{-# LANGUAGE CPP, TypeSynonymInstances #-}

{- |

Module : $Header$

Description : Interface to the Xml Parsing Facility

Copyright : (c) Ewaryst Schulz, DFKI 2009

License : GPLv2 or higher, see LICENSE.txt

Maintainer : ewaryst.schulz@dfki.de

Stability : provisional

Portability : portable

Provides an xml parse function which depends on external libraries.

-}

module Common.XmlParser (XmlParseable (parseXml), readXmlFile) where

-- XML version from 1.3.7 on required!

-- TODO: specify in var.mk this requirement correctly, it is now required to have

-- exactly version 1.3.7 not >= 1.3.7.

#ifdef XML137

import Text.XML.Light

#else

import Text.XML.Light.Version_1_3_7_or_later_required

#endif

import qualified Data.ByteString.Lazy as BS

#ifdef HEXPAT

import qualified Common.XmlExpat as XE

#endif

readXmlFile :: FilePath -> IO BS.ByteString

readXmlFile = BS.readFile

{- | This class provides an xml parsing function which is instantiated

by using the hexpat or the XML.Light library, dependent on the haskell

environment. -}

class XmlParseable a where

parseXml :: a -> Either String Element

#ifdef HEXPAT

instance XmlParseable BS.ByteString where

parseXml = XE.parseXml

-- 169MB on Basic/Algebra_I

#else

instance XmlParseable BS.ByteString where

parseXml s = case parseXMLDoc s of

Just x -> Right x

_ -> Left "parseXMLDoc: parse error"

-- 426MB on Basic/Algebra_I

#endif