net.sf.saxon.functions

Class Minimax

Implemented Interfaces:
EvaluableItem, InstructionInfoProvider, SequenceIterable, Serializable, SourceLocator

public class Minimax
extends CollatingFunction

This class implements the min() and max() functions

Field Summary

static int
MAX
static int
MIN

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

stringCollator

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

EVALUATE_METHOD, ITERATE_METHOD, PROCESS_METHOD, locationId, staticProperties

Method Summary

void
checkArguments(ExpressionVisitor visitor)
Static analysis: prevent sorting of the argument
int
computeCardinality()
Determine the cardinality of the function.
Item
evaluateItem(XPathContext context)
Evaluate the function
ItemType
getItemType(TypeHierarchy th)
Determine the item type of the value returned by the function
boolean
isIgnoreNaN()
Test whether NaN values are to be ignored
static AtomicValue
minimax(SequenceIterator iter, int operation, AtomicComparer atomicComparer, boolean ignoreNaN, XPathContext context)
Static method to evaluate the minimum or maximum of a sequence
Expression
optimize(ExpressionVisitor visitor, ItemType contextItemType)
Perform optimisation of an expression and its subexpressions.
void
setIgnoreNaN(boolean ignore)
Indicate whether NaN values should be ignored.

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

checkArguments, copy, getAtomicComparer, getCollator, getExpressionBaseURI, getStringCollator

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

addContextDocumentArgument, addDocToPathMap, checkArguments, computeCardinality, computeSpecialProperties, copy, getDetails, getErrorCodeForTypeErrors, getItemType, getRequiredType, makeSystemFunction, optimize, setDetails, useContextItemAsDefault

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

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

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

addToPathMap, adoptChildExpression, checkPermittedContents, computeCardinality, computeDependencies, computeSpecialProperties, computeStaticProperties, copy, display, doPromotion, dynamicError, effectiveBooleanValue, evaluateAsString, evaluateItem, explain, explain, findParentOf, getCardinality, getColumnNumber, getConstructType, getContainer, getDependencies, getExecutable, getHostLanguage, getImplementationMethod, getInstructionInfo, getIntrinsicDependencies, getItemType, getLineNumber, getLocationId, getLocationProvider, getPublicId, getSlotsUsed, getSpecialProperties, getSystemId, hasLoopingSubexpression, implementsStaticTypeCheck, iterate, iterateEvents, iterateSubExpressions, markTailFunctionCalls, optimize, process, promote, replaceSubExpression, resetLocalStaticProperties, setContainer, setFiltered, setFlattened, setLocationId, simplify, staticTypeCheck, suppressValidation, toString, typeCheck, typeError

Field Details

MAX

public static final int MAX
Field Value:
3

MIN

public static final int MIN
Field Value:
2

Method Details

checkArguments

public void checkArguments(ExpressionVisitor visitor)
            throws XPathException
Static analysis: prevent sorting of the argument
Overrides:
checkArguments in interface CollatingFunction

computeCardinality

public int computeCardinality()
Determine the cardinality of the function.
Overrides:
computeCardinality in interface SystemFunction

evaluateItem

public Item evaluateItem(XPathContext context)
            throws XPathException
Evaluate the function
Specified by:
evaluateItem in interface EvaluableItem
Overrides:
evaluateItem in interface Expression

getItemType

public ItemType getItemType(TypeHierarchy th)
Determine the item type of the value returned by the function
Overrides:
getItemType in interface SystemFunction
Parameters:
th - the type hierarchy cache
Returns:
the statically inferred type of the expression

isIgnoreNaN

public boolean isIgnoreNaN()
Test whether NaN values are to be ignored
Returns:
true if NaN values are to be ignored. This is the case for internally-generated min() and max() functions used to support general comparisons

minimax

public static AtomicValue minimax(SequenceIterator iter,
                                  int operation,
                                  AtomicComparer atomicComparer,
                                  boolean ignoreNaN,
                                  XPathContext context)
            throws XPathException
Static method to evaluate the minimum or maximum of a sequence
Parameters:
iter - Iterator over the input sequence
operation - either MIN or MAX
atomicComparer - an AtomicComparer used to compare values
ignoreNaN - true if NaN values are to be ignored
context - dynamic evaluation context
Returns:
the min or max value in the sequence, according to the rules of the fn:min() or fn:max() functions
Throws:
XPathException - typically if non-comparable values are found in the sequence

optimize

public Expression optimize(ExpressionVisitor visitor,
                           ItemType 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 interface SystemFunction
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)

setIgnoreNaN

public void setIgnoreNaN(boolean ignore)
Indicate whether NaN values should be ignored. For the external min() and max() function, a NaN value in the input causes the result to be NaN. Internally, however, min() and max() are also used in such a way that NaN values should be ignored.
Parameters:
ignore - true if NaN values are to be ignored when computing the min or max.