it is done

core/src/mindustry/editor/OperationStack.java

@@ -0,0 +1,51 @@
+package mindustry.editor;
+
+import arc.struct.Array;
+
+public class OperationStack{
+    private final static int maxSize = 10;
+    private Array<DrawOperation> stack = new Array<>();
+    private int index = 0;
+
+    public OperationStack(){
+
+    }
+
+    public void clear(){
+        stack.clear();
+        index = 0;
+    }
+
+    public void add(DrawOperation action){
+        stack.truncate(stack.size + index);
+        index = 0;
+        stack.add(action);
+
+        if(stack.size > maxSize){
+            stack.remove(0);
+        }
+    }
+
+    public boolean canUndo(){
+        return !(stack.size - 1 + index < 0);
+    }
+
+    public boolean canRedo(){
+        return !(index > -1 || stack.size + index < 0);
+    }
+
+    public void undo(){
+        if(!canUndo()) return;
+
+        stack.get(stack.size - 1 + index).undo();
+        index--;
+    }
+
+    public void redo(){
+        if(!canRedo()) return;
+
+        index++;
+        stack.get(stack.size - 1 + index).redo();
+
+    }
+}