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package org.apache.commons.configuration2.tree;

Definition of a Visitor interface for a configuration node structure.

This is a typical application of the GoF Visitor pattern. An object implementing this interface can be used to traverse a hierarchical structure of nodes in various ways. The type of the nodes in the structure is generic; a corresponding NodeHandler implementation must be available for navigating through the structure.

Note that the exact way the methods of a ConfigurationNodeVisitor are invoked is dependent on a specific traversal process.

Type parameters:
  • <T> – the type of the nodes processed by this visitor
Since:1.3
/** * <p> * Definition of a <em>Visitor</em> interface for a configuration node * structure. * </p> * <p> * This is a typical application of the GoF <em>Visitor</em> pattern. An object * implementing this interface can be used to traverse a hierarchical structure * of nodes in various ways. The type of the nodes in the structure is generic; * a corresponding {@link NodeHandler} implementation must be available for * navigating through the structure. * </p> * <p> * Note that the exact way the methods of a {@code ConfigurationNodeVisitor} are * invoked is dependent on a specific traversal process. * </p> * * @since 1.3 * @param <T> the type of the nodes processed by this visitor */
public interface ConfigurationNodeVisitor<T> {
Visits the specified node before the children of this node - if existing - are processed.
Params:
  • node – the node to be visited
  • handler – the NodeHandler
/** * Visits the specified node before the children of this node - if existing * - are processed. * * @param node the node to be visited * @param handler the {@code NodeHandler} */
void visitBeforeChildren(T node, NodeHandler<T> handler);
Visits the specified node after after its children - if existing - have been processed.
Params:
  • node – the node to be visited
  • handler – the NodeHandler
/** * Visits the specified node after after its children - if existing - have * been processed. * * @param node the node to be visited * @param handler the {@code NodeHandler} */
void visitAfterChildren(T node, NodeHandler<T> handler);
Returns a flag whether the current visit process should be aborted. This method allows a visitor implementation to state that it does not need any further data. It may be used e.g. by visitors that search for a certain node in the hierarchy. After that node was found, there is no need to process the remaining nodes, too. This method is called after each visited node. A result of true indicates that the current iteration is to be aborted.
Returns:a flag if the visit process should be stopped
/** * Returns a flag whether the current visit process should be aborted. This * method allows a visitor implementation to state that it does not need any * further data. It may be used e.g. by visitors that search for a certain * node in the hierarchy. After that node was found, there is no need to * process the remaining nodes, too. This method is called after each * visited node. A result of <strong>true</strong> indicates that the * current iteration is to be aborted. * * @return a flag if the visit process should be stopped */
boolean terminate(); }