Some refactoring in CUETools

CUETools/TreeNodes/FileSystemTreeNodeLocalDBFolder.cs

@@ -0,0 +1,31 @@
+using System.Collections.Generic;
+using System.Windows.Forms;
+using CUEControls;
+using CUETools.Processor;
+
+namespace JDP
+{
+    public abstract class FileSystemTreeNodeLocalDBFolder : FileSystemTreeNode
+    {
+        public List<CUEToolsLocalDBEntry> Group { get; protected set; }
+
+        public FileSystemTreeNodeLocalDBFolder(IIconManager icon_mgr)
+            : base(icon_mgr, true)
+        {
+        }
+
+        public void Purge(List<CUEToolsLocalDBEntry> entries)
+        {
+            foreach (TreeNode child in this.Nodes)
+            {
+                if (child is FileSystemTreeNodeLocalDBFolder)
+                    (child as FileSystemTreeNodeLocalDBFolder).Purge(entries);
+                if ((child is FileSystemTreeNodeLocalDBEntry && entries.Contains((child as FileSystemTreeNodeLocalDBEntry).Item))
+                    || (child is FileSystemTreeNodeLocalDBGroup && (child as FileSystemTreeNodeLocalDBGroup).Group.Count == 0))
+                    child.Remove();
+            }
+
+            this.Group.RemoveAll(item => entries.Contains(item));
+        }
+    }
+}