Class AccumulatorFn

All Implemented Interfaces:
Callable, FunctionItem, GroundedValue, Item, Sequence
Direct Known Subclasses:
AccumulatorFn.AccumulatorAfter, AccumulatorFn.AccumulatorBefore

public abstract class AccumulatorFn extends SystemFunction
Non-streaming implementation of accumulator-before() and accumulator-after()
  • Constructor Details

    • AccumulatorFn

      public AccumulatorFn()
  • Method Details

    • getPhase

      public abstract AccumulatorFn.Phase getPhase()
    • getResultItemType

      public ItemType getResultItemType(Expression[] args)
      Get the return type, given knowledge of the actual arguments
      Overrides:
      getResultItemType in class SystemFunction
      Parameters:
      args - the actual arguments supplied
      Returns:
      the best available item type that the function will return
    • getCardinality

      public int getCardinality(Expression[] args)
      Get the cardinality, given knowledge of the actual arguments
      Overrides:
      getCardinality in class SystemFunction
      Parameters:
      args - the actual arguments supplied
      Returns:
      the most precise available cardinality that the function will return
    • call

      public Sequence call(XPathContext context, Sequence[] arguments) throws XPathException
      Call the Callable.
      Parameters:
      context - the dynamic evaluation context
      arguments - the values of the arguments, supplied as Sequences.

      Generally it is advisable, if calling iterate() to process a supplied sequence, to call it only once; if the value is required more than once, it should first be converted to a GroundedValue by calling the utility methd SequenceTool.toGroundedValue().

      If the expected value is a single item, the item should be obtained by calling Sequence.head(): it cannot be assumed that the item will be passed as an instance of Item or AtomicValue.

      It is the caller's responsibility to perform any type conversions required to convert arguments to the type expected by the callee. An exception is where this Callable is explicitly an argument-converting wrapper around the original Callable.

      Returns:
      the result of the evaluation, in the form of a Sequence. It is the responsibility of the callee to ensure that the type of result conforms to the expected result type.
      Throws:
      XPathException - if a dynamic error occurs during the evaluation of the expression