Class SimpleNodeConstructor

All Implemented Interfaces:
ExportAgent, Locatable, IdentityComparable, Traceable
Direct Known Subclasses:
AttributeCreator, Comment, NamespaceConstructor, 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, and their XQuery equivalents
  • Field Details

    • selectOp

      protected Operand selectOp
  • Constructor Details

    • SimpleNodeConstructor

      public SimpleNodeConstructor()
      Default constructor used by subclasses
  • Method Details

    • setSelect

      public void setSelect(Expression select)
      Set the select expression: the value of this expression determines the string-value of the node
      Parameters:
      select - the expression that computes the string value of the node
    • getSelect

      public Expression getSelect()
      Get the select expression, that is the expression that computes the content of the constructed node. Note that this may correspond either to a select attribute or a contained sequence constructor in the case of XSLT; and in XQuery it corresponds to whatever expression is contained in the node constructpr.
      Returns:
      the expression used to compute the content of the node.
    • getSelectOp

      public Operand getSelectOp()
      Get the select operand, that is the operand that wraps the select expression
      Returns:
      the select operand
    • operands

      public Iterable<Operand> operands()
      Description copied from class: Expression
      Get the immediate sub-expressions of this expression, with information about the relationship of each expression to its parent expression.

      If the expression is a Callable, then it is required that the order of the operands returned by this function is the same as the order of arguments supplied to the corresponding call() method.

      Specified by:
      operands in class Instruction
      Returns:
      an iterator containing the sub-expressions of this expression
    • mayCreateNewNodes

      public final boolean mayCreateNewNodes()
      Ask whether this instruction creates new nodes. This implementation returns true.
      Overrides:
      mayCreateNewNodes in class Instruction
      Returns:
      true if the instruction creates new nodes under some input conditions (or if it can't be proved that it doesn't)
    • alwaysCreatesNewNodes

      public boolean alwaysCreatesNewNodes()
      Ask whether it is guaranteed that every item in the result of this instruction is a newly created node
      Overrides:
      alwaysCreatesNewNodes in class Instruction
      Returns:
      true if result of the instruction is always either an empty sequence or a sequence consisting entirely of newly created nodes
    • computeCardinality

      protected int computeCardinality()
      Get the cardinality of the sequence returned by evaluating this instruction
      Overrides:
      computeCardinality in class Instruction
      Returns:
      the static cardinality
    • computeSpecialProperties

      protected 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
    • allowExtractingCommonSubexpressions

      public boolean allowExtractingCommonSubexpressions()
      Ask whether common subexpressions found in the operands of this expression can be extracted and evaluated outside the expression itself. The result is irrelevant in the case of operands evaluated with a different focus, which will never be extracted in this way, even if they have no focus dependency.
      Overrides:
      allowExtractingCommonSubexpressions in class Expression
      Returns:
      false for this kind of expression
    • localTypeCheck

      public abstract void localTypeCheck(ExpressionVisitor visitor, ContextItemStaticInfo contextItemType) throws XPathException
      Method to perform type-checking specific to the kind of instruction
      Parameters:
      visitor - an expression visitor
      contextItemType - the static type of the context item
      Throws:
      XPathException - if a type error is detected
    • typeCheck

      public Expression typeCheck(ExpressionVisitor visitor, ContextItemStaticInfo contextInfo) 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. param visitor an expression visitor
      Overrides:
      typeCheck in class Expression
      Parameters:
      visitor - an expression visitor
      contextInfo - information about the dynamic context
      Returns:
      the rewritten expression
      Throws:
      XPathException - if any static errors are found in this expression or any of its children
    • optimize

      public Expression optimize(ExpressionVisitor visitor, ContextItemStaticInfo contextItemType) throws XPathException
      Description copied from class: 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.

      Overrides:
      optimize in class Expression
      Parameters:
      visitor - an expression visitor
      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 - if an error is discovered during this phase (typically a type error)
    • getStreamerName

      public String getStreamerName()
      Get the (partial) name of a class that supports streaming of this kind of expression
      Overrides:
      getStreamerName in class Expression
      Returns:
      the partial name of a class that can be instantiated to provide streaming support in Saxon-EE, or null if there is no such class
    • processValue

      public abstract void processValue(UnicodeString value, Outputter output, XPathContext context) throws XPathException
      Process the value of the node, to create the new node.
      Parameters:
      value - the string value of the new node
      output - the destination for the result
      context - the dynamic evaluation context
      Throws:
      XPathException - if a dynamic error occurs
    • evaluateItem

      public Item evaluateItem(XPathContext context) throws XPathException
      Evaluate as an 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

      public UnicodeString checkContent(UnicodeString data, XPathContext context) throws XPathException
      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:
      XPathException - if the content is invalid
    • evaluateNodeName

      public NodeName evaluateNodeName(XPathContext context) throws XPathException
      Run-time method to compute the name of the node being constructed. This is overridden for nodes that have a name. The default implementation returns -1, which is suitable for unnamed nodes such as comments
      Parameters:
      context - the XPath dynamic evaluation context
      Returns:
      the name pool nameCode identifying the name of the constructed node
      Throws:
      XPathException - if any failure occurs
    • 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.
      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
    • isLocal

      public boolean isLocal()