Package net.sf.saxon.functions.hof

Class UserFunctionReference

    • Method Detail

      • simplify

        public Expression simplify()
                    throws XPathException
        Description copied from class: Expression
        Simplify an expression. This performs any static optimization (by rewriting the expression as a different expression). The default implementation simplifies its operands.
        Overrides:
        simplify in class Expression
        Returns:
        the simplified expression (or the original if unchanged, or if modified in-situ)
        Throws:
        XPathException - if an error is discovered during expression rewriting

      • typeCheck

        public Expression typeCheck​(ExpressionVisitor visitor,
                            ContextItemStaticInfo contextInfo)
                     throws XPathException
        Perform type checking of an expression and its subexpressions. This is the second phase of static optimization.

        This checks statically that the operands of the expression have the correct type; if necessary it generates code to do run-time type checking or type conversion. A static type error is reported only if execution cannot possibly succeed, that is, if a run-time type error is inevitable. The call may return a modified form of the expression.

        This method is called after all references to functions and variables have been resolved to the declaration of the function or variable. However, the types of such functions and variables may not be accurately known if they have not been explicitly declared.

        Overrides:
        typeCheck in class Expression
        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)

      • optimize

        public Expression optimize​(ExpressionVisitor visitor,
                           ContextItemStaticInfo contextInfo)
                    throws XPathException
        Perform optimisation of an expression and its subexpressions. This is the third and final phase of static optimization.

        This method is called after all references to functions and variables have been resolved to the declaration of the function or variable, and after all type checking has been done.

        Overrides:
        optimize in class Expression
        Parameters:
        visitor - an expression visitor
        contextInfo - the static type of "." at the point where this expression is invoked. The parameter is set to null if it is known statically that the context item will be undefined. If the type of the context item is not known statically, the argument is set to Type.ITEM_TYPE
        Returns:
        the original expression, rewritten if appropriate to optimize execution
        Throws:
        XPathException - if an error is discovered during this phase (typically a type error)

      • getBindingSlot

        public int getBindingSlot()
        Get the binding slot to be used. This is the offset within the binding vector of the containing component where the actual target component is to be found.
        Specified by:
        getBindingSlot in interface ComponentInvocation
        Returns:
        the offset in the binding vector of the containing package where the target component can be found.

      • getFixedTarget

        public Component getFixedTarget()
        Get the target component if this is known in advance, that is, if the target component is private or final. Otherwise, return null.
        Specified by:
        getFixedTarget in interface ComponentInvocation
        Returns:
        the bound component if the binding has been fixed

      • setBindingSlot

        public void setBindingSlot​(int slot)
        Set the binding slot to be used. This is the offset within the binding vector of the containing component where the actual target component is to be found. The target template is not held directly in the invocation instruction/expression itself because it can be overridden in a using package.
        Specified by:
        setBindingSlot in interface ComponentInvocation
        Parameters:
        slot - the offset in the binding vector of the containing package where the target component can be found.

      • getSymbolicName

        public SymbolicName getSymbolicName()
        Get the symbolic name of the component that this invocation references
        Specified by:
        getSymbolicName in interface ComponentInvocation
        Returns:
        the symbolic name of the target component

      • getFunctionItemType

        public FunctionItemType getFunctionItemType​(TypeHierarchy th)
        Get the item type of the function item
        Parameters:
        th - the type hierarchy cache
        Returns:
        the function item's type

      • getFunctionName

        public StructuredQName getFunctionName()
        Get the name of the function, or null if it is anonymous
        Returns:
        the function name, or null for an anonymous inline function

      • getArity

        public int getArity()
        Get the arity of the function
        Returns:
        the number of arguments in the function signature

      • getImplementationMethod

        public int getImplementationMethod()
        An implementation of Expression must provide at least one of the methods evaluateItem(), iterate(), or process(). This method indicates which of these methods is provided directly. The other methods will always be available indirectly, using an implementation that relies on one of the other methods.
        Specified by:
        getImplementationMethod in class Expression
        Returns:
        the implementation method, for example Expression.ITERATE_METHOD or Expression.EVALUATE_METHOD or Expression.PROCESS_METHOD

      • getItemType

        public ItemType getItemType()
        Determine the data type of the expression, if possible. All expression 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 should always return a result, though it may be the best approximation that is available at the time.

        Specified by:
        getItemType in class Expression
        Returns:
        a value such as Type.STRING, Type.BOOLEAN, Type.NUMBER, Type.NODE, or Type.ITEM (meaning not known at compile time)

      • computeSpecialProperties

        protected int computeSpecialProperties()
        Compute the special properties of this expression.
        Overrides:
        computeSpecialProperties in class Expression
        Returns:
        the special properties, as a bit-significant integer

      • getStaticUType

        public UType getStaticUType​(UType contextItemType)
        Get the static type of the expression as a UType, following precisely the type inference rules defined in the XSLT 3.0 specification.
        Overrides:
        getStaticUType in class Expression
        Parameters:
        contextItemType - the static type of the context item
        Returns:
        the static item type of the expression according to the XSLT 3.0 defined rules

      • copy

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

      • evaluateItem

        public FunctionItem evaluateItem​(XPathContext context)
                          throws XPathException
        Evaluate an expression as a single item. This always returns either a single Item or null (denoting the empty sequence). No conversion is done. This method should not be used unless the static type of the expression is a subtype of "item" or "item?": that is, it should not be called if the expression may return a sequence. There is no guarantee that this condition will be detected.
        Overrides:
        evaluateItem in class Expression
        Parameters:
        context - The context in which the expression is to be evaluated
        Returns:
        the node or atomic value that results from evaluating the expression; or null to indicate that the result is an empty sequence
        Throws:
        XPathException - if any dynamic error occurs evaluating the expression

      • call

        public FunctionItem call​(XPathContext context,
                         Sequence[] arguments)
                  throws XPathException
        Call the Callable.
        Specified by:
        call in interface Callable
        Parameters:
        context - the dynamic evaluation context
        arguments - the values of the arguments, supplied as Sequences.

        Generally it is advisable, if calling iterate() to process a supplied sequence, to call it only once; if the value is required more than once, it should first be converted to a GroundedValue by calling the utility method SequenceTool.toGroundedValue().

        If the expected value is a single item, the item should be obtained by calling Sequence.head(): it cannot be assumed that the item will be passed as an instance of Item or AtomicValue.

        It is the caller's responsibility to perform any type conversions required to convert arguments to the type expected by the callee. An exception is where this Callable is explicitly an argument-converting wrapper around the original Callable.

        Returns:
        the result of the evaluation, in the form of a Sequence. It is the responsibility of the callee to ensure that the type of result conforms to the expected result type.
        Throws:
        XPathException - if a dynamic error occurs during the evaluation of the expression

      • getExpressionName

        public java.lang.String getExpressionName()
        Description copied from class: Expression
        Get a name identifying the kind of expression, in terms meaningful to a user.
        Overrides:
        getExpressionName in class Expression
        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 export() output displaying the expression.

      • toString

        public java.lang.String toString()
        Description copied from class: Expression

        The toString() method for an expression attempts to give a representation of the expression in an XPath-like form.

        For subclasses of Expression that represent XPath expressions, the result should always be a string that parses as an XPath 3.0 expression. The expression produced should be equivalent to the original making certain assumptions about the static context. In general the expansion will make no assumptions about namespace bindings, except that (a) the prefix "xs" is used to refer to the XML Schema namespace, and (b) the default function namespace is assumed to be the "fn" namespace.

        In the case of XSLT instructions and XQuery expressions, the toString() method gives an abstracted view of the syntax that is not designed in general to be parseable.

        Overrides:
        toString in class Expression
        Returns:
        a representation of the expression as a string

      • toShortString

        public java.lang.String toShortString()
        Description copied from class: Expression
        Produce a short string identifying the expression for use in error messages
        Overrides:
        toShortString in class Expression
        Returns:
        a short string, sufficient to identify the expression

      • export

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