Namespace declaration attributes and prefixes are normalized as
part of the normalizeDocument method of the Document interface as
if the following method described in pseudo code was called on the
document element.
void Element.normalizeNamespaces()
{
if ( Element's namespaceURI != null )
{
if ( Element's prefix/namespace pair (or default namespace,
if no prefix) are within the scope of a binding )
{
==> do nothing, declaration in scope is inherited
See example 1
}
else
{
==> Create a local namespace declaration attr for this namespace,
with Element's current prefix (or a default namespace, if
no prefix). If there's a conflicting local declaration
already present, change its value to use this namespace.
See example 2
// NOTE that this may break other nodes within this Element's
// subtree, if they're already using this prefix.
// They will be repaired when we reach them.
}
}
else
{
// Element has no namespace URI:
if ( Element has a colon in its name )
{
if ( Level 2 node )
{
==> report an error
}
else
{
// Level 1 node
if ( Name is not a QName )
{
==> report an error
}
else
{
if ( Prefix is bound to something )
{
==> report a warning
}
else
{
==> report an error
}
}
}
}
else
{
// Element has no namespace URI
// Element has no pseudo-prefix
if ( default Namespace in scope is "no namespace" )
{
==> do nothing, we're fine as we stand
}
else
{
if ( there's a conflicting local default namespace declaration
already present )
{
==> change its value to use this empty namespace.
See example 3
}
else
{
==> Set the default namespace to "no namespace" by creating or
changing a local declaration attribute: xmlns="".
See example 4
}
// NOTE that this may break other nodes within this Element's
// subtree, if they're already using the default namespaces.
// They will be repaired when we reach them.
}
}
}
//////// EXAMINE AND POLISH THE ATTRS ////////
for ( all Attrs of Element )
{
if ( Attr[i] has a namespace URI )
{
if ( Attr has no prefix, or has a prefix that conflicts with
a binding already active in scope )
{
if ( Element is in the scope of a non default binding for this
namespace )
{
if ( one or more prefix bindings are available )
{
if ( one is locally defined )
{
==> pick that one.
}
else
{
==> pick one arbitrarily
}
==> Change the Attr to use that prefix.
}
else
{
==> Create a local namespace declaration attr for this namespace
with a prefix not already used in the current scope and following
the pattern "NS" + index (starting at 1).
Change the Attr to use this prefix.
// NOTE that this may break other nodes within this Element's
// subtree, if they're already using this prefix.
// They will be repaired when we reach them.
}
}
}
else
{
// prefix does match but....
if ( namespace is "http://www.w3.org/2000/xmlns/" AND attribute does
not have the prefix "xmlns:" or the nodeName "xmlns" )
{
// While all Namespace Declarations belong to a reserved NSURI,
// it is _not_ true that all attributes having that NSURI are to be
// considered Namespace Declarations.
// According to the namespace spec, only "xmlns" and names having
// the xmlns: prefix should be interpreted as declarations. So:
if ( there is a non default binding for this namespace in scope
with a prefix other than "xmlns" )
{
if ( one is locally defined )
{
==> pick that one.
}
else
{
==> pick one arbitrarily
}
==> Change the Attr to use that prefix.
}
else
{
==> Create a local namespace declaration attr for this namespace
with a prefix not already used in the current scope and following
the pattern "NS" + index (starting at 1).
Change the Attr to use this prefix.
// NOTE that this may break other nodes within thisElement's
// subtree, if they're already using this prefix.
// They will be repaired when we reach them.
}
// end non-namespace-decl with namespace-decl URI
}
}
// end namespaced Attr
}
else
{
// Attr[i] has no namespace URI
if ( Attr[i] has a colon in its name )
{
if ( Level 2 node )
{
==> report an error
}
else
{
// Level 1 node
if ( Name is not a QName )
{
==> report an error
}
else
{
if ( Prefix is bound to something )
{
==> report a warning
}
else
{
==> report an error
}
}
}
}
else
{
// attr has no namespace URI and no prefix
// we're fine as we stand, since attrs don't use default
==> do nothing
}
}
} // end for-all-Attrs
// do this recursively
for ( all child elements of Element )
{
childElement.normalizeNamespaces()
}
} // end Element.normalizeNamespaces
The following describes in pseudo code the algorithm used in the
lookupNamespacePrefix method of the Node interface.
DOMString Element.lookupNamespacePrefix(in DOMString specifiedNamespaceURI)
{
if ( Element's namespaceURI == specifiedNamespaceURI )
{
return Element's prefix
}
else if ( Element has an Attr and
Attr's namespaceURI == "http://www.w3.org/2000/xmlns/" and
Attr's prefix == "xmlns" and
Attr's value == specifiedNamespaceURI )
{
return Attr's localName.
}
else if ( Element has an ancestor Element )
// EntityReferences may have to be skipped to get to it
{
return ancestorElement.lookupNamespacePrefix(specifiedNamespaceURI)
}
else {
return unknown (null)
}
}
The following describes in pseudo code the algorithm used in the
lookupNamespaceURI method of the Node interface.
DOMString Element.lookupNamespaceURI(in DOMString specifiedPrefix)
{
return lookupNamespaceURI(specifiedPrefix, this);
}
DOMString Element.lookupNamespaceURI(in DOMString specifiedPrefix, Element el)
{
if ( Element's namespace URI != null and
Element's prefix == specifiedPrefix and
el.lookupNamespacePrefix(Element's namespace URI) == specifiedPrefix )
{
return Element's namespace URI
}
else if ( Element has an Attr and
Attr's namespaceURI == "http://www.w3.org/2000/xmlns/" and
Attr's prefix == "xmlns" and
Attr's localName == specifiedPrefix and
el.lookupNamespacePrefix(Attr's value URI) == specifiedPrefix )
{
return Attr's value.
}
else if ( Element has an ancestor Element )
// EntityReferences may have to be skipped to get to it
{
return ancestorElement.lookupNamespaceURI(specifiedPrefix, el)
}
else {
return unknown (null)
}
}