net.sf.saxon.value

Class EmptySequence

public final class EmptySequence extends Value implements GroundedValue

An EmptySequence object represents a sequence containing no members.
Method Summary
ItemasItem()
Return the value in the form of an Item
booleaneffectiveBooleanValue()
Get the effective boolean value - always false
booleanequals(Object other)
Is this expression the same as another expression?
intgetCardinality()
Determine the static cardinality
static EmptySequencegetInstance()
Get the implicit instance of this class
ItemTypegetItemType(TypeHierarchy th)
Determine the item type
intgetLength()
Get the length of the sequence
inthashCode()
ItemitemAt(int n)
Get the n'th item in the sequence (starting from 0).
SequenceIteratoriterate()
Return an iteration over the sequence
GroundedValuesubsequence(int min, int length)
Get a subsequence of the value

Method Detail

asItem

public Item asItem()
Return the value in the form of an Item

Returns: the value in the form of an Item

effectiveBooleanValue

public boolean effectiveBooleanValue()
Get the effective boolean value - always false

equals

public boolean equals(Object other)
Is this expression the same as another expression?

Throws: ClassCastException if the values are not comparable

getCardinality

public int getCardinality()
Determine the static cardinality

getInstance

public static EmptySequence getInstance()
Get the implicit instance of this class

getItemType

public ItemType getItemType(TypeHierarchy th)
Determine the item type

Parameters: th the type hierarchy cache

getLength

public final int getLength()
Get the length of the sequence

Returns: always 0 for an empty sequence

hashCode

public int hashCode()

itemAt

public Item 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)

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.

iterate

public SequenceIterator iterate()
Return an iteration over the sequence

subsequence

public GroundedValue subsequence(int min, int length)
Get a subsequence of the value

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 returned length 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