X-Git-Url: http://gitweb.michael.orlitzky.com/?a=blobdiff_plain;f=src%2FXml.hs;h=ec409ac1b8f2eda9abda3312b020a347584c6cd0;hb=7be52948a693fbd8f79ba9035092b74b26775e4f;hp=3f7bb62cae43fc0cb8dbe42bf54741e448980fbd;hpb=6c1e96b2a155336038c010ebd4f28795b152e5b0;p=dead%2Fhtsn-import.git

diff --git a/src/Xml.hs b/src/Xml.hs
index 3f7bb62..ec409ac 100644
--- a/src/Xml.hs
+++ b/src/Xml.hs
@@ -4,13 +4,16 @@
 -- | General XML stuff.
 --
 module Xml (
+  Child(..),
   DtdName(..),
   FromXml(..),
   FromXmlFk(..),
   ToDb(..),
   parse_opts,
   pickle_unpickle,
-  unpickleable )
+  unpickleable,
+  unsafe_read_document,
+  unsafe_unpickle )
 where
 
 -- System imports.
@@ -21,6 +24,7 @@ import Text.XML.HXT.Core (
   (/>),
   PU,
   SysConfigList,
+  XmlTree,
   isElem,
   no,
   readDocument,
@@ -29,9 +33,12 @@ import Text.XML.HXT.Core (
   withSubstDTDEntities,
   withValidate,
   xpickleVal,
+  xunpickleDocument,
   xunpickleVal,
   yes )
 
+
+
 -- | Common associated type shared by 'FromXml' and 'FromXmlFk'. This
 --   basically just forces the client to define the \"database
 --   version\" of his type.
@@ -56,22 +63,30 @@ class (ToDb a) => FromXml a where
   from_xml :: a -> Db a
 
 
--- | Some database types cannot be constructed from the XML type
---   alone; they must be supplied a foreign key to a parent object
---   first. Members of this class can be converted from an XML
---   representation to a database representation in this manner.
+-- | A class for XML representations which are children of other
+--   elements. The foal is to associate a child XML element with its
+--   parent element's database type. This is required to construct the
+--   database analogue of @a@ in 'FromXmlFk'.
 --
-class (ToDb a) => FromXmlFk a where
+class Child a where
   -- | The type of our parent object, i.e. to the type to whom our
   --   foreign key will point.
   type Parent a :: *
 
+
+-- | Some database types cannot be constructed from the XML type
+--   alone; they must be supplied a foreign key to a parent object
+--   first. Members of this class can be converted from an XML
+--   representation to a database representation in this manner.
+--
+class (Child a, ToDb a) => FromXmlFk a where
   -- | The function that produces a @Db a@ out of a foreign key and an
   --   @a@. The parameter order makes it easier to map this function
   --   over a bunch of things.
   from_xml_fk :: DefaultKey (Parent a) -> a -> Db a
 
 
+
 -- | Represents the DTD filename (\"SYSTEM\") part of the DOCTYPE
 --   definition.
 newtype DtdName = DtdName String
@@ -143,3 +158,19 @@ unpickleable filepath unpickler = do
     try_unpickle = runX $ readDocument parse_opts filepath
                           >>>
                           xunpickleVal unpickler
+
+
+-- | Unpickle from a 'FilePath' using the given pickler. Explode if it
+--   doesn't work.
+--
+unsafe_unpickle :: FilePath -> PU a -> IO a
+unsafe_unpickle filepath unpickler =
+  fmap head $ runX $ xunpickleDocument unpickler parse_opts filepath
+
+
+-- | Read an XML document from a 'FilePath' into an XmlTree. Explode if it
+--   doesn't work.
+--
+unsafe_read_document :: FilePath -> IO XmlTree
+unsafe_read_document filepath =
+  fmap head $ runX $ readDocument parse_opts filepath