net.sf.saxon.expr

Class UnionConstructorFunction

java.lang.Object

net.sf.saxon.om.AbstractItem

net.sf.saxon.functions.AbstractFunction

net.sf.saxon.expr.UnionConstructorFunction

All Implemented Interfaces:

PullEvent, Callable, Function, GroundedValue, Item, Sequence

Direct Known Subclasses:

UnionCastableFunction

public class UnionConstructorFunction
extends AbstractFunction

Function to perform a cast to a union type

Field Summary

Fields

Modifier and Type	Field and Description
protected boolean	allowEmpty
protected NamespaceResolver	resolver
protected UnionType	targetType

Constructor Summary

Constructors

Constructor and Description
UnionConstructorFunction(UnionType targetType, NamespaceResolver resolver, boolean allowEmpty) Create a cast expression to a union type

Method Summary

Methods

Modifier and Type	Method and Description
AtomicSequence	call(XPathContext context, Sequence[] args) Invoke the function
AtomicSequence	cast(AtomicValue value, XPathContext context) Method to perform the cast of an atomic value to a union type
int	getArity() Get the arity of the function
String	getDescription() Get a description of this function for use in error messages.
FunctionItemType	getFunctionItemType() Get the item type of the function item
StructuredQName	getFunctionName() Get the name of the function, or null if it is anonymous
NamespaceResolver	getNamespaceResolver() Get the namespace resolver that will be used to resolve any namespace-sensitive values (such as QNames) when casting
protected OperandRole	getOperandRole() Get the usage (in terms of streamability analysis) of the single operand
UnionType	getTargetType() Get the union type that is the target of this cast operation
boolean	isAllowEmpty() Ask whether the value of the operand is allowed to be empty

Methods inherited from class net.sf.saxon.functions.AbstractFunction

atomize, deepEquals, effectiveBooleanValue, export, getOperandRoles, getStringValue, getStringValueCS, isArray, isMap, optimize, simplify, typeCheck

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

getLength, head, itemAt, iterate, reduce, subsequence

Methods inherited from class java.lang.Object

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

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

iterate

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

head

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

getLength, head, itemAt, reduce, subsequence

Field Detail

targetType

protected UnionType targetType

resolver

protected NamespaceResolver resolver

allowEmpty

protected boolean allowEmpty

Constructor Detail

UnionConstructorFunction

public UnionConstructorFunction(UnionType targetType,
                        NamespaceResolver resolver,
                        boolean allowEmpty)

Create a cast expression to a union type

Parameters:

targetType - the union type that is the result of the cast

allowEmpty - true if an empty sequence may be supplied as input, converting to an empty sequence on output

Method Detail

getOperandRole

protected OperandRole getOperandRole()

Get the usage (in terms of streamability analysis) of the single operand

Returns:

the operand usage

isAllowEmpty

public boolean isAllowEmpty()

Ask whether the value of the operand is allowed to be empty

Returns:

true if an empty sequence may be supplied as input, converting to an empty sequence on output

getTargetType

public UnionType getTargetType()

Get the union type that is the target of this cast operation

Returns:

the target type of the cast

getNamespaceResolver

public NamespaceResolver getNamespaceResolver()

Get the namespace resolver that will be used to resolve any namespace-sensitive values (such as QNames) when casting

Returns:

the namespace resolver, or null if there is none.

getFunctionItemType

public FunctionItemType getFunctionItemType()

Get the item type of the function item

Returns:

the function item's type

getFunctionName

public StructuredQName getFunctionName()

Get the name of the function, or null if it is anonymous

Returns:

the function name, or null for an anonymous inline function

getDescription

public String getDescription()

Get a description of this function for use in error messages. For named functions, the description is the function name (as a lexical QName). For others, it might be, for example, "inline function", or "partially-applied ends-with function".

Returns:

a description of the function for use in error messages

getArity

public int getArity()

Get the arity of the function

Returns:

the number of arguments in the function signature

cast

public AtomicSequence cast(AtomicValue value,
                  XPathContext context)
                    throws XPathException

Method to perform the cast of an atomic value to a union type

Parameters:

value - the input value to be converted. Must not be null.

context - the evaluation context

Returns:

the result of the conversion (may be a sequence if the union includes list types in its membership)

Throws:

XPathException - if the conversion fails

call

public AtomicSequence call(XPathContext context,
                  Sequence[] args)
                    throws XPathException

Invoke the function

Parameters:

context - the XPath dynamic evaluation context

args - the actual arguments to be supplied

Returns:

the result of invoking the function

Throws:

XPathException - if a dynamic error occurs within the function