## net.sf.saxon.evpull
Class NamespaceMaintainer

    java.lang.Object
      net.sf.saxon.evpull.NamespaceMaintainer

All Implemented Interfaces:
  EventIterator, PullEvent, NamespaceResolver

    public class NamespaceMaintainer

extends Object
implements EventIterator, NamespaceResolver

NamespaceMaintainer is an EventIterator responsible for maintaining namespace context in an event stream. It allows the current namespace context to be determined at any time while processing the stream of events.

Note that this class merely provides the service of keeping track of which namespaces are currently in scope. It does not attempt to remove duplicate namespace declarations, and it does not perform namespace fixup.

Constructor Summary
`NamespaceMaintainer(EventIterator base, NamePool namePool)` Create a namespace context for a pull-events pipeline

Method Summary
`protected short` `getURICode(short prefixCode)` Get the URI code corresponding to a given prefix code, by searching the in-scope namespaces.
`String` `getURIForPrefix(String prefix, boolean useDefault)` Get the namespace URI corresponding to a given prefix.
`boolean` `isFlatSequence()` Determine whether the EventIterator returns a flat sequence of events, or whether it can return nested event iterators
`Iterator` `iteratePrefixes()` Get an iterator over all the prefixes declared in this namespace context.
`PullEvent` `next()` Get the next event in the sequence

Methods inherited from class java.lang.Object
`clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

Constructor Detail

### NamespaceMaintainer

    public NamespaceMaintainer(EventIterator base,
                               NamePool namePool)

  Create a namespace context for a pull-events pipeline

  Parameters:
    `base` - the previous stage in the pipeline, from which events are read
    `namePool` - the NamePool

Method Detail

### isFlatSequence

    public boolean isFlatSequence()

  Determine whether the EventIterator returns a flat sequence of events, or whether it can return nested event iterators

  Specified by:
    `isFlatSequence` in interface `EventIterator`
  Returns:
    true if the next() method is guaranteed never to return an EventIterator

### next

    public PullEvent next()
                   throws XPathException

  Get the next event in the sequence

  Specified by:
    `next` in interface `EventIterator`
  Returns:
    the next event, or null when the sequence is exhausted. Note that since an EventIterator is itself a PullEvent, this method may return a nested iterator.
  Throws:
    `XPathException` - if a dynamic evaluation error occurs

### getURICode

    protected short getURICode(short prefixCode)

  Get the URI code corresponding to a given prefix code, by searching the in-scope namespaces. This is a service provided to subclasses.

  Parameters:
    `prefixCode` - the 16-bit prefix code required
  Returns:
    the 16-bit URI code, or -1 if the prefix is not found

### getURIForPrefix

    public String getURIForPrefix(String prefix,
                                  boolean useDefault)

  Get the namespace URI corresponding to a given prefix. Return null if the prefix is not in scope.

  Specified by:
    `getURIForPrefix` in interface `NamespaceResolver`
  Parameters:
    `prefix` - the namespace prefix
    `useDefault` - true if the default namespace is to be used when the prefix is ""
  Returns:
    the uri for the namespace, or null if the prefix is not in scope

### iteratePrefixes

    public Iterator iteratePrefixes()

  Get an iterator over all the prefixes declared in this namespace context. This will include the default namespace (prefix="") and the XML namespace where appropriate

  Specified by:
    `iteratePrefixes` in interface `NamespaceResolver`

Copyright (c) 2004-2010 Saxonica Limited. All rights reserved.