Package net.sf.saxon.xpath

Class XPathFunctionCall

java.lang.Object
net.sf.saxon.expr.Expression
net.sf.saxon.expr.FunctionCall
net.sf.saxon.xpath.XPathFunctionCall
All Implemented Interfaces:
Callable, ExportAgent, Locatable, IdentityComparable, Traceable
public class XPathFunctionCall extends FunctionCall implements Callable
This class is an expression that calls an external function supplied using the JAXP XPathFunction interface

  • Constructor Details

    • XPathFunctionCall

      public XPathFunctionCall(StructuredQName name, XPathFunction function)
      Default constructor
      Parameters:
      name - the qualified name of the function
      function - the target function

  • Method Details

    • getFunctionName

      public StructuredQName getFunctionName()
      Get the qualified name of the function being called
      Specified by:
      getFunctionName in class FunctionCall
      Returns:
      the qualified name

    • getTargetFunction

      public FunctionItem getTargetFunction(XPathContext context)
      Get the target function to be called
      Specified by:
      getTargetFunction in class FunctionCall
      Parameters:
      context - the dynamic evaluation context
      Returns:
      always null

    • preEvaluate

      public Expression preEvaluate(ExpressionVisitor visitor)
      preEvaluate: this method suppresses compile-time evaluation by doing nothing (because the external function might have side-effects and might use the context)
      Overrides:
      preEvaluate in class FunctionCall
      Parameters:
      visitor - an expression visitor
      Returns:
      the result of the early evaluation, or the original expression, or potentially a simplified expression

    • getIntrinsicDependencies

      public int getIntrinsicDependencies()
      Determine which aspects of the context the expression depends on. XPath external functions are given no access to context information so they cannot have any dependencies on it.
      Overrides:
      getIntrinsicDependencies in class Expression
      Returns:
      an integer containing bit-significant flags identifying the "intrinsic" dependencies. The flags are documented in class net.sf.saxon.value.StaticProperty

    • copy

      public Expression copy(RebindingMap rebindings)
      Copy an expression. This makes a deep copy.
      Specified by:
      copy in class Expression
      Parameters:
      rebindings - variables that need to be re-bound
      Returns:
      the copy of the original expression

    • addToPathMap

      public PathMap.PathMapNodeSet addToPathMap(PathMap pathMap, PathMap.PathMapNodeSet pathMapNodeSet)
      Add a representation of this expression to a PathMap. The PathMap captures a map of the nodes visited by an expression in a source tree.

      The default implementation of this method assumes that an expression does no navigation other than the navigation done by evaluating its subexpressions, and that the subexpressions are evaluated in the same context as the containing expression. The method must be overridden for any expression where these assumptions do not hold. For example, implementations exist for AxisExpression, ParentExpression, and RootExpression (because they perform navigation), and for the doc(), document(), and collection() functions because they create a new navigation root. Implementations also exist for PathExpression and FilterExpression because they have subexpressions that are evaluated in a different context from the calling expression.

      Overrides:
      addToPathMap in class Expression
      Parameters:
      pathMap - the PathMap to which the expression should be added
      pathMapNodeSet - the PathMapNodeSet to which the paths embodied in this expression should be added
      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. For an expression that does navigation, it represents the end of the arc in the path map that describes the navigation route. For other expressions, it is the same as the input pathMapNode.

    • iterate

      public SequenceIterator iterate(XPathContext context) throws XPathException
      Evaluate the function.
      Overrides:
      iterate in class FunctionCall
      Parameters:
      context - The context in which the function is to be evaluated
      Returns:
      a Value representing the result of the function.
      Throws:
      XPathException - if the function cannot be evaluated.

    • call

      public Sequence call(XPathContext context, Sequence[] argValues) throws XPathException
      Call an extension function previously identified using the bind() method. A subclass can override this method.
      Specified by:
      call in interface Callable
      Parameters:
      context - The XPath dynamic context
      argValues - The values of the arguments
      Returns:
      The value returned by the extension function
      Throws:
      XPathException - if a dynamic error occurs during the evaluation of the expression

    • getItemType

      public ItemType getItemType()
      Determine the data type of the expression, if possible. All expressions return sequences, in general; this method determines the type of the items within the sequence, assuming that (a) this is known in advance, and (b) it is the same for all items in the sequence.

      This method will always return a result, though it may be the best approximation that is available at the time.

      Specified by:
      getItemType in class Expression
      Returns:
      the item type

    • computeCardinality

      protected int computeCardinality()
      Determine the cardinality of the result
      Specified by:
      computeCardinality in class Expression
      Returns:
      ZERO_OR_MORE (we don't know)

    • getElaborator

      public Elaborator getElaborator()
      Make an elaborator for this expression
      Overrides:
      getElaborator in class Expression
      Returns:
      an appropriate Elaborator