net.sf.saxon.value

Class SequenceExtent

java.lang.Object

net.sf.saxon.value.SequenceExtent

All Implemented Interfaces:

GroundedValue, Sequence

Direct Known Subclasses:

OneOrMore

public class SequenceExtent
extends Object
implements GroundedValue

A sequence value implemented extensionally. That is, this class represents a sequence by allocating memory to each item in the sequence.

Constructor Summary

Constructors

Constructor and Description
SequenceExtent(Item[] items) Construct an sequence from an array of items.
SequenceExtent(List<? extends Item> list) Construct a SequenceExtent from a List.
SequenceExtent(SequenceExtent ext, int start, int length) Construct a SequenceExtent as a view of another SequenceExtent
SequenceExtent(SequenceIterator iter) Construct a sequence containing all the items in a SequenceIterator.

Method Summary

Methods

Modifier and Type	Method and Description
boolean	effectiveBooleanValue() Get the effective boolean value
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
String	getStringValue() Get the string value of this sequence.
CharSequence	getStringValueCS() Get the string value of this sequence.
Item	head() Get the first item in the sequence.
Item	itemAt(int n) Get the n'th item in the sequence (starting with 0 as the first item)
ListIterator	iterate() Return an iterator over this sequence.
static <T extends Item> GroundedValue	makeSequenceExtent(List<T> input) Factory method to make a Value holding the contents of any List of items
static GroundedValue	makeSequenceExtent(SequenceIterator iter) Factory method to make a Value holding the contents of any SequenceIterator
GroundedValue	reduce() Reduce the sequence to its simplest form.
UnfailingIterator	reverseIterate() Return an enumeration of this sequence in reverse order (used for reverse axes)
GroundedValue	subsequence(int start, int length) Get a subsequence of the value
String	toString()

Methods inherited from class java.lang.Object

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

Constructor Detail

SequenceExtent

public SequenceExtent(Item[] items)

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

SequenceExtent

public SequenceExtent(SequenceExtent ext,
              int start,
              int length)

Construct a SequenceExtent as a view of another SequenceExtent

Parameters:

ext - The existing SequenceExtent

start - zero-based offset of the first item in the existing SequenceExtent that is to be included in the new SequenceExtent

length - The number of items in the new SequenceExtent

SequenceExtent

public SequenceExtent(List<? extends Item> list)

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

SequenceExtent

public SequenceExtent(SequenceIterator iter)
               throws XPathException

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

Method Detail

makeSequenceExtent

public static GroundedValue makeSequenceExtent(SequenceIterator iter)
                                        throws XPathException

Factory method to make a Value holding the contents of any SequenceIterator

Parameters:

iter - a Sequence iterator that will be consumed to deliver the items in the sequence

Returns:

a ValueRepresentation holding the items delivered by the SequenceIterator. If the sequence is empty the result will be an instance of EmptySequence. If it is of length one, the result will be an Item. In all other cases, it will be an instance of SequenceExtent.

Throws:

XPathException - if an error occurs processing the values from the iterator.

makeSequenceExtent

public static <T extends Item> GroundedValue makeSequenceExtent(List<T> input)

Factory method to make a Value holding the contents of any List of items

Parameters:

input - a List containing the items in the sequence

Returns:

a ValueRepresentation holding the items in the list. If the sequence is empty the result will be an instance of EmptySequence. If it is of length one, the result will be an Item. In all other cases, it will be an instance of SequenceExtent.

getStringValue

public String getStringValue()
                      throws XPathException

Description copied from interface: GroundedValue

Get the string value of this sequence. The string value of an item is the result of applying the string() function. The string value of a sequence is the space-separated result of applying the string-join() function using a single space as the separator

Specified by:

getStringValue in interface GroundedValue

Returns:

the string value of the sequence.

Throws:

XPathException - if the sequence contains items that have no string value (for example, function items)

getStringValueCS

public CharSequence getStringValueCS()
                              throws XPathException

Description copied from interface: GroundedValue

Get the string value of this sequence. The string value of an item is the result of applying the string() function. The string value of a sequence is the space-separated result of applying the string-join() function using a single space as the separator

Specified by:

getStringValueCS in interface GroundedValue

Returns:

the string value of the sequence.

Throws:

XPathException - if the sequence contains items that have no string value (for example, function items)

head

public Item head()

Get the first item in the sequence.

Specified by:

head in interface GroundedValue

Specified by:

head in interface Sequence

Returns:

the first item in the sequence if there is one, or null if the sequence is empty

getLength

public int getLength()

Get the number of items in the sequence

Specified by:

getLength in interface GroundedValue

Returns:

the number of items in the sequence

getCardinality

public int getCardinality()

Determine the cardinality

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

Parameters:

th - the type hierarchy cache. If null, the returned value may be less precise

Returns:

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

itemAt

public Item itemAt(int n)

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

Specified by:

itemAt in interface GroundedValue

Parameters:

n - the position of the required item

Returns:

the n'th item in the sequence

iterate

public ListIterator iterate()

Return an iterator over this sequence.

Specified by:

iterate in interface GroundedValue

Specified by:

iterate in interface Sequence

Returns:

the required SequenceIterator, positioned at the start of the sequence

reverseIterate

public UnfailingIterator reverseIterate()

Return an enumeration of this sequence in reverse order (used for reverse axes)

Returns:

an AxisIterator that processes the items in reverse order

effectiveBooleanValue

public boolean effectiveBooleanValue()
                              throws XPathException

Get the effective boolean value

Specified by:

effectiveBooleanValue in interface GroundedValue

Returns:

the effective boolean value

Throws:

XPathException - if the sequence has no effective boolean value (for example a sequence of two integers)

subsequence

public GroundedValue subsequence(int start,
                        int length)

Get a subsequence of the value

Specified by:

subsequence in interface GroundedValue

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 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

toString

public String toString()

Overrides:

toString in class Object

reduce

public GroundedValue reduce()

Reduce the sequence to its simplest form. If the value is an empty sequence, the result will be EmptySequence.getInstance(). If the value is a single atomic value, the result will be an instance of AtomicValue. If the value is a single item of any other kind, the result will be an instance of One. Otherwise, the result will typically be unchanged.

Specified by:

reduce in interface GroundedValue

Returns:

the simplified sequence