The abstraction this class provides is a push down stack of variable
length frames of prefix to namespace mappings. Used for keeping track
of what namespaces are active at any given point as an XML document is
traversed or produced.
From a performance point of view, this data will both be modified frequently
(at a minimum, there will be one push and pop per XML element processed),
and scanned frequently (many of the "good" mappings will be at the bottom
of the stack). The one saving grace is that the expected maximum
cardinalities of the number of frames and the number of total mappings
is only in the dozens, representing the nesting depth of an XML document
and the number of active namespaces at any point in the processing.
Accordingly, this stack is implemented as a single array, will null
values used to indicate frame boundaries.
Reset the embedded iterator in this class to the top of the current
(i.e., last) frame. Note that this is not threadsafe, nor does it
provide multiple iterators, so don't use this recursively. Nor
should you modify the stack while iterating over it.
Add a mapping for a namespaceURI to the specified prefix to the top
frame in the stack. If the prefix is already mapped in that frame,
remap it to the (possibly different) namespaceURI.
public String getPrefix(String namespaceURI,
Return an active prefix for the given namespaceURI. NOTE : This
may return null even if the namespaceURI was actually mapped further
up the stack IF the prefix which was used has been repeated further
down the stack. I.e.:
*here's where we're looking*
If we look for a prefix for "namespace" at the indicated spot, we won't
find one because "pre" is actually mapped to "otherNamespace"