Class NSStack

  • public class NSStack
    extends Object
    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.

    • Constructor Detail

      • NSStack

        public NSStack()
    • Method Detail

      • push

        public void push()
        Create a new frame at the top of the stack.
      • pop

        public void pop()
        Remove the top frame from the stack.
      • cloneFrame

        public List<Mapping> cloneFrame()
        Return a copy of the current frame. Returns null if none are present.
      • topOfFrame

        public Mapping topOfFrame()
        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.
      • next

        public Mapping next()
        Return the next namespace mapping in the top frame.
      • add

        public void add​(String namespaceURI,
                        String prefix)
        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.
      • getPrefix

        public String getPrefix​(String namespaceURI,
                                boolean noDefault)
        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"

      • getPrefix

        public String getPrefix​(String namespaceURI)
        Return an active prefix for the given namespaceURI, including the default prefix ("").
      • getNamespaceURI

        public String getNamespaceURI​(String prefix)
        Given a prefix, return the associated namespace (if any).
      • dump

        public void dump​(String dumpPrefix)
        Produce a trace dump of the entire stack, starting from the top and including frame markers.