| net.sf.saxon.om.SequenceIterator
All known Subclasses: net.sf.saxon.expr.MappingIterator, net.sf.saxon.expr.UnionEnumeration, net.sf.saxon.expr.StringTokenIterator, net.sf.saxon.om.ClosingIterator, net.sf.saxon.expr.DifferenceEnumeration, net.sf.saxon.sort.DocumentOrderIterator, net.sf.saxon.instruct.RegexIterator, net.sf.saxon.expr.PositionIterator, net.sf.saxon.expr.IntersectionEnumeration, net.sf.saxon.expr.AppendIterator, net.sf.saxon.sort.SortedIterator, net.sf.saxon.expr.FilterIterator,
| SequenceIterator | | public interface SequenceIterator (Code) | | A SequenceIterator is used to iterate over any XPath 2 sequence (of values or nodes).
To get the next item in a sequence, call next(); if this returns null, you've
reached the end of the sequence.
A SequenceIterator keeps track of the current Item and the current position.
The objects returned by the SequenceIterator will always be either nodes
(class NodeInfo) or singleton values (class AtomicValue): these are represented
collectively by the interface Item.
This interface forms part of the public Saxon API. The JavaDoc "since" flag is used from
release 8.4 onwards to indicate methods that are considered to be a stable part
of the API. Methods without a "since" flag should not be regarded as a stable part
of the API.
Note that the stability of this interface applies to classes that use the interface,
not to classes that implement it. The interface may be extended in future to add new methods.
author:
Michael H. Kay
since:
8.4 |
| Field Summary | |
| final public static int | ATOMIZABLE
| | final public static int | GROUNDED
Property value: the iterator is "grounded". | | final public static int | LAST_POSITION_FINDER
Property value: the iterator knows the number of items that it will deliver. | | final public static int | LOOKAHEAD
Property value: the iterator knows whether there are more items still to come. |
| Method Summary | |
| public Item | current()
Get the current value in the sequence (the one returned by the
most recent call on next()). | | public SequenceIterator | getAnother()
Get another SequenceIterator that iterates over the same items as the original,
but which is repositioned at the start of the sequence.
This method allows access to all the items in the sequence without disturbing the
current position of the iterator. | | public int | getProperties()
Get properties of this iterator, as a bit-significant integer.
the properties of this iterator. | | public Item | next()
Get the next item in the sequence. | | public int | position()
Get the current position. |
| ATOMIZABLE | | final public static int ATOMIZABLE(Code) | | Property value: the iterator supports a setAtomizing() method, which requests (but does not require)
the iterator to atomize any nodes and return their typed values
|
| GROUNDED | | final public static int GROUNDED(Code) | | Property value: the iterator is "grounded". This means that (a) the
iterator must be an instance of
GroundedIterator , and (b) the
implementation of the materialize() method must be efficient (in particular,
it should not involve the creation of new objects)
|
| LAST_POSITION_FINDER | | final public static int LAST_POSITION_FINDER(Code) | | Property value: the iterator knows the number of items that it will deliver.
This means that (a) the iterator must be an instance of
net.sf.saxon.expr.LastPositionFinder ,
and (b) the implementation of the getLastPosition() method must be efficient (in particular,
it should take constant time, rather than time proportional to the length of the sequence)
|
| LOOKAHEAD | | final public static int LOOKAHEAD(Code) | | Property value: the iterator knows whether there are more items still to come. This means
that (a) the iterator must be an instance of
LookaheadIterator , and (b) the
implementation of the hasNext() method must be efficient (more efficient than the client doing
it)
|
| current | | public Item current()(Code) | | Get the current value in the sequence (the one returned by the
most recent call on next()). This will be null before the first
call of next(). This method does not change the state of the iterator.
the current item, the one most recently returned by a call onnext(). Returns null if next() has not been called, or if the endof the sequence has been reached.
since:
8.4 |
| getAnother | | public SequenceIterator getAnother() throws XPathException(Code) | | Get another SequenceIterator that iterates over the same items as the original,
but which is repositioned at the start of the sequence.
This method allows access to all the items in the sequence without disturbing the
current position of the iterator. Internally, its main use is in evaluating the last()
function.
This method does not change the state of the iterator.
exception:
XPathException - if any error occurs a SequenceIterator that iterates over the same items,positioned before the first item
since:
8.4 |
| getProperties | | public int getProperties()(Code) | | Get properties of this iterator, as a bit-significant integer.
the properties of this iterator. This will be some combination ofproperties such as GROUNDED, LAST_POSITION_FINDER,and LOOKAHEAD. It is alwaysacceptable to return the value zero, indicating that there are no known special properties.It is acceptable for the properties of the iterator to change depending on its state.
since:
8.6 |
| next | | public Item next() throws XPathException(Code) | | Get the next item in the sequence. This method changes the state of the
iterator, in particular it affects the result of subsequent calls of
position() and current().
throws:
XPathException - if an error occurs retrieving the next item the next item, or null if there are no more items. Once a callon next() has returned null, no further calls should be made. The preferredaction for an iterator if subsequent calls on next() are made is to returnnull again, and all implementations within Saxon follow this rule.
since:
8.4 |
| position | | public int position()(Code) | | Get the current position. This will usually be zero before the first call
on next(), otherwise it will be the number of times that next() has
been called. Once next() has returned null, the preferred action is
for subsequent calls on position() to return -1, but not all existing
implementations follow this practice. (In particular, the EmptyIterator
is stateless, and always returns 0 as the value of position(), whether
or not next() has been called.)
This method does not change the state of the iterator.
the current position, the position of the item returned by themost recent call of next(). This is 1 after next() has been successfullycalled once, 2 after it has been called twice, and so on. If next() hasnever been called, the method returns zero. If the end of the sequencehas been reached, the value returned will always be <= 0; the preferredvalue is -1.
since:
8.4 |
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