Class NumberFn

All Implemented Interfaces:
Serializable, SourceLocator, LocationProvider, SaxonLocator, EvaluableItem, ItemMappingFunction, SequenceIterable, InstructionInfo, Locator

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(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