Package org.apache.xpath.functions

Class Function

java.lang.Object
org.apache.xpath.Expression
org.apache.xpath.functions.Function
All Implemented Interfaces:
Serializable, SourceLocator, ExpressionNode, XPathVisitable
Direct Known Subclasses:
FuncCurrent, FuncExtFunction, FuncFalse, FuncLast, FuncPosition, FunctionOneArg, FuncTrue
public abstract class Function
extends Expression
This is a superclass of all XPath functions. This allows two ways for the class to be called. One method is that the super class processes the arguments and hands the results to the derived class, the other method is that the derived class may process it's own arguments, which is faster since the arguments don't have to be added to an array, but causes a larger code footprint.
See Also:
Serialized Form

  • Constructor Details

    • Function

      public Function()

  • Method Details

    • setArg

      public void setArg​(Expression arg, int argNum) throws WrongNumberArgsException
      Set an argument expression for a function. This method is called by the XPath compiler.
      Parameters:
      arg - non-null expression that represents the argument.
      argNum - The argument number index.
      Throws:
      WrongNumberArgsException - If the argNum parameter is beyond what is specified for this function.

    • checkNumberArgs

      public void checkNumberArgs​(int argNum) throws WrongNumberArgsException
      Check that the number of arguments passed to this function is correct. This method is meant to be overloaded by derived classes, to check for the number of arguments for a specific function type. This method is called by the compiler for static number of arguments checking.
      Parameters:
      argNum - The number of arguments that is being passed to the function.
      Throws:
      WrongNumberArgsException

    • reportWrongNumberArgs

      protected void reportWrongNumberArgs() throws WrongNumberArgsException
      Constructs and throws a WrongNumberArgException with the appropriate message for this function object. This method is meant to be overloaded by derived classes so that the message will be as specific as possible.
      Throws:
      WrongNumberArgsException

    • execute

      public XObject execute​(XPathContext xctxt) throws TransformerException
      Execute an XPath function object. The function must return a valid object.
      Specified by:
      execute in class Expression
      Parameters:
      xctxt - The execution current context.
      Returns:
      A valid XObject.
      Throws:
      TransformerException

    • callArgVisitors

      public void callArgVisitors​(XPathVisitor visitor)
      Call the visitors for the function arguments.

    • callVisitors

      public void callVisitors​(ExpressionOwner owner, XPathVisitor visitor)
      Description copied from interface: XPathVisitable
      This will traverse the heararchy, calling the visitor for each member. If the called visitor method returns false, the subtree should not be called.
      Parameters:
      owner - The owner of the visitor, where that path may be rewritten if needed.
      visitor - The visitor whose appropriate method will be called.
      See Also:
      XPathVisitable.callVisitors(ExpressionOwner, XPathVisitor)

    • deepEquals

      public boolean deepEquals​(Expression expr)
      Description copied from class: Expression
      Compare this object with another object and see if they are equal, include the sub heararchy.
      Specified by:
      deepEquals in class Expression
      Parameters:
      expr - Another expression object.
      Returns:
      true if this objects class and the expr object's class are the same, and the data contained within both objects are considered equal.
      See Also:
      Expression.deepEquals(Expression)

    • postCompileStep

      public void postCompileStep​(Compiler compiler)
      This function is currently only being used by Position() and Last(). See respective functions for more detail.