Class DocumentSorter

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

public class DocumentSorter extends UnaryExpression
A DocumentSorter is an expression that sorts a sequence of nodes into document order.
See Also:
  • Constructor Details

    • DocumentSorter

      public DocumentSorter(Expression base)
  • Method Details

    • simplify

      public Expression simplify(StaticContext env) throws XPathException
      Description copied from class: UnaryExpression
      Simplify an expression
      Specified by:
      simplify in interface Expression
      Overrides:
      simplify in class UnaryExpression
      Parameters:
      env - the static context
      Returns:
      the simplified expression
      Throws:
      XPathException - if an error is discovered during expression rewriting
    • optimize

      public Expression optimize(Optimizer opt, StaticContext env, ItemType contextItemType) throws XPathException
      Description copied from class: UnaryExpression
      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:
      XPathException
    • computeSpecialProperties

      public int computeSpecialProperties()
      Description copied from class: UnaryExpression
      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 UnaryExpression
    • promote

      public Expression promote(PromotionOffer offer) throws XPathException
      Promote this expression if possible
      Specified by:
      promote in interface Expression
      Overrides:
      promote in class UnaryExpression
      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
      Returns:
      if the offer is not accepted, return this expression unchanged. Otherwise return the result of rewriting the expression to promote this subexpression
      Throws:
      XPathException - if any error is detected
    • iterate

      public SequenceIterator iterate(XPathContext context) throws XPathException
      Description copied from class: ComputedExpression
      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 ComputedExpression
      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
    • effectiveBooleanValue

      public boolean effectiveBooleanValue(XPathContext context) throws XPathException
      Description copied from class: ComputedExpression
      Get the effective boolean value of the expression. This returns false if the value is the empty sequence, a zero-length string, a number equal to zero, or the boolean false. Otherwise it returns true.
      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