Class InstanceOfExpression

All Implemented Interfaces:
Serializable, SourceLocator, Container, Expression, InstructionInfoProvider

public final class InstanceOfExpression extends UnaryExpression
InstanceOf Expression: implements "Expr instance of data-type"
See Also:
  • Field Details

    • targetType

      ItemType targetType
    • targetCardinality

      int targetCardinality
  • Constructor Details

  • Method Details

    • typeCheck

      public Expression typeCheck(StaticContext env, ItemType contextItemType) throws XPathException
      Type-check the expression
      Specified by:
      typeCheck in interface Expression
      Overrides:
      typeCheck in class UnaryExpression
      Parameters:
      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 checked expression
      Throws:
      XPathException
    • optimize

      public Expression optimize(Optimizer opt, StaticContext env, ItemType contextItemType) throws XPathException
      Perform optimisation of an expression and its subexpressions.

      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.

      Specified by:
      optimize in interface Expression
      Overrides:
      optimize in class UnaryExpression
      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:
      StaticError - if an error is discovered during this phase (typically a type error)
      XPathException
    • equals

      public boolean equals(Object other)
      Is this expression the same as another expression?
      Overrides:
      equals in class UnaryExpression
    • computeCardinality

      public int computeCardinality()
      Determine the cardinality
      Overrides:
      computeCardinality in class UnaryExpression
    • getItemType

      public ItemType getItemType(TypeHierarchy th)
      Determine the data type of the result of the InstanceOf expression
      Specified by:
      getItemType in interface Expression
      Overrides:
      getItemType in class UnaryExpression
      Parameters:
      th -
      Returns:
      the item type of the items in the result sequence, insofar as this is known statically.
    • evaluateItem

      public Item evaluateItem(XPathContext context) throws XPathException
      Evaluate the expression
      Specified by:
      evaluateItem in interface Expression
      Overrides:
      evaluateItem in class ComputedExpression
      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
    • effectiveBooleanValue

      public boolean effectiveBooleanValue(XPathContext context) throws XPathException
      Evaluate the expression as a boolean
      Specified by:
      effectiveBooleanValue in interface Expression
      Overrides:
      effectiveBooleanValue in class ComputedExpression
      Parameters:
      context - The context in which the expression is to be evaluated
      Returns:
      the effective boolean value
      Throws:
      XPathException - if any dynamic error occurs evaluating the expression
    • displayOperator

      protected String displayOperator(Configuration config)
      Give a string representation of the operator for use in diagnostics
      Specified by:
      displayOperator in class UnaryExpression
      Parameters:
      config -
      Returns:
      the operator, as a string
    • display

      public void display(int level, PrintStream out, Configuration config)
      Diagnostic print of expression structure
      Specified by:
      display in interface Expression
      Overrides:
      display in class UnaryExpression
      Parameters:
      level - indentation level for this expression
      out - Output destination
      config -