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Proposal for Additions for Namespace Fixup

From: Alex Milowski <alex@milowski.org>
Date: Thu, 6 Sep 2007 09:38:15 -0700
Message-ID: <28d56ece0709060938s3c59d6c8k818f7499d957c8fb@mail.gmail.com>
To: "XProc WG" <public-xml-processing-model-wg@w3.org>

This proposal gets us a long way there.  It does not cover the case
where a generated
prefix conflicts with a existing prefix on descendants of the element where the
namespace declaration was added.  I'm willing to let the serializer
deal with that
situation but encourage implementations to detect (or avoid) and fix
such problems.

That is, I could generate prefixes that are UUIDs and, while *huge*, they would
never conflict.  A implementation could then have a "formula 1 mode" that could
crash and burn or a "super safe" mode that uses something like a UUID.  As such,
there are solutions to this problem that guarantee generated prefixes do not
conflict with existing prefixes.


Here's the proposal:

In general:

"Unless stated otherwise, when a namespace binding is added, a unique prefix
is generated."

"Any element or attribute generated by a step in this library as output
 must have a namespace name binding in the in-scope namespaces of that
 generated element."


1. p:add-attribute:

If a namespace binding does not exist for the namespace name
of the attribute, a namespace binding must be added where the prefix
from the QName should be used if it is not already bound to another
namespace.  Otherwise, the prefix bound to the attribute's namespace
in the in-scope namespaces is used in the attribute information item generated.

2. p:insert and p:replace

When the element is copied into the resulting document, all the in-scope
namespaces must be declared unless the prefix is bound to the same
namespace name by an ancestor.

3. p:rename

If the target being renamed is an element, the following namespace adjustments
must be made for the namespace name used by the new element:

   * if the namespace name is not bound to a prefix, a namespace
declaration must
     be added where the prefix from the QName should be used if it is
not already
     bound to another namespace. .  Otherwise, the prefix bound to the
namespace
     name must be used.

   * if there is no namespace name, a default namespace name
declaration must be
     added or replaced setting it to the empty string (no namespace).

   * if the default namespace name is changed and there is an in-scope default
     namespace name, the original default namespace name must be declared on
     all child elements.

If the target being renamed is an attribute, then if the namespace
name is not bound to
a prefix, a namespace declaration must be added where the prefix from
the QName should be
used if it is not already bound to another namespace. .  Otherwise,
the prefix bound to the
namespace name must be used.

4. p:wrap

If the namespace name is not bound to a prefix, a namespace declaration must
be added where the prefix from the QName should be used if it is not already
bound to another namespace. .  Otherwise, the prefix bound to the namespace
name must be used.

5. p:wrap-sequence

The namespace name must be declared using the prefix specified.

Note: There are no consequences here since we are wrapping document elements
and there are no in-scope namespaces except the predefined namespaces
and prefixes.

6. p:unwrap

Any namespace declarations on the element being unwrapped must be copied to the
element children.

7. p:set-attributes

For each attribute being added, if a namespace binding does not exist for the
namespace name of the attribute, a namespace binding must be added where
the prefix from the QName should be used if it is not already bound to another
namespace.  Otherwise, the prefix bound to the attribute's namespace
in the in-scope namespaces is used in the attribute information item generated.

8. p:xslt

When an element is generated from the xsl:element or an attribute from
xsl:attribute,
this step must guarantee that an namespace declaration exists for the namespace
name used.  As necessary, the step must add namespace declarations in the output
of the transformation if the XSLT processor does not do so.


-- 
--Alex Milowski
"The excellence of grammar as a guide is proportional to the paucity of the
inflexions, i.e. to the degree of analysis effected by the language
considered."

Bertrand Russell in a footnote of Principles of Mathematics
Received on Thursday, 6 September 2007 16:38:20 GMT

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