[imps] Extending the tree builder test format to cover SVG and MathML

[Henri Sivonen]

I think we should extend the html5lib tree builder test format to  
cover MathML and SVG. This means the need to express that an element  
is in the MathML or SVG namespace and the ability to express that an  
attribute is in the XML or XLink namespace.

Strictly speaking, it would also require dealing with the xmlns  
namespace, however, I suggest we don't mix xmlns attribute testing  
with the rest of foreign content testing, because namespace  
declaration attributes are special e.g. in SAX and, therefore,  
requiring xmlns attributes to be preserved and in the right order  
causes hardship for implementations that map to XML APIs that don't  
represent namespace declarations as attributes.

Since the tree builder output can't have arbitrary namespaces, we  
don't need namespace URIs and can instead use more compact symbols.

I suggest representing a MathML element by prefixing the name with "m  
" like this: <m annotation-xml>. SVG element would be prefixed with "s  
": <s foreignContent>.

I suggest prefixing XLink attributes with "xlink ", XML attributes  
with "xml " and xmlns attributes prefixed with "xmlns ".

I suggest using thus prefixed name (i.e. e.g. "xlink href") as the  
attribute order sort key.

Space as the delimiter can't collide with any character that can be  
tokenized as part of a name.

Opinions?

-- 
Henri Sivonen
hsivonen at iki.fi
http://hsivonen.iki.fi/