io.github.qudtlib.tools.contribute.support.tree.TreeWalker Maven / Gradle / Ivy

Go to download

Show more of this group Show more artifacts with this name
Show all versions of qudtlib-tools Show documentation

There is a newer version: 6.8.0

package io.github.qudtlib.tools.contribute.support.tree;

import java.util.ArrayList;
import java.util.Comparator;
import java.util.List;
import java.util.Objects;

public class TreeWalker {
    private Node root;
    private Comparator> iterationOrderComparator = null;

    public TreeWalker(Node root) {
        Objects.requireNonNull(root);
        this.root = root;
    }

    public TreeWalker sorted(Comparator> comparator) {
        this.iterationOrderComparator = comparator;
        return this;
    }

    public static  TreeWalker of(Node root) {
        return new TreeWalker(root);
    }

    public void walkDepthFirst(NodeVisitor visitor) {
        walkDepthFirstInternal(root, visitor, 0, 0, 0);
    }

    private void walkDepthFirstInternal(
            Node node, NodeVisitor visitor, int depth, int siblings, int orderInSiblings) {
        NodeVisitor.NodeAndPositionInTree nodeAndPositionInTree =
                new NodeVisitor.NodeAndPositionInTree<>(node, depth, siblings, orderInSiblings);
        visitor.enter(nodeAndPositionInTree);
        List> children = new ArrayList<>(node.getChildren());
        if (this.iterationOrderComparator != null) {
            children.sort(this.iterationOrderComparator);
        }
        for (int i = 0; i < children.size(); i++) {
            walkDepthFirstInternal(children.get(i), visitor, depth + 1, children.size() - 1, i);
        }
        visitor.exit(nodeAndPositionInTree);
    }
}