Class SimpleNodeConstructor

All Implemented Interfaces:
Serializable, SourceLocator, Container, Expression, TailCallReturner, InstructionInfoProvider
Direct Known Subclasses:
Attribute, Comment, FixedAttribute, Namespace, ProcessingInstruction, ValueOf

public abstract class SimpleNodeConstructor extends Instruction
Common superclass for XSLT instructions whose content template produces a text value: xsl:attribute, xsl:comment, xsl:processing-instruction, xsl:namespace, and xsl:text
See Also:
  • Field Details

  • Constructor Details

    • SimpleNodeConstructor

      public SimpleNodeConstructor()
  • Method Details

    • setSelect

      public void setSelect(Expression select, Configuration config) throws StaticError
      Throws:
      StaticError
    • getSelect

      public Expression getSelect()
    • createsNewNodes

      public final boolean createsNewNodes()
      Determine whether this instruction creates new nodes. This implementation returns true.
      Overrides:
      createsNewNodes in class Instruction
    • simplify

      public Expression simplify(StaticContext env) throws XPathException
      Description copied from class: Instruction
      Simplify an expression. This performs any static optimization (by rewriting the expression as a different expression). The default implementation does nothing.
      Specified by:
      simplify in interface Expression
      Specified by:
      simplify in class Instruction
      Parameters:
      env - the static context
      Returns:
      the simplified expression
      Throws:
      XPathException - if an error is discovered during expression rewriting
    • computeSpecialProperties

      public int computeSpecialProperties()
      Get the static properties of this expression (other than its type). The result is bit-signficant. These properties are used for optimizations. In general, if property bit is set, it is true, but if it is unset, the value is unknown.
      Overrides:
      computeSpecialProperties in class Instruction
      Returns:
      a set of flags indicating static properties of this expression
    • localTypeCheck

      public abstract void localTypeCheck(StaticContext env, ItemType contextItemType) throws XPathException
      Throws:
      XPathException
    • typeCheck

      public Expression typeCheck(StaticContext env, ItemType contextItemType) throws XPathException
      The typeCheck() method is called in XQuery, where node constructors are implemented as Expressions. In this case the required type for the select expression is a single string.
      Parameters:
      env - The static context for the query
      contextItemType - the static type of "." at the point where this expression is invoked. The parameter is set to null if it is known statically that the context item will be undefined. If the type of the context item is not known statically, the argument is set to Type.ITEM_TYPE
      Returns:
      the rewritten expression
      Throws:
      XPathException - if any static errors are found in this expression or any of its children
    • optimize

      public Expression optimize(Optimizer opt, StaticContext env, ItemType contextItemType) throws XPathException
      Description copied from interface: Expression
      Perform optimisation of an expression and its subexpressions. This is the third and final phase of static optimization.

      This method is called after all references to functions and variables have been resolved to the declaration of the function or variable, and after all type checking has been done.

      Parameters:
      opt - the optimizer in use. This provides access to supporting functions; it also allows different optimization strategies to be used in different circumstances.
      env - the static context of the expression
      contextItemType - the static type of "." at the point where this expression is invoked. The parameter is set to null if it is known statically that the context item will be undefined. If the type of the context item is not known statically, the argument is set to Type.ITEM_TYPE
      Returns:
      the original expression, rewritten if appropriate to optimize execution
      Throws:
      XPathException
    • iterateSubExpressions

      public Iterator iterateSubExpressions()
      Description copied from class: ComputedExpression
      Get the immediate sub-expressions of this expression. Default implementation returns a zero-length array, appropriate for an expression that has no sub-expressions.
      Specified by:
      iterateSubExpressions in interface Expression
      Overrides:
      iterateSubExpressions in class ComputedExpression
      Returns:
      an iterator containing the sub-expressions of this expression
    • replaceSubExpression

      public boolean replaceSubExpression(Expression original, Expression replacement)
      Replace one subexpression by a replacement subexpression
      Specified by:
      replaceSubExpression in interface Container
      Overrides:
      replaceSubExpression in class ComputedExpression
      Parameters:
      original - the original subexpression
      replacement - the replacement subexpression
      Returns:
      true if the original subexpression is found
    • expandChildren

      public CharSequence expandChildren(XPathContext context) throws XPathException
      Expand the stylesheet elements subordinate to this one, returning the result as a string. The expansion must not generate any element or attribute nodes.
      Parameters:
      context - The dynamic context for the transformation
      Throws:
      XPathException
    • evaluateItem

      public Item evaluateItem(XPathContext context) throws XPathException
      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 Instruction
      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
    • checkContent

      protected String checkContent(String data, XPathContext context) throws DynamicError
      Check the content of the node, and adjust it if necessary. The checks depend on the node kind.
      Parameters:
      data - the supplied content
      context - the dynamic context
      Returns:
      the original content, unless adjustments are needed
      Throws:
      DynamicError - if the content is invalid
    • evaluateNameCode

      public int evaluateNameCode(XPathContext context) throws XPathException, XPathException
      Throws:
      XPathException
    • iterate

      public SequenceIterator iterate(XPathContext context) throws XPathException
      Description copied from class: Instruction
      Return an Iterator to iterate over the values of a sequence. The value of every expression can be regarded as a sequence, so this method is supported for all expressions. This default implementation handles iteration for expressions that return singleton values: for non-singleton expressions, the subclass must provide its own implementation.
      Specified by:
      iterate in interface Expression
      Overrides:
      iterate in class Instruction
      Parameters:
      context - supplies the context for evaluation
      Returns:
      a SequenceIterator that can be used to iterate over the result of the expression
      Throws:
      XPathException - if any dynamic error occurs evaluating the expression
    • display

      public void display(int level, PrintStream out, Configuration config)
      Display this instruction as an expression, for diagnostics
      Parameters:
      level - indentation level for this expression
      out - Output destination
      config -
    • 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 Instruction
      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