org.jsoup.select.NodeVisitor Maven / Gradle / Ivy
package org.jsoup.select;
import org.jsoup.nodes.Element;
import org.jsoup.nodes.Node;
/**
Node visitor interface. Provide an implementing class to {@link NodeTraversor} or to {@link Node#traverse(NodeVisitor)}
to iterate through nodes.
This interface provides two methods, {@link #head} and {@link #tail}. The head method is called when the node is first
seen, and the tail method when all of the node's children have been visited. As an example, {@code head} can be used to
emit a start tag for a node, and {@code tail} to create the end tag. The {@code tail} method defaults to a no-op, so
the {@code head} method is the {@link FunctionalInterface}.
Example:
doc.body().traverse((node, depth) -> {
switch (node) {
case Element el -> print(el.tag() + ": " + el.ownText());
case DataNode data -> print("Data: " + data.getWholeData());
default -> print(node.nodeName() + " at depth " + depth);
}
});
*/
@FunctionalInterface
public interface NodeVisitor {
/**
Callback for when a node is first visited.
The node may be modified (e.g. {@link Node#attr(String)}, replaced {@link Node#replaceWith(Node)}) or removed
{@link Node#remove()}. If it's {@code instanceOf Element}, you may cast it to an {@link Element} and access those
methods.
@param node the node being visited.
@param depth the depth of the node, relative to the root node. E.g., the root node has depth 0, and a child node
of that will have depth 1.
*/
void head(Node node, int depth);
/**
Callback for when a node is last visited, after all of its descendants have been visited.
This method has a default no-op implementation.
Note that neither replacement with {@link Node#replaceWith(Node)} nor removal with {@link Node#remove()} is
supported during {@code tail()}.
@param node the node being visited.
@param depth the depth of the node, relative to the root node. E.g., the root node has depth 0, and a child node
of that will have depth 1.
*/
default void tail(Node node, int depth) {
// no-op by default, to allow just specifying the head() method
}
}