TreeList

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

Features:

• Fast and simple serialization/deserialization: Only the data and depth of the tree node.
• Fast iteration and children enumeration: Thanks to the underlying List<>.
• Moderate modification performance: Also due to the List<> structure.
• Prefab workflow support: Includes Apply/Revert functionality.
• Copy/Paste/Undo support: Enables streamlined editing.
• UIToolkit and IMGUI editors: Mostly equivalent in functionality.
• Dark/light skin compatibility: Offers seamless UI integration.

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

Tested in Unity 2022.3 LTS and Unity 6.

Basic code sample for TreeList<> class

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 usage

Add/remove nodes (UIToolkit, dark theme)

Search values in a tree (IMGUI, dark theme)

Drag and drop nodes to move or copy ( Ctrl+drag ) (IMGUI, light theme). Note: there is a minor issue with Ctrl+dragging in the UIToolkit implementation—the drag icon does not change from 'move' to 'copy,' even though the copy operation works as expected.

Work with prefabs (apply and revert) and copy/paste operations for the entire tree property, individual tree node values, and properties of complex node levels (UIToolkit light theme). Apologies for the custom context menu for node values—I couldn't find a way to integrate the native context menu without disrupting the native menu for separate node values.

The TreeList inspector makes a strong effort to support custom property drawers for properties, including dynamic heights, and decorators such as 'Header.' This support is also available for the IMGUI inspector.

I tested the editor's performance with a randomly generated tree containing 1,000 nodes and approximately 15 levels of depth. The editor's responsiveness was notably good.

Questions?

Feel free to post your question in Discussions

License

This library is under the MIT License