InputManager -> Container where KeyBindings are involved

osu.Game/Input/Bindings/DatabasedKeyBindingContainer.cs

@@ -0,0 +1,61 @@
+// Copyright (c) 2007-2018 ppy Pty Ltd <contact@ppy.sh>.
+// Licensed under the MIT Licence - https://raw.githubusercontent.com/ppy/osu/master/LICENCE
+
+using System;
+using System.Collections.Generic;
+using osu.Framework.Allocation;
+using osu.Framework.Input.Bindings;
+using osu.Game.Rulesets;
+using System.Linq;
+
+namespace osu.Game.Input.Bindings
+{
+    /// <summary>
+    /// A KeyBindingInputManager with a database backing for custom overrides.
+    /// </summary>
+    /// <typeparam name="T">The type of the custom action.</typeparam>
+    public class DatabasedKeyBindingContainer<T> : KeyBindingContainer<T>
+        where T : struct
+    {
+        private readonly RulesetInfo ruleset;
+
+        private readonly int? variant;
+
+        private KeyBindingStore store;
+
+        public override IEnumerable<KeyBinding> DefaultKeyBindings => ruleset.CreateInstance().GetDefaultKeyBindings(variant ?? 0);
+
+        /// <summary>
+        /// Create a new instance.
+        /// </summary>
+        /// <param name="ruleset">A reference to identify the current <see cref="Ruleset"/>. Used to lookup mappings. Null for global mappings.</param>
+        /// <param name="variant">An optional variant for the specified <see cref="Ruleset"/>. Used when a ruleset has more than one possible keyboard layouts.</param>
+        /// <param name="simultaneousMode">Specify how to deal with multiple matches of <see cref="KeyCombination"/>s and <see cref="T"/>s.</param>
+        public DatabasedKeyBindingContainer(RulesetInfo ruleset = null, int? variant = null, SimultaneousBindingMode simultaneousMode = SimultaneousBindingMode.None)
+            : base(simultaneousMode)
+        {
+            this.ruleset = ruleset;
+            this.variant = variant;
+
+            if (ruleset != null && variant == null)
+                throw new InvalidOperationException($"{nameof(variant)} can not be null when a non-null {nameof(ruleset)} is provided.");
+        }
+
+        [BackgroundDependencyLoader]
+        private void load(KeyBindingStore keyBindings)
+        {
+            store = keyBindings;
+            store.KeyBindingChanged += ReloadMappings;
+        }
+
+        protected override void Dispose(bool isDisposing)
+        {
+            base.Dispose(isDisposing);
+
+            if (store != null)
+                store.KeyBindingChanged -= ReloadMappings;
+        }
+
+        protected override void ReloadMappings() => KeyBindings = store.Query(ruleset?.ID, variant).ToList();
+    }
+}