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module PennFormat(parseTreebank, showTree) where
import Text.PrettyPrint
import Data.Tree
import Data.Char
parseTreebank :: String -> [Tree String]
parseTreebank [] = []
parseTreebank (c:cs)
| isSpace c = parseTreebank cs
| c == '(' = let (ts,cs1) = parseTrees cs
in ts ++ parseTreebank cs1
parseTrees [] = ([],[])
parseTrees (c:cs)
| isSpace c = parseTrees cs
| c == ')' = ([],cs)
| c == '(' = let (w, cs1) = parseWord cs
(children,cs2) = parseTrees cs1
(rest, cs3) = parseTrees cs2
in (Node (normalize w) children : rest,cs3)
| otherwise = let (w, cs1) = parseWord (c:cs)
(rest, cs2) = parseTrees cs1
in (Node w [] : rest,cs2)
normalize tag =
let (tag0,mod) = break (=='-') tag
in if null tag0
then tag
else tag0
parseWord = break (\c -> isSpace c || c == '(' || c == ')')
printTree (Node w []) = text w
printTree (Node l children) = parens (text l <+> hsep (map printTree children))
showTree :: Tree String -> String
showTree = render . printTree
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