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158 lines
4.5 KiB
Haskell
158 lines
4.5 KiB
Haskell
module GF.CFGM.PrintCFG where
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-- pretty-printer generated by the BNF converter
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import GF.CFGM.AbsCFG
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import Char
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-- the top-level printing method
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printTree :: Print a => a -> String
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printTree = render . prt 0
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type Doc = [ShowS] -> [ShowS]
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doc :: ShowS -> Doc
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doc = (:)
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render :: Doc -> String
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render d = rend 0 (map ($ "") $ d []) "" where
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rend i ss = case ss of
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"[" :ts -> showChar '[' . rend i ts
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"(" :ts -> showChar '(' . rend i ts
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"{" :ts -> showChar '{' . new (i+1) . rend (i+1) ts
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"}" : ";":ts -> new (i-1) . space "}" . showChar ';' . new (i-1) . rend (i-1) ts
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"}" :ts -> new (i-1) . showChar '}' . new (i-1) . rend (i-1) ts
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";" :ts -> showChar ';' . new i . rend i ts
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t : "," :ts -> showString t . space "," . rend i ts
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t : ")" :ts -> showString t . showChar ')' . rend i ts
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t : "]" :ts -> showString t . showChar ']' . rend i ts
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t :ts -> space t . rend i ts
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_ -> id
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new i = showChar '\n' . replicateS (2*i) (showChar ' ') . dropWhile isSpace
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space t = showString t . (\s -> if null s then "" else (' ':s))
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parenth :: Doc -> Doc
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parenth ss = doc (showChar '(') . ss . doc (showChar ')')
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concatS :: [ShowS] -> ShowS
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concatS = foldr (.) id
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concatD :: [Doc] -> Doc
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concatD = foldr (.) id
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replicateS :: Int -> ShowS -> ShowS
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replicateS n f = concatS (replicate n f)
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-- the printer class does the job
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class Print a where
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prt :: Int -> a -> Doc
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prtList :: [a] -> Doc
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prtList = concatD . map (prt 0)
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instance Print a => Print [a] where
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prt _ = prtList
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instance Print Char where
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prt _ s = doc (showChar '\'' . mkEsc '\'' s . showChar '\'')
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prtList s = doc (showChar '"' . concatS (map (mkEsc '"') s) . showChar '"')
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mkEsc :: Char -> Char -> ShowS
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mkEsc q s = case s of
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_ | s == q -> showChar '\\' . showChar s
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'\\'-> showString "\\\\"
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'\n' -> showString "\\n"
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'\t' -> showString "\\t"
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_ -> showChar s
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prPrec :: Int -> Int -> Doc -> Doc
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prPrec i j = if j<i then parenth else id
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instance Print Integer where
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prt _ x = doc (shows x)
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prtList es = case es of
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[] -> (concatD [])
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[x] -> (concatD [prt 0 x])
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x:xs -> (concatD [prt 0 x , doc (showString ",") , prt 0 xs])
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instance Print Double where
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prt _ x = doc (shows x)
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instance Print Ident where
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prt _ (Ident i) = doc (showString i)
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instance Print SingleQuoteString where
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prt _ (SingleQuoteString i) = doc (showString i)
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instance Print Grammars where
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prt i e = case e of
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Grammars grammars -> prPrec i 0 (concatD [prt 0 grammars])
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instance Print Grammar where
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prt i e = case e of
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Grammar id flags rules -> prPrec i 0 (concatD [doc (showString "grammar") , prt 0 id , prt 0 flags , prt 0 rules , doc (showString "end") , doc (showString "grammar")])
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prtList es = case es of
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[] -> (concatD [])
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x:xs -> (concatD [prt 0 x , prt 0 xs])
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instance Print Flag where
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prt i e = case e of
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StartCat category -> prPrec i 0 (concatD [doc (showString "startcat") , prt 0 category])
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prtList es = case es of
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[] -> (concatD [])
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x:xs -> (concatD [prt 0 x , doc (showString ";") , prt 0 xs])
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instance Print Rule where
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prt i e = case e of
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Rule fun profiles category symbols -> prPrec i 0 (concatD [prt 0 fun , doc (showString ":") , prt 0 profiles , doc (showString ".") , prt 0 category , doc (showString "->") , prt 0 symbols])
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prtList es = case es of
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[] -> (concatD [])
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x:xs -> (concatD [prt 0 x , doc (showString ";") , prt 0 xs])
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instance Print Fun where
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prt i e = case e of
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Cons id -> prPrec i 0 (concatD [prt 0 id])
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Coerce -> prPrec i 0 (concatD [doc (showString "_")])
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instance Print Profiles where
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prt i e = case e of
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Profiles profiles -> prPrec i 0 (concatD [doc (showString "[") , prt 0 profiles , doc (showString "]")])
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instance Print Profile where
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prt i e = case e of
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UnifyProfile ns -> prPrec i 0 (concatD [doc (showString "[") , prt 0 ns , doc (showString "]")])
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ConstProfile id -> prPrec i 0 (concatD [prt 0 id])
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prtList es = case es of
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[] -> (concatD [])
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[x] -> (concatD [prt 0 x])
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x:xs -> (concatD [prt 0 x , doc (showString ",") , prt 0 xs])
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instance Print Symbol where
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prt i e = case e of
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CatS category -> prPrec i 0 (concatD [prt 0 category])
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TermS str -> prPrec i 0 (concatD [prt 0 str])
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prtList es = case es of
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[] -> (concatD [doc (showString ".")])
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[x] -> (concatD [prt 0 x])
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x:xs -> (concatD [prt 0 x , prt 0 xs])
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instance Print Category where
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prt i e = case e of
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Category singlequotestring -> prPrec i 0 (concatD [prt 0 singlequotestring])
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