README-namespace.md

Improved Namespace Support for Anti-XML

These are my notes on improving the namespace support for anti-xml.

Ideas/thoughs

Consistent naming

Rename "scope" to "namespace", ensure that the naming and concepts are closer to the XML specs.

Selectors and namespaces

Selecting a child nodes with \, should it require the child elements to be in the same namespace as the element it's applied on?

I think it should as that'll give a consumer the least number of surprises. When doing the xpath-like lookups you're already in a "lax mode" and only picking out stuff that you know and ignoring the rest.

Make NamespaceBinding look like a linked list

In XML elements might override namespace prefixes, for example:

<!--
  Element namespace: "urn:a"
  Namespace bindings: "urn:a"
 -->
<root xmlns="urn:a">
  <a>
    <!--
      Element namespace: "urn:person"
      Namespace bindings: "urn:person", "urn:a"
    -->
    <person xmlns="urn:person">
      <!--
        Element namespace: "urn:person"
        Namespace bindings: "urn:person", "urn:a"
      -->
      <name>Captain Awesome</name>
    </person>
  </a>
  <!--
    Element namespace: "urn:person"
    Namespace bindings: person="urn:person", "urn:a"

    This is the same element as the above <persion/>
  -->
  <person:person xmlns:person="urn:person">
    <!--
      Element namespace: "urn:person"
      Namespace bindings: "urn:person", "urn:a"
    -->
    <person:name>Captain Awesome</name>
  </person:person>
</root>

Another example:

<!--
  Element namespace: None
  Namespace bindings: None
 -->
<root>
  <!--
    Element namespace: "urn:person"
    Namespace bindings: "urn:person", "urn:a"
  -->
  <person xmlns="urn:person">
    <!--
      Element namespace: "urn:person"
      Namespace bindings: "urn:person", "urn:a"
    -->
    <name>Captain Awesome</name>
  </person>
</root>

With these example it's easy to see that the NamespaceBinding objects can be easily share between Elem objects and will give a rather conservative memory usage as child bindings just reference a parent binding.

Namespace collisions

TODO: this really isn't a problem as far as I can tell - trygve

As it is now there's nothing that prevent namespace collisions. If there's a generic piece of code that generate a "person" Elem inside the "urn:person" namespace and another piece of code that generate a "car" Elem stuff will get complicated:

<root>
  <person xmlns="urn:person"/>
  <car xmlns="urn:car"/>
</root>

Reuse specs for sax and stax parser

Right now they're almost the same but both have some extra tests which apply to the other parser too. I don't know how to do that best with specs, but there's got to be a clever way.

TODO

• Use the same concepts for namespacing attributes as elements.
• Update documentation and examples.

Completed

Make anti-xml be namespace-oriented, not prefix-oriented

• Added a "NamespaceBinding" class which contain the current bindings. Similar to scala.xml's bindings.
• The "scope" field is not an Option, however it can reference the empty namespace binding. This is mainly a memory optimalization so that the bindings doesn't have to be wrapped in an Option and unwrapped all the time when pattern matching them.