Package net.sf.saxon.value
Class EmptySequence
java.lang.Object
net.sf.saxon.value.Value
net.sf.saxon.value.EmptySequence
- All Implemented Interfaces:
Serializable
,SequenceIterable
,GroundedValue
,ValueRepresentation
An EmptySequence object represents a sequence containing no members.
- See Also:
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Field Summary
Fields inherited from class net.sf.saxon.value.Value
EMPTY_CLASS_ARRAY, INDETERMINATE_ORDERING
Fields inherited from interface net.sf.saxon.om.ValueRepresentation
EMPTY_VALUE_ARRAY
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Method Summary
Modifier and TypeMethodDescriptionasItem()
Return the value in the form of an Itemboolean
Get the effective boolean value - always falseboolean
Is this expression the same as another expression?int
Determine the static cardinalitystatic EmptySequence
Get the implicit instance of this classDetermine the item typefinal int
Get the length of the sequenceint
hashCode()
itemAt
(int n) Get the n'th item in the sequence (starting from 0).iterate()
Return an iteration over the sequencesubsequence
(int min, int length) Get a subsequence of the valueMethods inherited from class net.sf.saxon.value.Value
asItem, asIterator, asValue, checkPermittedContents, convertToJava, fromItem, getCanonicalLexicalRepresentation, getIterator, getSchemaComparable, getStringValue, getStringValueCS, iterate, makeQNameValue, process, reduce, stringToNumber, toString
Methods inherited from class java.lang.Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait
Methods inherited from interface net.sf.saxon.om.ValueRepresentation
getStringValue, getStringValueCS
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Method Details
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getInstance
Get the implicit instance of this class -
iterate
Return an iteration over the sequence -
asItem
Return the value in the form of an Item -
getItemType
Determine the item type- Overrides:
getItemType
in classValue
- Parameters:
th
- the type hierarchy cache- Returns:
- for the default implementation: AnyItemType (not known)
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getCardinality
public int getCardinality()Determine the static cardinality- Overrides:
getCardinality
in classValue
- Returns:
- the cardinality
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getLength
public final int getLength()Get the length of the sequence -
equals
Is this expression the same as another expression?- Overrides:
equals
in classValue
- Throws:
ClassCastException
- if the values are not comparable
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hashCode
public int hashCode() -
effectiveBooleanValue
public boolean effectiveBooleanValue()Get the effective boolean value - always false- Overrides:
effectiveBooleanValue
in classValue
- Returns:
- the effective boolean value
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itemAt
Get the n'th item in the sequence (starting from 0). This is defined for all Values, but its real benefits come for a sequence Value stored extensionally (or for a MemoClosure, once all the values have been read)- Specified by:
itemAt
in interfaceGroundedValue
- Overrides:
itemAt
in classValue
- Parameters:
n
- position of the required item, counting from zero.- Returns:
- the n'th item in the sequence, where the first item in the sequence is numbered zero. If n is negative or >= the length of the sequence, returns null.
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subsequence
Get a subsequence of the value- Specified by:
subsequence
in interfaceGroundedValue
- Parameters:
min
- the index of the first item to be included in the result, counting from zero. A negative value is taken as zero. If the value is beyond the end of the sequence, an empty sequence is returnedlength
- the number of items to be included in the result. Specify Integer.MAX_VALUE to get the subsequence up to the end of the base sequence. If the value is negative, an empty sequence is returned. If the value goes off the end of the sequence, the result returns items up to the end of the sequence- Returns:
- the required subsequence. If min is
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