net.sf.saxon.functions
Class NumberFn

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.NumberFn
All Implemented Interfaces:
Serializable, SourceLocator, 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
 PathMap.PathMapNodeSet addDocToPathMap(PathMap pathMap, PathMap.PathMapNodeSet pathMapNodes)
          Add a representation of a doc() call or similar function to a PathMap.
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(ExpressionVisitor visitor)
          Simplify and validate.
 
Methods inherited from class net.sf.saxon.functions.SystemFunction
checkArguments, computeCardinality, computeSpecialProperties, copy, getDetails, getErrorCodeForTypeErrors, getItemType, makeSystemFunction, optimize, setDetails
 
Methods inherited from class net.sf.saxon.expr.FunctionCall
addExternalFunctionCallToPathMap, equals, explain, getArguments, getDisplayName, getFunctionName, getNumberOfArguments, hashCode, iterateSubExpressions, preEvaluate, promote, replaceSubExpression, setArguments, setFunctionName, toString, typeCheck
 
Methods inherited from class net.sf.saxon.expr.Expression
addToPathMap, adoptChildExpression, checkPermittedContents, computeDependencies, computeStaticProperties, display, doPromotion, effectiveBooleanValue, evaluateAsString, explain, findParentOf, getCardinality, getColumnNumber, getContainer, getDependencies, getExecutable, getHostLanguage, getImplementationMethod, getInstructionInfo, getIntrinsicDependencies, getLineNumber, getLocationId, getLocationProvider, getPublicId, getSlotsUsed, getSpecialProperties, getSystemId, hasLoopingSubexpression, implementsStaticTypeCheck, iterate, iterateEvents, markTailFunctionCalls, process, setContainer, setFiltered, setFlattened, setLocationId, staticTypeCheck, suppressValidation
 
Methods inherited from class java.lang.Object
getClass, notify, notifyAll, wait, wait, wait
 

Constructor Detail

NumberFn

public NumberFn()
Method Detail

simplify

public Expression simplify(ExpressionVisitor visitor)
                    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
Parameters:
visitor - an expression visitor
Returns:
the simplified expression
Throws:
XPathException - if an error is discovered during expression rewriting

addDocToPathMap

public PathMap.PathMapNodeSet addDocToPathMap(PathMap pathMap,
                                              PathMap.PathMapNodeSet pathMapNodes)
Add a representation of a doc() call or similar function to a PathMap. This is a convenience method called by the addToPathMap() methods for doc(), document(), collection() and similar functions. These all create a new root expression in the path map.

Overrides:
addDocToPathMap in class SystemFunction
Parameters:
pathMap - the PathMap to which the expression should be added
pathMapNodes - the node in the PathMap representing the focus at the point where this expression is called. Set to null if this expression appears at the top level.
Returns:
the pathMapNode representing the focus established by this expression, in the case where this expression is the first operand of a path expression or filter expression

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.

Parameters:
value - the value to be converted
Returns:
the result of the conversion

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


Copyright (C) Michael H. Kay. All rights reserved.