com.github.mike10004.xvfbmanager.ListTreeNode Maven / Gradle / Ivy

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package com.github.mike10004.xvfbmanager;

import com.google.common.collect.ImmutableList;
import com.google.common.collect.Iterables;
import com.google.common.collect.Iterators;

import javax.annotation.concurrent.NotThreadSafe;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;
import java.util.function.Function;

import static com.google.common.base.Preconditions.checkNotNull;
import static com.google.common.base.Preconditions.checkState;

/**
 * Implementation of a tree node that uses an array list for its children.
 * @param  the label type
 */
@NotThreadSafe
public class ListTreeNode implements TreeNode {

    private TreeNode parent;
    private final T label;
    private List> children;

    public ListTreeNode(T label) {
        this.label = checkNotNull(label, "label must be non-null");
        children = ImmutableList.of();
    }

    @Override
    public T getLabel() {
        return label;
    }

    @Override
    public Iterable> children() {
        List> children_ = children;
        if (children_ instanceof ImmutableList) {
            return children_;
        } else {
            return Collections.unmodifiableList(children);
        }
    }

    @Override
    public int getLevel() {
        int level = 0;
        TreeNode node = parent;
        while (node != null) {
            level++;
            node = node.getParent();
        }
        return level;
    }

    @Override
    public int getChildCount() {
        return children.size();
    }

    @Override
    public TreeNode getParent() {
        return parent;
    }

    @Override
    public TreeNode setParent(TreeNode parent) {
        TreeNode oldParent = this.parent;
        this.parent = parent;
        checkState(Iterables.contains(parent.children(), this), "setParent can only be called on child nodes");
        return oldParent;
    }

    @Override
    public ListTreeNode addChild(TreeNode child) {
        List> children_ = children;
        if (children_ instanceof ImmutableList) {
            this.children = children_ = new ArrayList<>(children_);
        }
        children_.add(child);
        child.setParent(this);
        return this;
    }

    @Override
    public boolean isRoot() {
        return parent == null;
    }

    @Override
    public NodeTraversal breadthFirstTraversal() {
        Iterable> bf = TreeNode.Utils.traverser().breadthFirst(this);
        return new NodeTraversal() {
            @Override
            public Iterable labels() {
                Function, T> f = TreeNode.Utils.labelFunction();
                //noinspection StaticPseudoFunctionalStyleMethod
                return Iterables.transform(bf, f::apply);
            }

            @Override
            public Iterator> iterator() {
                return bf.iterator();
            }
        };
    }

    @Override
    public boolean isLeaf() {
        return getChildCount() == 0;
    }

    @Override
    public String toString() {
        int childCount = getChildCount();
        boolean leaf = childCount == 0;
        return "ListTreeNode{" +
                (isRoot() ? "root" : (leaf ? "leaf" : "node")) +
                ", label=" + label +
                ", children.size=" + childCount +
                '}';
    }
}