Class Aggregate

    • Constructor Detail

      • Aggregate

        public Aggregate()
    • Method Detail

      • getItemType

        public ItemType getItemType​(TypeHierarchy th)
        Determine the item type of the value returned by the function
        Specified by:
        getItemType in interface Expression
        Overrides:
        getItemType in class SystemFunction
        Parameters:
        th -
        Returns:
        a value such as Type.STRING, Type.BOOLEAN, Type.NUMBER, Type.NODE, or Type.ITEM (meaning not known at compile time)
      • evaluateItem

        public Item evaluateItem​(XPathContext context)
                          throws XPathException
        Evaluate the function
        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
      • 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
      • isCountFunction

        public static boolean isCountFunction​(Expression exp)
        Determine whether a given expression is a call to the count() function