KeycodeSet: move to Keyboard.zig

The file was too short and did't make much sense on its own; actually,
it's quite clearly part of the Keyboard logic.

 river/Keyboard.zig   | 54 +++++++++++++++++++++++++++++++++++++-
 river/KeycodeSet.zig | 74 ----------------------------------------------------
 river/Seat.zig       |  5 ++--
 3 files changed, 55 insertions(+), 78 deletions(-)

diff --git a/river/Keyboard.zig b/river/Keyboard.zig
index 67dbbfd..946523b 100644
--- a/river/Keyboard.zig
+++ b/river/Keyboard.zig
@@ -26,12 +26,64 @@ const globber = @import("globber");
 const server = &@import("main.zig").server;
 const util = @import("util.zig");
 
-const KeycodeSet = @import("KeycodeSet.zig");
 const Seat = @import("Seat.zig");
 const InputDevice = @import("InputDevice.zig");
 
 const log = std.log.scoped(.keyboard);
 
+const EatReason = enum {
+    /// Not eaten
+    none,
+    mapping,
+    im_grab,
+};
+
+pub const KeycodeSet = struct {
+    items: [32]u32 = undefined,
+    reason: [32]EatReason = undefined,
+    len: usize = 0,
+
+    pub fn add(set: *KeycodeSet, new: u32, reason: EatReason) EatReason {
+        for (set.items[0..set.len]) |item| assert(new != item);
+
+        comptime assert(@typeInfo(std.meta.fieldInfo(KeycodeSet, .items).type).Array.len ==
+            @typeInfo(std.meta.fieldInfo(wlr.Keyboard, .keycodes).type).Array.len);
+
+        if (set.len == set.items.len) {
+            log.err("KeycodeSet limit reached, code {d} omitted", .{new});
+            // We can't eat the release, don't eat the press
+            return .none;
+        }
+
+        set.items[set.len] = new;
+        set.reason[set.len] = reason;
+        set.len += 1;
+
+        return reason;
+    }
+
+    pub fn remove(set: *KeycodeSet, old: u32) EatReason {
+        for (set.items[0..set.len], set.reason[0..set.len], 0..) |item, reason, idx| {
+            if (old == item) {
+                set.len -= 1;
+                if (set.len > 0) {
+                    set.items[idx] = set.items[set.len];
+                    set.reason[idx] = set.reason[set.len];
+                }
+
+                return reason;
+            }
+        }
+
+        return .none;
+    }
+
+    /// Removes other's contents from set (if present), regardless of reason
+    pub fn subtract(set: *KeycodeSet, other: KeycodeSet) void {
+        for (other.items[0..other.len]) |item| _ = set.remove(item);
+    }
+};
+
 device: InputDevice,
 
 /// Pressed keys for which a mapping was triggered on press
diff --git a/river/KeycodeSet.zig b/river/KeycodeSet.zig
deleted file mode 100644
index 7484bda..0000000
--- a/river/KeycodeSet.zig
+++ /dev/null
@@ -1,74 +0,0 @@
-// This file is part of river, a dynamic tiling wayland compositor.
-//
-// Copyright 2022 - 2024 The River Developers
-//
-// This program is free software: you can redistribute it and/or modify
-// it under the terms of the GNU General Public License as published by
-// the Free Software Foundation, version 3.
-//
-// This program is distributed in the hope that it will be useful,
-// but WITHOUT ANY WARRANTY; without even the implied warranty of
-// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
-// GNU General Public License for more details.
-//
-// You should have received a copy of the GNU General Public License
-// along with this program. If not, see <https://www.gnu.org/licenses/>.
-
-const Self = @This();
-
-const std = @import("std");
-const assert = std.debug.assert;
-const log = std.log.scoped(.keyboard);
-
-const wlr = @import("wlroots");
-
-const EatReason = enum {
-    /// Not eaten
-    none,
-    mapping,
-    im_grab,
-};
-
-items: [32]u32 = undefined,
-reason: [32]EatReason = undefined,
-len: usize = 0,
-
-pub fn add(self: *Self, new: u32, reason: EatReason) EatReason {
-    for (self.items[0..self.len]) |item| assert(new != item);
-
-    comptime assert(@typeInfo(std.meta.fieldInfo(Self, .items).type).Array.len ==
-        @typeInfo(std.meta.fieldInfo(wlr.Keyboard, .keycodes).type).Array.len);
-
-    if (self.len == self.items.len) {
-        log.err("KeycodeSet limit reached, code {d} omitted", .{new});
-        // We can't eat the release, don't eat the press
-        return .none;
-    }
-
-    self.items[self.len] = new;
-    self.reason[self.len] = reason;
-    self.len += 1;
-
-    return reason;
-}
-
-pub fn remove(self: *Self, old: u32) EatReason {
-    for (self.items[0..self.len], self.reason[0..self.len], 0..) |item, reason, idx| {
-        if (old == item) {
-            self.len -= 1;
-            if (self.len > 0) {
-                self.items[idx] = self.items[self.len];
-                self.reason[idx] = self.reason[self.len];
-            }
-
-            return reason;
-        }
-    }
-
-    return .none;
-}
-
-/// Removes other's contents from self (if present), regardless of reason
-pub fn subtract(self: *Self, other: Self) void {
-    for (other.items[0..other.len]) |item| _ = self.remove(item);
-}
diff --git a/river/Seat.zig b/river/Seat.zig
index 68679fe..d83f7af 100644
--- a/river/Seat.zig
+++ b/river/Seat.zig
@@ -1,6 +1,6 @@
 // This file is part of river, a dynamic tiling wayland compositor.
 //
-// Copyright 2020 The River Developers
+// Copyright 2020 - 2024 The River Developers
 //
 // This program is free software: you can redistribute it and/or modify
 // it under the terms of the GNU General Public License as published by
@@ -34,7 +34,6 @@ const InputManager = @import("InputManager.zig");
 const InputRelay = @import("InputRelay.zig");
 const Keyboard = @import("Keyboard.zig");
 const KeyboardGroup = @import("KeyboardGroup.zig");
-const KeycodeSet = @import("KeycodeSet.zig");
 const LayerSurface = @import("LayerSurface.zig");
 const LockSurface = @import("LockSurface.zig");
 const Mapping = @import("Mapping.zig");
@@ -305,7 +304,7 @@ pub fn keyboardEnterOrLeave(self: *Self, target_surface: ?*wlr.Surface) void {
 
 fn keyboardNotifyEnter(self: *Self, wlr_surface: *wlr.Surface) void {
     if (self.wlr_seat.getKeyboard()) |wlr_keyboard| {
-        var keycodes = KeycodeSet{
+        var keycodes = Keyboard.KeycodeSet{
             .items = wlr_keyboard.keycodes,
             .reason = .{.none} ** 32,
             .len = wlr_keyboard.num_keycodes,