Class NumberFn

All Implemented Interfaces:
Serializable, SourceLocator, Container, Expression, ItemMappingFunction, 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:
  • Constructor Details

    • NumberFn

      public NumberFn()
  • Method Details

    • 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
      Specified by:
      simplify in interface Expression
      Overrides:
      simplify in class FunctionCall
      Parameters:
      env - the static context
      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 Expression
      Overrides:
      evaluateItem in class ComputedExpression
      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