Package net.sf.saxon.expr.instruct

Class SimpleNodeConstructor

    • Field Detail

      • selectOp

        protected Operand selectOp

    • Constructor Detail

      • SimpleNodeConstructor

        public SimpleNodeConstructor()
        Default constructor used by subclasses

    • Method Detail

      • setSelect

        public void setSelect​(Expression select)
        Set the select expression: the value of this expression determines the string-value of the node
        Parameters:
        select - the expression that computes the string value of the node

      • getSelect

        public Expression getSelect()
        Get the select expression, that is the expression that computes the content of the constructed node. Note that this may correspond either to a select attribute or a contained sequence constructor in the case of XSLT; and in XQuery it corresponds to whatever expression is contained in the node constructpr.
        Returns:
        the expression used to compute the content of the node.

      • operands

        public java.lang.Iterable<Operand> operands()
        Description copied from class: Expression
        Get the immediate sub-expressions of this expression, with information about the relationship of each expression to its parent expression. Default implementation works off the results of iterateSubExpressions()

        If the expression is a Callable, then it is required that the order of the operands returned by this function is the same as the order of arguments supplied to the corresponding call() method.

        Specified by:
        operands in class Instruction
        Returns:
        an iterator containing the sub-expressions of this expression

      • mayCreateNewNodes

        public final boolean mayCreateNewNodes()
        Ask whether this instruction creates new nodes. This implementation returns true.
        Overrides:
        mayCreateNewNodes in class Instruction
        Returns:
        true if the instruction creates new nodes under some input conditions (or if it can't be proved that it doesn't)

      • alwaysCreatesNewNodes

        public boolean alwaysCreatesNewNodes()
        Ask whether it is guaranteed that every item in the result of this instruction is a newly created node
        Overrides:
        alwaysCreatesNewNodes in class Instruction
        Returns:
        true if result of the instruction is always either an empty sequence or a sequence consisting entirely of newly created nodes

      • computeCardinality

        public int computeCardinality()
        Get the cardinality of the sequence returned by evaluating this instruction
        Overrides:
        computeCardinality in class Instruction
        Returns:
        the static cardinality

      • computeSpecialProperties

        public int computeSpecialProperties()
        Get the static properties of this expression (other than its type). The result is bit-signficant. These properties are used for optimizations. In general, if property bit is set, it is true, but if it is unset, the value is unknown.
        Overrides:
        computeSpecialProperties in class Instruction
        Returns:
        a set of flags indicating static properties of this expression

      • allowExtractingCommonSubexpressions

        public boolean allowExtractingCommonSubexpressions()
        Ask whether common subexpressions found in the operands of this expression can be extracted and evaluated outside the expression itself. The result is irrelevant in the case of operands evaluated with a different focus, which will never be extracted in this way, even if they have no focus dependency.
        Overrides:
        allowExtractingCommonSubexpressions in class Expression
        Returns:
        false for this kind of expression

      • localTypeCheck

        public abstract void localTypeCheck​(ExpressionVisitor visitor,
                                    ContextItemStaticInfo contextItemType)
                             throws XPathException
        Method to perform type-checking specific to the kind of instruction
        Parameters:
        visitor - an expression visitor
        contextItemType - the static type of the context item
        Throws:
        XPathException - if a type error is detected

      • typeCheck

        public Expression typeCheck​(ExpressionVisitor visitor,
                            ContextItemStaticInfo contextInfo)
                     throws XPathException
        The typeCheck() method is called in XQuery, where node constructors are implemented as Expressions. In this case the required type for the select expression is a single string. param visitor an expression visitor
        Overrides:
        typeCheck in class Expression
        Parameters:
        contextInfo - information about the dynamic context
        visitor - an expression visitor
        Returns:
        the rewritten expression
        Throws:
        XPathException - if any static errors are found in this expression or any of its children

      • optimize

        public Expression optimize​(ExpressionVisitor visitor,
                           ContextItemStaticInfo contextItemType)
                    throws XPathException
        Description copied from class: Expression
        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
        contextItemType - 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)

      • getStreamerName

        public java.lang.String getStreamerName()
        Get the (partial) name of a class that supports streaming of this kind of expression
        Overrides:
        getStreamerName in class Expression
        Returns:
        the partial name of a class that can be instantiated to provide streaming support in Saxon-EE, or null if there is no such class

      • processValue

        public abstract void processValue​(java.lang.CharSequence value,
                                  Outputter output,
                                  XPathContext context)
                           throws XPathException
        Process the value of the node, to create the new node.
        Parameters:
        value - the string value of the new node
        output - the destination for the result
        context - the dynamic evaluation context
        Throws:
        XPathException - if a dynamic error occurs

      • evaluateItem

        public Item evaluateItem​(XPathContext context)
                  throws XPathException
        Evaluate as an expression.
        Overrides:
        evaluateItem in class Instruction
        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

      • checkContent

        protected java.lang.String checkContent​(java.lang.String data,
                                        XPathContext context)
                                 throws XPathException
        Check the content of the node, and adjust it if necessary. The checks depend on the node kind.
        Parameters:
        data - the supplied content
        context - the dynamic context
        Returns:
        the original content, unless adjustments are needed
        Throws:
        XPathException - if the content is invalid

      • evaluateNodeName

        public NodeName evaluateNodeName​(XPathContext context)
                          throws XPathException
        Run-time method to compute the name of the node being constructed. This is overridden for nodes that have a name. The default implementation returns null, which is suitable for unnamed nodes such as comments
        Parameters:
        context - the XPath dynamic evaluation context
        Returns:
        the name pool nameCode identifying the name of the constructed node
        Throws:
        XPathException - if any failure occurs

      • iterate

        public SequenceIterator iterate​(XPathContext context)
                         throws XPathException
        Description copied from class: Instruction
        Return an Iterator to iterate over the values of a sequence. The value of every expression can be regarded as a sequence, so this method is supported for all expressions. This default implementation handles iteration for expressions that return singleton values: for non-singleton expressions, the subclass must provide its own implementation.
        Overrides:
        iterate in class Instruction
        Parameters:
        context - supplies the context for evaluation
        Returns:
        a SequenceIterator that can be used to iterate over the result of the expression
        Throws:
        XPathException - if any dynamic error occurs evaluating the expression

      • isLocal

        public boolean isLocal()