## com.saxonica.functions.extfn
Class GeneralFilterFunction

    java.lang.Object
      net.sf.saxon.lib.ExtensionFunctionDefinition
          com.saxonica.functions.extfn.GeneralFilterFunction

All Implemented Interfaces:
  Serializable

Direct Known Subclasses:
  Highest, Leading, Lowest, Sort

    public abstract class GeneralFilterFunction

extends ExtensionFunctionDefinition

This class provides an abstract framework for a collection of extension functions that have the same general characteristics: (a) the first argument is a sequence, (b) the result is a subset/rearrangement of that sequence, (d) the second argument is a single argument function that is applied to the members of the sequence, (e) the default function if the second argument is omitted is fn:data(), (e) the processing may depend on the default collation.

See Also:
  Serialized Form

Nested Class Summary
`static class` `GeneralFilterFunction.GeneralFilterFunctionCall`

Constructor Summary
`GeneralFilterFunction()`

Method Summary
`SequenceType[]` `getArgumentTypes()` Get the required types for the arguments of this function, counting from zero
`int` `getMaximumNumberOfArguments()` Get the maximum number of arguments allowed by the function
`int` `getMinimumNumberOfArguments()` Get the minimum number of arguments required by the function
`SequenceType` `getResultType(SequenceType[] suppliedArgumentTypes)` Get the type of the result of the function

Methods inherited from class net.sf.saxon.lib.ExtensionFunctionDefinition
`dependsOnFocus, getCompilerForJava, getFunctionQName, hasSideEffects, makeCallExpression, trustResultType`

Methods inherited from class java.lang.Object
`clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

Constructor Detail

### GeneralFilterFunction

    public GeneralFilterFunction()

Method Detail

### getMinimumNumberOfArguments

    public int getMinimumNumberOfArguments()

  Get the minimum number of arguments required by the function

  Overrides:
    `getMinimumNumberOfArguments` in class `ExtensionFunctionDefinition`
  Returns:
    the minimum number of arguments that must be supplied in a call to this function

### getMaximumNumberOfArguments

    public int getMaximumNumberOfArguments()

  Get the maximum number of arguments allowed by the function

  Overrides:
    `getMaximumNumberOfArguments` in class `ExtensionFunctionDefinition`
  Returns:
    the maximum number of arguments that may be supplied in a call to this function

### getArgumentTypes

    public SequenceType[] getArgumentTypes()

  Get the required types for the arguments of this function, counting from zero

  Specified by:
    `getArgumentTypes` in class `ExtensionFunctionDefinition`
  Returns:
    the required types of the argument, as defined by the function signature. Normally this should be an array of size `getMaximumNumberOfArguments()`; however for functions that allow a variable number of arguments, the array can be smaller than this, with the last entry in the array providing the required type for all the remaining arguments.

### getResultType

    public SequenceType getResultType(SequenceType[] suppliedArgumentTypes)

  Get the type of the result of the function

  Specified by:
    `getResultType` in class `ExtensionFunctionDefinition`
  Parameters:
    `suppliedArgumentTypes` - the static types of the arguments to the function. This is provided so that a more precise result type can be returned in the common case where the type of the result depends on the type of the first argument. The value will be null if the function call has no arguments.
  Returns:
    the return type of the function, as defined by its function signature

Copyright (c) 2004-2010 Saxonica Limited. All rights reserved.