+-- | Safe 'read' function returning data encapsulated in a Result
+tryRead :: (Monad m, Read a) => String -> String -> m a
+tryRead name s =
+ let sols = readsPrec 0 s
+ in case sols of
+ (v, ""):[] -> return v
+ (_, e):[] -> fail $ name ++ ": leftover characters when parsing '"
+ ++ s ++ "': '" ++ e ++ "'"
+ _ -> fail $ name ++ ": cannot parse string '" ++ s ++ "'"
+
+-- | Lookups a node into an assoc list
+lookupNode :: (Monad m) => String -> String -> [(String, Int)] -> m Int
+lookupNode node inst ktn =
+ case lookup node ktn of
+ Nothing -> fail $ "Unknown node '" ++ node ++ "' for instance " ++ inst
+ Just idx -> return idx
+
+-- | Load a node from a field list
+loadNode :: (Monad m) => [String] -> m (String, Node.Node)
+loadNode (name:tm:nm:fm:td:fd:fo:[]) = do
+ new_node <-
+ if any (== "?") [tm,nm,fm,td,fd] || fo == "Y" then
+ return $ Node.create 0 0 0 0 0 True
+ else do
+ vtm <- tryRead name tm
+ vnm <- tryRead name nm
+ vfm <- tryRead name fm
+ vtd <- tryRead name td
+ vfd <- tryRead name fd
+ return $ Node.create vtm vnm vfm vtd vfd False
+ return (name, new_node)
+loadNode s = fail $ "Invalid/incomplete node data: '" ++ (show s) ++ "'"
+
+-- | Load an instance from a field list
+loadInst :: (Monad m) =>
+ [(String, Int)] -> [String] -> m (String, Instance.Instance)
+loadInst ktn (name:mem:dsk:status:pnode:snode:[]) = do
+ pidx <- lookupNode pnode name ktn
+ sidx <- (if null snode then return noSecondary
+ else lookupNode snode name ktn)
+ vmem <- tryRead name mem
+ vdsk <- tryRead name dsk
+ when (sidx == pidx) $ fail $ "Instance " ++ name ++
+ " has same primary and secondary node - " ++ pnode
+ let newinst = Instance.create vmem vdsk status pidx sidx
+ return (name, newinst)
+loadInst _ s = fail $ "Invalid/incomplete instance data: '" ++ (show s) ++ "'"
+