Class FunctionProxy


public class FunctionProxy extends Function
This class acts as a proxy for an extension function defined as a method in a user-defined class
  • Constructor Details

    • FunctionProxy

      public FunctionProxy()
      Constructor: creates an uncommitted FunctionProxy
  • Method Details

    • setFunctionName

      public boolean setFunctionName(Class reqClass, String localName)
      setFunctionName: locates the external class and the method (or candidate methods) to which this function relates. At this stage addArguments() will have normally been called, so the number of arguments is known. If no method of the required name is located, an exception is saved, but it is not thrown until an attempt is made to evaluate the function. All methods that match the required number of arguments are saved in a list (candidateMethods), a decision among these methods is made at run-time when the types of the actual arguments are known.

      The method is also used while calling function-available(). In this case the number of arguments is not known (it will be set to zero). We return true if a match was found, regardless of the number of arguments.

      Parameters:
      reqClass - The Java class name
      localName - The local name used in the XPath function call
      Returns:
      true if the function is available (with some number of arguments).
    • getDataType

      public int getDataType()
      Determine the data type of the expression, if possible
      Specified by:
      getDataType in class Expression
      Returns:
      Value.ANY (meaning not known in advance)
    • getName

      public String getName()
      Get the name of the function
      Specified by:
      getName in class Function
      Returns:
      the name of the function, as used in XSL expressions, but excluding its namespace prefix
    • simplify

      public Expression simplify() throws XPathException
      Simplify the function (by simplifying its arguments)
      Overrides:
      simplify in class Expression
      Returns:
      the simplified expression
      Throws:
      XPathException
    • getDependencies

      public int getDependencies()
      Determine which aspects of the context the expression depends on. The result is a bitwise-or'ed value composed from constants such as Context.VARIABLES and Context.CURRENT_NODE
      Specified by:
      getDependencies in class Expression
    • reduce

      public Expression reduce(int dependencies, Context context) throws XPathException
      Perform a partial evaluation of the expression, by eliminating specified dependencies on the context.
      Specified by:
      reduce in class Expression
      Parameters:
      dependencies - The dependencies to be removed
      context - The context to be used for the partial evaluation
      Returns:
      a new expression that does not have any of the specified dependencies
      Throws:
      XPathException
    • getBestFit

      public Object getBestFit(Value[] argValues) throws XPathException
      Get the best fit amongst all the candidate methods or constructors
      Returns:
      the result is either a Method or a Constructor. In JDK 1.2 these have a common superclass, AccessibleObject, but this is not available in JDK 1.1, which we still support.
      Throws:
      XPathException
    • evaluate

      public Value evaluate(Context context) throws XPathException
      Evaluate the function.
      Specified by:
      evaluate in class Expression
      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.
    • evaluateAsString

      public String evaluateAsString(Context context) throws XPathException
      Description copied from class: Expression
      Evaluate an expression as a String.
      The result of x.evaluateAsString(c) must be equivalent to x.evaluate(c).asString(); but optimisations are possible when it is known that a string result is required, especially in the case of a NodeSet.
      Overrides:
      evaluateAsString in class Expression
      Parameters:
      context - The context in which the expression is to be evaluated
      Returns:
      the value of the expression, evaluated in the current context
      Throws:
      XPathException
    • evaluateAsNumber

      public double evaluateAsNumber(Context context) throws XPathException
      Description copied from class: Expression
      Evaluate an expression as a Number.
      The result of x.evaluateAsNumber(c) must be equivalent to x.evaluate(c).asNumber(); but optimisations are possible when it is known that a numeric result is required, especially in the case of a NodeSet.
      Overrides:
      evaluateAsNumber in class Expression
      Parameters:
      context - The context in which the expression is to be evaluated
      Returns:
      the value of the expression, evaluated in the current context
      Throws:
      XPathException
    • evaluateAsBoolean

      public boolean evaluateAsBoolean(Context context) throws XPathException
      Description copied from class: Expression
      Evaluate an expression as a Boolean.
      The result of x.evaluateAsBoolean(c) must be equivalent to x.evaluate(c).asBoolean(); but optimisations are possible when it is known that a boolean result is required, especially in the case of a NodeSet.
      Overrides:
      evaluateAsBoolean in class Expression
      Parameters:
      context - The context in which the expression is to be evaluated
      Returns:
      the value of the expression, evaluated in the current context
      Throws:
      XPathException
    • enumerate

      public NodeEnumeration enumerate(Context context, boolean requireSorted) throws XPathException
      Description copied from class: Expression
      Return an enumeration of nodes in a nodeset.
      Overrides:
      enumerate in class Expression
      Parameters:
      context - The context in which the expression is to be evaluated
      requireSorted - Indicates whether the nodes are required in document order. If this is false, they may come in any order, but there will be no duplicates.
      Throws:
      XPathException - when the expression does not return a nodeset.
    • convertJavaObjectToXPath

      public static Value convertJavaObjectToXPath(Object result, Controller controller) throws XPathException
      Convert a Java object to an XPath value. This method is called to handle the result of an external function call (but only if the required type is not known), and also to process global parameters passed to the stylesheet.
      Throws:
      XPathException