net.sf.saxon.instruct
Class ValueOf

java.lang.Object
  extended bynet.sf.saxon.instruct.Instruction
      extended bynet.sf.saxon.instruct.ExprInstruction
          extended bynet.sf.saxon.instruct.SimpleNodeConstructor
              extended bynet.sf.saxon.instruct.ValueOf
All Implemented Interfaces:
Expression, java.io.Serializable, javax.xml.transform.SourceLocator

public final class ValueOf
extends SimpleNodeConstructor

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

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 javax.xml.transform.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:
javax.xml.transform.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
Throws:
XPathException

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