1 files changed, 51 insertions, 0 deletions
diff --git a/src/SMAPI/Framework/Input/KeyboardStateBuilder.cs b/src/SMAPI/Framework/Input/KeyboardStateBuilder.cs
new file mode 100644
index 00000000..12d780f6
--- /dev/null
+++ b/src/SMAPI/Framework/Input/KeyboardStateBuilder.cs
@@ -0,0 +1,51 @@
+using System.Collections.Generic;
+using System.Linq;
+using Microsoft.Xna.Framework.Input;
+
+namespace StardewModdingAPI.Framework.Input
+{
+    /// <summary>Manipulates keyboard state.</summary>
+    internal class KeyboardStateBuilder
+    {
+        /*********
+        ** Fields
+        *********/
+        /// <summary>The pressed buttons.</summary>
+        private readonly HashSet<Keys> PressedButtons;
+
+
+        /*********
+        ** Public methods
+        *********/
+        /// <summary>Construct an instance.</summary>
+        /// <param name="state">The initial state.</param>
+        public KeyboardStateBuilder(KeyboardState state)
+        {
+            this.PressedButtons = new HashSet<Keys>(state.GetPressedKeys());
+        }
+
+        /// <summary>Override the states for a set of buttons.</summary>
+        /// <param name="overrides">The button state overrides.</param>
+        public KeyboardStateBuilder OverrideButtons(IDictionary<SButton, SButtonState> overrides)
+        {
+            foreach (var pair in overrides)
+            {
+                if (pair.Key.TryGetKeyboard(out Keys key))
+                {
+                    if (pair.Value.IsDown())
+                        this.PressedButtons.Add(key);
+                    else
+                        this.PressedButtons.Remove(key);
+                }
+            }
+
+            return this;
+        }
+
+        /// <summary>Build an equivalent state.</summary>
+        public KeyboardState ToState()
+        {
+            return new KeyboardState(this.PressedButtons.ToArray());
+        }
+    }
+}