Package net.sf.saxon.expr.sort
Class SortedIterator
java.lang.Object
net.sf.saxon.expr.sort.SortedIterator
- All Implemented Interfaces:
Closeable
,AutoCloseable
,LastPositionFinder
,SequenceIterator
,LookaheadIterator
- Direct Known Subclasses:
SortedGroupIterator
public class SortedIterator
extends Object
implements SequenceIterator, LastPositionFinder, LookaheadIterator
Class to do a sorted iteration
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Field Summary
FieldsModifier and TypeFieldDescriptionprotected AtomicComparer[]
protected final XPathContext
protected int
protected int
protected SortKeyEvaluator
protected ObjectToBeSorted[]
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Constructor Summary
ConstructorsConstructorDescriptionSortedIterator
(XPathContext context, SequenceIterator base, SortKeyEvaluator sortKeyEvaluator, AtomicComparer[] comparators, boolean createNewContext) Create a sorted iterator -
Method Summary
Modifier and TypeMethodDescriptionprotected void
Create an array holding the items to be sorted and the values of their sort keysprotected SequenceIterator
int
Get the last position (that is, the number of items in the sequence).boolean
hasNext()
Determine whether there are more items to come.next()
Get the next item, in sorted ordervoid
setHostLanguage
(HostLanguage language) Set the host languageboolean
Ask whether this iterator supports use of thegetLength()
method.boolean
Ask whether the hasNext() method can be called.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
close
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Field Details
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sortKeyEvaluator
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comparators
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values
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count
protected int count -
position
protected int position -
context
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Constructor Details
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SortedIterator
public SortedIterator(XPathContext context, SequenceIterator base, SortKeyEvaluator sortKeyEvaluator, AtomicComparer[] comparators, boolean createNewContext) Create a sorted iterator- Parameters:
context
- the dynamic XPath evaluation contextbase
- an iterator over the sequence to be sortedsortKeyEvaluator
- an object that allows the n'th sort key for a given item to be evaluatedcomparators
- an array of AtomicComparers, one for each sort key, for comparing sort key valuescreateNewContext
- true if sort keys are computed relative to the item being sorted (as in XSLT but not XQuery)
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Method Details
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getBaseIterator
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setHostLanguage
Set the host language- Parameters:
language
- the host language (for exampleHostLanguage.XQUERY
)
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supportsHasNext
public boolean supportsHasNext()Description copied from interface:LookaheadIterator
Ask whether the hasNext() method can be called. This method must be called before calling hasNext(), because some iterators implement this interface, but only support look-ahead under particular circumstances (this is usually because they delegate to another iterator)- Specified by:
supportsHasNext
in interfaceLookaheadIterator
- Returns:
- true if the
LookaheadIterator.hasNext()
method is available
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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 method
supportsHasNext()
returns true.- Specified by:
hasNext
in interfaceLookaheadIterator
- Returns:
- true if there are more items in the sequence
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next
Get the next item, in sorted order- Specified by:
next
in interfaceSequenceIterator
- 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.
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supportsGetLength
public boolean supportsGetLength()Ask whether this iterator supports use of thegetLength()
method. This method should always be called before callinggetLength()
, because an iterator that implements this interface may support use ofgetLength()
in some situations and not in others- Specified by:
supportsGetLength
in interfaceLastPositionFinder
- Returns:
- true if the
getLength()
method can be called to determine the length of the underlying sequence.
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getLength
public int getLength()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 theLastPositionFinder.supportsGetLength()
has been called and has returned true.- Specified by:
getLength
in interfaceLastPositionFinder
- Returns:
- the number of items in the sequence
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buildArray
Create an array holding the items to be sorted and the values of their sort keys- Throws:
XPathException
- if an error occurs for example in evaluating a sort key
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