Package net.sf.saxon.value
Class SingletonItem<T extends Item>
java.lang.Object
net.sf.saxon.value.Value<T>
net.sf.saxon.value.SingletonItem<T>
- All Implemented Interfaces:
GroundedValue<T>
,ValueRepresentation<T>
A value that is a sequence containing zero or one items. Used only for items that are not atomic values
(that is, nodes, and function items)
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Field Summary
FieldsFields inherited from class net.sf.saxon.value.Value
INDETERMINATE_ORDERING
Fields inherited from interface net.sf.saxon.om.ValueRepresentation
EMPTY_VALUE_ARRAY
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Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptionasItem()
Return the value in the form of an Itemboolean
Get the effective boolean valueint
Determine the static cardinalityDetermine the data type of the items in the expression.int
Get the length of the sequenceConvert the value to a string, using the serialization rules.itemAt
(int n) Get the n'th item in the sequence (starting from 0).iterate()
Return an enumeration of this nodeset value.void
process
(XPathContext context) Process the instruction, without returning any tail callssubsequence
(int start, int length) Get a subsequence of the valueMethods inherited from class net.sf.saxon.value.Value
asItem, asIterator, asValue, checkPermittedContents, convertToJava, equals, fromItem, getCanonicalLexicalRepresentation, getIterator, getSchemaComparable, getSequenceLength, getStringValueCS, hashCode, isIdentical, reduce
Methods inherited from class java.lang.Object
clone, finalize, getClass, notify, notifyAll, toString, wait, wait, wait
Methods inherited from interface net.sf.saxon.om.ValueRepresentation
getStringValueCS
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Field Details
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item
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Constructor Details
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SingletonItem
Create a node-set containing zero or one nodes- Parameters:
item
- The node or function-item to be contained in the node-set, or null if the sequence is to be empty
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Method Details
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asItem
Return the value in the form of an Item -
process
Process the instruction, without returning any tail calls- Overrides:
process
in classValue<T extends Item>
- Parameters:
context
- The dynamic context, giving access to the current node, the current variables, etc.- Throws:
XPathException
- if an error occurs (for example if the value is a closure that needs to be evaluated)
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getItemType
Determine the data type of the items in the expression. This method determines the most precise type that it can, because it is called when testing that the node conforms to a required type.- Overrides:
getItemType
in classValue<T extends Item>
- Parameters:
th
- the type hierarchy cache- Returns:
- the most precise possible type of the node.
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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 int getLength()Get the length of the sequence -
itemAt
Get the n'th item in the sequence (starting from 0). This is defined for all SequenceValues, but its real benefits come for a SequenceValue 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
Get a subsequence of the value- Specified by:
subsequence
in interfaceGroundedValue<T extends Item>
- Parameters:
start
- 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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iterate
Return an enumeration of this nodeset value. -
effectiveBooleanValue
public boolean effectiveBooleanValue()Get the effective boolean value- Overrides:
effectiveBooleanValue
in classValue<T extends Item>
- Returns:
- the effective boolean value
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getStringValue
Convert the value to a string, using the serialization rules. For atomic values this is the same as a cast; for sequence values it gives a space-separated list. For QNames and NOTATIONS, or lists containing them, it fails.- Specified by:
getStringValue
in interfaceValueRepresentation<T extends Item>
- Overrides:
getStringValue
in classValue<T extends Item>
- Returns:
- the result of converting the value to a string
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