Package net.sf.saxon.value

Class SingletonNode

    • Constructor Detail

      • SingletonNode

        public SingletonNode​(NodeInfo node)
        Create a node-set containing zero or one nodes
        Parameters:
        node - The node to be contained in the node-set, or null if the node-set is to be empty

    • Method Detail

      • 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 prefered.

      • process

        public void process​(XPathContext context)
             throws XPathException
        Process the instruction, without returning any tail calls
        Specified by:
        process in interface Expression
        Overrides:
        process in class Value
        Parameters:
        context - The dynamic context, giving access to the current node, the current variables, etc.
        Throws:
        XPathException

      • getItemType

        public ItemType getItemType​(TypeHierarchy th)
        Determine the data type of the items in the expression. This method determines the most precise type that it can, because it is called when testing that the node conforms to a required type.
        Specified by:
        getItemType in interface Expression
        Overrides:
        getItemType in class Value
        Parameters:
        th -
        Returns:
        the most precise possible type of the node.

      • itemAt

        public Item itemAt​(int n)
            throws XPathException
        Get the n'th item in the sequence (starting from 0). This is defined for all SequenceValues, but its real benefits come for a SequenceValue stored extensionally (or for a MemoClosure, once all the values have been read)
        Overrides:
        itemAt in class Value
        Throws:
        XPathException

      • getNode

        public NodeInfo getNode()
        Get the node that forms the node-set. Return null if there is none.

      • getSpecialProperties

        public int getSpecialProperties()
        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.
        Specified by:
        getSpecialProperties in interface Expression
        Overrides:
        getSpecialProperties in class Value
        Returns:
        StaticProperty.NON_CREATIVE

      • iterate

        public SequenceIterator iterate​(XPathContext context)
        Return an enumeration of this nodeset value.
        Parameters:
        context - The context in which the expression is to be evaluated. Note that this context must contain a stackframe with sufficient slots to allow evaluation of any variables contained in the expression (including variables allocated internally by the optimizer)
        Returns:
        a SequenceIterator that can be used to iterate over the result of the expression

      • evaluateItem

        public Item evaluateItem​(XPathContext context)
        Evaluate as an item
        Specified by:
        evaluateItem in interface Expression
        Overrides:
        evaluateItem in class Value
        Parameters:
        context - The context in which the expression is to be evaluated. Note that this context must contain a stackframe with sufficient slots to allow evaluation of any variables contained in the expression (including variables allocated internally by the optimizer)
        Returns:
        the node or atomic value that results from evaluating the expression; or null to indicate that the result is an empty sequence

      • effectiveBooleanValue

        public boolean effectiveBooleanValue​(XPathContext context)
        Get the effective boolean value
        Specified by:
        effectiveBooleanValue in interface Expression
        Overrides:
        effectiveBooleanValue in class Value
        Parameters:
        context - The context in which the expression is to be evaluated
        Returns:
        the effective boolean value

      • getStringValue

        public java.lang.String getStringValue()
        Convert the value to a string, using the serialization rules. For atomic values this is the same as a cast; for sequence values it gives a space-separated list. For QNames and NOTATIONS, or lists containing them, it fails.
        Specified by:
        getStringValue in interface ValueRepresentation
        Overrides:
        getStringValue in class Value

      • evaluateAsString

        public java.lang.String evaluateAsString​(XPathContext context)
                                  throws XPathException
        Evaluate an expression as a String. This function must only be called in contexts where it is known that the expression will return a single string (or where an empty sequence is to be treated as a zero-length string). Implementations should not attempt to convert the result to a string, other than converting () to "". This method is used mainly to evaluate expressions produced by compiling an attribute value template.
        Specified by:
        evaluateAsString in interface Expression
        Overrides:
        evaluateAsString in class Value
        Parameters:
        context - The context in which the expression is to be evaluated
        Returns:
        the value of the expression, evaluated in the current context. The expression must return a string or (); if the value of the expression is (), this method returns "".
        Throws:
        XPathException - if any dynamic error occurs evaluating the expression

      • display

        public void display​(int depth,
                    java.io.PrintStream out,
                    Configuration config)
        Diagnostic display
        Specified by:
        display in interface Expression
        Overrides:
        display in class Value
        Parameters:
        depth - indentation level for this expression
        out - Output destination