st_var (genAnoPat t)) (caseexpr b)]
>
> caseexpr (Shift1 e) = shiftRHS e -- this must be an error-correcting transition
> caseexpr (ReduceN rs) = switch st_var ([ (genStack (stack r), reduceRHS r) | r <- rs ]
> ++ [ (anon, notpossible x_var) | backtrFlag ])
> caseexpr (ReduceReduce rs)= foldr1 (<|>) [ switch st_var ([ (genStack (stack r), reduceRHS r)]
> ++ [(anon, frown (Set.empty))]) | r <- rs ] -- TODO: pass set of expected tokens
> caseexpr (TokenCase es bs la) -- does not work with a monadic lexer
> = switch tr_var ([ ( genNewPat x False, caseexpr t)
> | (x, t) <- es ]
> ++ [(anon, catchallRHS bs la)])
> caseexpr _ = impossible "Standard.caseexpr"
Code for shift actions. NB `|insert|' shift actions (which are akin to
epsilon transitions) must be treated specially (no input is consumed).
> shift e@(s, t, _) flag = funbind (parse_n s st_var (genNewPat t flag)) (shiftRHS e)
>
> shiftRHS e@(s, t, s') = trace
> (hsPutStrLn <$>
> [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
required 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 = [ reduce r x | r <- rs ]
>
> reduce r x = funbind (parse_n (current r) (genStack (stack r)) (genAnoPat x))
> (reduceRHS r)
>
> reduceRHS (Reduce _st e@(_s, v, s') _ _ i)
> | isStart v = trace
> (hsPutStrLn <$> [stringLiteral "\"accept\""])
> (evaluate (argsOf v) (\ args -> hsReturn <$> [ntName v <$> args]))
> | otherwise = trace traceReduce
> (evaluate (argsOf v) (\ args ->
> proceed_n s' (con_s_s e <$> (st_var : args))))
> where
> traceReduce = hsPutStrLn <$> [stringLiteral ("\"reduce by " ++ show i ++ "\"")]
>
> proceed_n s st' = parse_n s st' x_var
> reduceRHS _ = impossible "Standard.reduceRHS"
Generate input pattern for reduce action with anonymous variables (to
avoid name capture).
> genAnoPat Nothing = x_var
> genAnoPat (Just v)
> | lexFlag = asPat t_var (anonymous v)
> | isNewEOF (pattern v)= asPat ts_var (asPat tr_var hsNil)
> | otherwise = asPat ts_var (anonymous v <:> tr_var)
Generate stack pattern for reduce action.
> genStack Nil = st_var
> genStack (st :> e@(_, v, _))
> = con_s_s e <$> (genStack st : argsOf v)
Tracing.
> trace tr e
> | trFlag = tr <>>> e
> | otherwise = e
The catchall 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)
>
> impossibleCase s = funbind (parse_n s st_var x_var) (notpossible x_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)
> _ <||> _ = impossible "Standard.<||>"
> e1 <|> e2
> | backtrFlag = Infix e1 (ident "`mplus`") e2
> | otherwise = e1
Names.
> parse_n i st ts = parse_var i <$> [ts, st]
> notpossible ts = impossible_var <$> [ts]
> parse_var i = wrap_var ("parse_" ++ smangle 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'"
> con_s_s (s, _v, s') = wrap_con ("T_" ++ smangle s ++ "_" ++ smangle 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)
|
