Make Meta a simple structure

fco2/Errors.hs

@@ -1,32 +1,15 @@
 -- | Error handling and reporting.
 module Errors where
 
-import Data.Generics
-import Control.Monad.Error
-
 import qualified AST as A
 import Metadata
 
-data OccError = OccError {
-    errorText :: String,
-    errorPos :: Maybe OccSourcePos
-  }
-  deriving (Show, Eq, Typeable, Data)
-
-type OccErrorT m a = ErrorT OccError m a
-
 die :: String -> a
 die s = error $ "\n\nError:\n" ++ s
 
 dieInternal :: Monad m => String -> m a
 dieInternal s = die $ "Internal error: " ++ s
 
-formatPos :: Meta -> String
-formatPos m
-    = case findSourcePos m of
-        Just o -> show o
-        Nothing -> "?"
-
 dieP :: Monad m => Meta -> String -> m a
-dieP m s = die $ formatPos m ++ ": " ++ s
+dieP m s = die $ show m ++ ": " ++ s
 

fco2/GenerateC.hs

@@ -62,7 +62,7 @@ overArray :: A.Variable -> (SubscripterFunction -> Maybe (CGen ())) -> CGen ()
 overArray var func
     =  do ps <- get
           let A.Array ds _ = fromJust $ typeOfVariable ps var
-          let m = []
+          let m = emptyMeta
           specs <- sequence [makeNonceVariable "i" m A.Int A.VariableName A.Original | _ <- ds]
           let indices = [A.Variable m n | A.Specification _ n _ <- specs]
 
@@ -668,7 +668,7 @@ declareInit (A.Chan _) var
 declareInit t@(A.Array ds t') var
     = Just $ do init <- case t' of
                           A.Chan _ ->
-                            do let m = []
+                            do let m = emptyMeta
                                A.Specification _ store _ <- makeNonceVariable "storage" m (A.Array ds A.Int) A.VariableName A.Original
                                let storeV = A.Variable m store
                                tell ["Channel "]

fco2/Metadata.hs

@@ -1,29 +1,24 @@
--- | Metadata.
+-- | Metadata -- i.e. source position.
 module Metadata where
 
 import Data.Generics
-import Data.List
 
-type Meta = [Metadatum]
-
-data OccSourcePos = OccSourcePos String Int Int
+data Meta = Meta {
+    metaFile :: Maybe String,
+    metaLine :: Int,
+    metaColumn :: Int
+  }
   deriving (Eq, Typeable, Data)
 
-instance Show OccSourcePos where
-  show (OccSourcePos file line col) = file ++ ":" ++ show line ++ ":" ++ show col
-
-data Metadatum =
-  MdSourcePos OccSourcePos
-  deriving (Show, Eq, Typeable, Data)
-
-findSourcePos :: Meta -> Maybe OccSourcePos
-findSourcePos ms
-    =  do sps <- find (\x -> case x of MdSourcePos _ -> True
-                                       otherwise -> False) ms
-          return $ case sps of MdSourcePos sp -> sp
-
-formatSourcePos :: Meta -> String
-formatSourcePos m = case findSourcePos m of
-                      Just (OccSourcePos f l c) -> "<@" ++ show l ++ ":" ++ show c ++ ">"
-                      Nothing -> "<?>"
+emptyMeta :: Meta
+emptyMeta = Meta {
+              metaFile = Nothing,
+              metaLine = 0,
+              metaColumn = 0
+            }
 
+instance Show Meta where
+  show m =
+      case metaFile m of
+        Just s -> s ++ ":" ++ show (metaLine m) ++ ":" ++ show (metaColumn m)
+        Nothing -> "no source position"

fco2/Parse.hs

@@ -234,15 +234,14 @@ eol = do { whiteSpace; reserved eolMarker } <?> "end of line"
 --}}}
 
 --{{{ helper functions
-getSourcePos :: OccParser OccSourcePos
-getSourcePos
-  =  do pos <- getPosition
-        return $ OccSourcePos (sourceName pos) (sourceLine pos) (sourceColumn pos)
-
 md :: OccParser Meta
 md
-  =  do pos <- getSourcePos
-        return [MdSourcePos pos]
+  =  do pos <- getPosition
+        return Meta {
+                 metaFile = Just $ sourceName pos,
+                 metaLine = sourceLine pos,
+                 metaColumn = sourceColumn pos
+               }
 
 tryVX :: OccParser a -> OccParser b -> OccParser a
 tryVX p q = try (do { v <- p; q; return v })
@@ -1474,6 +1473,6 @@ parseFile file ps
 parseProgram :: Monad m => String -> ParseState -> m (A.Process, ParseState)
 parseProgram file ps
     =  do (f, ps') <- parseFile file ps
-          return (f $ A.Main [], ps')
+          return (f $ A.Main emptyMeta, ps')
 --}}}
 

fco2/PrettyShow.hs

@@ -38,7 +38,7 @@ doString :: String -> Doc
 doString s = text $ show s
 
 doMeta :: Meta -> Doc
-doMeta m = text $ formatSourcePos m
+doMeta m = text $ show m
 
 doAny :: Data a => a -> Doc
 doAny = doGeneral `ext1Q` doList `extQ` doString `extQ` doMeta

fco2/TODO

@@ -12,8 +12,6 @@ that takes several expressions.
 
 The show instance for types should produce occam-looking types.
 
-Redo Meta as a structure rather than a list.
-
 ParseState should be called something more sensible, since most of it has
 nothing to do with parsing.
 

fco2/Types.hs

@@ -154,7 +154,7 @@ makeConstant m n = A.ExprLiteral m $ A.Literal m A.Int $ A.IntLiteral m (show n)
 
 -- | Find the Meta value in an expression.
 metaOfExpression :: A.Expression -> Meta
-metaOfExpression e = concat $ gmapQ (mkQ [] findMeta) e
+metaOfExpression e = head $ gmapQ (mkQ emptyMeta findMeta) e
   where
     findMeta :: Meta -> Meta
     findMeta m = m