net.sf.saxon.instruct
Class ValueOf

java.lang.Object
  |
  +--net.sf.saxon.expr.ComputedExpression
        |
        +--net.sf.saxon.instruct.Instruction
              |
              +--net.sf.saxon.instruct.InstructionWithChildren
                    |
                    +--net.sf.saxon.instruct.SimpleNodeConstructor
                          |
                          +--net.sf.saxon.instruct.ValueOf
All Implemented Interfaces:
Container, Expression, InstructionInfoProvider, 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.InstructionWithChildren
children
 
Fields inherited from class net.sf.saxon.expr.ComputedExpression
locationId, staticProperties
 
Fields inherited from interface net.sf.saxon.expr.Expression
EVALUATE_METHOD, ITERATE_METHOD, PROCESS_METHOD
 
Constructor Summary
ValueOf(Expression select, boolean disable)
           
 
Method Summary
 void display(int level, NamePool pool, java.io.PrintStream out)
          Display this instruction as an expression, for diagnostics
 Item evaluateItem(XPathContext context)
          Evaluate as an expression.
 int getCardinality()
          Determine the static cardinality of the expression.
 int getInstructionNameCode()
          Get the name of this instruction for diagnostic and tracing purposes
 ItemType getItemType()
          Get the item type of the items returned by evaluating this instruction
 TailCall processLeavingTail(XPathContext context)
          ProcessLeavingTail: called to do the real work of this instruction.
protected  void promoteInst(PromotionOffer offer)
          Offer promotion for subexpressions.
 void setIsNumberingInstruction()
          Indicate that this is really an xsl:nunber instruction
 void typeCheck(StaticContext env, ItemType contextItemType)
           
 
Methods inherited from class net.sf.saxon.instruct.SimpleNodeConstructor
analyze, checkContent, evaluateNameCode, expandChildren, iterate, iterateSubExpressions, setSelect, setSeparator, simplify
 
Methods inherited from class net.sf.saxon.instruct.InstructionWithChildren
displayChildren, getChildren, processChildren, processChildrenLeavingTail, setChildren
 
Methods inherited from class net.sf.saxon.instruct.Instruction
appendItem, assembleParams, assembleTunnelParams, computeCardinality, computeSpecialProperties, dynamicError, dynamicError, effectiveBooleanValue, evaluateAsString, getImplementationMethod, getInstructionInfo, getSourceLocator, process, promote
 
Methods inherited from class net.sf.saxon.expr.ComputedExpression
adoptChildExpression, computeDependencies, computeStaticProperties, dynamicError, dynamicError, getColumnNumber, getConstructType, getDependencies, getExecutable, getIntrinsicDependencies, getLineNumber, getLocationId, getParentExpression, getPublicId, getSpecialProperties, getSystemId, markTailFunctionCalls, resetStaticProperties, setLocationId, setParentExpression, typeError
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 
Methods inherited from interface javax.xml.transform.SourceLocator
getColumnNumber, getLineNumber, getPublicId, getSystemId
 

Constructor Detail

ValueOf

public ValueOf(Expression select,
               boolean disable)
Method Detail

setIsNumberingInstruction

public void setIsNumberingInstruction()
Indicate that this is really an xsl:nunber instruction


getInstructionNameCode

public int getInstructionNameCode()
Get the name of this instruction for diagnostic and tracing purposes

Overrides:
getInstructionNameCode in class Instruction

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

getItemType

public ItemType getItemType()
Description copied from class: Instruction
Get the item type of the items returned by evaluating this instruction

Specified by:
getItemType in interface Expression
Overrides:
getItemType in class Instruction
Returns:
the static item type of the instruction

getCardinality

public int getCardinality()
Description copied from class: ComputedExpression
Determine the static cardinality of the expression. This establishes how many items there will be in the result of the expression, at compile time (i.e., without actually evaluating the result.

Specified by:
getCardinality in interface Expression
Overrides:
getCardinality in class ComputedExpression
Returns:
one of the values Cardinality.ONE_OR_MORE, Cardinality.ZERO_OR_MORE, Cardinality.EXACTLY_ONE, Cardinality.ZERO_OR_ONE, Cardinality.EMPTY. This default implementation returns ZERO_OR_MORE (which effectively gives no information).

typeCheck

public void typeCheck(StaticContext env,
                      ItemType contextItemType)
Specified by:
typeCheck in class SimpleNodeConstructor

processLeavingTail

public TailCall processLeavingTail(XPathContext context)
                            throws XPathException
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.
XPathException

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,
                    java.io.PrintStream out)
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
pool - NamePool used to expand any names appearing in the expression
out - Output destination