I'm trying to think of a way to translate this input, to the output below: Input: <test> <foo name="a"> <wahoo>A</wahoo> </foo> <foo name="b"> <wahoo>B</wahoo> </foo> <foo name="c"> <wahoo>C</wahoo> </foo> <group> <bar ref="b"/> <bar ref="a"/> </group> </test> Output: <test> <group> <wahoo>B</wahoo> <wahoo>A</wahoo> </group> </test> That is, anywhere there is a 'bar', replace it with the contents of the 'foo' it references. I'm having a difficult time representing this with HXT's Arrow API because the value of the 'ref' attribute is the output of an arrow, but I need it to be just a plain string so that I could use it as an input parameter to the 'hasAttrValue' function. A similar problem, using 'processTopDown', once I traverse to a 'bar' node, I need to then traverse the root again to find the 'foo', but I'm in the context of the 'bar' node, not the root. My ears are open to solutions with HaXML or Scrap Your XML-plate, or anything else. Thanks, Greg
Adding some code to go along with my last post:
main = do
[tree] <- runX (readDocument [(a_validate, "0")] "text.xml")
[fooDoc] <- runX (constA tree >>> processChildren isFoo)
[expanded] <- runX (constA tree >>> processTopDown (expandNode fooDoc
`when` hasName "bar"))
[status] <- runX (constA expanded >>> writeDocument [] "-" >>>
getErrStatus)
(putStrLn . show) status
where
expandNode :: (ArrowXml a) => XmlTree -> a XmlTree XmlTree
expandNode :: (ArrowXml a) => XmlTree -> a XmlTree XmlTree
expandNode foos = this -- what here???
isFoo = deep (hasName "foo")
The issue is that in 'expandNode', I have an XmlTree (foos) and an arrow
whose input is the node to be replaced (also an XmlTree), but I need a
String and an arrow whose input is the XmlTree (foos):
expandNode' :: (ArrowXml a) => String -> a XmlTree XmlTree
expandNode' name = processChildren (hasAttrValue "name" name)
Somewhat related, if the output of an arrow is a string, can I get access to
that string without using 'runX':
getAttrValuehttp://www.fh-wedel.de/%7Esi/HXmlToolbox/hdoc_arrow/Text-XML-HXT-Arrow-XmlAr...::
String -> a
XmlTreehttp://www.fh-wedel.de/%7Esi/HXmlToolbox/hdoc_arrow/Text-XML-HXT-DOM-TypeDef...String
Are Arrows the wrong tool for this job?
Thanks,
Greg
On 7/14/06, Greg Fitzgerald
I'm trying to think of a way to translate this input, to the output below:
Input: <test> <foo name="a"> <wahoo>A</wahoo> </foo> <foo name="b"> <wahoo>B</wahoo> </foo> <foo name="c"> <wahoo>C</wahoo> </foo> <group> <bar ref="b"/> <bar ref="a"/> </group> </test>
Output: <test> <group> <wahoo>B</wahoo> <wahoo>A</wahoo> </group> </test>
That is, anywhere there is a 'bar', replace it with the contents of the
'foo' it references. I'm having a difficult time representing this with HXT's Arrow API because the value of the 'ref' attribute is the output of an arrow, but I need it to be just a plain string so that I could use it as an input parameter to the 'hasAttrValue' function. A similar problem, using 'processTopDown', once I traverse to a 'bar' node, I need to then traverse the root again to find the 'foo', but I'm in the context of the 'bar' node, not the root.
My ears are open to solutions with HaXML or Scrap Your XML-plate, or
anything else.
Thanks,
Greg
Assuming my last post was too hideous for anyone to take the time to attempt
to comprehend, let me try to simplify:
How can I extract the input of an arrow so that I can use it as a parameter
of a normal function?
How do I implement 'f' such that it can call 'g'?
f :: (ArrowXml a) => XmlTree -> a String XmlTree
g :: (ArrowXml a) => String -> a XmlTree XmlTree
Thanks,
Greg
On 7/14/06, Greg Fitzgerald
Adding some code to go along with my last post:
main = do [tree] <- runX (readDocument [(a_validate, "0")] " text.xml") [fooDoc ] <- runX (constA tree >>> processChildren isFoo) [expanded] <- runX (constA tree >>> processTopDown (expandNode fooDoc `when` hasName "bar")) [status] <- runX (constA expanded >>> writeDocument [] "-" >>> getErrStatus) (putStrLn . show) status where expandNode :: (ArrowXml a) => XmlTree -> a XmlTree XmlTree expandNode :: (ArrowXml a) => XmlTree -> a XmlTree XmlTree expandNode foos = this -- what here??? isFoo = deep (hasName "foo")
The issue is that in 'expandNode', I have an XmlTree (foos) and an arrow whose input is the node to be replaced (also an XmlTree), but I need a String and an arrow whose input is the XmlTree (foos):
expandNode' :: (ArrowXml a) => String -> a XmlTree XmlTree expandNode' name = processChildren (hasAttrValue "name" name)
Somewhat related, if the output of an arrow is a string, can I get access to that string without using 'runX': getAttrValuehttp://www.fh-wedel.de/%7Esi/HXmlToolbox/hdoc_arrow/Text-XML-HXT-Arrow-XmlAr...:: String -> a XmlTreehttp://www.fh-wedel.de/%7Esi/HXmlToolbox/hdoc_arrow/Text-XML-HXT-DOM-TypeDef...String
Are Arrows the wrong tool for this job?
Thanks, Greg
On 7/14/06, Greg Fitzgerald < garious@gmail.com> wrote:
I'm trying to think of a way to translate this input, to the output
below:
Input: <test> <foo name="a"> <wahoo>A</wahoo> </foo> <foo name="b"> <wahoo>B</wahoo> </foo> <foo name="c"> <wahoo>C</wahoo> </foo> <group> <bar ref="b"/> <bar ref="a"/> </group> </test>
Output: <test> <group> <wahoo>B</wahoo> <wahoo>A</wahoo> </group> </test>
That is, anywhere there is a 'bar', replace it with the contents of the
'foo' it references. I'm having a difficult time representing this with HXT's Arrow API because the value of the 'ref' attribute is the output of an arrow, but I need it to be just a plain string so that I could use it as an input parameter to the 'hasAttrValue' function. A similar problem, using 'processTopDown', once I traverse to a 'bar' node, I need to then traverse the root again to find the 'foo', but I'm in the context of the 'bar' node, not the root.
My ears are open to solutions with HaXML or Scrap Your XML-plate, or
anything else.
Thanks,
Greg
Greg Fitzgerald wrote:
Assuming my last post was too hideous for anyone to take the time to attempt to comprehend, let me try to simplify: How can I extract the input of an arrow so that I can use it as a parameter of a normal function?
How do I implement 'f' such that it can call 'g'? f :: (ArrowXml a) => XmlTree -> a String XmlTree g :: (ArrowXml a) => String -> a XmlTree XmlTree
ArrowXml is a subclass of ArrowApply, so it is possible. For example: f xml = pure (\s -> (g s, xml)) >>> app The $< operator from Control.Arrow.ArrowList might also be useful ($<) :: (c -> a b d) -> a b c -> a b d Brandon
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