Package net.sf.saxon.expr.sort
Class SortedIterator
- java.lang.Object
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- net.sf.saxon.expr.sort.SortedIterator
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- All Implemented Interfaces:
java.io.Closeable
,java.lang.AutoCloseable
,LastPositionFinder
,SequenceIterator
,LookaheadIterator
- Direct Known Subclasses:
SortedGroupIterator
public class SortedIterator extends java.lang.Object implements SequenceIterator, LastPositionFinder, LookaheadIterator
Class to do a sorted iteration
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Field Summary
Fields Modifier and Type Field Description protected AtomicComparer[]
comparators
protected XPathContext
context
protected int
count
protected int
position
protected SortKeyEvaluator
sortKeyEvaluator
protected ObjectToBeSorted[]
values
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Constructor Summary
Constructors Constructor Description SortedIterator(XPathContext context, SequenceIterator base, SortKeyEvaluator sortKeyEvaluator, AtomicComparer[] comparators, boolean createNewContext)
Create a sorted iterator
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description protected void
buildArray()
Create an array holding the items to be sorted and the values of their sort keysprotected SequenceIterator
getBaseIterator()
int
getLength()
Get the last position (that is, the number of items in the sequence).boolean
hasNext()
Determine whether there are more items to come.Item
next()
Get the next item, in sorted ordervoid
setHostLanguage(HostLanguage language)
Set the host languageboolean
supportsGetLength()
Ask whether this iterator supports use of thegetLength()
method.boolean
supportsHasNext()
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
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Methods inherited from interface net.sf.saxon.om.SequenceIterator
close
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Field Detail
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sortKeyEvaluator
protected SortKeyEvaluator sortKeyEvaluator
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comparators
protected AtomicComparer[] comparators
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values
protected ObjectToBeSorted[] values
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count
protected int count
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position
protected int position
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context
protected final XPathContext context
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Constructor Detail
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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 Detail
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getBaseIterator
protected SequenceIterator getBaseIterator()
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setHostLanguage
public void setHostLanguage(HostLanguage language)
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
public Item 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
protected void buildArray() throws XPathException
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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