New line character is not escaped in attribute when using MarkupBuilder

My previous comment was mangled, so I rather try to attach a patch.

But if you say the spec says "new lines in attribute value should be converted to single space" and then produce , isn't that wrong? would you want to use " "?

Do you have a link to the relevant part of the spec?

The link to spec is: http://www.w3.org/TR/xml/#AVNormalize

It says when parsing, white space characters #x20, #xD, #xA, #x9 should be converted to #x20 (space). Then, all leading and trailing spaces are removed and all sequences of spaces are merged to one space.

So, now I see that my patch is not enough. The generator should also convert spaces and tabs to their escape sequences, assuming that attribute value should be preserved exactly as is after parsing it back.

To Jochen: we probably didn't understand each other. The normalizing attribute value occurs in XML parser. I expect that generating xml and parsing it back should provide the same values. But if you generate XML with attribute value containing new line, parse it back, you get a space.

Sorry, but in later comment I stated that TAB and SPACE characters should be escaped too ('\t' -> "	" and ' ' -> "&#32"). For the same reasons as \n and \r.

I am wondering whether I am totally following what you would like. Are you wanting the first or second line:

\t -> 	
\t -> 	

because I am wondering whether even the earlier changes are want you wanted?

The first line is what I meant, and similarly for SPACE. To be sure, I attach a code snippet from MarkupBuilder.java, it is most precise after all

That is what you said before - I would be worried about us producing "non-standard" looking XML. Can you elaborate a bit more on what kind of round-tripping you are trying to enable?

Hello, I went through the spec again (few times) and tried another libraries(Java DOM, Transformer, SAX Parser). I realized that I made mistake concerning a SPACE character. It can be produced as is. I was mistaken by this part of spec:

If the attribute type is not CDATA, then the XML processor MUST further process the normalized attribute value by discarding any leading and trailing space (#x20) characters, and by replacing sequences of space (#x20) characters by a single space (#x20) character.

But, 2 paragraphs later:

All attributes for which no declaration has been read SHOULD be treated by a non-validating processor as if declared CDATA.

So, SPACES don't need to be produced as escape sequences. I tried groovy.xml.XMLParser and it keeps them as they are.

So, only TAB character should be escaped. This is test, which should pass:

import groovy.xml.*

doTest("  hello  world  ") //  (1)
doTest("hello\nworld")     //  (2)
doTest("hello\rworld")     //  (3)
doTest("hello\tworld")     //  (4)

def doTest(String value) {
  StringWriter w = new StringWriter()
  new MarkupBuilder(w).root(a:value)
  xml2 = new XmlParser().parseText(w.toString())
  assert value == xml2.@a
}

Original version fails in parts (2), (3) and (4), after your changes it still fails in part (4). The part (1) passes, which is confirmation of what I said in this comment.

Tab is now escaped too. Thanks for all the feedback and information.