net.sf.saxon.instruct
Class ValueOf

java.lang.Object
  net.sf.saxon.instruct.Instruction
      net.sf.saxon.instruct.ExprInstruction
          net.sf.saxon.instruct.SimpleNodeConstructor
              net.sf.saxon.instruct.ValueOf

All Implemented Interfaces:

Serializable, SourceLocator, Expression

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, separator

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

children

Constructor Summary

ValueOf(Expression select, boolean disable)

Method Summary

void	display(int level, NamePool pool) Display this instruction as an expression, for diagnostics
Item	evaluateItem(XPathContext context) Evaluate as an expression.
SequenceType	getResultType() Get the static type of the value returned by the instruction
TailCall	processLeavingTail(XPathContext context) ProcessLeavingTail: called to do the real work of this instruction.
void	promoteInst(PromotionOffer offer) Offer promotion for subexpressions.
void	setInstructionDetails(Controller controller, NamePool namePool, InstructionDetails details) Get the name of this instruction for diagnostic and tracing purposes
void	typeCheck(StaticContext env)

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

analyze, evaluateNameCode, expandChildren, getXPathExpressions, setSelect, setSeparator

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

effectiveBooleanValue, evaluateAsString, getCardinality, getDependencies, getItemType, getSpecialProperties, getSubExpressions, iterate, promote, simplify

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

assembleParams, assembleTunnelParams, getChildren, getColumnNumber, getInstructionDetails, getInstructionName, getLineNumber, getPublicId, getSystemId, getSystemId, process, processChildren, processChildrenLeavingTail, recoverableError, setChildren, setSourceLocation, styleError, styleError

Methods inherited from class java.lang.Object

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

Constructor Detail

ValueOf

public ValueOf(Expression select,
               boolean disable)

Method Detail

setInstructionDetails

public void setInstructionDetails(Controller controller,
                                  NamePool namePool,
                                  InstructionDetails details)

Get the name of this instruction for diagnostic and tracing purposes

Specified by:

setInstructionDetails in class Instruction

promoteInst

public 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.

Specified by:

promoteInst in class ExprInstruction

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

getResultType

public SequenceType getResultType()

Description copied from class: Instruction

Get the static type of the value returned by the instruction

Overrides:

getResultType in class Instruction

Returns:

the SequenceType that the returned value will conform to.

typeCheck

public void typeCheck(StaticContext env)
               throws XPathException

Specified by:

typeCheck in class SimpleNodeConstructor

Throws:

XPathException

processLeavingTail

public TailCall processLeavingTail(XPathContext context)
                            throws TransformerException

Description copied from class: Instruction

ProcessLeavingTail: called to do the real work of this instruction. This method must be implemented in each subclass. The results of the instruction are written to the current Receiver, which can be obtained via the Controller.

Specified by:

processLeavingTail in class Instruction

Parameters:

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

Returns:

null if the instruction has completed execution; or a TailCall indicating a function call or template call that is delegated to the caller, to be made after the stack has been unwound so as to save stack space.

Throws:

TransformerException

evaluateItem

public Item evaluateItem(XPathContext context)
                  throws XPathException

Description copied from class: SimpleNodeConstructor

Evaluate as an expression. We rely on the fact that when these instructions are generated by XQuery, there will always be a valueExpression to evaluate the content

Specified by:

evaluateItem in interface Expression

Overrides:

evaluateItem in class SimpleNodeConstructor

Parameters:

context - 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

display

public void display(int level,
                    NamePool pool)

Display this instruction as an expression, for diagnostics

Specified by:

display in interface Expression

Overrides:

display in class SimpleNodeConstructor

Parameters:

level - indentation level for this expression