com.icl.saxon.expr

## Class FunctionProxy

- java.lang.Object
- - com.icl.saxon.expr.Expression
  - - com.icl.saxon.expr.Function
    - - com.icl.saxon.expr.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

- - ### Field Summary

    - ### Fields inherited from class com.icl.saxon.expr.Function

      `argument`

    - ### Fields inherited from class com.icl.saxon.expr.Expression

      `staticContext`

  - ### Constructor Summary

    Constructors
    Constructor and Description
    `FunctionProxy()` Constructor: creates an uncommitted FunctionProxy

  - ### Method Summary

    Methods
    Modifier and Type | Method and Description
    --- | ---
    `static Value` | `convertJavaObjectToXPath(java.lang.Object result, Controller controller)` Convert a Java object to an XPath value.
    `NodeEnumeration` | `enumerate(Context context, boolean requireSorted)` Return an enumeration of nodes in a nodeset.
    `Value` | `evaluate(Context context)` Evaluate the function.
    `boolean` | `evaluateAsBoolean(Context context)` 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.
    `double` | `evaluateAsNumber(Context context)` 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.
    `java.lang.String` | `evaluateAsString(Context context)` 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.
    `java.lang.Object` | `getBestFit(Value[] argValues)` Get the best fit amongst all the candidate methods or constructors
    `int` | `getDataType()` Determine the data type of the expression, if possible
    `int` | `getDependencies()` Determine which aspects of the context the expression depends on.
    `java.lang.String` | `getName()` Get the name of the function
    `Expression` | `reduce(int dependencies, Context context)` Perform a partial evaluation of the expression, by eliminating specified dependencies on the context.
    `boolean` | `setFunctionName(java.lang.Class reqClass, java.lang.String localName)` setFunctionName: locates the external class and the method (or candidate methods) to which this function relates.
    `Expression` | `simplify()` Simplify the function (by simplifying its arguments)

    - ### Methods inherited from class com.icl.saxon.expr.Function

      `addArgument, checkArgumentCount, display, getNumberOfArguments`

    - ### Methods inherited from class com.icl.saxon.expr.Expression

      `containsReferences, evaluateAsNodeSet, getStaticContext, indent, isContextDocumentNodeSet, make, outputStringValue, setStaticContext, usesCurrent`

    - ### Methods inherited from class java.lang.Object

      `clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

- - ### Constructor Detail

    - #### FunctionProxy

          public FunctionProxy()

      Constructor: creates an uncommitted FunctionProxy

  - ### Method Detail

    - #### setFunctionName

          public boolean setFunctionName(java.lang.Class reqClass,
                                java.lang.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 java.lang.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 java.lang.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 java.lang.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(java.lang.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`