net.sf.saxon.functions

Class Concat

java.lang.Object

net.sf.saxon.functions.AbstractFunction

net.sf.saxon.functions.SystemFunction

net.sf.saxon.functions.Concat

All Implemented Interfaces:

Callable, PushableFunction, Function, GroundedValue, Item, Sequence

public class Concat
extends SystemFunction
implements PushableFunction

Implementation of the fn:concat() function

Constructor Summary

Constructors

Constructor and Description
Concat()

Method Summary

Modifier and Type	Method and Description
StringValue	call(XPathContext context, Sequence[] arguments) Call the Callable.
java.lang.String	getCompilerName() Get the (local) name of a class that can be used to generate bytecode for this system function
FunctionItemType	getFunctionItemType() Get the item type of the function item
SequenceType	getRequiredType(int arg) Get the required type of the nth argument
Expression	makeOptimizedFunctionCall(ExpressionVisitor visitor, ContextItemStaticInfo contextInfo, Expression... arguments) Allow the function to create an optimized call based on the values of the actual arguments
void	process(Outputter destination, XPathContext context, Sequence[] arguments) Evaluate the function in "push" mode
protected Sequence	resultIfEmpty(int arg) Ask if the function always returns a known result when one of the arguments is an empty sequence

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

dependsOnContextItem, dynamicCall, equals, export, exportAdditionalArguments, exportAttributes, fixArguments, getArity, getCardinality, getContextNode, getDescription, getDetails, getErrorCodeForTypeErrors, getFunctionName, getIntegerBounds, getNetCost, getOperandRoles, getResultItemType, getResultItemType, getRetainedStaticContext, getSpecialProperties, getStaticBaseUriString, getStreamerName, getUniStringArg, hashCode, importAttributes, isSequenceVariadic, isTrustedResultType, makeCall, makeFunction, makeFunctionCall, setArity, setDetails, setRetainedStaticContext, supplyTypeInformation, toShortString, toString, typeCheckCaller

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

atomize, deepEquals, effectiveBooleanValue, getAnnotations, getUnicodeStringValue, isArray, isMap, makeNewContext, simplify, typeCheck

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

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

getGenre

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

getLength, getStringValue, head, isStreamed, itemAt, iterate, reduce, subsequence

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

asIterable, concatenate, containsNode, materialize

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

makeRepeatable

Constructor Detail

Concat

public Concat()

Method Detail

resultIfEmpty

protected Sequence resultIfEmpty(int arg)

Description copied from class: SystemFunction

Ask if the function always returns a known result when one of the arguments is an empty sequence

Overrides:

resultIfEmpty in class SystemFunction

Parameters:

arg - the argument whose value is an empty sequence (counting from zero)

Returns:

the value to be returned when this argument is an empty sequence, or null if unknown / not applicable

getFunctionItemType

public FunctionItemType getFunctionItemType()

Get the item type of the function item

Specified by:

getFunctionItemType in interface Function

Overrides:

getFunctionItemType in class SystemFunction

Returns:

the function item's type

makeOptimizedFunctionCall

public Expression makeOptimizedFunctionCall(ExpressionVisitor visitor,
                                            ContextItemStaticInfo contextInfo,
                                            Expression... arguments)
                                     throws XPathException

Allow the function to create an optimized call based on the values of the actual arguments

Overrides:

makeOptimizedFunctionCall in class SystemFunction

Parameters:

visitor - the expression visitor

contextInfo - information about the context item

arguments - the supplied arguments to the function call. Note: modifying the contents of this array should not be attempted, it is likely to have no effect.

Returns:

either a function call on this function, or an expression that delivers the same result, or null indicating that no optimization has taken place

Throws:

XPathException - if an error is detected

call

public StringValue call(XPathContext context,
                        Sequence[] arguments)
                 throws XPathException

Description copied from interface: Callable

Call the Callable.

Specified by:

call in interface Callable

Parameters:

context - the dynamic evaluation context

arguments - the values of the arguments, supplied as Sequences.

Generally it is advisable, if calling iterate() to process a supplied sequence, to call it only once; if the value is required more than once, it should first be converted to a GroundedValue by calling the utility method SequenceTool.toGroundedValue().

If the expected value is a single item, the item should be obtained by calling Sequence.head(): it cannot be assumed that the item will be passed as an instance of Item or AtomicValue.

It is the caller's responsibility to perform any type conversions required to convert arguments to the type expected by the callee. An exception is where this Callable is explicitly an argument-converting wrapper around the original Callable.

Returns:

the result of the evaluation, in the form of a Sequence. It is the responsibility of the callee to ensure that the type of result conforms to the expected result type.

Throws:

XPathException - if a dynamic error occurs during the evaluation of the expression

process

public void process(Outputter destination,
                    XPathContext context,
                    Sequence[] arguments)
             throws XPathException

Description copied from interface: PushableFunction

Evaluate the function in "push" mode

Specified by:

process in interface PushableFunction

Parameters:

destination - the destination for the function result

context - the dynamic evaluation context

arguments - the supplied arguments to the function

Throws:

XPathException - if a dynamic error occurs during the evaluation

getRequiredType

public SequenceType getRequiredType(int arg)

Get the required type of the nth argument

Overrides:

getRequiredType in class SystemFunction

Parameters:

arg - the number of the argument whose type is requested, zero-based

Returns:

the required type of the argument as defined in the function signature

getCompilerName

public java.lang.String getCompilerName()

Description copied from class: SystemFunction

Get the (local) name of a class that can be used to generate bytecode for this system function

Overrides:

getCompilerName in class SystemFunction

Returns:

the name of a bytecode generation class, or null if there is no bytecode support for this function