Package org.apache.xpath

Class XPathVisitor

  • Direct Known Subclasses:
    AbsPathChecker, ExpressionVisitor, HasPositionalPredChecker, VarNameCollector, XSLTVisitor
    public class XPathVisitor
extends java.lang.Object
    A derivation from this class can be passed to a class that implements the XPathVisitable interface, to have the appropriate method called for each component of the XPath. Aside from possible other uses, the main intention is to provide a reasonable means to perform expression rewriting.

    Each method has the form boolean visitComponentType(ExpressionOwner owner, ComponentType compType). The ExpressionOwner argument is the owner of the component, and can be used to reset the expression for rewriting. If a method returns false, the sub hierarchy will not be traversed.

    This class is meant to be a base class that will be derived by concrete classes, and doesn't much except return true for each method.

    • Constructor Detail

      • XPathVisitor

        public XPathVisitor()

    • Method Detail

      • visitLocationPath

        public boolean visitLocationPath​(ExpressionOwner owner,
                                 LocPathIterator path)
        Visit a LocationPath.
        Parameters:
        owner - The owner of the expression, to which the expression can be reset if rewriting takes place.
        path - The LocationPath object.
        Returns:
        true if the sub expressions should be traversed.

      • visitUnionPath

        public boolean visitUnionPath​(ExpressionOwner owner,
                              UnionPathIterator path)
        Visit a UnionPath.
        Parameters:
        owner - The owner of the expression, to which the expression can be reset if rewriting takes place.
        path - The UnionPath object.
        Returns:
        true if the sub expressions should be traversed.

      • visitStep

        public boolean visitStep​(ExpressionOwner owner,
                         NodeTest step)
        Visit a step within a location path.
        Parameters:
        owner - The owner of the expression, to which the expression can be reset if rewriting takes place.
        step - The Step object.
        Returns:
        true if the sub expressions should be traversed.

      • visitPredicate

        public boolean visitPredicate​(ExpressionOwner owner,
                              Expression pred)
        Visit a predicate within a location path. Note that there isn't a proper unique component for predicates, and that the expression will be called also for whatever type Expression is.
        Parameters:
        owner - The owner of the expression, to which the expression can be reset if rewriting takes place.
        pred - The predicate object.
        Returns:
        true if the sub expressions should be traversed.

      • visitBinaryOperation

        public boolean visitBinaryOperation​(ExpressionOwner owner,
                                    Operation op)
        Visit a binary operation.
        Parameters:
        owner - The owner of the expression, to which the expression can be reset if rewriting takes place.
        op - The operation object.
        Returns:
        true if the sub expressions should be traversed.

      • visitUnaryOperation

        public boolean visitUnaryOperation​(ExpressionOwner owner,
                                   UnaryOperation op)
        Visit a unary operation.
        Parameters:
        owner - The owner of the expression, to which the expression can be reset if rewriting takes place.
        op - The operation object.
        Returns:
        true if the sub expressions should be traversed.

      • visitVariableRef

        public boolean visitVariableRef​(ExpressionOwner owner,
                                Variable var)
        Visit a variable reference.
        Parameters:
        owner - The owner of the expression, to which the expression can be reset if rewriting takes place.
        var - The variable reference object.
        Returns:
        true if the sub expressions should be traversed.

      • visitFunction

        public boolean visitFunction​(ExpressionOwner owner,
                             Function func)
        Visit a function.
        Parameters:
        owner - The owner of the expression, to which the expression can be reset if rewriting takes place.
        func - The function reference object.
        Returns:
        true if the sub expressions should be traversed.

      • visitMatchPattern

        public boolean visitMatchPattern​(ExpressionOwner owner,
                                 StepPattern pattern)
        Visit a match pattern.
        Parameters:
        owner - The owner of the expression, to which the expression can be reset if rewriting takes place.
        pattern - The match pattern object.
        Returns:
        true if the sub expressions should be traversed.

      • visitUnionPattern

        public boolean visitUnionPattern​(ExpressionOwner owner,
                                 UnionPattern pattern)
        Visit a union pattern.
        Parameters:
        owner - The owner of the expression, to which the expression can be reset if rewriting takes place.
        pattern - The union pattern object.
        Returns:
        true if the sub expressions should be traversed.

      • visitStringLiteral

        public boolean visitStringLiteral​(ExpressionOwner owner,
                                  XString str)
        Visit a string literal.
        Parameters:
        owner - The owner of the expression, to which the expression can be reset if rewriting takes place.
        str - The string literal object.
        Returns:
        true if the sub expressions should be traversed.

      • visitNumberLiteral

        public boolean visitNumberLiteral​(ExpressionOwner owner,
                                  XNumber num)
        Visit a number literal.
        Parameters:
        owner - The owner of the expression, to which the expression can be reset if rewriting takes place.
        num - The number literal object.
        Returns:
        true if the sub expressions should be traversed.