net.sf.saxon.functions

Class Concat

java.lang.Object

net.sf.saxon.expr.Expression

net.sf.saxon.expr.FunctionCall

net.sf.saxon.functions.SystemFunctionCall

net.sf.saxon.functions.Concat

All Implemented Interfaces:

SourceLocator, Callable, IdentityComparable, InstructionInfo

public class Concat
extends SystemFunctionCall
implements Callable

Implementation of the fn:concat() function

Field Summary

Fields inherited from class net.sf.saxon.functions.SystemFunctionCall

operation

Fields inherited from class net.sf.saxon.expr.FunctionCall

argument

Fields inherited from class net.sf.saxon.expr.Expression

EFFECTIVE_BOOLEAN_VALUE, EVALUATE_METHOD, ITEM_FEED_METHOD, ITERATE_METHOD, locationId, MAX_SEQUENCE_LENGTH, MAX_STRING_LENGTH, PROCESS_METHOD, staticProperties, UNBOUNDED_LOWER, UNBOUNDED_UPPER, WATCH_METHOD

Constructor Summary

Constructors

Constructor and Description
Concat()

Method Summary

Methods

Modifier and Type	Method and Description
StringValue	call(XPathContext context, Sequence[] arguments) Call the Callable.
CharSequence	evaluateAsString(XPathContext c) Evaluate the function in a string context
StringValue	evaluateItem(XPathContext c) Evaluate in a general context
ExpressionCompiler	getExpressionCompiler() Return the compiler of the Concat expression
FunctionItemType	getFunctionItemType(TypeHierarchy th) Get the item type of the function item
protected SequenceType	getRequiredType(int arg) Get the required type of the nth argument
Iterable<Operand>	operands() Get the immediate sub-expressions of this expression, with information about the relationship of each expression to its parent expression.
void	process(XPathContext context) Process the instruction in push mode.

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

addContextDocumentArgument, addDocToPathMap, bindStaticContext, checkArguments, computeCardinality, computeSpecialProperties, copy, equalOrNull, equals, getContextNode, getConvertingCallable, getDefaultArgumentNode, getDetails, getErrorCodeForTypeErrors, getImplementationMethod, getItemType, getOperation, makeSystemFunction, optimize, setDetails, toShortString, useContextItemAsDefault

Methods inherited from class net.sf.saxon.expr.FunctionCall

addExternalFunctionCallToPathMap, checkArgumentCount, explain, getArguments, getDisplayName, getExpressionName, getFunctionName, getNumberOfArguments, hashCode, preEvaluate, promote, replaceOperand, setArguments, setFunctionName, simplifyArguments, toString, typeCheck

Methods inherited from class net.sf.saxon.expr.Expression

addToPathMap, adoptChildExpression, checkForUpdatingSubexpressions, checkPermittedContents, clearStreamabilityData, computeDependencies, computeStaticProperties, doPromotion, dynamicError, effectiveBooleanValue, evaluatePendingUpdates, explain, getCardinality, getColumnNumber, getConfiguration, getConstructType, getContainer, getDependencies, getEvaluationMethod, getHostLanguage, getIntegerBounds, getIntrinsicDependencies, getLineNumber, getLocationId, getObjectName, getPosture, getProperties, getProperty, getPublicId, getSlotsUsed, getSpecialProperties, getStreamability, getStreamingAdjunct, getSweep, getSystemId, hasVariableBinding, identityHashCode, implementsStaticTypeCheck, isIdentical, isSubtreeExpression, isUpdatingExpression, isVacuousExpression, iterate, iterateEvents, makeStreamingAdjunct, markTailFunctionCalls, operandList, resetLocalStaticProperties, setContainer, setEvaluationMethod, setFiltered, setFlattened, setLocationId, setPostureAndSweep, simplify, staticTypeCheck, suppressValidation, toPattern, toStreamingPattern, typeError, unordered

Methods inherited from class java.lang.Object

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

Constructor Detail

Concat

public Concat()

Method Detail

getFunctionItemType

public FunctionItemType getFunctionItemType(TypeHierarchy th)

Get the item type of the function item

Overrides:

getFunctionItemType in class SystemFunctionCall

Parameters:

th - the type hierarchy cache

Returns:

the function item's type

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 methd 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

getRequiredType

protected SequenceType getRequiredType(int arg)

Get the required type of the nth argument

Overrides:

getRequiredType in class SystemFunctionCall

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

operands

public Iterable<Operand> operands()

Get the immediate sub-expressions of this expression, with information about the relationship of each expression to its parent expression.

Overrides:

operands in class SystemFunctionCall

Returns:

an iterator containing the sub-expressions of this expression

evaluateAsString

public CharSequence evaluateAsString(XPathContext c)
                              throws XPathException

Evaluate the function in a string context

Overrides:

evaluateAsString in class Expression

Parameters:

c - The context in which the expression is to be evaluated

Returns:

the value of the expression, evaluated in the current context. The expression must return a string or (); if the value of the expression is (), this method returns "".

Throws:

XPathException - if any dynamic error occurs evaluating the expression

evaluateItem

public StringValue evaluateItem(XPathContext c)
                         throws XPathException

Evaluate in a general context

Overrides:

evaluateItem in class Expression

Parameters:

c - The context in which the expression is to be evaluated

Returns:

the node or atomic value that results from evaluating the expression; or null to indicate that the result is an empty sequence

Throws:

XPathException - if any dynamic error occurs evaluating the expression

process

public void process(XPathContext context)
             throws XPathException

Process the instruction in push mode. This avoids constructing the concatenated string in memory, instead each argument can be sent straight to the serializer.

Overrides:

process in class Expression

Parameters:

context - The dynamic context, giving access to the current node, the current variables, etc.

Throws:

XPathException - if a dynamic error occurs

getExpressionCompiler

public ExpressionCompiler getExpressionCompiler()

Return the compiler of the Concat expression

Overrides:

getExpressionCompiler in class Expression

Returns:

the relevant ExpressionCompiler