net.sf.saxon.functions

Class Minimax

java.lang.Object

net.sf.saxon.expr.Expression

net.sf.saxon.expr.FunctionCall

net.sf.saxon.functions.SystemFunctionCall

net.sf.saxon.functions.CollatingFunction

net.sf.saxon.functions.Minimax

All Implemented Interfaces:

SourceLocator, Callable, IdentityComparable, InstructionInfo

Direct Known Subclasses:

Max, Min

public abstract class Minimax
extends CollatingFunction

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

Field Summary

Fields

Modifier and Type	Field and Description
static int	MAX
static int	MIN

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

staticCollation

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
Minimax()

Method Summary

Methods

Modifier and Type	Method and Description
void	checkArguments(ExpressionVisitor visitor) Static analysis: prevent sorting of the argument and preallocate a comparer if possible
int	computeCardinality() Determine the cardinality of the function.
Expression	copy() Copy an expression.
boolean	equals(Object o) Determine whether two expressions are equivalent
AtomicValue	evaluateItem(XPathContext context) Evaluate the function
BuiltInAtomicType	getArgumentType()
AtomicComparer	getAtomicComparer(XPathContext context)
protected int	getCollationArgument() Get the argument position (0-based) containing the collation name
AtomicComparer	getComparer()
ExpressionCompiler	getExpressionCompiler() Return the compiler of the Minimax expression
int	getImplementationMethod() Get implementation method
ItemType	getItemType() Determine the item type of the value returned by the function
MinimaxAdjunct	getStreamingAdjunct() Get a class that supports streamed evaluation of this expression
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, ContextItemStaticInfo contextItemType) Perform optimisation of an expression and its subexpressions.
void	setIgnoreNaN(boolean ignore) Indicate whether NaN values should be ignored.
Expression	typeCheck(ExpressionVisitor visitor, ContextItemStaticInfo contextInfo) Type-check the expression

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

bindStaticContext, expandCollationURI, getAtomicComparer, getCollator, getCollatorFromLastArgument, getExpressionBaseURI, getPreAllocatedAtomicComparer, getStaticCollation, preAllocateComparer

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

addContextDocumentArgument, addDocToPathMap, computeSpecialProperties, equalOrNull, 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

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, iterate, 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

Methods inherited from interface net.sf.saxon.expr.Callable

call

Field Detail

MIN

public static final int MIN

See Also:

Constant Field Values

MAX

public static final int MAX

See Also:

Constant Field Values

Constructor Detail

Minimax

public Minimax()

Method Detail

getCollationArgument

protected int getCollationArgument()

Get the argument position (0-based) containing the collation name

Specified by:

getCollationArgument in class CollatingFunction

Returns:

the position of the argument containing the collation URI

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. This is the case for internally-generated min() and max() functions used to support general comparisons.

Parameters:

ignore - true if NaN values are to be ignored when computing the min or max.

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

getComparer

public AtomicComparer getComparer()

getArgumentType

public BuiltInAtomicType getArgumentType()

getImplementationMethod

public int getImplementationMethod()

Get implementation method

Overrides:

getImplementationMethod in class SystemFunctionCall

Returns:

a value that indicates this function is capable of being streamed

checkArguments

public void checkArguments(ExpressionVisitor visitor)
                    throws XPathException

Static analysis: prevent sorting of the argument and preallocate a comparer if possible

Overrides:

checkArguments in class CollatingFunction

Parameters:

visitor - the expression visitor

Throws:

XPathException - if the arguments are incorrect

computeCardinality

public int computeCardinality()

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

typeCheck

public Expression typeCheck(ExpressionVisitor visitor,
                   ContextItemStaticInfo contextInfo)
                     throws XPathException

Type-check the expression

Overrides:

typeCheck in class FunctionCall

Parameters:

visitor - an expression visitor

contextInfo - Information available statically about the context item: whether it is (possibly) absent; its static type; its streaming posture.

Returns:

the original expression, rewritten to perform necessary run-time type checks, and to perform other type-related optimizations

Throws:

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

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)

getItemType

public ItemType getItemType()

Determine the item type of the value returned by the function

Overrides:

getItemType in class SystemFunctionCall

Returns:

the statically inferred type of the expression

copy

public Expression copy()

Copy an expression. This makes a deep copy.

Overrides:

copy in class CollatingFunction

Returns:

the copy of the original expression

equals

public boolean equals(Object o)

Determine whether two expressions are equivalent

Overrides:

equals in class CollatingFunction

evaluateItem

public AtomicValue 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

getAtomicComparer

public AtomicComparer getAtomicComparer(XPathContext context)
                                 throws XPathException

Throws:

XPathException

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

getExpressionCompiler

public ExpressionCompiler getExpressionCompiler()

Return the compiler of the Minimax expression

Overrides:

getExpressionCompiler in class Expression

Returns:

the relevant ExpressionCompiler

getStreamingAdjunct

public MinimaxAdjunct getStreamingAdjunct()

Get a class that supports streamed evaluation of this expression

Overrides:

getStreamingAdjunct in class Expression

Returns:

the relevant StreamingAdjunct, or null if none is available