Function

All Superinterfaces:

Callable, GroundedValue, Item, PullEvent, Sequence

All Known Subinterfaces:

ArrayItem, MapItem

All Known Implementing Classes:

Abs, AbstractFunction, AccessorFn, AccessorFn.DayFromDate, AccessorFn.DayFromDateTime, AccessorFn.DaysFromDuration, AccessorFn.HoursFromDateTime, AccessorFn.HoursFromDuration, AccessorFn.HoursFromTime, AccessorFn.LocalNameFromQName, AccessorFn.MinutesFromDateTime, AccessorFn.MinutesFromDuration, AccessorFn.MinutesFromTime, AccessorFn.MonthFromDate, AccessorFn.MonthFromDateTime, AccessorFn.MonthsFromDuration, AccessorFn.NamespaceUriFromQName, AccessorFn.PrefixFromQName, AccessorFn.SecondsFromDateTime, AccessorFn.SecondsFromDuration, AccessorFn.SecondsFromTime, AccessorFn.TimezoneFromDate, AccessorFn.TimezoneFromDateTime, AccessorFn.TimezoneFromTime, AccessorFn.YearFromDate, AccessorFn.YearFromDateTime, AccessorFn.YearsFromDuration, AccumulatorFn, AccumulatorFn.AccumulatorAfter, AccumulatorFn.AccumulatorBefore, Adjust_1, Adjust_2, Aggregate, AnalyzeStringFn, ApplyFn, AtomicConstructorFunction, AvailableEnvironmentVariables, AvailableSystemProperties, Average, BaseUri_1, BooleanFn, CallableFunction, Ceiling, CodepointEqual, CodepointsToString, CoercedFunction, CollatingFunctionFixed, CollatingFunctionFree, CollationKeyFn, CollectionFn, Compare, CompileTimeFunction, Concat, ConstantFunction, ConstantFunction.False, ConstantFunction.True, Contains, ContainsToken, ContextAccessorFunction, ContextItemAccessorFunction, ContextItemAccessorFunction.Number_0, ContextItemAccessorFunction.StringAccessor, CopyOfFn, Count, Current, CurrentGroup, CurrentGroupingKey, CurrentMergeGroup, CurrentMergeKey, CurrentOutputUri, CurriedFunction, CurriedSystemFunction, Data_1, DateTimeConstructor, DeepEqual, DistinctValues, Doc, DocAvailable, DocumentFn, DocumentUri_1, DynamicContextAccessor, DynamicContextAccessor.CurrentDate, DynamicContextAccessor.CurrentDateTime, DynamicContextAccessor.CurrentTime, DynamicContextAccessor.DefaultLanguage, DynamicContextAccessor.ImplicitTimezone, ElementAvailable, Empty, EncodeForUri, EndsWith, EnvironmentVariable, Error, EscapeHtmlUri, Exists, FilterFn, Floor, FoldingFunction, FoldLeftFn, FoldRightFn, ForEachFn, ForEachPairFn, FormatDate, FormatInteger, FormatNumber, FormatNumber.FormatNumberFixed, FunctionArity, FunctionAvailable, FunctionLookup, FunctionName, GenerateId_1, HasChildren_1, HashTrieMap, HeadFn, Idref, IndexOf, InlineFunction, Innermost, InScopePrefixes, InsertBefore, IriToUri, JsonDoc, JsonToXMLFn, KeyFn, Lang, ListCastableFunction, ListConstructorFunction, LoadXqueryModule, LocalName_1, LowerCase, Matches, MemoFunction, Minimax, Minimax.Max, Minimax.Min, Name_1, NamespaceForPrefix, NamespaceUri_1, Nilled_1, NodeName_1, NormalizeSpace_1, NormalizeUnicode, NotFn, Number_1, OriginalFunction, Outermost, ParseIetfDate, ParseJsonFn, ParseXml, ParseXmlFragment, Path_1, PositionAndLast, PositionAndLast.Last, PositionAndLast.Position, Put, QNameFn, RandomNumberGenerator, RangeKey, RegexFunction, RegexFunctionSansFlags, RegexGroup, Remove, Replace, ResolveQName, ResolveURI, Reverse, Root_1, Round, RoundHalfToEven, ScalarSystemFunction, Serialize, SerializeJsonFn, SimpleArrayItem, SnapshotFn, SortOne, SortTwo, StartsWith, StaticContextAccessor, StaticContextAccessor.DefaultCollation, StaticContextAccessor.StaticBaseUri, StreamAvailable, String_1, StringJoin, StringLength_1, StringToCodepoints, Subsequence_2, Subsequence_3, Substring, SubstringAfter, SubstringBefore, Sum, SuperId, SuperId.ElementWithId, SuperId.Id, SystemFunction, SystemProperty, TailFn, Tokenize_1, Tokenize_3, Trace, TransformFn, Translate, Translate.TranslateFixed, TreatFn, TreatFn.ExactlyOne, TreatFn.OneOrMore, TreatFn.ZeroOrOne, TypeAvailable, UnionCastableFunction, UnionConstructorFunction, Unordered, UnparsedEntity, UnparsedEntity.UnparsedEntityPublicId, UnparsedEntity.UnparsedEntityUri, UnparsedText, UnparsedTextAvailable, UnparsedTextFunction, UnparsedTextLines, UpperCase, UriCollection, UserFunction, UserFunctionReference.BoundUserFunction, XMLToJsonFn, XMLToJsonTransform
```
public interface Function
extends Item, Callable, GroundedValue
```
XDM 3.0 introduces a third kind of item, beyond nodes and atomic values: the function. Functions implement this interface.

Method Summary

Methods
Modifier and Type	Method and Description
`Sequence`	`call(XPathContext context, Sequence[] args)` Invoke the function
`boolean`	`deepEquals(Function other, XPathContext context, AtomicComparer comparer, int flags)` Test whether this FunctionItem is deep-equal to another function item, under the rules of the deep-equal function
`void`	`export(ExpressionPresenter out)` Output information about this function item to the diagnostic explain() output
`int`	`getArity()` Get the arity of the function
`String`	`getDescription()` Get a description of this function for use in error messages.
`FunctionItemType`	`getFunctionItemType()` Get the item type of the function item
`StructuredQName`	`getFunctionName()` Get the name of the function, or null if it is anonymous
`OperandRole[]`	`getOperandRoles()` Get the roles of the arguments, for the purposes of streaming
`boolean`	`isArray()` Ask whether this function item is an array
`boolean`	`isMap()` Ask whether this function item is a map
`UnfailingIterator`	`iterate()` Get an iterator over all the items in the sequence

Methods inherited from interface net.sf.saxon.om.Item
atomize, getStringValue, getStringValueCS, head

Methods inherited from interface net.sf.saxon.om.GroundedValue
effectiveBooleanValue, getLength, getStringValue, getStringValueCS, head, itemAt, reduce, subsequence

- Method Detail
  - iterate
```
UnfailingIterator iterate()
```
    Get an iterator over all the items in the sequence
    
    Specified by:
    
    iterate in interface GroundedValue
    
    Specified by:
    
    iterate in interface Sequence
    
    Returns:
    an iterator over all the items
  - isMap
```
boolean isMap()
```
    Ask whether this function item is a map
    
    Returns:
    true if this function item is a map, otherwise false
  - isArray
```
boolean isArray()
```
    Ask whether this function item is an array
    
    Returns:
    true if this function item is an array, otherwise false
  - getFunctionItemType
```
FunctionItemType getFunctionItemType()
```
    Get the item type of the function item
    
    Returns:
    the function item's type
  - getFunctionName
```
StructuredQName getFunctionName()
```
    Get the name of the function, or null if it is anonymous
    
    Returns:
    the function name, or null for an anonymous inline function
  - getArity
```
int getArity()
```
    Get the arity of the function
    
    Returns:
    the number of arguments in the function signature
  - getOperandRoles
```
OperandRole[] getOperandRoles()
```
    Get the roles of the arguments, for the purposes of streaming
    
    Returns:
    an array of OperandRole objects, one for each argument
  - call
```
Sequence call(XPathContext context,
            Sequence[] args)
              throws XPathException
```
    Invoke the function
    
    Specified by:
    
    call in interface Callable
    
    Parameters:
    context - the XPath dynamic evaluation context
    args - the actual arguments to be supplied
    
    Returns:
    the result of invoking the function
    
    Throws:
    
    XPathException - if a dynamic error occurs within the function
  - deepEquals
```
boolean deepEquals(Function other,
                 XPathContext context,
                 AtomicComparer comparer,
                 int flags)
                   throws XPathException
```
    Test whether this FunctionItem is deep-equal to another function item, under the rules of the deep-equal function
    
    Parameters:
    other - the other function item
    context - the dynamic evaluation context
    comparer - the object to perform the comparison
    flags - options for how the comparison is performed
    
    Returns:
    true if the two function items are deep-equal
    
    Throws:
    
    XPathException - if the comparison cannot be performed
  - getDescription
```
String getDescription()
```
    Get a description of this function for use in error messages. For named functions, the description is the function name (as a lexical QName). For others, it might be, for example, "inline function", or "partially-applied ends-with function".
    
    Returns:
    a description of the function for use in error messages
  - export
```
void export(ExpressionPresenter out)
```
    Output information about this function item to the diagnostic explain() output

Interface Function

Method Summary

Methods inherited from interface net.sf.saxon.om.Item

Methods inherited from interface net.sf.saxon.om.GroundedValue

Method Detail

iterate

isMap

isArray

getFunctionItemType

getFunctionName

getArity

getOperandRoles

call

deepEquals

getDescription

export