Package net.sf.saxon.functions
Class FoldingFunction
java.lang.Object
net.sf.saxon.functions.AbstractFunction
net.sf.saxon.functions.SystemFunction
net.sf.saxon.functions.FoldingFunction
- All Implemented Interfaces:
Callable
,FunctionItem
,GroundedValue
,Item
,Sequence
- Direct Known Subclasses:
ArrayFunctionSet.ArrayFromSequence
,Average
,FoldLeftFn
,StringJoin
,Sum
Implementation of aggregate functions such as sum() and avg() that supply a fold() function. Such
functions are automatically streamable.
-
Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptioncall
(XPathContext context, Sequence[] arguments) Evaluate the expressionabstract Fold
getFold
(XPathContext context, Sequence... additionalArguments) Create the Fold object which actually performs the evaluation.Get a name that identifies the class that can be used to evaluate this function in streaming mode, that is, supplying one item or event at a time as it is delivered by the parser.Methods inherited from class net.sf.saxon.functions.SystemFunction
dependsOnContextItem, dynamicCall, equals, export, exportAdditionalArguments, exportAttributes, fixArguments, getArity, getCardinality, getContextNode, getDescription, getDetails, getElaborator, getErrorCodeForTypeErrors, getFunctionItemType, getFunctionName, getIntegerBounds, getNetCost, getOperandRoles, getRequiredType, getResultItemType, getResultItemType, getRetainedStaticContext, getSpecialProperties, getStaticBaseUriString, getUniStringArg, hashCode, importAttributes, isSequenceVariadic, isTrustedResultType, makeCall, makeFunction, makeFunction40, makeFunctionCall, makeOptimizedFunctionCall, resultIfEmpty, setArity, setDetails, setRetainedStaticContext, supplyTypeInformation, toShortString, toString, typeCheckCaller
Methods inherited from class net.sf.saxon.functions.AbstractFunction
atomize, deepEqual40, deepEquals, effectiveBooleanValue, getAnnotations, getUnicodeStringValue, isArray, isMap, makeNewContext, simplify, typeCheck
Methods inherited from class java.lang.Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait
Methods inherited from interface net.sf.saxon.om.FunctionItem
getGenre
Methods inherited from interface net.sf.saxon.om.GroundedValue
asIterable, concatenate, containsNode, materialize
Methods inherited from interface net.sf.saxon.om.Item
getLength, getStringValue, head, isStreamed, itemAt, iterate, reduce, subsequence
Methods inherited from interface net.sf.saxon.om.Sequence
makeRepeatable
-
Constructor Details
-
FoldingFunction
public FoldingFunction()
-
-
Method Details
-
getFold
public abstract Fold getFold(XPathContext context, Sequence... additionalArguments) throws XPathException Create the Fold object which actually performs the evaluation. Must be implemented in every subclass.- Parameters:
context
- the dynamic evaluation contextadditionalArguments
- the values of all arguments other than the first.- Returns:
- the Fold object used to compute the function
- Throws:
XPathException
- if a dynamic error occurs
-
call
Evaluate the expression- Parameters:
context
- the dynamic evaluation contextarguments
- the values of the arguments, supplied as Sequences- Returns:
- the result of the evaluation, in the form of a Sequence
- Throws:
XPathException
- if a dynamic error occurs during the evaluation of the expression
-
getStreamerName
Description copied from class:SystemFunction
Get a name that identifies the class that can be used to evaluate this function in streaming mode, that is, supplying one item or event at a time as it is delivered by the parser. Special streaming support is generally available in Saxon-EE for all system functions that take a sequence as their argument.- Overrides:
getStreamerName
in classSystemFunction
- Returns:
- a name that identifies a class that supports streamed evaluation of this system
function, or null if no such class is available. The mapping of names to classes is
defined in the Saxon-EE class
StreamerMap
. In non-streaming Saxon editions (HE and PE) the method always returns null.
-