net.sf.saxon.functions
Class NumberFn

java.lang.Object
  net.sf.saxon.expr.Expression
      net.sf.saxon.expr.FunctionCall
          net.sf.saxon.functions.SystemFunction
              net.sf.saxon.functions.NumberFn

All Implemented Interfaces:

Serializable, SourceLocator, Container, EvaluableItem, ItemMappingFunction, SequenceIterable, InstructionInfoProvider

public class NumberFn
extends SystemFunction
implements ItemMappingFunction

Implements the XPath number() function. This can also be used as a mapping function in a MappingIterator to map a sequence of values to numbers.

See Also:

Serialized Form

Field Summary

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

EVALUATE_METHOD, ITERATE_METHOD, PROCESS_METHOD

Constructor Summary

NumberFn()

Method Summary

static DoubleValue	convert(AtomicValue value) Static method to perform the same conversion as the number() function.
Item	evaluateItem(XPathContext context) Evaluate in a general context
Item	map(Item item) Mapping function for use when converting a sequence of atomic values to doubles using the rules of the number() function
Expression	simplify(StaticContext env) Simplify and validate.

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

checkArguments, computeCardinality, computeSpecialProperties, display, getDetails, getErrorCodeForTypeErrors, getItemType, main, makeSystemFunction, optimize, setDetails

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

getArguments, getDisplayName, getFunctionNameCode, getNumberOfArguments, iterateSubExpressions, preEvaluate, promote, replaceSubExpression, setArguments, setFunctionNameCode, typeCheck

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

adoptChildExpression, checkPermittedContents, computeDependencies, computeStaticProperties, doPromotion, effectiveBooleanValue, evaluateAsString, getCardinality, getColumnNumber, getContainingProcedure, getDependencies, getExecutable, getHostLanguage, getImplementationMethod, getInstructionInfo, getIntrinsicDependencies, getLineNumber, getLocationId, getLocationProvider, getParentExpression, getPublicId, getSlotsUsed, getSpecialProperties, getSystemId, hasBadParentPointer, iterate, markTailFunctionCalls, process, resetStaticProperties, setLocationId, setParentExpression, setParentExpression, suppressValidation

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

NumberFn

public NumberFn()

Method Detail

simplify

public Expression simplify(StaticContext env)
                    throws XPathException

Simplify and validate. This is a pure function so it can be simplified in advance if the arguments are known

Overrides:

simplify in class FunctionCall

Returns:

the simplified expression

Throws:

XPathException - if an error is discovered during expression rewriting

evaluateItem

public Item evaluateItem(XPathContext context)
                  throws XPathException

Evaluate in a general context

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

convert

public static DoubleValue convert(AtomicValue value)

Static method to perform the same conversion as the number() function. This is different from the convert(Type.DOUBLE) in that it produces NaN rather than an error for non-numeric operands.

map

public Item map(Item item)
         throws XPathException

Mapping function for use when converting a sequence of atomic values to doubles using the rules of the number() function

Specified by:

map in interface ItemMappingFunction

Parameters:

item - The input item to be mapped.

Returns:

either the output item, or null.

Throws:

XPathException