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java.lang.Object
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+--net.sf.saxon.expr.ComputedExpression
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+--net.sf.saxon.expr.FunctionCall
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+--net.sf.saxon.functions.SystemFunction
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+--net.sf.saxon.functions.Aggregate
This class implements the sum(), avg(), count() functions,
| Field Summary | |
static int |
AVG
|
static int |
COUNT
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static int |
SUM
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| 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.ComputedExpression |
locationId, staticProperties |
| Fields inherited from interface net.sf.saxon.expr.Expression |
EVALUATE_METHOD, ITERATE_METHOD, PROCESS_METHOD |
| Constructor Summary | |
Aggregate()
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| Method Summary | |
void |
checkArguments(StaticContext env)
Static analysis: prevent sorting of the argument |
static int |
count(SequenceIterator iter)
Get the number of items in a sequence identified by a SequenceIterator |
Item |
evaluateItem(XPathContext context)
Evaluate the function |
ItemType |
getItemType()
Determine the item type of the value returned by the function |
static boolean |
isCountFunction(Expression exp)
Determine whether a given expression is a call to the count() function |
| Methods inherited from class net.sf.saxon.functions.SystemFunction |
addContextDocumentArgument, computeCardinality, display, getDetails, getRequiredType, main, makeSystemFunction, setDetails, useContextItemAsDefault |
| Methods inherited from class net.sf.saxon.expr.FunctionCall |
analyze, checkArgumentCount, getDisplayName, getFunctionNameCode, getNumberOfArguments, iterateSubExpressions, preEvaluate, promote, setArguments, setFunctionNameCode, simplify, simplifyArguments |
| Methods inherited from class java.lang.Object |
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
| Field Detail |
public static final int SUM
public static final int AVG
public static final int COUNT
| Constructor Detail |
public Aggregate()
| Method Detail |
public void checkArguments(StaticContext env)
throws XPathException
checkArguments in class SystemFunctionXPathExceptionpublic ItemType getItemType()
getItemType in interface ExpressiongetItemType in class SystemFunction
public Item evaluateItem(XPathContext context)
throws XPathException
evaluateItem in interface ExpressionevaluateItem in class ComputedExpressioncontext - The context in which the expression is to be evaluated
XPathException - if any dynamic error occurs evaluating the
expression
public static int count(SequenceIterator iter)
throws XPathException
iter - The SequenceIterator. This method moves the current position
of the supplied iterator; if this isn't safe, make a copy of the iterator
first by calling getAnother(). The supplied iterator must be positioned
before the first item (there must have been no call on next()).
XPathException - if a failure occurs reading the input sequencepublic static boolean isCountFunction(Expression exp)
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