com.saxonica.extfn
Class HighestOrLowest

java.lang.Object
  net.sf.saxon.functions.ExtensionFunctionCall
      com.saxonica.extfn.GeneralFilterFunction.GeneralFilterFunctionCall
          com.saxonica.extfn.HighestOrLowest

All Implemented Interfaces:

Serializable

public class HighestOrLowest
extends GeneralFilterFunction.GeneralFilterFunctionCall

This class implements the saxon:highest() and saxon:lowest() extension functions.

The first argument is a sequence S, the second a function F (defaulting to fn:data). The function returns the item or items I in the input sequence S for which F(I) has its highest/lowest value. It is not possible to specify a collation; the default collation is used when comparing strings.

See Also:

Serialized Form

Field Summary

Fields inherited from class com.saxonica.extfn.GeneralFilterFunction.GeneralFilterFunctionCall

atomizer, defaultCollation

Constructor Summary

HighestOrLowest()

Method Summary

SequenceIterator

call(SequenceIterator[] arguments, XPathContext context) Evaluate this function call at run-time

Methods inherited from class com.saxonica.extfn.GeneralFilterFunction.GeneralFilterFunctionCall

copyLocalData, supplyStaticContext

Methods inherited from class net.sf.saxon.functions.ExtensionFunctionCall

effectiveBooleanValue, getDefinition, rewrite, setDefinition

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

HighestOrLowest

public HighestOrLowest()

Method Detail

call

public SequenceIterator call(SequenceIterator[] arguments,
                             XPathContext context)
                      throws XPathException

Evaluate this function call at run-time

Specified by:

call in class ExtensionFunctionCall

Parameters:

arguments - The values of the arguments to the function call. Each argument value (which is in general a sequence) is supplied in the form of an iterator over the items in the sequence. If required, the supplied sequence can be materialized by calling, for example, new SequenceExtent(arguments[i]). If the argument is always a singleton, then the single item may be obtained by calling arguments[i].next(). The implementation is not obliged to read all the items in each SequenceIterator if they are not required to compute the result; but if any SequenceIterator is not read to completion, it is good practice to call its close() method.

context - The XPath dynamic evaluation context

Returns:

an iterator over the results of the function. If the result is a single item, it can be returned in the form of a SingletonIterator. If the result is an empty sequence, the method should return EmptyIterator.getInstance()

Throws:

XPathException - if a dynamic error occurs during evaluation of the function. The Saxon run-time code will add information about the error location.