Package net.sf.saxon.expr

Class ExpressionVisitor

  • public class ExpressionVisitor
extends java.lang.Object
    The ExpressionVisitor supports the various phases of processing of an expression tree which require a recursive walk of the tree structure visiting each node in turn. In maintains a stack holding the ancestor nodes of the node currently being visited.

    • Constructor Detail

      • ExpressionVisitor

        public ExpressionVisitor()
        Create an ExpressionVisitor

    • Method Detail

      • getConfiguration

        public Configuration getConfiguration()
        Get the Saxon configuration
        Returns:
        the Saxon configuration

      • setConfiguration

        public void setConfiguration​(Configuration configuration)
        Set the Saxon configuration
        Parameters:
        configuration - the Saxon configuration

      • getContainer

        public Container getContainer()
        Get the container of the expressions being visited
        Returns:
        the container

      • setContainer

        public void setContainer​(Container container)
        Set the container of the expressions being visited
        Parameters:
        container - the container

      • getExecutable

        public Executable getExecutable()
        Get the Executable containing the expressions being visited
        Returns:
        the Executable

      • setExecutable

        public void setExecutable​(Executable executable)
        Set the Executable containing the expressions being visited
        Parameters:
        executable - the Executable

      • getStack

        public java.util.Stack getStack()
        Get the stack containing all the expressions currently being visited
        Returns:
        the expression stack holding all the containing expressions of the current expression; the objects on this Stack are instances of Expression

      • setStack

        public void setStack​(java.util.Stack stack)
        Set the stack used to hold the expressions being visited
        Parameters:
        stack - the expression stack

      • getStaticContext

        public StaticContext getStaticContext()
        Get the static context for the expressions being visited. Note: this may not reflect all changes in static context (e.g. namespace context, base URI) applying to nested expressions
        Returns:
        the static context

      • setStaticContext

        public void setStaticContext​(StaticContext staticContext)
        Set the static context for the expressions being visited. Note: this may not reflect all changes in static context (e.g. namespace context, base URI) applying to nested expressions
        Parameters:
        staticContext - the static context

      • getCurrentExpression

        public Expression getCurrentExpression()
        Get the current expression, the one being visited
        Returns:
        the current expression

      • make

        public static ExpressionVisitor make​(StaticContext env)
        Factory method: make an expression visitor
        Parameters:
        env - the static context
        Returns:
        the new expression visitor

      • typeCheck

        public Expression typeCheck​(Expression exp,
                            ItemType contextItemType)
                     throws XPathException
        Type check an expression, via the ExpressionVisitor
        Parameters:
        exp - the expression to be typechecked
        contextItemType - the static type of the context item for this expression
        Returns:
        the expression that results from type checking (this may be wrapped in expressions that perform dynamic checking of the item type or cardinality, or that perform atomization or numeric promotion)
        Throws:
        XPathException - if static type checking fails, that is, if the expression cannot possibly deliver a value of the required type

      • optimize

        public Expression optimize​(Expression exp,
                           ItemType contextItemType)
                    throws XPathException
        Optimize an expression, via the ExpressionVisitor
        Parameters:
        exp - the expression to be typechecked
        contextItemType - the static type of the context item for this expression
        Returns:
        the rewritten expression
        Throws:
        XPathException

      • getParentExpression

        public Expression getParentExpression()
        Get the parent expression of the current expression in the expression tree
        Returns:
        the parent of the current expression (or null if this is the root)

      • isLoopingSubexpression

        public boolean isLoopingSubexpression​(Expression ancestor)
        Return true if the current expression at the top of the visitor's stack is evaluated repeatedly when a given ancestor expression is evaluated once
        Parameters:
        ancestor - the ancestor expression. May be null, in which case the search goes all the way to the base of the stack.
        Returns:
        true if the current expression is evaluated repeatedly

      • resetStaticProperties

        public final void resetStaticProperties()
        Reset the static properties for the current expression and for all its containing expressions. This should be done whenever the expression is changed in a way that might affect the properties. It causes the properties to be recomputed next time they are needed.