net.sf.saxon.instruct
Class ValueOf

java.lang.Object
  net.sf.saxon.expr.Expression
      net.sf.saxon.instruct.Instruction
          net.sf.saxon.instruct.SimpleNodeConstructor
              net.sf.saxon.instruct.ValueOf

All Implemented Interfaces:

Serializable, SourceLocator, LocationProvider, SaxonLocator, EvaluableItem, SequenceIterable, DivisibleInstruction, TailCallReturner, InstructionInfo, Locator

public final class ValueOf
extends SimpleNodeConstructor

An xsl:value-of element in the stylesheet.
The xsl:value-of element takes attributes:

• a mandatory attribute select="expression". This must be a valid String expression
• an optional disable-output-escaping attribute, value "yes" or "no"
• an optional separator attribute. This is handled at compile-time: if the separator attribute is present, the select expression passed in here will be a call to the string-join() function.

See Also:

Serialized Form

Field Summary

Fields inherited from class net.sf.saxon.instruct.SimpleNodeConstructor

select

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

EVALUATE_METHOD, ITERATE_METHOD, locationId, PROCESS_METHOD, staticProperties

Constructor Summary

ValueOf(Expression select, boolean disable, boolean noNodeIfEmpty)
Create a new ValueOf expression

Method Summary

void	checkPermittedContents(SchemaType parentType, StaticContext env, boolean whole) Check statically that the results of the expression are capable of constructing the content of a given schema type.
int	computeCardinality() Get the cardinality of the sequence returned by evaluating this instruction
Expression	convertToStringJoin(StaticContext env) Convert this value-of instruction to an expression that delivers the string-value of the resulting text node.
Expression	copy() Copy an expression.
Item	evaluateItem(XPathContext context) Evaluate this expression, returning the resulting text node to the caller
void	explain(ExpressionPresenter out) Diagnostic print of expression structure.
int	getInstructionNameCode() Get the name of this instruction for diagnostic and tracing purposes
ItemType	getItemType(TypeHierarchy th) Get the item type of the items returned by evaluating this instruction
int	getOptions() Test for any special options such as disable-output-escaping
boolean	isDisableOutputEscaping() Test whether disable-output-escaping was requested
boolean	isNumberingInstruction() Determine whether this is really an xsl:number instruction
void	localTypeCheck(ExpressionVisitor visitor, ItemType contextItemType) Method to perform type-checking specific to the kind of instruction
TailCall	processLeavingTail(XPathContext context) Process this instruction, sending the resulting text node to the current output destination
protected void	processValue(CharSequence value, XPathContext context) Process the value of the node, to create the new node.
protected void	promoteInst(PromotionOffer offer) Offer promotion for subexpressions.
void	setIsNumberingInstruction() Indicate that this is really an xsl:nunber instruction

Methods inherited from class net.sf.saxon.instruct.SimpleNodeConstructor

checkContent, computeSpecialProperties, createsNewNodes, evaluateNameCode, expandChildren, getSelect, iterate, iterateSubExpressions, optimize, processLeft, processRight, replaceSubExpression, setSelect, simplify, typeCheck

Methods inherited from class net.sf.saxon.instruct.Instruction

assembleParams, assembleTunnelParams, dynamicError, evaluateAsString, getConstructType, getImplementationMethod, getSourceLocator, isXSLT, process, promote

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

addToPathMap, adoptChildExpression, checkForUpdatingSubexpressions, computeDependencies, computeStaticProperties, doPromotion, dynamicError, effectiveBooleanValue, evaluatePendingUpdates, explain, getCardinality, getColumnNumber, getColumnNumber, getContainer, getDependencies, getExecutable, getHostLanguage, getIntrinsicDependencies, getLineNumber, getLineNumber, getLocationId, getLocationProvider, getObjectName, getProperties, getProperty, getPublicId, getSlotsUsed, getSpecialProperties, getSystemId, getSystemId, hasLoopingSubexpression, implementsStaticTypeCheck, isSubtreeExpression, isUpdatingExpression, isVacuousExpression, iterateEvents, iterateSameFocusSubExpressions, markTailFunctionCalls, resetLocalStaticProperties, setContainer, setFiltered, setFlattened, setLocationId, staticTypeCheck, suppressValidation, toString, typeError

Methods inherited from class java.lang.Object

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

Methods inherited from interface javax.xml.transform.SourceLocator

getColumnNumber, getLineNumber, getPublicId, getSystemId

Constructor Detail

ValueOf

public ValueOf(Expression select,
               boolean disable,
               boolean noNodeIfEmpty)

Create a new ValueOf expression

Parameters:

select - the select expression

disable - true if disable-output-escaping is in force

noNodeIfEmpty - true if the instruction is to return () if the select expression is (), false if it is to return an empty text node

Method Detail

setIsNumberingInstruction

public void setIsNumberingInstruction()

Indicate that this is really an xsl:nunber instruction

isNumberingInstruction

public boolean isNumberingInstruction()

Determine whether this is really an xsl:number instruction

Returns:

true if this derives from xsl:number

getInstructionNameCode

public int getInstructionNameCode()

Get the name of this instruction for diagnostic and tracing purposes

Overrides:

getInstructionNameCode in class Instruction

Returns:

the namecode of the instruction name

promoteInst

protected void promoteInst(PromotionOffer offer)
                    throws XPathException

Offer promotion for subexpressions. The offer will be accepted if the subexpression is not dependent on the factors (e.g. the context item) identified in the PromotionOffer. By default the offer is not accepted - this is appropriate in the case of simple expressions such as constant values and variable references where promotion would give no performance advantage. This method is always called at compile time.

Overrides:

promoteInst in class SimpleNodeConstructor

Parameters:

offer - details of the offer, for example the offer to move expressions that don't depend on the context to an outer level in the containing expression

Throws:

XPathException - if any error is detected

getOptions

public int getOptions()

Test for any special options such as disable-output-escaping

Returns:

any special options

isDisableOutputEscaping

public boolean isDisableOutputEscaping()

Test whether disable-output-escaping was requested

Returns:

true if disable-output-escaping was requested

getItemType

public ItemType getItemType(TypeHierarchy th)

Description copied from class: Instruction

Get the item type of the items returned by evaluating this instruction

Overrides:

getItemType in class Instruction

Parameters:

th - the type hierarchy cache

Returns:

the static item type of the instruction

computeCardinality

public int computeCardinality()

Description copied from class: SimpleNodeConstructor

Get the cardinality of the sequence returned by evaluating this instruction

Overrides:

computeCardinality in class SimpleNodeConstructor

Returns:

the static cardinality

localTypeCheck

public void localTypeCheck(ExpressionVisitor visitor,
                           ItemType contextItemType)

Description copied from class: SimpleNodeConstructor

Method to perform type-checking specific to the kind of instruction

Specified by:

localTypeCheck in class SimpleNodeConstructor

Parameters:

visitor - an expression visitor

contextItemType - the static type of the context item

copy

public Expression copy()

Copy an expression. This makes a deep copy.

Specified by:

copy in class Expression

Returns:

the copy of the original expression

checkPermittedContents

public void checkPermittedContents(SchemaType parentType,
                                   StaticContext env,
                                   boolean whole)
                            throws XPathException

Check statically that the results of the expression are capable of constructing the content of a given schema type.

Overrides:

checkPermittedContents in class Expression

Parameters:

parentType - The schema type

env - the static context

whole - true if this expression is to account for the whole value of the type

Throws:

XPathException - if the expression doesn't match the required content type

convertToStringJoin

public Expression convertToStringJoin(StaticContext env)

Convert this value-of instruction to an expression that delivers the string-value of the resulting text node. This will often be a call on the string-join function.

Parameters:

env - the static evaluation context

Returns:

the converted expression

processLeavingTail

public TailCall processLeavingTail(XPathContext context)
                            throws XPathException

Process this instruction, sending the resulting text node to the current output destination

Specified by:

processLeavingTail in interface TailCallReturner

Overrides:

processLeavingTail in class SimpleNodeConstructor

Parameters:

context - the dynamic evaluation context

Returns:

Always returns null

Throws:

XPathException

processValue

protected void processValue(CharSequence value,
                            XPathContext context)
                     throws XPathException

Process the value of the node, to create the new node.

Specified by:

processValue in class SimpleNodeConstructor

Parameters:

value - the string value of the new node

context - the dynamic evaluation context

Throws:

XPathException

evaluateItem

public Item evaluateItem(XPathContext context)
                  throws XPathException

Evaluate this expression, returning the resulting text node to the caller

Specified by:

evaluateItem in interface EvaluableItem

Overrides:

evaluateItem in class SimpleNodeConstructor

Parameters:

context - the dynamic evaluation context

Returns:

the parentless text node that results from evaluating this instruction, or null to represent an empty sequence

Throws:

XPathException

explain

public void explain(ExpressionPresenter out)

Diagnostic print of expression structure. The abstract expression tree is written to the supplied output destination.

Specified by:

explain in class Expression

Parameters:

out - the expression presenter used to display the structure