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