net.sf.saxon.functions

Class Sum

java.lang.Object

net.sf.saxon.expr.Expression

net.sf.saxon.expr.FunctionCall

net.sf.saxon.functions.SystemFunctionCall

net.sf.saxon.functions.FoldingFunction

net.sf.saxon.functions.Sum

All Implemented Interfaces:

SourceLocator, Callable, IdentityComparable, InstructionInfo

public class Sum
extends FoldingFunction

Implementation of the fn:sum function

Field Summary

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

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, ITEM_FEED_METHOD, ITERATE_METHOD, locationId, MAX_SEQUENCE_LENGTH, MAX_STRING_LENGTH, PROCESS_METHOD, staticProperties, UNBOUNDED_LOWER, UNBOUNDED_UPPER, WATCH_METHOD

Constructor Summary

Constructors

Constructor and Description
Sum()

Method Summary

Methods

Modifier and Type	Method and Description
int	computeCardinality() Determine the cardinality of the function.
ExpressionCompiler	getExpressionCompiler() Return the compiler of the Sum expression
Fold	getFold(XPathContext context, Sequence... additionalArguments) Create the Fold object which actually performs the evaluation.
int	getImplementationMethod() Get implementation method
ItemType	getItemType() Determine the item type of the value returned by the function
Expression	optimize(ExpressionVisitor visitor, ContextItemStaticInfo contextItemType) Perform optimisation of an expression and its subexpressions.
static AtomicValue	total(SequenceIterator in, XPathContext context, SourceLocator locator) Static method to compute a total, invoked from compiled bytecode

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

call, evaluateItem, getStreamingAdjunct, iterate

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

addContextDocumentArgument, addDocToPathMap, bindStaticContext, checkArguments, computeSpecialProperties, copy, equalOrNull, equals, getContextNode, getConvertingCallable, getDefaultArgumentNode, getDetails, getErrorCodeForTypeErrors, getFunctionItemType, getOperation, getRequiredType, makeSystemFunction, operands, setDetails, toShortString, useContextItemAsDefault

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

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

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

addToPathMap, adoptChildExpression, checkForUpdatingSubexpressions, checkPermittedContents, clearStreamabilityData, computeDependencies, computeStaticProperties, doPromotion, dynamicError, effectiveBooleanValue, evaluateAsString, evaluatePendingUpdates, explain, getCardinality, getColumnNumber, getConfiguration, getConstructType, getContainer, getDependencies, getEvaluationMethod, getHostLanguage, getIntegerBounds, getIntrinsicDependencies, getLineNumber, getLocationId, getObjectName, getPosture, getProperties, getProperty, getPublicId, getSlotsUsed, getSpecialProperties, getStreamability, getSweep, getSystemId, hasVariableBinding, identityHashCode, implementsStaticTypeCheck, isIdentical, isSubtreeExpression, isUpdatingExpression, isVacuousExpression, iterateEvents, makeStreamingAdjunct, markTailFunctionCalls, operandList, process, resetLocalStaticProperties, setContainer, setEvaluationMethod, setFiltered, setFlattened, setLocationId, setPostureAndSweep, simplify, staticTypeCheck, suppressValidation, toPattern, toStreamingPattern, typeError, unordered

Methods inherited from class java.lang.Object

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

Constructor Detail

Sum

public Sum()

Method Detail

optimize

public Expression optimize(ExpressionVisitor visitor,
                  ContextItemStaticInfo contextItemType)
                    throws XPathException

Perform optimisation of an expression and its subexpressions.

This method is called after all references to functions and variables have been resolved to the declaration of the function or variable, and after all type checking has been done.

Overrides:

optimize in class SystemFunctionCall

Parameters:

visitor - an expression visitor

contextItemType - the static type of "." at the point where this expression is invoked. The parameter is set to null if it is known statically that the context item will be undefined. If the type of the context item is not known statically, the argument is set to Type.ITEM_TYPE

Returns:

the original expression, rewritten if appropriate to optimize execution

Throws:

XPathException - if an error is discovered during this phase (typically a type error)

getImplementationMethod

public int getImplementationMethod()

Get implementation method

Overrides:

getImplementationMethod in class FoldingFunction

Returns:

a value that indicates this function is capable of being streamed

getItemType

public ItemType getItemType()

Description copied from class: SystemFunctionCall

Determine the item type of the value returned by the function

Overrides:

getItemType in class SystemFunctionCall

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: SystemFunctionCall

Determine the cardinality of the function.

Overrides:

computeCardinality in class SystemFunctionCall

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

getFold

public Fold getFold(XPathContext context,
           Sequence... additionalArguments)
             throws XPathException

Create the Fold object which actually performs the evaluation.

Specified by:

getFold in class FoldingFunction

Parameters:

context - the dynamic evaluation context

additionalArguments - 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

total

public static AtomicValue total(SequenceIterator in,
                XPathContext context,
                SourceLocator locator)
                         throws XPathException

Static method to compute a total, invoked from compiled bytecode

Parameters:

in - the sequence of items to be summed

context - dynamic context for evaluation

locator - expression location for diagnostics

Returns:

null if the input is empty, otherwise the total as defined by the semantics of the sum() function

Throws:

XPathException - if a dynamic error occurs

getExpressionCompiler

public ExpressionCompiler getExpressionCompiler()

Return the compiler of the Sum expression

Overrides:

getExpressionCompiler in class Expression

Returns:

the relevant ExpressionCompiler