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/*
* Copyright (C) 2007-2010 Júlio Vilmar Gesser.
* Copyright (C) 2011, 2013-2016 The JavaParser Team.
*
* This file is part of JavaParser.
*
* JavaParser can be used either under the terms of
* a) the GNU Lesser General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
* b) the terms of the Apache License
*
* You should have received a copy of both licenses in LICENCE.LGPL and
* LICENCE.APACHE. Please refer to those files for details.
*
* JavaParser is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*/
package com.github.javaparser.ast.visitor;
import com.github.javaparser.ast.Node;
import java.util.ArrayList;
import java.util.LinkedList;
import java.util.Queue;
/**
* Iterate over all the nodes in (a part of) the AST. In contrast to the visit methods in Node, these methods are
* implemented in a simple recursive way which should be more efficient. A disadvantage is that they cannot be quit in
* the middle of their traversal.
*/
public abstract class TreeVisitor {
public void visitLeavesFirst(Node node) {
for (Node child : node.getChildNodes()) {
visitLeavesFirst(child);
}
process(node);
}
/**
* Performs a pre-order node traversal starting with a given node. When each node is visited, {@link #process(Node)}
* is called for further processing.
*
* @param node The node at which the traversal begins.
* @see <a href="https://en.wikipedia.org/wiki/Pre-order">Pre-order traversal</a>
*/
public void visitPreOrder(Node node) {
process(node);
new ArrayList<>(node.getChildNodes()).forEach(this::visitPreOrder);
}
/**
* Performs a post-order node traversal starting with a given node. When each node is visited, {@link
* #process(Node)} is called for further processing.
*
* @param node The node at which the traversal begins.
* @see <a href="https://en.wikipedia.org/wiki/Post-order">Post-order traversal</a>
*/
public void visitPostOrder(Node node) {
new ArrayList<>(node.getChildNodes()).forEach(this::visitPostOrder);
process(node);
}
/**
* Performs a pre-order node traversal starting with a given node. When each node is visited, {@link #process(Node)}
* is called for further processing.
*
* @param node The node at which the traversal begins.
* @see <a href="https://en.wikipedia.org/wiki/Pre-order">Pre-order traversal</a>
* @deprecated As of release 3.1.0, replaced by {@link #visitPreOrder(Node)}
*/
@Deprecated
public void visitDepthFirst(Node node) {
visitPreOrder(node);
}
/**
* https://en.wikipedia.org/wiki/Breadth-first_search
*
* @param node the start node, and the first one that is passed to process(node).
*/
public void visitBreadthFirst(Node node) {
final Queue<Node> queue = new LinkedList<>();
queue.offer(node);
while (queue.size() > 0) {
final Node head = queue.peek();
for (Node child : head.getChildNodes()) {
queue.offer(child);
}
process(queue.poll());
}
}
/**
* Process the given node.
*
* @param node The current node to process.
*/
public abstract void process(Node node);
/**
* Performs a simple traversal over all nodes that have the passed node as their parent.
*/
public void visitDirectChildren(Node node) {
new ArrayList<>(node.getChildNodes()).forEach(this::process);
}
}
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