com.saxonica.deploy
Class Tail

java.lang.Object
  net.sf.saxon.value.Value
      com.saxonica.deploy.Tail

All Implemented Interfaces:

Serializable, SequenceIterable, ValueRepresentation

public final class Tail
extends Value

A sequence value implemented as the trailing part of an underlying value

This class is currently used only in compiled queries

See Also:

Serialized Form

Field Summary

Fields inherited from class net.sf.saxon.value.Value

INDETERMINATE_ORDERING

Fields inherited from interface net.sf.saxon.om.ValueRepresentation

EMPTY_VALUE_ARRAY

Method Summary

int	getCardinality() Determine the cardinality
ItemType	getItemType(TypeHierarchy th) Get the (lowest common) item type.
int	getLength() Get the number of items in the sequence
Comparable	getSchemaComparable() Get a Comparable value that implements the XML Schema ordering comparison semantics for this value.
Item	itemAt(int n) Get the n'th item in the sequence (starting with 0 as the first item)
SequenceIterator	iterate() Return an iterator over this sequence.
static Value	make(Value value, int start) Static factory method
Value	reduce() Reduce a value to its simplest form.

Methods inherited from class net.sf.saxon.value.Value

asItem, asItem, asIterator, asValue, checkPermittedContents, convertToJava, effectiveBooleanValue, equals, fromItem, getCanonicalLexicalRepresentation, getIterator, getStringValue, getStringValueCS, isIdentical, iterate, process, stringToNumber

Methods inherited from class java.lang.Object

clone, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

make

public static Value make(Value value,
                         int start)

Static factory method

Parameters:

value - The underlying value

start - zero-based offset of the first item to be included

Returns:

the constructed value

reduce

public Value reduce()
             throws XPathException

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

Overrides:

reduce in class Value

Returns:

the value in simplified form

Throws:

XPathException

getLength

public int getLength()
              throws XPathException

Get the number of items in the sequence

Overrides:

getLength in class Value

Returns:

the number of items in the sequence

Throws:

XPathException

getCardinality

public int getCardinality()

Determine the cardinality

Overrides:

getCardinality in class Value

Returns:

the cardinality of the sequence, using the constants defined in net.sf.saxon.value.Cardinality

See Also:

Cardinality

getItemType

public ItemType getItemType(TypeHierarchy th)

Get the (lowest common) item type. This implementation simply returns the ItemType of the underlying sequence, even though the items included in the tail might belong to a narrower type

Overrides:

getItemType in class Value

Parameters:

th - the type hierarchy cache

Returns:

ItemType identifying an item type to which all the items in this sequence conform

itemAt

public Item itemAt(int n)
            throws XPathException

Get the n'th item in the sequence (starting with 0 as the first item)

Overrides:

itemAt in class Value

Parameters:

n - the position of the required item

Returns:

the n'th item in the sequence

Throws:

XPathException

iterate

public SequenceIterator iterate()
                         throws XPathException

Return an iterator over this sequence.

Specified by:

iterate in class Value

Returns:

the required SequenceIterator, positioned at the start of the sequence

Throws:

XPathException - if a dynamic error occurs. This is possible only in the case of values that are materialized lazily, that is, where the iterate() method leads to computation of an expression that delivers the values.

getSchemaComparable

public Comparable getSchemaComparable()

Get a Comparable value that implements the XML Schema ordering comparison semantics for this value. The default implementation returns "this", which ensures that comparisons between list values are handled by the equals() and compareTo() methods on this class itself. This is overridden for atomic values.

In the case of data types that are partially ordered, the returned Comparable extends the standard semantics of the compareTo() method by returning the value Value.INDETERMINATE_ORDERING when there is no defined order relationship between two given values.

Overrides:

getSchemaComparable in class Value

Returns:

a Comparable that follows XML Schema comparison rules