SortedIterator

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

All Implemented Interfaces:

LastPositionFinder, Sortable, SequenceIterator, LookaheadIterator

Direct Known Subclasses:

SortedGroupIterator
```
public class SortedIterator
extends Object
implements SequenceIterator, LastPositionFinder, LookaheadIterator, Sortable
```
Class to do a sorted iteration

Field Summary

Fields
Modifier and Type	Field and Description
`protected SequenceIterator`	`base`
`protected AtomicComparer[]`	`comparators`
`protected XPathContext`	`context`
`protected int`	`count`
`protected int`	`position`
`protected SortKeyEvaluator`	`sortKeyEvaluator`
`protected ObjectToBeSorted[]`	`values`

Fields inherited from interface net.sf.saxon.om.SequenceIterator
GROUNDED, LAST_POSITION_FINDER, LOOKAHEAD

Constructor Summary

Constructors
Constructor and Description
`SortedIterator(XPathContext context, SequenceIterator base, SortKeyEvaluator sortKeyEvaluator, AtomicComparer[] comparators, boolean createNewContext)` Create a sorted iterator

Method Summary

Methods
Modifier and Type	Method and Description
`protected void`	`buildArray()` Create an array holding the items to be sorted and the values of their sort keys
`void`	`close()` Close the iterator.
`int`	`compare(int a, int b)` Compare two items in sorted sequence (needed to implement the Sortable interface)
`Item`	`current()` Get the current value in the sequence (the one returned by the most recent call on next()).
`SequenceIterator`	`getAnother()` Get another SequenceIterator that iterates over the same items as the original, but which is repositioned at the start of the sequence.
`int`	`getLength()` Get the last position (that is, the number of items in the sequence).
`int`	`getProperties()` Get properties of this iterator, as a bit-significant integer.
`boolean`	`hasNext()` Determine whether there are more items to come.
`Item`	`next()` Get the next item, in sorted order
`int`	`position()` Get the current position.
`void`	`setHostLanguage(int language)` Set the host language
`void`	`swap(int a, int b)` Swap two items (needed to implement the Sortable interface)

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

- Field Detail
  - base
```
protected SequenceIterator base
```
  - sortKeyEvaluator
```
protected SortKeyEvaluator sortKeyEvaluator
```
  - comparators
```
protected AtomicComparer[] comparators
```
  - values
```
protected ObjectToBeSorted[] values
```
  - count
```
protected int count
```
  - position
```
protected int position
```
  - context
```
protected XPathContext context
```
- Constructor Detail
  - SortedIterator
```
public SortedIterator(XPathContext context,
              SequenceIterator base,
              SortKeyEvaluator sortKeyEvaluator,
              AtomicComparer[] comparators,
              boolean createNewContext)
```
    Create a sorted iterator
    
    Parameters:
    context - the dynamic XPath evaluation context
    base - an iterator over the sequence to be sorted
    sortKeyEvaluator - an object that allows the n'th sort key for a given item to be evaluated
    comparators - an array of AtomicComparers, one for each sort key, for comparing sort key values
    createNewContext -
- Method Detail
  - setHostLanguage
```
public void setHostLanguage(int language)
```
    Set the host language
    
    Parameters:
    language - the host language (for example Configuration.XQUERY)
  - hasNext
```
public boolean hasNext()
```
    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 bit setting SequenceIterator.LOOKAHEAD
    
    Specified by:
    
    hasNext in interface LookaheadIterator
    
    Returns:
    true if there are more items in the sequence
  - next
```
public Item next()
          throws XPathException
```
    Get the next item, in sorted order
    
    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
  - current
```
public Item current()
```
    Description copied from interface: SequenceIterator
    
    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.
    
    Specified by:
    
    current in interface SequenceIterator
    
    Returns:
    the current item, the one most recently returned by a call on next(). Returns null if next() has not been called, or if the end of the sequence has been reached.
  - position
```
public int position()
```
    Description copied from interface: SequenceIterator
    
    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.
    
    Specified by:
    
    position in interface SequenceIterator
    
    Returns:
    the current position, the position of the item returned by the most recent call of next(). This is 1 after next() has been successfully called once, 2 after it has been called twice, and so on. If next() has never been called, the method returns zero. If the end of the sequence has been reached, the value returned will always be <= 0; the preferred value is -1.
  - 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.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
  - 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.
    (Currently, closing an iterator is important only 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 SequenceIterator
  - getAnother
```
public SequenceIterator getAnother()
                            throws XPathException
```
    Description copied from interface: SequenceIterator
    
    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.
    
    Some implementations of this method may regenerate the input sequence, creating new nodes with different identity from the original. This is not recommended, but is hard to prevent. This causes no problem for the primary usage of this method to support the last() function, but it has been known to cause trouble in other situations.
    
    Specified by:
    
    getAnother in interface SequenceIterator
    
    Returns:
    a SequenceIterator that iterates over the same items, positioned before the first item
    
    Throws:
    
    XPathException - if any error occurs
  - getProperties
```
public int 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.GROUNDED, SequenceIterator.LAST_POSITION_FINDER, and SequenceIterator.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.
  - buildArray
```
protected void buildArray()
                   throws XPathException
```
    Create an array holding the items to be sorted and the values of their sort keys
    
    Throws:
    
    XPathException
  - compare
```
public int compare(int a,
          int b)
```
    Compare two items in sorted sequence (needed to implement the Sortable interface)
    
    Specified by:
    
    compare in interface Sortable
    
    Returns:
    <0 if obj[a]0 if obj[a]>obj[b]
  - swap
```
public void swap(int a,
        int b)
```
    Swap two items (needed to implement the Sortable interface)
    
    Specified by:
    
    swap in interface Sortable

Class SortedIterator

Field Summary

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

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

base

sortKeyEvaluator

comparators

values

count

position

context

Constructor Detail

SortedIterator

Method Detail

setHostLanguage

hasNext

next

current

position

getLength

close

getAnother

getProperties

buildArray

compare

swap