Package net.sf.saxon.om

Class One<T extends Item>

java.lang.Object

net.sf.saxon.om.ZeroOrOne<T>

net.sf.saxon.om.One<T>

All Implemented Interfaces:

GroundedValue, Sequence

public class One<T extends Item>
extends ZeroOrOne<T>

A sequence containing exactly one item. The main use of this class is in declaring the expected arguments of reflexive method calls, where the use of One(T) rather than T emphasizes that the value must not be null/empty, and generates type-checking code to ensure that it is not empty.

To extract the wrapped item, use ZeroOrOne.head().

Constructor Summary

Constructors

Constructor	Description
One(T item)	Create an instance of the class

Method Summary

Modifier and Type	Method	Description
static One<BooleanValue>	bool(boolean value)	Convenience function to create a singleton boolean value
static One<DoubleValue>	dbl(double value)	Convenience function to create a singleton double value
static One<IntegerValue>	integer(long value)	Convenience function to create a singleton integer value
ConstrainedIterator<T>	iterate()	Return an iterator over this value.
static One<StringValue>	string(java.lang.String value)	Convenience function to create a singleton string value

Methods inherited from class net.sf.saxon.om.ZeroOrOne

effectiveBooleanValue, empty, getLength, getStringValue, getStringValueCS, head, itemAt, reduce, subsequence, toString

Methods inherited from class java.lang.Object

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

Methods inherited from interface net.sf.saxon.om.GroundedValue

asIterable, concatenate, containsNode, materialize, toShortString

Methods inherited from interface net.sf.saxon.om.Sequence

makeRepeatable

Constructor Detail

One

public One(T item)

Create an instance of the class

Parameters:

item - The single item to be contained in the sequence. Must not be null.

Throws:

java.lang.NullPointerException - if item is null.

Method Detail

iterate

public ConstrainedIterator<T> iterate()

Return an iterator over this value.

Specified by:

iterate in interface GroundedValue

Specified by:

iterate in interface Sequence

Overrides:

iterate in class ZeroOrOne<T extends Item>

Returns:

an iterator (meaning a Saxon SequenceIterator rather than a Java Iterator) over all the items in this Sequence.

bool

public static One<BooleanValue> bool(boolean value)

Convenience function to create a singleton boolean value

Parameters:

value - the boolean value

Returns:

the boolean value wrapped as a One<BooleanValue>

string

public static One<StringValue> string(java.lang.String value)

Convenience function to create a singleton string value

Parameters:

value - the string value.. If null, the result will represent a zero-length string

Returns:

the string value wrapped as a One<StringValue>

integer

public static One<IntegerValue> integer(long value)

Convenience function to create a singleton integer value

Parameters:

value - the integer value

Returns:

the integer value wrapped as a One<IntegerValue>

dbl

public static One<DoubleValue> dbl(double value)

Convenience function to create a singleton double value

Parameters:

value - the double value

Returns:

the double value wrapped as a One<DoubleValue>