1 files changed, 56 insertions, 0 deletions
diff --git a/src/runtime/haskell-bind/CId.hs b/src/runtime/haskell-bind/CId.hs
new file mode 100644
index 000000000..74db63c2c
--- /dev/null
+++ b/src/runtime/haskell-bind/CId.hs
@@ -0,0 +1,56 @@
+module CId (CId(..), 
+                mkCId, wildCId,
+                readCId, showCId,
+                
+                -- utils
+                pCId, pIdent, ppCId) where
+
+import Control.Monad
+import qualified Data.ByteString.Char8 as BS
+import Data.Char
+import qualified Text.ParserCombinators.ReadP as RP
+import qualified Text.PrettyPrint as PP
+
+
+
+-- | An abstract data type that represents
+-- identifiers for functions and categories in PGF.
+newtype CId = CId BS.ByteString deriving (Eq,Ord)
+
+wildCId :: CId
+wildCId = CId (BS.singleton '_')
+
+-- | Creates a new identifier from 'String'
+mkCId :: String -> CId
+mkCId s = CId (BS.pack s)
+
+-- | Reads an identifier from 'String'. The function returns 'Nothing' if the string is not valid identifier.
+readCId :: String -> Maybe CId
+readCId s = case [x | (x,cs) <- RP.readP_to_S pCId s, all isSpace cs] of
+              [x] -> Just x
+              _   -> Nothing
+
+-- | Renders the identifier as 'String'
+showCId :: CId -> String
+showCId (CId x) = BS.unpack x
+
+instance Show CId where
+    showsPrec _ = showString . showCId
+
+instance Read CId where
+    readsPrec _ = RP.readP_to_S pCId
+
+pCId :: RP.ReadP CId
+pCId = do s <- pIdent
+          if s == "_"
+            then RP.pfail
+            else return (mkCId s)
+
+pIdent :: RP.ReadP String
+pIdent = liftM2 (:) (RP.satisfy isIdentFirst) (RP.munch isIdentRest)
+  where
+    isIdentFirst c = c == '_' || isLetter c
+    isIdentRest c = c == '_' || c == '\'' || isAlphaNum c
+
+ppCId :: CId -> PP.Doc
+ppCId = PP.text . showCId