Class ValueOf

All Implemented Interfaces:
Serializable, SourceLocator, LocationProvider, SaxonLocator, EvaluableItem, SequenceIterable, 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:
  • Constructor Details

    • 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 Details

    • 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
      Specified by:
      processLeavingTail in class Instruction
      Parameters:
      context - the dynamic evaluation context
      Returns:
      Always returns null
      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