Hi Henry,
> I have just spent many hours staring at code and losing some hair. My
> hope is to save you the same experience someday. Here was my goal:
>
> Take some XML, like <photo url="somewhere" align="left" alt=""/> and
> replace the align attribute with a class attribute, but only if the
> value of the align attribute was not null. This led to to followed
> (hugely condensed) attempts:
you could try the following:
------------------------------------
module Align where
import Text.XML.HXT.Core
doc = concat $
[ "<collection>"
, "<photo url='somewhere' align='left' alt=''/>"
, "<photo url='somewhere' align='' alt=''/>"
, "</collection>"
]
main =
runX ( constA doc
>>>
readFromString []
>>>
writeDocument [withIndent yes] ""
>>>
modifyAlt
>>>
writeDocument [withIndent yes] ""
)
modifyAlt
= processTopDownUntil
(isPhotoWithNonEmptyAlign `guards` addClassAttr)
isPhotoWithNonEmptyAlign
= hasName "photo"
>>>
hasAttrValue "align" (not .null)
addClassAttr
= addAttr "class" "someclass"
>>>
removeAttr "align"
------------------------------------
Cheers,
Uwe
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