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

FunctionProxy()
Constructor: creates an uncommitted FunctionProxy

Method Summary

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