Package net.sf.saxon.value
Class SequenceExtent
java.lang.Object
net.sf.saxon.value.Value
net.sf.saxon.value.SequenceExtent
- All Implemented Interfaces:
Serializable
,Expression
,ValueRepresentation
A sequence value implemented extensionally. That is, this class represents a sequence
by allocating memory to each item in the sequence.
- See Also:
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Field Summary
Fields inherited from class net.sf.saxon.value.Value
EMPTY_CLASS_ARRAY
Fields inherited from interface net.sf.saxon.expr.Expression
EVALUATE_METHOD, ITERATE_METHOD, PROCESS_METHOD
Fields inherited from interface net.sf.saxon.om.ValueRepresentation
EMPTY_VALUE_ARRAY
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Constructor Summary
ConstructorsConstructorDescriptionSequenceExtent
(List list) Construct a SequenceExtent from a List.SequenceExtent
(Item[] items) Construct an sequence from an array of items.SequenceExtent
(Item[] value, int start, int length) Construct a SequenceExtent from part of an array of itemsConstruct a sequence containing all the items in a SequenceIterator.SequenceExtent
(SequenceExtent ext, int start, int length) Construct a SequenceExtent as a view of another SequenceExtent -
Method Summary
Modifier and TypeMethodDescriptionboolean
effectiveBooleanValue
(XPathContext context) Get the effective boolean valueint
Determine the cardinalityint
An implementation of Expression must provide at least one of the methods evaluateItem(), iterate(), or process().Get the (lowest common) item typeint
Get the number of items in the sequenceitemAt
(int n) Get the n'th item in the sequence (starting with 0 as the first item)iterate
(XPathContext context) Return an iterator over this sequence.static ValueRepresentation
Factory method to make a Value holding the contents of any SequenceIteratorreduce()
Reduce a value to its simplest form.Return an enumeration of this sequence in reverse order (used for reverse axes)simplify()
Simplify this SequenceExtentvoid
swap
(int a, int b) Swap two items (needed to support sorting)Methods inherited from class net.sf.saxon.value.Value
asItem, asIterator, asValue, checkPermittedContents, convert, convertJavaObjectToXPath, convertToJava, display, equals, evaluateAsString, evaluateItem, getDependencies, getIterator, getParentExpression, getSpecialProperties, getStringValue, getStringValueCS, hashCode, iterateSubExpressions, makeQNameValue, optimize, process, promote, simplify, stringToNumber, toString, typeCheck
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Constructor Details
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SequenceExtent
Construct an sequence from an array of items. Note, the array of items is used as is, which means the caller must not subsequently change its contents.- Parameters:
items
- the array of items to be included in the sequence
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SequenceExtent
Construct a SequenceExtent from part of an array of items- Parameters:
value
- The arraystart
- zero-based offset of the first item in the array that is to be included in the new SequenceExtentlength
- The number of items in the new SequenceExtent
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SequenceExtent
Construct a SequenceExtent as a view of another SequenceExtent- Parameters:
ext
- The existing SequenceExtentstart
- zero-based offset of the first item in the existing SequenceExtent that is to be included in the new SequenceExtentlength
- The number of items in the new SequenceExtent
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SequenceExtent
Construct a SequenceExtent from a List. The members of the list must all be Items- Parameters:
list
- the list of items to be included in the sequence
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SequenceExtent
Construct a sequence containing all the items in a SequenceIterator.- Parameters:
iter
- The supplied sequence of items. This must be positioned at the start, so that hasNext() returns true if there are any nodes in the node-set, and next() returns the first node.- Throws:
XPathException
- if reading the items using the SequenceIterator raises an error
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Method Details
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makeSequenceExtent
Factory method to make a Value holding the contents of any SequenceIterator- Throws:
XPathException
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getImplementationMethod
public int getImplementationMethod()An implementation of Expression must provide at least one of the methods evaluateItem(), iterate(), or process(). This method indicates which of these methods is preferred. -
simplify
Simplify this SequenceExtent -
reduce
Reduce a value to its simplest form. If the value is a closure or some other form of deferred value such as a FunctionCallPackage, then it is reduced to a SequenceExtent. If it is a SequenceExtent containing a single item, then it is reduced to that item. One consequence that is exploited by class FilterExpression is that if the value is a singleton numeric value, then the result will be an instance of NumericValue -
getLength
public int getLength()Get the number of items in the sequence -
getCardinality
public int getCardinality()Determine the cardinality- Specified by:
getCardinality
in interfaceExpression
- Overrides:
getCardinality
in classValue
- Returns:
- the cardinality of the sequence, using the constants defined in net.sf.saxon.value.Cardinality
- See Also:
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getItemType
Get the (lowest common) item type- Specified by:
getItemType
in interfaceExpression
- Overrides:
getItemType
in classValue
- Parameters:
th
-- Returns:
- integer identifying an item type to which all the items in this sequence conform
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itemAt
Get the n'th item in the sequence (starting with 0 as the first item) -
swap
public void swap(int a, int b) Swap two items (needed to support sorting)- Parameters:
a
- the position of the first item to be swappedb
- the position of the second item to be swapped
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iterate
Return an iterator over this sequence.- Parameters:
context
- dynamic evaluation context; not used in this implementation of the method- Returns:
- the required SequenceIterator, positioned at the start of the sequence
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reverseIterate
Return an enumeration of this sequence in reverse order (used for reverse axes)- Returns:
- an AxisIterator that processes the items in reverse order
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effectiveBooleanValue
Get the effective boolean value- Specified by:
effectiveBooleanValue
in interfaceExpression
- Overrides:
effectiveBooleanValue
in classValue
- Parameters:
context
- The context in which the expression is to be evaluated- Returns:
- the effective boolean value
- Throws:
XPathException
- if any dynamic error occurs evaluating the expression
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