Package net.sf.saxon.value
Class EmptySequence<T extends Item>
- java.lang.Object
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- net.sf.saxon.value.Value<T>
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- net.sf.saxon.value.EmptySequence<T>
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- All Implemented Interfaces:
GroundedValue<T>
,ValueRepresentation<T>
public final class EmptySequence<T extends Item> extends Value<T> implements GroundedValue<T>
An EmptySequence object represents a sequence containing no members.
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Field Summary
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Fields inherited from class net.sf.saxon.value.Value
INDETERMINATE_ORDERING
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Fields inherited from interface net.sf.saxon.om.ValueRepresentation
EMPTY_VALUE_ARRAY
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Method Summary
All Methods Static Methods Instance Methods Concrete Methods Modifier and Type Method Description Item
asItem()
Return the value in the form of an Itemboolean
effectiveBooleanValue()
Get the effective boolean value - always falseboolean
equals(java.lang.Object other)
Is this expression the same as another expression?int
getCardinality()
Determine the static cardinalitystatic <T extends Item>
EmptySequence<T>getInstance()
Get the implicit instance of this classItemType
getItemType(TypeHierarchy th)
Determine the item typeint
getLength()
Get the length of the sequenceint
hashCode()
T
itemAt(int n)
Get the n'th item in the sequence (starting from 0).SequenceIterator<T>
iterate()
Return an iteration over the sequenceGroundedValue<T>
subsequence(int min, int length)
Get a subsequence of the valuejava.lang.String
toString()
Returns a string representation of the object.-
Methods inherited from class net.sf.saxon.value.Value
asItem, asIterator, asValue, checkPermittedContents, convertToJava, fromItem, getCanonicalLexicalRepresentation, getIterator, getSchemaComparable, getSequenceLength, getStringValue, getStringValueCS, isIdentical, process, reduce
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Methods inherited from class java.lang.Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait
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Methods inherited from interface net.sf.saxon.om.ValueRepresentation
getStringValue, getStringValueCS
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Method Detail
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getInstance
public static <T extends Item> EmptySequence<T> getInstance()
Get the implicit instance of this class- Returns:
- the singular instances of this class: an empty sequence
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iterate
public SequenceIterator<T> iterate()
Return an iteration over the sequence
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asItem
public Item asItem()
Return the value in the form of an Item
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getItemType
public ItemType getItemType(TypeHierarchy th)
Determine the item type- Overrides:
getItemType
in classValue<T extends Item>
- 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<T extends Item>
- Returns:
- the cardinality
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getLength
public final int getLength()
Get the length of the sequence
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equals
public boolean equals(java.lang.Object other)
Is this expression the same as another expression?
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effectiveBooleanValue
public boolean effectiveBooleanValue()
Get the effective boolean value - always false- Overrides:
effectiveBooleanValue
in classValue<T extends Item>
- Returns:
- the effective boolean value
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itemAt
public T itemAt(int n)
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<T extends Item>
- Overrides:
itemAt
in classValue<T extends Item>
- 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
public GroundedValue<T> subsequence(int min, int length)
Get a subsequence of the value- Specified by:
subsequence
in interfaceGroundedValue<T extends Item>
- 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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toString
public java.lang.String toString()
Returns a string representation of the object.- Overrides:
toString
in classjava.lang.Object
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