Package com.saxonica.expr

Class JavaExtensionFunctionCall

    • Constructor Detail

      • JavaExtensionFunctionCall

        public JavaExtensionFunctionCall()
        Default constructor

    • Method Detail

      • init

        public void init​(StructuredQName functionName,
                 java.lang.Class<?> theClass,
                 java.lang.reflect.AccessibleObject object,
                 Configuration config)
        Initialization: creates an ExtensionFunctionCall
        Parameters:
        functionName - the name of the function, for display purposes
        theClass - the Java class containing the method to be called
        object - the method, field, or constructor of the Java class to be called
        config - the Configuration

      • getExpressionName

        public java.lang.String getExpressionName()
        Get a name identifying the kind of expression, in terms meaningful to a user.
        Overrides:
        getExpressionName in class FunctionCall
        Returns:
        a name identifying the kind of expression, in terms meaningful to a user. The name will always be in the form of a lexical XML QName, and should match the name used in explain() output displaying the expression.

      • 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

      • typeCheck

        public Expression typeCheck​(ExpressionVisitor visitor,
                            ContextItemStaticInfo contextInfo)
                     throws XPathException
        Description copied from class: FunctionCall
        Type-check the expression. This also calls preEvaluate() to evaluate the function if all the arguments are constant; functions that do not require this behavior can override the preEvaluate method.
        Overrides:
        typeCheck in class FunctionCall
        Parameters:
        visitor - an expression visitor
        contextInfo - Information available statically about the context item: whether it is (possibly) absent; its static type; its streaming posture.
        Returns:
        the original expression, rewritten to perform necessary run-time type checks, and to perform other type-related optimizations
        Throws:
        XPathException - if an error is discovered during this phase (typically a type error)

      • adjustRequiredType

        public boolean adjustRequiredType​(JavaExternalObjectType requiredType)
                           throws XPathException
        When a call to a Java extension function appears in a context where there the required type is a Java external object (typically an xsl:variable with a declared type, or as an argument to another Java extension function), notify this required type so that the process of converting the result to an XDM value can be short-circuited.
        Overrides:
        adjustRequiredType in class FunctionCall
        Parameters:
        requiredType - the required type of the result of the function, determined by the context in which the function call appears
        Returns:
        Ok if the type has been successfully adjusted
        Throws:
        XPathException - if the required return type is incompatible with the type actually returned by the Java method

      • copy

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

      • getIntrinsicDependencies

        public int getIntrinsicDependencies()
        Determine which aspects of the context the expression depends on. The result is a bitwise-or'ed value composed from constants such as XPathContext.VARIABLES and XPathContext.CURRENT_NODE
        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

      • isSubtreeExpression

        public boolean isSubtreeExpression()
        Determine whether the expression can be evaluated without reference to the part of the context document outside the subtree rooted at the context node.
        Overrides:
        isSubtreeExpression in class Expression
        Returns:
        true if the expression has no dependencies on the context node, or if the only dependencies on the context node are downward selections using the self, child, descendant, attribute, and namespace axes.

      • 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.

      • isNodeCheckRequired

        public boolean isNodeCheckRequired()
        Ask whether the result needs to be checked to ensure it contains no nodes from the wrong Configuration
        Returns:
        true if the result needs to be checked

      • evaluateItem

        public Item evaluateItem​(XPathContext context)
                  throws XPathException
        Evaluate the function returning a single item or null.
        Overrides:
        evaluateItem 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.

      • getTargetClass

        public java.lang.Class<?> getTargetClass()
        Get the class containing the method being called
        Returns:
        the class containing the target method

      • getTargetMethod

        public java.lang.reflect.AccessibleObject getTargetMethod()
        Get the target method (or field, or constructor) being called
        Returns:
        the target method, field, or constructor

      • getParameterTypes

        public java.lang.Class<?>[] getParameterTypes()
        Get the types of the arguments
        Returns:
        an array of classes representing the declared types of the arguments to the method or constructor

      • 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 evaluation 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

      • getReturnClass

        public java.lang.Class<?> getReturnClass()
        Get the Java class of the value returned by the method
        Returns:
        the Java class of the value returned by the method

      • getArgumentConverters

        public PJConverter[] getArgumentConverters()
        Get the converters used to convert the arguments from XPath values to Java values
        Returns:
        an array of converters, one per argument

      • getResultConverter

        public JPConverter getResultConverter()
        Get the converter used to convert the result from a Java object to an XPath value
        Returns:
        the converter that is used

      • invokeConstructor

        protected java.lang.Object invokeConstructor​(java.lang.reflect.Constructor<?> constructor,
                                             java.lang.Object[] params)
                                      throws java.lang.InstantiationException,
                                             java.lang.IllegalAccessException,
                                             java.lang.reflect.InvocationTargetException
        Invoke a constructor. This method is provided separately so that it can be refined in a subclass. For example, a subclass might perform tracing of calls, or might trap exceptions.
        Parameters:
        constructor - The constructor to be invoked
        params - The parameters to be passed to the constructor
        Returns:
        The object returned by the constructor
        Throws:
        java.lang.InstantiationException - if the invocation throws an InstantiationException
        java.lang.IllegalAccessException - if the invocation throws an IllegalAccessException
        java.lang.reflect.InvocationTargetException - if the invocation throws an InvocationTargetException (which happens when the constructor itself throws an exception)

      • invokeMethod

        protected java.lang.Object invokeMethod​(java.lang.reflect.Method method,
                                        java.lang.Object instance,
                                        java.lang.Object[] params)
                                 throws java.lang.IllegalAccessException,
                                        java.lang.reflect.InvocationTargetException
        Invoke a method. This method is provided separately so that it can be refined in a subclass. For example, a subclass might perform tracing of calls, or might trap exceptions.
        Parameters:
        method - The method to be invoked
        instance - The object on which the method is to be invoked. This is set to null if the method is static.
        params - The parameters to be passed to the method
        Returns:
        The object returned by the method
        Throws:
        java.lang.IllegalAccessException - if the invocation throws an IllegalAccessException
        java.lang.reflect.InvocationTargetException - if the invocation throws an InvocationTargetException (which happens when the method itself throws an exception)

      • getField

        protected java.lang.Object getField​(java.lang.reflect.Field field,
                                    java.lang.Object instance)
                             throws java.lang.IllegalAccessException
        Access a field. This method is provided separately so that it can be refined in a subclass. For example, a subclass might perform tracing of calls, or might trap exceptions.
        Parameters:
        field - The field to be retrieved
        instance - The object whose field is to be retrieved. This is set to null if the field is static.
        Returns:
        The value of the field
        Throws:
        java.lang.IllegalAccessException - if the invocation throws an IllegalAccessException

      • applyFunctionConversionRules

        public static Sequence applyFunctionConversionRules​(Sequence suppliedValue,
                                                    SequenceType requiredType,
                                                    StructuredQName functionName,
                                                    int argPosition,
                                                    XPathContext context)
                                             throws XPathException
        Utility method available for use in called extension functions to check that a supplied argument conforms to a required type, and perform conversion using the function conversion rules if not
        Parameters:
        suppliedValue - the value supplied by the caller
        requiredType - the type required for the argument
        functionName - the name of the function (for diagnostics)
        argPosition - the ordinal position of the argument being checked in the XPath function call, starting at 0 for the first argument
        context - the XPath dynamic context
        Returns:
        the result of applying the function conversion rules (with XPath 1.0 compatibility mode set to false)
        Throws:
        XPathException - if type checking fails

      • toCamelCase

        public static java.lang.String toCamelCase​(java.lang.String name,
                                           boolean debug,
                                           Logger diag)
        Convert a name to camelCase (by removing hyphens and changing the following letter to capitals)
        Parameters:
        name - the name to be converted to camelCase
        debug - true if tracing is required
        diag - the output stream for diagnostic trace output
        Returns:
        the camelCased name

      • isReturnVoidAsThis

        public boolean isReturnVoidAsThis()

      • export

        public void export​(ExpressionPresenter out)
            throws XPathException
        Diagnostic print of expression structure. The abstract expression tree is written to the supplied output destination.
        Specified by:
        export in interface ExportAgent
        Overrides:
        export in class FunctionCall
        Parameters:
        out - the destination of the output
        Throws:
        XPathException - if the export fails, for example if an expression is found that won't work in the target environment.

      • allocateArgumentEvaluators

        protected void allocateArgumentEvaluators()
        Allocate evaluation functions for each argument (in field argumentEvaluators)