Package net.sf.saxon.pattern

Class LocationPathPattern

  • All Implemented Interfaces:
    java.io.Serializable, javax.xml.transform.SourceLocator, Container
    public final class LocationPathPattern
extends Pattern
    A LocationPathPattern represents a path, for example of the form A/B/C... The components are represented as a linked list, each component pointing to its predecessor
    See Also:
    Serialized Form

    • Field Detail

      • parentPattern

        public Pattern parentPattern

      • ancestorPattern

        public Pattern ancestorPattern

      • numberOfFilters

        protected int numberOfFilters

      • equivalentExpr

        protected Expression equivalentExpr

      • firstElementPattern

        protected boolean firstElementPattern

      • lastElementPattern

        protected boolean lastElementPattern

      • specialFilter

        protected boolean specialFilter

    • Constructor Detail

      • LocationPathPattern

        public LocationPathPattern()

    • Method Detail

      • addFilter

        public void addFilter​(Expression filter)
        Add a filter to the pattern (while under construction)
        Parameters:
        filter - The predicate (a boolean expression or numeric expression) to be added

      • getDependencies

        public int getDependencies()
        Get the dependencies of the pattern. The only possible dependency for a pattern is on local variables. This is analyzed in those patterns where local variables may appear.
        Overrides:
        getDependencies in class Pattern

      • iterateSubExpressions

        public java.util.Iterator iterateSubExpressions()
        Iterate over the subexpressions within this pattern
        Overrides:
        iterateSubExpressions in class Pattern

      • replaceSubExpression

        public boolean replaceSubExpression​(Expression original,
                                    Expression replacement)
        Replace one subexpression by a replacement subexpression
        Specified by:
        replaceSubExpression in interface Container
        Overrides:
        replaceSubExpression in class Pattern
        Parameters:
        original - the original subexpression
        replacement - the replacement subexpression
        Returns:
        true if the original subexpression is found

      • promote

        public void promote​(PromotionOffer offer)
             throws XPathException
        Offer promotion for subexpressions within this pattern. The offer will be accepted if the subexpression is not dependent on the factors (e.g. the context item) identified in the PromotionOffer. By default the offer is not accepted - this is appropriate in the case of simple expressions such as constant values and variable references where promotion would give no performance advantage. This method is always called at compile time.

        Unlike the corresponding method on Expression, this method does not return anything: it can make internal changes to the pattern, but cannot return a different pattern. Only certain kinds of promotion are applicable within a pattern: specifically, promotions affecting local variable references within the pattern.

        Overrides:
        promote in class Pattern
        Parameters:
        offer - details of the offer, for example the offer to move expressions that don't depend on the context to an outer level in the containing expression
        Throws:
        XPathException - if any error is detected

      • matches

        public boolean matches​(NodeInfo node,
                       XPathContext context)
                throws XPathException
        Determine whether the pattern matches a given node.
        Specified by:
        matches in class Pattern
        Parameters:
        node - the node to be tested
        context - The dynamic context. Only relevant if the pattern uses variables, or contains calls on functions such as document() or key().
        Returns:
        true if the pattern matches, else false
        Throws:
        XPathException

      • internalMatches

        protected boolean internalMatches​(NodeInfo node,
                                  XPathContext context)
                           throws XPathException
        Test whether the pattern matches, but without changing the current() node
        Overrides:
        internalMatches in class Pattern
        Parameters:
        node - The NodeInfo representing the Element or other node to be tested against the Pattern
        context - The dynamic context. Only relevant if the pattern uses variables, or contains calls on functions such as document() or key().
        Returns:
        true if the node matches the Pattern, false otherwise
        Throws:
        XPathException

      • getNodeKind

        public int getNodeKind()
        Determine the types of nodes to which this pattern applies. Used for optimisation. For patterns that match nodes of several types, return Node.NODE
        Overrides:
        getNodeKind in class Pattern
        Returns:
        the type of node matched by this pattern. e.g. Node.ELEMENT or Node.TEXT

      • getFingerprint

        public int getFingerprint()
        Determine the fingerprint of nodes to which this pattern applies. Used for optimisation.
        Overrides:
        getFingerprint in class Pattern
        Returns:
        the fingerprint of nodes matched by this pattern.

      • getNodeTest

        public NodeTest getNodeTest()
        Get a NodeTest that all the nodes matching this pattern must satisfy
        Specified by:
        getNodeTest in class Pattern

      • resolveCurrent

        public void resolveCurrent​(LetExpression let,
                           PromotionOffer offer)
                    throws XPathException
        If the pattern contains any calls on current(), this method is called to modify such calls to become variable references to a variable declared in a specially-allocated local variable
        Parameters:
        let - the expression that assigns the local variable. This returns a dummy result, and is executed just before evaluating the pattern, to get the value of the context item into the variable.
        offer - A PromotionOffer used to process the expressions and change the call on current() into a variable reference
        Throws:
        XPathException