net.sf.saxon.functions
Class Minimax

java.lang.Object
  extended by net.sf.saxon.expr.Expression
      extended by net.sf.saxon.expr.FunctionCall
          extended by net.sf.saxon.functions.SystemFunction
              extended by net.sf.saxon.functions.CollatingFunction
                  extended by net.sf.saxon.functions.Minimax
All Implemented Interfaces:
Serializable, SourceLocator, LocationProvider, SaxonLocator, EvaluableItem, SequenceIterable, InstructionInfo, Locator

public class Minimax
extends CollatingFunction

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

See Also:
Serialized Form

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, EVENT_FEED_METHOD, ITEM_FEED_METHOD, ITERATE_METHOD, locationId, PROCESS_METHOD, PUSH_SELECTION, staticProperties, WATCH_METHOD
 
Constructor Summary
Minimax()
           
 
Method Summary
 void checkArguments(ExpressionVisitor visitor)
          Static analysis: prevent sorting of the argument
 int computeCardinality()
          Determine the cardinality of the function.
 Expression copy()
          Copy an expression.
 Item evaluateItem(XPathContext context)
          Evaluate the function
 AtomicComparer getAtomicComparer(XPathContext context)
           
 int getImplementationMethod()
          Get implementation method
 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
getAbsoluteCollationURI, getAtomicComparer, getCollator, getExpressionBaseURI, getStringCollator
 
Methods inherited from class net.sf.saxon.functions.SystemFunction
addContextDocumentArgument, addDocToPathMap, computeSpecialProperties, getDetails, getErrorCodeForTypeErrors, getRequiredType, makeSystemFunction, setDetails, useContextItemAsDefault
 
Methods inherited from class net.sf.saxon.expr.FunctionCall
addExternalFunctionCallToPathMap, checkArgumentCount, equals, explain, getArguments, getDisplayName, getExpressionName, getFunctionName, getNumberOfArguments, hashCode, iterateSubExpressions, preEvaluate, promote, replaceSubExpression, setArguments, setFunctionName, simplify, simplifyArguments, toString, typeCheck
 
Methods inherited from class net.sf.saxon.expr.Expression
addToPathMap, adoptChildExpression, checkForUpdatingSubexpressions, checkPermittedContents, computeDependencies, computeStaticProperties, doPromotion, dynamicError, effectiveBooleanValue, evaluateAsString, evaluatePendingUpdates, explain, getCardinality, getColumnNumber, getColumnNumber, getConstructType, getContainer, getDependencies, getEvaluationMethod, getExecutable, getHostLanguage, getIntrinsicDependencies, getLineNumber, getLineNumber, getLocationId, getLocationProvider, getObjectName, getProperties, getProperty, getPublicId, getSlotsUsed, getSpecialProperties, getSystemId, getSystemId, hasLoopingSubexpression, implementsStaticTypeCheck, isSubtreeExpression, isUpdatingExpression, isVacuousExpression, iterate, iterateEvents, iterateSameFocusSubExpressions, markTailFunctionCalls, process, resetLocalStaticProperties, setContainer, setEvaluationMethod, setFiltered, setFlattened, setLocationId, staticTypeCheck, suppressValidation, typeError
 
Methods inherited from class java.lang.Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait
 

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

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.

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

getImplementationMethod

public int getImplementationMethod()
Get implementation method

Overrides:
getImplementationMethod in class SystemFunction
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

Overrides:
checkArguments in class CollatingFunction
Parameters:
visitor - the expression visitor
Throws:
XPathException

computeCardinality

public int computeCardinality()
Determine the cardinality of the function.

Overrides:
computeCardinality in class SystemFunction
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

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 class 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)

getItemType

public ItemType getItemType(TypeHierarchy th)
Determine the item type of the value returned by the function

Overrides:
getItemType in class SystemFunction
Parameters:
th - the type hierarchy cache
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

evaluateItem

public Item evaluateItem(XPathContext context)
                  throws XPathException
Evaluate the function

Specified by:
evaluateItem in interface EvaluableItem
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


Copyright (c) 2004-2010 Saxonica Limited. All rights reserved.