net.sf.saxon.functions
Class Average
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.Average
- All Implemented Interfaces:
- Serializable, SourceLocator, LocationProvider, SaxonLocator, CallableExpression, InstructionInfo, Locator
public class Average
- extends Aggregate
- implements CallableExpression
Implementation of the fn:avg function
- See Also:
- Serialized Form
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 |
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 |
Average
public Average()
getImplementationMethod
public int getImplementationMethod()
- Description copied from class:
SystemFunction
- An implementation of Expression must provide at least one of the methods evaluateItem(), iterate(), or process().
This method indicates which of these methods is provided directly. The other methods will always be available
indirectly, using an implementation that relies on one of the other methods.
- Overrides:
getImplementationMethod
in class SystemFunction
- Returns:
- the implementation method, for example
Expression.ITERATE_METHOD
or Expression.EVALUATE_METHOD
or
Expression.PROCESS_METHOD
getItemType
public ItemType getItemType(TypeHierarchy th)
- 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()
- 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
average
public static AtomicValue average(SequenceIterator iter,
XPathContext context,
SourceLocator location)
throws XPathException
- Calculate average
- Parameters:
iter
- iterator over the items to be totalledcontext
- the XPath dynamic contextlocation
- location of the expression in the source for diagnostics
- Returns:
- the average of the values
- Throws:
XPathException
call
public SequenceIterator call(SequenceIterator[] arguments,
XPathContext context)
throws XPathException
- Description copied from interface:
CallableExpression
- Evaluate the expression
- Specified by:
call
in interface CallableExpression
- Parameters:
arguments
- the values of the arguments, supplied as SequenceIteratorscontext
- the dynamic evaluation context
- Returns:
- the result of the evaluation, in the form of a SequenceIterator
- Throws:
XPathException
- if a dynamic error occurs during the evaluation of the expression
Copyright (c) 2004-2011 Saxonica Limited. All rights reserved.