net.sf.saxon.functions

Class Minimax

java.lang.Object

net.sf.saxon.om.AbstractItem

net.sf.saxon.functions.AbstractFunction

net.sf.saxon.functions.SystemFunction

net.sf.saxon.functions.CollatingFunctionFixed

net.sf.saxon.functions.Minimax

All Implemented Interfaces:

Callable, StatefulSystemFunction, Function, GroundedValue, Item, Sequence

Direct Known Subclasses:

Minimax.Max, Minimax.Min

public abstract class Minimax
extends CollatingFunctionFixed

This class implements the min() and max() functions, with the collation argument already known.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	Minimax.Max Concrete subclass to define the fn:max() function
static class	Minimax.Min Concrete subclass to define the fn:min() function

Constructor Summary

Constructors

Constructor and Description
Minimax()

Method Summary

Modifier and Type	Method and Description
ZeroOrOne<AtomicValue>	call(XPathContext context, Sequence[] arguments) Evaluate the function
void	exportAttributes(ExpressionPresenter out) Export any context attributes held within the SystemFunction object.
PlainType	getArgumentType()
AtomicComparer	getAtomicComparer(XPathContext context) During evaluation, get the pre-allocated atomic comparer if available, or allocate a new one otherwise
int	getCardinality(Expression[] arguments) Determine the cardinality of the function.
AtomicComparer	getComparer()
java.lang.String	getCompilerName() Get the (local) name of a class that can be used to generate bytecode for this system function
ItemType	getResultItemType(Expression[] args) Get the return type, given knowledge of the actual arguments
java.lang.String	getStreamerName() Get a name that identifies the class that can be used to evaluate this function in streaming mode, that is, supplying one item or event at a time as it is delivered by the parser.
void	importAttributes(java.util.Properties attributes) Import any attributes found in the export file, that is, any attributes output using the exportAttributes method
boolean	isIgnoreNaN() Test whether NaN values are to be ignored
abstract boolean	isMaxFunction() Method to be implemented in subclasses to indicate whether the function implements fn:min() or fn:max()
Expression	makeOptimizedFunctionCall(ExpressionVisitor visitor, ContextItemStaticInfo contextInfo, Expression... arguments) Allow the function to create an optimized call based on the values of the actual arguments
static AtomicValue	minimax(SequenceIterator iter, boolean isMaxFunction, AtomicComparer atomicComparer, boolean ignoreNaN, XPathContext context) Static method to evaluate the minimum or maximum of a sequence
void	setIgnoreNaN(boolean ignore) Indicate whether NaN values should be ignored.
void	supplyTypeInformation(ExpressionVisitor visitor, ContextItemStaticInfo contextItemType, Expression[] arguments) Static analysis: preallocate a comparer if possible

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

copy, getPreAllocatedAtomicComparer, getStringCollator, isSubstringMatchingFunction, preAllocateComparer, setCollationName, setRetainedStaticContext

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

dependsOnContextItem, dynamicCall, equals, export, exportAdditionalArguments, fixArguments, getArity, getContextNode, getDescription, getDetails, getErrorCodeForTypeErrors, getFunctionItemType, getFunctionName, getIntegerBounds, getNetCost, getOperandRoles, getRequiredType, getResultItemType, getRetainedStaticContext, getSpecialProperties, getStaticBaseUriString, isTrustedResultType, makeCall, makeFunction, makeFunctionCall, resultIfEmpty, setArity, setDetails, typeCheckCaller

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

atomize, deepEquals, effectiveBooleanValue, getAnnotations, getStringValue, getStringValueCS, isArray, isMap, makeNewContext, simplify, typeCheck

Methods inherited from class net.sf.saxon.om.AbstractItem

getLength, head, isStreamed, itemAt, iterate, reduce, subsequence

Methods inherited from class java.lang.Object

clone, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface net.sf.saxon.om.Function

iterate

Methods inherited from interface net.sf.saxon.om.Item

head

Methods inherited from interface net.sf.saxon.om.GroundedValue

getLength, head, itemAt, reduce, subsequence

Constructor Detail

Minimax

public Minimax()

Method Detail

isMaxFunction

public abstract boolean isMaxFunction()

Method to be implemented in subclasses to indicate whether the function implements fn:min() or fn:max()

Returns:

true if this is the fn:max() function

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 PlainType getArgumentType()

getResultItemType

public ItemType getResultItemType(Expression[] args)

Description copied from class: SystemFunction

Get the return type, given knowledge of the actual arguments

Overrides:

getResultItemType in class SystemFunction

Parameters:

args - the actual arguments supplied

Returns:

the best available item type that the function will return

supplyTypeInformation

public void supplyTypeInformation(ExpressionVisitor visitor,
                                  ContextItemStaticInfo contextItemType,
                                  Expression[] arguments)
                           throws XPathException

Static analysis: preallocate a comparer if possible

Overrides:

supplyTypeInformation in class SystemFunction

Parameters:

visitor - an expression visitor, providing access to the static context and configuration

contextItemType - information about whether the context item is set, and what its type is

arguments - the expressions appearing as arguments in the function call

Throws:

XPathException

getCardinality

public int getCardinality(Expression[] arguments)

Determine the cardinality of the function.

Overrides:

getCardinality in class SystemFunction

Parameters:

arguments - the actual arguments supplied

Returns:

the most precise available cardinality that the function will return

makeOptimizedFunctionCall

public Expression makeOptimizedFunctionCall(ExpressionVisitor visitor,
                                            ContextItemStaticInfo contextInfo,
                                            Expression... arguments)
                                     throws XPathException

Description copied from class: SystemFunction

Allow the function to create an optimized call based on the values of the actual arguments

Overrides:

makeOptimizedFunctionCall in class SystemFunction

Parameters:

visitor - the expression visitor

contextInfo - information about the context item

arguments - the supplied arguments to the function call. Note: modifying the contents of this array should not be attempted, it is likely to have no effect.

Returns:

either a function call on this function, or an expression that delivers the same result, or null indicating that no optimization has taken place

Throws:

XPathException - if an error is detected

getAtomicComparer

public AtomicComparer getAtomicComparer(XPathContext context)

Description copied from class: CollatingFunctionFixed

During evaluation, get the pre-allocated atomic comparer if available, or allocate a new one otherwise

Overrides:

getAtomicComparer in class CollatingFunctionFixed

Parameters:

context - the dynamic evaluation context

Returns:

the pre-allocated comparer if one is available; otherwise, a newly allocated one, using the specified StringCollator for comparing strings

minimax

public static AtomicValue minimax(SequenceIterator iter,
                                  boolean isMaxFunction,
                                  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

isMaxFunction - true for the max() function, false for min()

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

call

public ZeroOrOne<AtomicValue> call(XPathContext context,
                                   Sequence[] arguments)
                            throws XPathException

Evaluate the function

Parameters:

context - the dynamic evaluation context

arguments - the values of the arguments, supplied as Sequences

Returns:

the result of the evaluation, in the form of a Sequence

Throws:

XPathException - if a dynamic error occurs during the evaluation of the expression

exportAttributes

public void exportAttributes(ExpressionPresenter out)

Description copied from class: SystemFunction

Export any context attributes held within the SystemFunction object. The implementation will normally make one or more calls on out.emitAttribute(name, value).

Overrides:

exportAttributes in class CollatingFunctionFixed

Parameters:

out - the export destination

importAttributes

public void importAttributes(java.util.Properties attributes)
                      throws XPathException

Description copied from class: SystemFunction

Import any attributes found in the export file, that is, any attributes output using the exportAttributes method

Overrides:

importAttributes in class CollatingFunctionFixed

Parameters:

attributes - the attributes, as a properties object

Throws:

XPathException

getCompilerName

public java.lang.String getCompilerName()

Description copied from class: SystemFunction

Get the (local) name of a class that can be used to generate bytecode for this system function

Overrides:

getCompilerName in class SystemFunction

Returns:

the name of a bytecode generation class, or null if there is no bytecode support for this function

getStreamerName

public java.lang.String getStreamerName()

Description copied from class: SystemFunction

Get a name that identifies the class that can be used to evaluate this function in streaming mode, that is, supplying one item or event at a time as it is delivered by the parser. Special streaming support is generally available in Saxon-EE for all system functions that take a sequence as their argument.

Overrides:

getStreamerName in class SystemFunction

Returns:

a name that identifies a class that supports streamed evaluation of this system function, or null if no such class is available. The mapping of names to classes is defined in the Saxon-EE class StreamerMap. In non-streaming Saxon editions (HE and PE) the method always returns null.