Class Count

All Implemented Interfaces:
Serializable, SourceLocator, LocationProvider, SaxonLocator, InstructionInfo, Locator

public class Count extends Aggregate
Implementation of the fn:count function
See Also:
  • Constructor Details

    • Count

      public Count()
  • Method Details

    • getImplementationMethod

      public int getImplementationMethod()
      Description copied from class: SystemFunction
      An implementation of Expression must provide at least one of the methods evaluateItem(), iterate(), or process(). This method indicates which of these methods is provided directly. The other methods will always be available indirectly, using an implementation that relies on one of the other methods.
      Overrides:
      getImplementationMethod in class SystemFunction
      Returns:
      the implementation method, for example Expression.ITERATE_METHOD or Expression.EVALUATE_METHOD or Expression.PROCESS_METHOD
    • getIntegerBounds

      public IntegerValue[] getIntegerBounds()
      For an expression that returns an integer or a sequence of integers, get a lower and upper bound on the values of the integers that may be returned, from static analysis. The default implementation returns null, meaning "unknown" or "not applicable". Other implementations return an array of two IntegerValue objects, representing the lower and upper bounds respectively. The values UNBOUNDED_LOWER and UNBOUNDED_UPPER are used by convention to indicate that the value may be arbitrarily large. The values MAX_STRING_LENGTH and MAX_SEQUENCE_LENGTH are used to indicate values limited by the size of a string or the size of a sequence.
      Overrides:
      getIntegerBounds in class Expression
      Returns:
      the lower and upper bounds of integer values in the result, or null to indicate unknown or not applicable.
    • evaluateItem

      public Item evaluateItem(XPathContext context) throws XPathException
      Evaluate the function
      Overrides:
      evaluateItem in class Expression
      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
    • count

      public static int count(SequenceIterator iter) throws XPathException
      Get the number of items in a sequence identified by a SequenceIterator
      Parameters:
      iter - The SequenceIterator. This method moves the current position of the supplied iterator; if this isn't safe, make a copy of the iterator first by calling getAnother(). The supplied iterator must be positioned before the first item (there must have been no call on next()).
      Returns:
      the number of items in the underlying sequence
      Throws:
      XPathException - if a failure occurs reading the input sequence