ZLinq VisualElement Traverser

gistfile1.txt

using UnityEngine.UIElements;
using ZLinq; // https://github.com/Cysharp/ZLinq

public struct VisualElementTraverser : ITraverser<VisualElementTraverser, VisualElement> {
    readonly VisualElement current;
    int nextChildIndex;
    readonly int totalChildren;

    public VisualElementTraverser(VisualElement origin) {
        current = origin;
        nextChildIndex = 0;
        totalChildren = origin?.childCount ?? 0;
    }

    public VisualElement Origin => current;

    public VisualElementTraverser ConvertToTraverser(VisualElement next) => new(next);

    public bool TryGetParent(out VisualElement parent) {
        parent = current?.parent;
        return parent != null;
    }

    public bool TryGetHasChild(out bool hasChild) {
        hasChild = totalChildren > 0;
        return true;
    }

    public bool TryGetChildCount(out int count) {
        count = totalChildren;
        return true;
    }

    public bool TryGetNextChild(out VisualElement child) {
        if (nextChildIndex < totalChildren) {
            child = current[nextChildIndex++];
            return true;
        }

        child = null;
        return false;
    }

    public bool TryGetNextSibling(out VisualElement next) {
        if (current == null || current.parent == null) {
            next = null;
            return false;
        }

        var parent = current.parent;
        var index = parent.IndexOf(current);

        if (index >= 0 && index + 1 < parent.childCount) {
            next = parent[index + 1];
            return true;
        }

        next = null;
        return false;
    }

    public bool TryGetPreviousSibling(out VisualElement previous) {
        if (current == null || current.parent == null) {
            previous = null;
            return false;
        }

        var parent = current.parent;
        var index = parent.IndexOf(current);

        if (index > 0) {
            previous = parent[index - 1];
            return true;
        }

        previous = null;
        return false;
    }

    public void Dispose() { }
}