JOOX.$() doesn't support whitespace between comment and root element

[andreasevers]

Expected behavior and actual behavior:

The following code:

import org.joox.JOOX;
import org.junit.jupiter.api.Test;

class JOOXTest {
	@Test
	void shouldParseComments() {
		String xmlData = """
		<!-- comment -->
		<root></root>
		""";
		JOOX.$(xmlData).document();
	}
}

should correctly parse.
However, it fails with the following exception:

org.w3c.dom.DOMException: HIERARCHY_REQUEST_ERR: An attempt was made to insert a node where it is not permitted.

	at java.xml/com.sun.org.apache.xerces.internal.dom.CoreDocumentImpl.insertBefore(CoreDocumentImpl.java:439)
	at java.xml/com.sun.org.apache.xerces.internal.dom.ParentNode.internalInsertBefore(ParentNode.java:330)
	at java.xml/com.sun.org.apache.xerces.internal.dom.ParentNode.insertBefore(ParentNode.java:286)
	at java.xml/com.sun.org.apache.xerces.internal.dom.CoreDocumentImpl.insertBefore(CoreDocumentImpl.java:447)
	at java.xml/com.sun.org.apache.xerces.internal.dom.NodeImpl.appendChild(NodeImpl.java:230)
	at org.joox.JOOX.$(JOOX.java:99)
	at JOOXTest.shouldParseComments(JOOXTest.java:18)
	at java.base/java.lang.reflect.Method.invoke(Method.java:568)
	at java.base/java.util.ArrayList.forEach(ArrayList.java:1511)
	at java.base/java.util.ArrayList.forEach(ArrayList.java:1511)

This is especially relevant for copyright notices at the start of a file.

Steps to reproduce the problem:

Run the test.

Versions:

• jOOX: 2.0.0
• Java: 17

[lukaseder]

Thanks for your report. I agree this should probably work, assuming there are no forbidden content elements in the prolog (e.g. unsupported whitespace: https://www.w3.org/TR/xml/#NT-prolog).

[lukaseder]

The problem is indeed whitespace. This works:

String xmlData = "<!-- comment --><root></root>";

This doesn't:

String xmlData = "<!-- comment --> <root></root>";

But this does, again:

String xmlData = "<?xml version=\"1.0\"?> <!-- comment --> <root></root>";

It's weird that the XMLDecl seems to be mandatory here. It isn't according to the specs:

prolog	   ::=   	XMLDecl? Misc* (doctypedecl Misc*)?

Let's see if jOOX can work around this.

[lukaseder]

Related: #128

[lukaseder]

Well, it seems that the Document node simply doesn't allow for any Text node to be appended as a child, irrespective of its content. It should check if the content matches this:

S	   ::=   	(#x20 | #x9 | #xD | #xA)+

But alas, it doesn't. I guess the only safe solution here is to remove the whitespace for now.

[lukaseder]

The alternative would be to parse the Document directly, rather than parsing a DocumentFragment, when wrapping things with $(...)

[lukaseder]

Fixed for version 2.0.1

[andreasevers]

Much appreciated Lukas!