TreeList

TreeList is a simple generic tree data type with Unity Editor support. It's based on a List<> internally so its name.

Features:

Fast serialization/deserialization (only data and depth of the tree node)
Fast iteration, children enumeration (because of the List)
Not so fast modification (because of the List)
Prefab workflow support (Apply/Revert)
Copy/Paste/Undo support
UIToolkit and IMGUI editors (mostly equivalent in functionality)
Dark/light skin compatible

Installation

Install a package from a Git URL. Please take a look at Unity Manual for instructions and use https://github.com/Silentor/TreeList.git?path=/Packages/com.Silentor.TreeList URL in Package Manager to install package.

Or add "com.silentor.treelist": "https://github.com/Silentor/TreeList.git?path=/Packages/com.Silentor.TreeList" line to your Packages/manifest.json file

Usage

Basic code sample

public class Sample : MonoBehaviour
{
    public TreeList<String> StringTree;

    private void Awake( )
    {
        StringTree = new TreeList<String>();

        //Add root node
        var rootNode = StringTree.Add( "I am Root", null );
        
        //Add children nodes to root node
        rootNode.AddChildren( "child1", "child2", "child3", "child4" );

        //Enumerate children of root node
        var childs = rootNode.GetChildren(  ).ToArray();

        //Add child to 'child3' node
        var grandChild = childs[2].AddChild( "grand child" );

        //Move 'child1' to the grandchild node as a child
        StringTree.Move( childs[0], grandChild );

        //Remove node from tree
        StringTree.Remove( childs[1] );

        //Print tree structure and values
        Debug.Log( StringTree.ToHierarchyString() );

        /*
        Value = 'I am Root' (level = 0, )
           Value = 'child3' (level = 1, parent 'I am Root')
               Value = 'grand child' (level = 2, parent 'child3')
                   Value = 'child1' (level = 3, parent 'grand child')
           Value = 'child4' (level = 1, parent 'I am Root')
        */
    }
}

Methods GetChildren() and GetChildrenBFS() return IEnumerable so it allocates a little. If you want zero-allocation get-children logic for tight loops please use GetChildrenNonAlloc() and GetChildrenBFSNonAlloc() methods. They receive List<> parameter for result list and do not allocate if list capacity is enough.

Unity inspector

Add/remove nodes (UIToolkit, dark theme)

Search values in a tree (IMGUI, dark theme)

Drag and drop nodes to move around or copy ( Ctrl+drag ) (IMGUI, light theme). There is a small issue with Ctrl+dragging in UIToolkit implementation, drag icon does not change from "move" to "copy" while copy operation is working.

Work with prefabs (apply, revert) and copy/paste of entire tree property, tree node value and properties of complex node levels (UIToolkit, light theme). Sorry for the themed context menu for node values, I didn't find a way to hook up the native context menu without ruining native menu for separate node values.

TreeList inspector tries hard to support custom property drawers for values (dynamic height includes), property attributes like Header etc. Even for IMGUI inspector (dark theme).

I have tested editor performance for a random tree with 1000 nodes and ~15 depth and editor responsiveness was quite good.

Questions?

Feel free to post your question in Discussions

License

This library is under the MIT License