unpickleable )
where
+-- System imports.
import Control.Exception ( SomeException(..), catch )
import Text.XML.HXT.Core (
(>>>),
PU,
SysConfigList,
XmlPickler(..),
- hasName,
+ isElem,
readDocument,
runX,
withRemoveWS,
yes )
--- | A typeclass for XML types that can be converted into an associated
--- database type. The story behind this is long, but basically, we need
--- to different types for each XML thingie we're going to import: a
--- database type and an XML type. Both Groundhog and HXT are very
--- particular about the types that they can use, and there's no way
--- to reuse e.g. a type that HXT can pickle in Groundhog. So this
--- typeclass gives us a way to get the database type from the XML
--- type that we have to define for HXT.
+-- | A typeclass for XML types that can be converted into an
+-- associated database type. The story behind this is long, but
+-- basically, we need to different types most XML thingies we're
+-- going to import: a database type and an XML type.
+--
+-- Both Groundhog and HXT are very particular about the types that
+-- they can use, and there's no way to reuse e.g. a type that HXT
+-- can pickle in Groundhog. This typeclass gives us a standard way
+-- to get the database type from the XML type that we have to define
+-- for HXT.
--
class FromXml a where
- -- | Each instance a must declare its associated database type (Db a)
+ -- | Each instance @a@ must declare its associated database type @Db a@.
type Db a :: *
- -- | And provide a function for getting a (Db a) out of an "a".
+ -- | And provide a function for getting a @Db a@ out of an @a@.
from_xml :: a -> Db a
--- | Represents the DTD filename ("SYSTEM") part of the DOCTYPE
+-- | Represents the DTD filename (\"SYSTEM\") part of the DOCTYPE
-- definition.
newtype DtdName = DtdName String
-- | A list of options passed to 'readDocument' when we parse an XML
-- document. All cosmetic whitespace should be removed, otherwise we
--- have to parse it in each pickler.
+-- would have to parse whitespace in each (un)pickler.
--
parse_opts :: SysConfigList
parse_opts = [ withRemoveWS yes ]
--- | Given a root element name and a file path, return both the
--- original unpickled root "object" and the one that was constructed
--- by pickled and unpickling the original. This is used in a number
--- of XML tests which pickle/unpickle and then make sure that the
--- output is the same as the input.
+-- | Given an @unpickler@ and a @filepath@, attempt to unpickle the
+-- root element of @filepath@ using @unpickler@ and return both the
+-- original unpickled object and one constructed by pickling and
+-- unpickling that original. This is used in a number of XML tests
+-- which pickle/unpickle and then make sure that the output is the
+-- same as the input.
--
-- We return the object instead of an XmlTree (which would save us
-- an unpickle call) because otherwise the type of @a@ in the call
-- before/after results from this function agree does not mean that
-- the document was successfully unpickled!
--
-pickle_unpickle :: XmlPickler a
- => String
- -> FilePath
+pickle_unpickle :: PU a -- ^ @unpickler@ returning an @a@
+ -> FilePath -- ^ Path to the document to unpickle.
-> IO ([a], [a])
-pickle_unpickle root_element filepath = do
+pickle_unpickle unpickler filepath = do
-- We need to check only the root message element since
-- readDocument produces a bunch of other junk.
expected <- runX arr_getobj
actual <- runX $ arr_getobj
>>>
- xpickleVal xpickle
+ xpickleVal unpickler
>>>
- xunpickleVal xpickle
+ xunpickleVal unpickler
return (expected, actual)
where
arr_getobj = readDocument parse_opts filepath
/>
- hasName root_element
+ isElem -- Drop the extra junk readDocument pulls in.
>>>
- xunpickleVal xpickle
+ xunpickleVal unpickler
-- would result. By taking the unpickler as an argument, we allow
-- the caller to indirectly specify a concrete type.
--
-unpickleable :: XmlPickler a => FilePath -> PU a -> IO Bool
+-- Apologies the the name; unpickleable means \"we can unpickle
+-- it\", not \"not pickleable.\"
+--
+unpickleable :: FilePath -> PU a -> IO Bool
unpickleable filepath unpickler = do
xmldoc <- try_unpickle `catch` (\(SomeException _) -> return [])
return $ (not . null) xmldoc