net.sf.saxon.functions
Class Sum

java.lang.Object
  net.sf.saxon.expr.Expression
      net.sf.saxon.expr.FunctionCall
          net.sf.saxon.functions.SystemFunction
              net.sf.saxon.functions.Aggregate
                  net.sf.saxon.functions.Sum

All Implemented Interfaces:

Serializable, SourceLocator, LocationProvider, SaxonLocator, InstructionInfo, Locator

public class Sum
extends Aggregate

Implementation of the fn:sum function

See Also:

Serialized Form

Field Summary

Fields inherited from class net.sf.saxon.functions.SystemFunction

operation

Fields inherited from class net.sf.saxon.expr.FunctionCall

argument

Fields inherited from class net.sf.saxon.expr.Expression

EFFECTIVE_BOOLEAN_VALUE, EVALUATE_METHOD, EVENT_FEED_METHOD, ITEM_FEED_METHOD, ITERATE_METHOD, locationId, MAX_SEQUENCE_LENGTH, MAX_STRING_LENGTH, PROCESS_METHOD, PUSH_SELECTION, staticProperties, UNBOUNDED_LOWER, UNBOUNDED_UPPER, WATCH_METHOD

Constructor Summary

Sum()

Method Summary

int	computeCardinality() Determine the cardinality of the function.
Item	evaluateItem(XPathContext context) Evaluate the function
int	getImplementationMethod() Get implementation method
ItemType	getItemType(TypeHierarchy th) Determine the item type of the value returned by the function
static AtomicValue	total(SequenceIterator iter, XPathContext context, SourceLocator location) Calculate the total of a sequence.

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

checkArguments

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

addContextDocumentArgument, addDocToPathMap, computeSpecialProperties, copy, equals, getDetails, getErrorCodeForTypeErrors, getOperation, getRequiredType, makeSystemFunction, optimize, setDetails, useContextItemAsDefault

Methods inherited from class net.sf.saxon.expr.FunctionCall

addExternalFunctionCallToPathMap, checkArgumentCount, explain, getArguments, getDisplayName, getExpressionName, getFunctionName, getNumberOfArguments, hashCode, iterateSubExpressions, preEvaluate, promote, replaceSubExpression, setArguments, setFunctionName, simplify, simplifyArguments, toString, typeCheck

Methods inherited from class net.sf.saxon.expr.Expression

addToPathMap, adoptChildExpression, checkForUpdatingSubexpressions, checkPermittedContents, computeDependencies, computeStaticProperties, doPromotion, dynamicError, effectiveBooleanValue, evaluateAsString, evaluatePendingUpdates, explain, getCardinality, getColumnNumber, getColumnNumber, getConstructType, getContainer, getDependencies, getEvaluationMethod, getExecutable, getHostLanguage, getIntegerBounds, getIntrinsicDependencies, getLineNumber, getLineNumber, getLocationId, getLocationProvider, getObjectName, getProperties, getProperty, getPublicId, getSlotsUsed, getSpecialProperties, getSystemId, getSystemId, hasLoopingSubexpression, hasVariableBinding, implementsStaticTypeCheck, isSubtreeExpression, isUpdatingExpression, isVacuousExpression, iterate, iterateEvents, iterateSameFocusSubExpressions, markTailFunctionCalls, process, resetLocalStaticProperties, setContainer, setEvaluationMethod, setFiltered, setFlattened, setLocationId, staticTypeCheck, suppressValidation, typeError

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

Sum

public Sum()

Method Detail

getImplementationMethod

public int getImplementationMethod()

Get implementation method

Overrides:

getImplementationMethod in class SystemFunction

Returns:

a value that indicates this function is capable of being streamed

getItemType

public ItemType getItemType(TypeHierarchy th)

Description copied from class: SystemFunction

Determine the item type of the value returned by the function

Overrides:

getItemType in class SystemFunction

Parameters:

th - the type hierarchy cache

Returns:

a value such as Type.STRING, Type.BOOLEAN, Type.NUMBER, Type.NODE, or Type.ITEM (meaning not known at compile time)

computeCardinality

public int computeCardinality()

Description copied from class: SystemFunction

Determine the cardinality of the function.

Overrides:

computeCardinality in class SystemFunction

Returns:

the computed cardinality, as one of the values StaticProperty.ALLOWS_ZERO_OR_ONE, StaticProperty.EXACTLY_ONE, StaticProperty.ALLOWS_ONE_OR_MORE, StaticProperty.ALLOWS_ZERO_OR_MORE

evaluateItem

public Item evaluateItem(XPathContext context)
                  throws XPathException

Evaluate the function

Overrides:

evaluateItem in class Expression

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

total

public static AtomicValue total(SequenceIterator iter,
                                XPathContext context,
                                SourceLocator location)
                         throws XPathException

Calculate the total of a sequence.

Parameters:

iter - iterator over the items to be totalled

context - the XPath dynamic context

location - location of the expression in the source for diagnostics

Returns:

the total, according to the rules of the XPath sum() function, but returning null if the sequence is empty. (It's then up to the caller to decide what the correct result is for an empty sequence.

Throws:

XPathException