Validation.hs

-- |
-- This module provides a state filter as a main function for validating XML documents.
--
-- The real validation is done with pure filters from module 'Text.XML.HXT.Validator.ValidationFilter'
--
-- Author : .\\artin Schmidt
-- Version : $Id: Validation.hs,v 1.2 2004/11/23 15:50:23 hxml Exp $

module Text.XML.HXT.Validator.Validation
    ( getValidatedDoc
    , module Text.XML.HXT.Validator.ValidationFilter
    )

where

import Text.XML.HXT.DOM.XmlTree
import Text.XML.HXT.DOM.XmlState

import Text.XML.HXT.Validator.ValidationFilter

import Text.XML.HXT.Parser.XmlOutput
    ( traceTree
    , traceSource
    , traceMsg
    )

-- ------------------------------------------------------------

-- |
-- monadic filter for validating and transforming a wellformed document.
--
-- the "main" function for validation.
--
-- the input tree must consist of a root node with a complete document and DTD.
-- Result is the single element list containing same tree but tranformed with respect to the DTD,
-- or, in case of errors, the root with an empty list of children

getValidatedDoc		:: XmlStateFilter state
getValidatedDoc
    = traceMsg 1 "validating document"
      .>>
      ( ( runValidation
	  .>>
	  traceTree
	  .>>
	  traceSource
	)
	`whenM` (isRoot .> getChildren)
      )
      where
      runValidation t
	  = do
	    issueError $$< res
	    ( if null errs
	      then ( traceMsg 1 "transforming validated document"
		     .>>
		     liftMf transform
		   )
	      else liftMf (setStatus c_err "validating document")
	      ) t
	    where
	    res  = validate t
	    errs = isXError .> neg isWarning $$ res

-- ------------------------------------------------------------