1 files changed, 89 insertions, 0 deletions
diff --git a/dom/gamepad/GamepadHandle.h b/dom/gamepad/GamepadHandle.h
new file mode 100644
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+++ b/dom/gamepad/GamepadHandle.h
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+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+// This file defines a strongly-typed opaque gamepad handle
+//
+// The handle is designed to be copied around and passed over IPC. It keeps
+// track of which "provider" created the handle so it can ensure that
+// providers are never mixed. It also allows each provider to have its own
+// algorithm for generating gamepad IDs, since the VR and Platform services
+// do it differently.
+
+#ifndef mozilla_dom_gamepad_GamepadHandle_h
+#define mozilla_dom_gamepad_GamepadHandle_h
+#include "mozilla/Tuple.h"
+#include "PLDHashTable.h"
+#include <type_traits>
+#include <cinttypes>
+
+namespace IPC {
+
+template <class>
+struct ParamTraits;
+
+}  // namespace IPC
+
+namespace mozilla::gfx {
+
+class VRDisplayClient;
+class VRManager;
+
+}  // namespace mozilla::gfx
+
+namespace mozilla::dom {
+
+class GamepadPlatformService;
+class GamepadServiceTest;
+class XRInputSource;
+
+// The "kind" of a gamepad handle is based on which provider created it
+enum class GamepadHandleKind : uint8_t {
+  GamepadPlatformManager,
+  VR,
+};
+
+class GamepadHandle {
+ public:
+  // Allow handle to be passed around as a simple object
+  GamepadHandle() = default;
+  GamepadHandle(const GamepadHandle&) = default;
+  GamepadHandle& operator=(const GamepadHandle&) = default;
+
+  // Helps code know which manager to send requests to
+  GamepadHandleKind GetKind() const;
+
+  // Define operators so the handle can compared and stored in maps
+  friend bool operator==(const GamepadHandle& a, const GamepadHandle& b);
+  friend bool operator!=(const GamepadHandle& a, const GamepadHandle& b);
+  friend bool operator<(const GamepadHandle& a, const GamepadHandle& b);
+
+  PLDHashNumber Hash() const;
+
+ private:
+  explicit GamepadHandle(uint32_t aValue, GamepadHandleKind aKind);
+  uint32_t GetValue() const { return mValue; }
+
+  uint32_t mValue{0};
+  GamepadHandleKind mKind{GamepadHandleKind::GamepadPlatformManager};
+
+  // These are the classes that are "gamepad managers". They are allowed to
+  // create new handles and inspect their actual value
+  friend class mozilla::dom::GamepadPlatformService;
+  friend class mozilla::dom::GamepadServiceTest;
+  friend class mozilla::dom::XRInputSource;
+  friend class mozilla::gfx::VRDisplayClient;
+  friend class mozilla::gfx::VRManager;
+
+  // Allow IPDL to serialize us
+  friend struct IPC::ParamTraits<mozilla::dom::GamepadHandle>;
+};
+
+static_assert(std::is_trivially_copyable<GamepadHandle>::value,
+              "GamepadHandle must be trivially copyable");
+
+}  // namespace mozilla::dom
+
+#endif  // mozilla_dom_gamepad_GamepadHandle_h