hxt-8.0.0: src/Text/XML/HXT/DTDValidation/IdValidation.hs
-- ------------------------------------------------------------
{- |
Module : Text.XML.HXT.DTDValidation.IdValidation
Copyright : Copyright (C) 2008 Uwe Schmidt
License : MIT
Maintainer : Uwe Schmidt (uwe@fh-wedel.de)
Stability : experimental
Portability: portable
This module provides functions for checking special ID/IDREF/IDREFS constraints.
Checking special ID\/IDREF\/IDREFS constraints means:
- checking that all ID values are unique.
- checking that all IDREF\/IDREFS values match the value of some ID attribute
ID-Validation should be started before or after validating the document.
First all nodes with ID attributes are collected from the document, then
it is validated that values of ID attributes do not occure more than once.
During a second iteration over the document it is validated that there exists
an ID attribute value for IDREF\/IDREFS attribute values.
-}
-- ------------------------------------------------------------
module Text.XML.HXT.DTDValidation.IdValidation
( validateIds
)
where
import Data.Maybe
import Text.XML.HXT.DTDValidation.TypeDefs
import Text.XML.HXT.DTDValidation.AttributeValueValidation
-- ------------------------------------------------------------
-- |
-- Lookup-table which maps element names to their validation functions. The
-- validation functions are XmlFilters.
type IdEnvTable = [IdEnv]
type IdEnv = (ElemName, IdFct)
type ElemName = String
type IdFct = XmlArrow
-- ------------------------------------------------------------
-- |
-- Perform the validation of the ID/IDREF/IDREFS constraints.
--
-- * 1.parameter dtdPart : the DTD subset (Node @DOCTYPE@) of the XmlTree
--
-- - 2.parameter doc : the document subset of the XmlTree
--
-- - returns : a list of errors
validateIds :: XmlTree -> XmlArrow
validateIds dtdPart
= validateIds' $< listA (traverseTree idEnv)
where
idAttrTypes = runLA (getChildren >>> isIdAttrType) dtdPart
elements = runLA (getChildren >>> isDTDElement) dtdPart
atts = runLA (getChildren >>> isDTDAttlist) dtdPart
idEnv = buildIdCollectorFcts idAttrTypes
validateIds' :: XmlTrees -> XmlArrow
validateIds' idNodeList
= ( constA idNodeList >>> checkForUniqueIds idAttrTypes )
<+>
checkIdReferences idRefEnv
where
idRefEnv = buildIdrefValidationFcts idAttrTypes elements atts idNodeList
-- |
-- Traverse the XmlTree in preorder.
--
-- * 1.parameter idEnv : lookup-table which maps element names to their validation functions
--
-- - returns : list of errors
traverseTree :: IdEnvTable -> XmlArrow
traverseTree idEnv
= multi (isElem `guards` (idFct $< getName))
where
idFct :: String -> XmlArrow
idFct name = fromMaybe none . lookup name $ idEnv
-- |
-- Returns the value of an element's ID attribute. The attribute name has to be
-- retrieved first from the DTD.
--
-- * 1.parameter dtdPart : list of ID attribute definitions from the DTD
--
-- - 2.parameter n : element which ID attribute value should be returned
--
-- - returns : normalized value of the ID attribute
getIdValue :: XmlTrees -> XmlTree -> String
getIdValue dns
= concat . runLA (single getIdValue')
where
getIdValue' :: LA XmlTree String
getIdValue'
= isElem `guards` catA (map getIdVal dns)
where
getIdVal dn
| isDTDAttlistNode dn = hasName elemName
`guards`
( getAttrValue0 attrName
>>>
arr (normalizeAttributeValue (Just dn))
)
| otherwise = none
where
al = getDTDAttributes dn
elemName = dtd_name al
attrName = dtd_value al
-- ------------------------------------------------------------
-- |
-- Build collector functions which return XTag nodes with ID attributes from
-- a document.
--
-- * 1.parameter dtdPart : the children of the @DOCTYPE@ node
--
-- - returns : lookup-table which maps element names to their collector function
buildIdCollectorFcts :: XmlTrees -> IdEnvTable
buildIdCollectorFcts idAttrTypes
= concatMap buildIdCollectorFct idAttrTypes
where
buildIdCollectorFct :: XmlTree -> [IdEnv]
buildIdCollectorFct dn
| isDTDAttlistNode dn = [(elemName, hasAttr attrName)]
| otherwise = []
where
al = getDTDAttributes dn
elemName = dtd_name al
attrName = dtd_value al
-- |
-- Build validation functions for checking if IDREF\/IDREFS values match a value
-- of some ID attributes.
--
-- * 1.parameter dtdPart : the children of the @DOCTYPE@ node
--
-- - 2.parameter idNodeList : list of all XTag nodes with ID attributes
--
-- - returns : lookup-table which maps element names to their validation function
buildIdrefValidationFcts :: XmlTrees -> XmlTrees -> XmlTrees -> XmlTrees -> IdEnvTable
buildIdrefValidationFcts idAttrTypes elements atts idNodeList
= concatMap buildElemValidationFct elements
where
idValueList = map (getIdValue idAttrTypes) idNodeList
buildElemValidationFct :: XmlTree -> [IdEnv]
buildElemValidationFct dn
| isDTDElementNode dn = [(elemName, buildIdrefValidationFct idRefAttrTypes)]
| otherwise = []
where
al = getDTDAttributes dn
elemName = dtd_name al
idRefAttrTypes = (isAttlistOfElement elemName >>> isIdRefAttrType) $$ atts
buildIdrefValidationFct :: XmlTrees -> XmlArrow
buildIdrefValidationFct
= catA . map buildIdref
buildIdref :: XmlTree -> XmlArrow
buildIdref dn
| isDTDAttlistNode dn = isElem >>> (checkIdref $< getName)
| otherwise = none
where
al = getDTDAttributes dn
attrName = dtd_value al
attrType = dtd_type al
checkIdref :: String -> XmlArrow
checkIdref name
= hasAttr attrName
`guards`
( checkIdVal $< getAttrValue attrName )
where
checkIdVal :: String -> XmlArrow
checkIdVal av
| attrType == k_idref
= checkValueDeclared attrValue
| null valueList
= err ( "Attribute " ++ show attrName ++
" of Element " ++ show name ++
" must have at least one name."
)
| otherwise
= catA . map checkValueDeclared $ valueList
where
valueList = words attrValue
attrValue = normalizeAttributeValue (Just dn) av
checkValueDeclared :: String -> XmlArrow
checkValueDeclared attrValue
= if attrValue `elem` idValueList
then none
else err ( "An Element with identifier " ++ show attrValue ++
" must appear in the document."
)
-- ------------------------------------------------------------
-- |
-- Validate that all ID values are unique within a document.
-- Validity constraint: ID (3.3.1 \/p. 25 in Spec)
--
-- * 1.parameter idNodeList : list of all XTag nodes with ID attributes
--
-- - 2.parameter dtdPart : the children of the @DOCTYPE@ node
--
-- - returns : a list of errors
checkForUniqueIds :: XmlTrees -> LA XmlTrees XmlTree
checkForUniqueIds idAttrTypes -- idNodeList
= fromSLA [] ( unlistA
>>>
isElem
>>>
(checkForUniqueId $<< getName &&& this)
)
where
checkForUniqueId :: String -> XmlTree -> SLA [String] XmlTree XmlTree
checkForUniqueId name x
= ifA ( getState
>>>
isA (attrValue `elem`)
)
(err ( "Attribute value " ++ show attrValue ++ " of type ID for element " ++
show name ++ " must be unique within the document." ))
(nextState (attrValue:) >>> none)
where
attrValue = getIdValue (isAttlistOfElement name $$ idAttrTypes) x
-- |
-- Validate that all IDREF\/IDREFS values match the value of some ID attribute.
-- Validity constraint: IDREF (3.3.1 \/ p.26 in Spec)
--
-- * 1.parameter idRefEnv : lookup-table which maps element names to their validation function
--
-- - 2.parameter doc : the document to validate
--
-- - returns : a list of errors
checkIdReferences :: IdEnvTable -> LA XmlTree XmlTree
checkIdReferences idRefEnv
= traverseTree idRefEnv
-- ------------------------------------------------------------