java.lang.Object
- net.sf.saxon.expr.sort.GroupAdjacentIterator

All Implemented Interfaces:

java.io.Closeable, java.lang.AutoCloseable, LastPositionFinder, GroupIterator, SequenceIterator, LookaheadIterator
```
public class GroupAdjacentIterator
extends java.lang.Object
implements GroupIterator, LastPositionFinder, LookaheadIterator
```
A GroupAdjacentIterator iterates over a sequence of groups defined by xsl:for-each-group group-adjacent="x". The groups are returned in order of first appearance.
Each step of this iterator advances to the first item of the next group, leaving the members of that group in a saved list.

Nested Class Summary
- Nested classes/interfaces inherited from interface net.sf.saxon.om.SequenceIterator
  SequenceIterator.Property

Constructor Summary

Constructors
Constructor	Description
`GroupAdjacentIterator(Expression select, Expression keyExpression, XPathContext baseContext, StringCollator collator, boolean composite)`

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`void`	`close()`	Close the iterator.
`AtomicSequence`	`getCurrentGroupingKey()`	Get the grouping key of the current group
`int`	`getLength()`	Get the last position (that is, the number of items in the sequence).
`java.util.EnumSet<SequenceIterator.Property>`	`getProperties()`	Get properties of this iterator, as a bit-significant integer.
`ManualGroupIterator`	`getSnapShot(XPathContext context)`	Get a sequence which is a snapshot of this sequence at the current position
`boolean`	`hasNext()`	Determine whether there are more items to come.
`SequenceIterator`	`iterateCurrentGroup()`	Get an iterator over the members of the current group, in population order.
`Item`	`next()`	Get the next item in the sequence.

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

Methods inherited from interface net.sf.saxon.om.SequenceIterator
forEachOrFail, materialize

- Constructor Detail
  - GroupAdjacentIterator
```
public GroupAdjacentIterator(Expression select,
                             Expression keyExpression,
                             XPathContext baseContext,
                             StringCollator collator,
                             boolean composite)
                      throws XPathException
```
    Throws:
    
    XPathException
- Method Detail
  - getLength
```
public int getLength()
              throws XPathException
```
    Description copied from interface: LastPositionFinder
    
    Get the last position (that is, the number of items in the sequence). This method is non-destructive: it does not change the state of the iterator. The result is undefined if the next() method of the iterator has already returned null. This method must not be called unless the result of getProperties() on the iterator includes the bit setting SequenceIterator.Property.LAST_POSITION_FINDER
    
    Specified by:
    
    getLength in interface LastPositionFinder
    
    Returns:
    
    the number of items in the sequence
    
    Throws:
    
    XPathException - if an error occurs evaluating the sequence in order to determine the number of items
  - getCurrentGroupingKey
```
public AtomicSequence getCurrentGroupingKey()
```
    Description copied from interface: GroupIterator
    
    Get the grouping key of the current group
    
    Specified by:
    
    getCurrentGroupingKey in interface GroupIterator
    
    Returns:
    
    the current grouping key in the case of group-by or group-adjacent, or null in the case of group-starting-with and group-ending-with
  - iterateCurrentGroup
```
public SequenceIterator iterateCurrentGroup()
```
    Description copied from interface: GroupIterator
    
    Get an iterator over the members of the current group, in population order. This must always be a clean iterator, that is, an iterator that starts at the first item of the group.
    
    Specified by:
    
    iterateCurrentGroup in interface GroupIterator
    
    Returns:
    
    an iterator over all the members of the current group, in population order.
  - hasNext
```
public boolean hasNext()
```
    Description copied from interface: LookaheadIterator
    
    Determine whether there are more items to come. Note that this operation is stateless and it is not necessary (or usual) to call it before calling next(). It is used only when there is an explicit need to tell if we are at the last element.
    This method must not be called unless the result of getProperties() on the iterator includes the property SequenceIterator.Property.LOOKAHEAD
    
    Specified by:
    
    hasNext in interface LookaheadIterator
    
    Returns:
    
    true if there are more items in the sequence
  - next
```
public Item next()
          throws XPathException
```
    Description copied from interface: SequenceIterator
    
    Get the next item in the sequence. This method changes the state of the iterator.
    
    Specified by:
    
    next in interface SequenceIterator
    
    Returns:
    
    the next item, or null if there are no more items. Once a call on next() has returned null, no further calls should be made. The preferred action for an iterator if subsequent calls on next() are made is to return null again, and all implementations within Saxon follow this rule.
    
    Throws:
    
    XPathException - if an error occurs retrieving the next item
  - close
```
public void close()
```
    Description copied from interface: SequenceIterator
    
    Close the iterator. This indicates to the supplier of the data that the client does not require any more items to be delivered by the iterator. This may enable the supplier to release resources. After calling close(), no further calls on the iterator should be made; if further calls are made, the effect of such calls is undefined.
    For example, the iterator returned by the unparsed-text-lines() function has a close() method that causes the underlying input stream to be closed, whether or not the file has been read to completion.
    
    Closing an iterator is important when the data is being "pushed" in another thread. Closing the iterator terminates that thread and means that it needs to do no additional work. Indeed, failing to close the iterator may cause the push thread to hang waiting for the buffer to be emptied.
    
    Specified by:
    
    close in interface java.lang.AutoCloseable
    
    Specified by:
    
    close in interface java.io.Closeable
    
    Specified by:
    
    close in interface SequenceIterator
  - getProperties
```
public java.util.EnumSet<SequenceIterator.Property> getProperties()
```
    Get properties of this iterator, as a bit-significant integer.
    
    Specified by:
    
    getProperties in interface SequenceIterator
    
    Returns:
    
    the properties of this iterator. This will be some combination of properties such as SequenceIterator.Property.GROUNDED, SequenceIterator.Property.LAST_POSITION_FINDER, and SequenceIterator.Property.LOOKAHEAD. It is always acceptable 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.
  - getSnapShot
```
public ManualGroupIterator getSnapShot(XPathContext context)
```
    Description copied from interface: GroupIterator
    
    Get a sequence which is a snapshot of this sequence at the current position
    
    Specified by:
    
    getSnapShot in interface GroupIterator

Class GroupAdjacentIterator

Nested Class Summary

Nested classes/interfaces inherited from interface net.sf.saxon.om.SequenceIterator

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Methods inherited from interface net.sf.saxon.om.SequenceIterator

Constructor Detail

GroupAdjacentIterator

Method Detail

getLength

getCurrentGroupingKey

iterateCurrentGroup

hasNext

next

close

getProperties

getSnapShot