Class PathExpression


  • public class PathExpression
    extends NodeSetExpression
    An expression that establishes a set of nodes by following relationships between nodes in the document. Specifically, it consists of a start expression which defines a set of nodes, and a Step which defines a relationship to be followed from those nodes to create a new set of nodes.
    • Field Detail

      • dependencies

        int dependencies
    • Constructor Detail

      • PathExpression

        public PathExpression​(Expression start,
                              Step step)
        Constructor
        Parameters:
        start - A node-set expression denoting the absolute or relative set of nodes from which the navigation path should start.
        step - The step to be followed from each node in the start expression to yield a new node-set
    • Method Detail

      • getDependencies

        public int getDependencies()
        Determine which aspects of the context the expression depends on. The result is a bitwise-or'ed value composed from constants such as Context.VARIABLES and Context.CURRENT_NODE
        Specified by:
        getDependencies in class Expression
      • isContextDocumentNodeSet

        public boolean isContextDocumentNodeSet()
        Determine, in the case of an expression whose data type is Value.NODESET, whether all the nodes in the node-set are guaranteed to come from the same document as the context node. Used for optimization.
        Overrides:
        isContextDocumentNodeSet in class Expression
      • reduce

        public Expression reduce​(int dep,
                                 Context context)
                          throws XPathException
        Perform a partial evaluation of the expression, by eliminating specified dependencies on the context.
        Specified by:
        reduce in class Expression
        Parameters:
        dep - The dependencies to be removed
        context - The context to be used for the partial evaluation
        Returns:
        a new expression that does not have any of the specified dependencies
        Throws:
        XPathException
      • enumerate

        public NodeEnumeration enumerate​(Context context,
                                         boolean sort)
                                  throws XPathException
        Evaluate the path-expression in a given context to return a NodeSet
        Specified by:
        enumerate in class NodeSetExpression
        Parameters:
        context - the evaluation context
        sort - true if the returned nodes must be in document order
        Throws:
        XPathException - when the expression does not return a nodeset.
      • display

        public void display​(int level)
        Diagnostic print of expression structure
        Specified by:
        display in class Expression