moved GUI project to a subdirectory.

GUI/HistoryStack.cs

@@ -0,0 +1,109 @@
+//! \file       HistoryStack.cs
+//! \date       Sun Aug 21 01:06:53 2011
+//! \brief      action history stack interface (undo/redo).
+//
+// Copyright (C) 2011 by poddav
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to
+// deal in the Software without restriction, including without limitation the
+// rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+// sell copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+// IN THE SOFTWARE.
+
+using System;
+using System.Collections.Generic;
+using System.Linq;
+
+namespace Rnd.Windows
+{
+    public class HistoryStack<State>
+    {
+        private List<State>     m_back    = new List<State>();
+        private Stack<State>    m_forward = new Stack<State>();
+
+        public int Limit { get; set; }
+
+        public IEnumerable<State> UndoStack { get { return m_back; } }
+        public IEnumerable<State> RedoStack { get { return m_forward; } }
+
+        public HistoryStack (int limit = 50)
+        {
+            Limit = limit;
+        }
+
+        public State Undo (State current)
+        {
+            if (!CanUndo())
+                return default(State);
+
+            m_forward.Push (current);
+            current = m_back.Last();
+            m_back.RemoveAt (m_back.Count - 1);
+            OnStateChanged();
+
+            return current;
+        }
+
+        public State Redo (State current)
+        {
+            if (!CanRedo())
+                return default(State);
+
+            m_back.Add (current);
+            current = m_forward.Pop();
+            OnStateChanged();
+
+            return current;
+        }
+
+        public bool CanUndo ()
+        {
+            return m_back.Any();
+        }
+
+        public bool CanRedo ()
+        {
+            return m_forward.Any();
+        }
+
+        public void Push (State current)
+        {
+            m_back.Add (current);
+            if (m_back.Count > Limit)
+                m_back.RemoveRange (0, m_back.Count - Limit);
+
+            m_forward.Clear();
+            OnStateChanged();
+        }
+
+        public void Clear ()
+        {
+            if (m_back.Any() || m_forward.Any())
+            {
+                m_back.Clear();
+                m_forward.Clear();
+                OnStateChanged();
+            }
+        }
+
+        public event EventHandler StateChanged;
+
+        private void OnStateChanged ()
+        {
+            if (StateChanged != null)
+                StateChanged (this, EventArgs.Empty);
+        }
+    }
+}