net.sf.saxon.instruct
Class ValueOf

java.lang.Object
  extended by net.sf.saxon.expr.Expression
      extended by net.sf.saxon.instruct.Instruction
          extended by net.sf.saxon.instruct.SimpleNodeConstructor
              extended by 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:

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


Copyright (c) Saxonica Limited. All rights reserved.