before remove validation board

Gameboard.ShogiUI.BoardState/Array2D.cs

@@ -1,20 +1,21 @@
 using System;
 using System.Collections;
 using System.Collections.Generic;
-using System.Linq;
-using System.Text;
-using System.Threading.Tasks;
 
 namespace Gameboard.ShogiUI.BoardState
 {
-  public class Array2D<T> : IEnumerable
+  public class Array2D<T> : IEnumerable<T>
   {
+    /// <returns>False to stop iterating.</returns>
+    public delegate void ForEachDelegate(T element, int x, int y);
     private readonly T[] array;
     private readonly int width;
+    private readonly int height;
 
     public Array2D(int width, int height)
     {
       this.width = width;
+      this.height = height;
       array = new T[width * height];
     }
 
@@ -24,6 +25,48 @@ namespace Gameboard.ShogiUI.BoardState
       set => array[y * width + x] = value;
     }
 
+    public void ForEach(ForEachDelegate callback)
+    {
+      for (var x = 0; x < width; x++)
+      {
+        for (var y = 0; y < height; y++)
+        {
+          callback(this[x, y], x, y);
+        }
+      }
+    }
+
+    public void ForEachNotNull(ForEachDelegate callback)
+    {
+      for (var x = 0; x < width; x++)
+      {
+        for (var y = 0; y < height; y++)
+        {
+          if (this[x, y] != null)
+            callback(this[x, y], x, y);
+        }
+      }
+    }
+
+    // TODO: Figure out a better return type, or make this class specific to ShogiBoard.
+    public BoardVector IndexOf(Predicate<T> predicate)
+    {
+      for (var x = 0; x < width; x++)
+        for (var y = 0; y < height; y++)
+        {
+          if (this[x, y] != null && predicate(this[x, y]))
+          {
+            return new BoardVector(x, y);
+          }
+        }
+      return null;
+    }
+
+    public IEnumerator<T> GetEnumerator()
+    {
+      foreach (var item in array) yield return item;
+    }
+
     IEnumerator IEnumerable.GetEnumerator() => array.GetEnumerator();
   }
 }