net.sf.saxon.functions

Class Minimax

public class Minimax extends CollatingFunction

This class implements the min() and max() functions
Field Summary
static intMAX
static intMIN
Method Summary
voidcheckArguments(ExpressionVisitor visitor)
Static analysis: prevent sorting of the argument
intcomputeCardinality()
Determine the cardinality of the function.
ItemevaluateItem(XPathContext context)
Evaluate the function
ItemTypegetItemType(TypeHierarchy th)
Determine the item type of the value returned by the function
booleanisIgnoreNaN()
Test whether NaN values are to be ignored
static AtomicValueminimax(SequenceIterator iter, int operation, AtomicComparer atomicComparer, boolean ignoreNaN, XPathContext context)
Static method to evaluate the minimum or maximum of a sequence
Expressionoptimize(ExpressionVisitor visitor, ItemType contextItemType)
Perform optimisation of an expression and its subexpressions.
voidsetIgnoreNaN(boolean ignore)
Indicate whether NaN values should be ignored.

Field Detail

MAX

public static final int MAX

MIN

public static final int MIN

Method Detail

checkArguments

public void checkArguments(ExpressionVisitor visitor)
Static analysis: prevent sorting of the argument

computeCardinality

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

evaluateItem

public Item evaluateItem(XPathContext context)
Evaluate the function

getItemType

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

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)
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)
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.

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 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.