Class BooleanFn

All Implemented Interfaces:
Callable, Function, GroundedValue, Item, Sequence

public class BooleanFn extends SystemFunction
This class supports the XPath function boolean()
  • Constructor Details

    • BooleanFn

      public BooleanFn()
  • Method Details

    • supplyTypeInformation

      public void supplyTypeInformation(ExpressionVisitor visitor, ContextItemStaticInfo contextItemType, Expression[] arguments) throws XPathException
      Description copied from class: SystemFunction
      Method called during static type checking. This method may be implemented in subclasses so that functions can take advantage of knowledge of the types of the arguments that will be supplied.
      Overrides:
      supplyTypeInformation in class SystemFunction
      Parameters:
      visitor - an expression visitor, providing access to the static context and configuration
      contextItemType - information about whether the context item is set, and what its type is
      arguments - the expressions appearing as arguments in the function call
      Throws:
      XPathException
    • rewriteEffectiveBooleanValue

      public static Expression rewriteEffectiveBooleanValue(Expression exp, ExpressionVisitor visitor, ContextItemStaticInfo contextItemType) throws XPathException
      Optimize an expression whose effective boolean value is required. It is appropriate to apply this rewrite to any expression whose value will be obtained by calling the Expression.effectiveBooleanValue() method (and not otherwise)
      Parameters:
      exp - the expression whose EBV is to be evaluated
      visitor - an expression visitor
      contextItemType - the type of the context item for this expression
      Returns:
      an expression that returns the EBV of exp, or null if no optimization was possible
      Throws:
      XPathException - if static errors are found
    • call

      public BooleanValue call(XPathContext c, Sequence[] arguments) throws XPathException
      Description copied from interface: Function
      Invoke the function
      Parameters:
      c - the XPath dynamic evaluation context
      arguments - the actual arguments to be supplied
      Returns:
      the result of invoking the function
      Throws:
      XPathException - if a dynamic error occurs within the function
    • makeFunctionCall

      public Expression makeFunctionCall(Expression[] arguments)
      Description copied from class: SystemFunction
      Make an expression that either calls this function, or that is equivalent to a call on this function
      Overrides:
      makeFunctionCall in class SystemFunction
      Parameters:
      arguments - the supplied arguments to the function call
      Returns:
      either a function call on this function, or an expression that delivers the same result
    • getCompilerName

      public String getCompilerName()
      Description copied from class: SystemFunction
      Get the (local) name of a class that can be used to generate bytecode for this system function
      Overrides:
      getCompilerName in class SystemFunction
      Returns:
      the name of a bytecode generation class, or null if there is no bytecode support for this function
    • getStreamerName

      public String getStreamerName()
      Description copied from class: SystemFunction
      Get a name that identifies the class that can be used to evaluate this function in streaming mode, that is, supplying one item or event at a time as it is delivered by the parser. Special streaming support is generally available in Saxon-EE for all system functions that take a sequence as their argument.
      Overrides:
      getStreamerName in class SystemFunction
      Returns:
      a name that identifies a class that supports streamed evaluation of this system function, or null if no such class is available. The mapping of names to classes is defined in the Saxon-EE class StreamerMap. In non-streaming Saxon editions (HE and PE) the method always returns null.