EditorActions.UpdateLayerEnum()

EditorActions.cs

using UnityEngine;
using UnityEditor;
using System.Collections;
using System.IO;

public class EditorActions
{
    [MenuItem ("Toolkit/Tags and Layers/Update Layer.cs")]
    static void UpdateLayerConstants()
    {
        // Writes a file named Layer.cs containing a Layer class with constants for each layer as both an
        // index number and a mask.
        
        string filename = GetFullPathToFirstAssetWithFilename("Layer.cs");
        if(!string.IsNullOrEmpty(filename))
        {
            if(!EditorUtility.DisplayDialog("Overwrite existing Layer.cs file?", string.Format("Full path: {0}", filename), "Overwrite", "Cancel"))
                return;
        }
        else
        {
            filename = Application.dataPath + "/Layer.cs";
            if(!EditorUtility.DisplayDialog("Create a new Layer.cs file?", string.Format("Full path: {0}", filename), "Create", "Cancel"))
                return;
        }
        
        using(var fileStream = File.CreateText(filename))
        {
            fileStream.WriteLine("// File generated by EditorActions.UpdateLayerConstants()");
            fileStream.WriteLine();
            fileStream.WriteLine("public static class Layer");
            fileStream.WriteLine("{");
            
            for(int i = 0; i < 32; ++i)
            {
                var name = LayerMask.LayerToName(i);
                if(!string.IsNullOrEmpty(name))
                {
                    name = name.Replace(" ", string.Empty);
                    fileStream.WriteLine("\tpublic const int {0} = {1};", name + "Index", i);
                    fileStream.WriteLine("\tpublic const int {0} = 0x{1:X8};", name + "Mask", 1 << i);
                }
            }
            
            fileStream.WriteLine("}");
        }
        
        AssetDatabase.Refresh();
    }
    
    static string GetFullPathToFirstAssetWithFilename(string filename)
    {
        var files = Directory.GetFiles(Application.dataPath, filename, SearchOption.AllDirectories);
        return (files.Length > 0 ? files[0] : "");
    }
}