Implement KeyboardClassifier interface in rust

DD: go/project-imposter-android
This CL includes:
- Rust interface setup

Next CL to include:
- Basic categorization into alphabetic and non-alphabetic
- Updating categorization based on key presses

Test: atest --host libinput_rust_test
Test: atest inputflinger_tests
Bug: 263559234
Flag: com.android.input.flags.enable_keyboard_classifier_rust_impl
Change-Id: I52773be992ddd8efaa9546e0af8b0a78515d931c
diff --git a/services/inputflinger/reader/include/EventHub.h b/services/inputflinger/reader/include/EventHub.h
index 39d2f5b..7cf584d 100644
--- a/services/inputflinger/reader/include/EventHub.h
+++ b/services/inputflinger/reader/include/EventHub.h
@@ -85,64 +85,67 @@
 
 /*
  * Input device classes.
+ *
+ * These classes are duplicated in rust side here: /frameworks/native/libs/input/rust/input.rs.
+ * If any new classes are added, we need to add them in rust input side too.
  */
 enum class InputDeviceClass : uint32_t {
     /* The input device is a keyboard or has buttons. */
-    KEYBOARD = 0x00000001,
+    KEYBOARD = android::os::IInputConstants::DEVICE_CLASS_KEYBOARD,
 
     /* The input device is an alpha-numeric keyboard (not just a dial pad). */
-    ALPHAKEY = 0x00000002,
+    ALPHAKEY = android::os::IInputConstants::DEVICE_CLASS_ALPHAKEY,
 
     /* The input device is a touchscreen or a touchpad (either single-touch or multi-touch). */
-    TOUCH = 0x00000004,
+    TOUCH = android::os::IInputConstants::DEVICE_CLASS_TOUCH,
 
     /* The input device is a cursor device such as a trackball or mouse. */
-    CURSOR = 0x00000008,
+    CURSOR = android::os::IInputConstants::DEVICE_CLASS_CURSOR,
 
     /* The input device is a multi-touch touchscreen or touchpad. */
-    TOUCH_MT = 0x00000010,
+    TOUCH_MT = android::os::IInputConstants::DEVICE_CLASS_TOUCH_MT,
 
     /* The input device is a directional pad (implies keyboard, has DPAD keys). */
-    DPAD = 0x00000020,
+    DPAD = android::os::IInputConstants::DEVICE_CLASS_DPAD,
 
     /* The input device is a gamepad (implies keyboard, has BUTTON keys). */
-    GAMEPAD = 0x00000040,
+    GAMEPAD = android::os::IInputConstants::DEVICE_CLASS_GAMEPAD,
 
     /* The input device has switches. */
-    SWITCH = 0x00000080,
+    SWITCH = android::os::IInputConstants::DEVICE_CLASS_SWITCH,
 
     /* The input device is a joystick (implies gamepad, has joystick absolute axes). */
-    JOYSTICK = 0x00000100,
+    JOYSTICK = android::os::IInputConstants::DEVICE_CLASS_JOYSTICK,
 
     /* The input device has a vibrator (supports FF_RUMBLE). */
-    VIBRATOR = 0x00000200,
+    VIBRATOR = android::os::IInputConstants::DEVICE_CLASS_VIBRATOR,
 
     /* The input device has a microphone. */
-    MIC = 0x00000400,
+    MIC = android::os::IInputConstants::DEVICE_CLASS_MIC,
 
     /* The input device is an external stylus (has data we want to fuse with touch data). */
-    EXTERNAL_STYLUS = 0x00000800,
+    EXTERNAL_STYLUS = android::os::IInputConstants::DEVICE_CLASS_EXTERNAL_STYLUS,
 
     /* The input device has a rotary encoder */
-    ROTARY_ENCODER = 0x00001000,
+    ROTARY_ENCODER = android::os::IInputConstants::DEVICE_CLASS_ROTARY_ENCODER,
 
     /* The input device has a sensor like accelerometer, gyro, etc */
-    SENSOR = 0x00002000,
+    SENSOR = android::os::IInputConstants::DEVICE_CLASS_SENSOR,
 
     /* The input device has a battery */
-    BATTERY = 0x00004000,
+    BATTERY = android::os::IInputConstants::DEVICE_CLASS_BATTERY,
 
     /* The input device has sysfs controllable lights */
-    LIGHT = 0x00008000,
+    LIGHT = android::os::IInputConstants::DEVICE_CLASS_LIGHT,
 
     /* The input device is a touchpad, requiring an on-screen cursor. */
-    TOUCHPAD = 0x00010000,
+    TOUCHPAD = android::os::IInputConstants::DEVICE_CLASS_TOUCHPAD,
 
     /* The input device is virtual (not a real device, not part of UI configuration). */
-    VIRTUAL = 0x40000000,
+    VIRTUAL = android::os::IInputConstants::DEVICE_CLASS_VIRTUAL,
 
     /* The input device is external (not built-in). */
-    EXTERNAL = 0x80000000,
+    EXTERNAL = android::os::IInputConstants::DEVICE_CLASS_EXTERNAL,
 };
 
 enum class SysfsClass : uint32_t {
diff --git a/services/inputflinger/reader/include/InputDevice.h b/services/inputflinger/reader/include/InputDevice.h
index 4c9af2e..2a7e262 100644
--- a/services/inputflinger/reader/include/InputDevice.h
+++ b/services/inputflinger/reader/include/InputDevice.h
@@ -79,6 +79,8 @@
 
     inline bool isIgnored() { return !getMapperCount() && !mController; }
 
+    inline KeyboardType getKeyboardType() const { return mKeyboardType; }
+
     bool isEnabled();
 
     void dump(std::string& dump, const std::string& eventHubDevStr);
@@ -124,6 +126,8 @@
 
     void addKeyRemapping(int32_t fromKeyCode, int32_t toKeyCode);
 
+    void setKeyboardType(KeyboardType keyboardType);
+
     void bumpGeneration();
 
     [[nodiscard]] NotifyDeviceResetArgs notifyReset(nsecs_t when);
@@ -196,6 +200,7 @@
     uint32_t mSources;
     bool mIsWaking;
     bool mIsExternal;
+    KeyboardType mKeyboardType = KeyboardType::NONE;
     std::optional<uint8_t> mAssociatedDisplayPort;
     std::optional<std::string> mAssociatedDisplayUniqueIdByPort;
     std::optional<std::string> mAssociatedDisplayUniqueIdByDescriptor;
@@ -470,6 +475,10 @@
     }
     inline void bumpGeneration() { mDevice.bumpGeneration(); }
     inline const PropertyMap& getConfiguration() const { return mDevice.getConfiguration(); }
+    inline KeyboardType getKeyboardType() const { return mDevice.getKeyboardType(); }
+    inline void setKeyboardType(KeyboardType keyboardType) {
+        return mDevice.setKeyboardType(keyboardType);
+    }
 
 private:
     InputDevice& mDevice;
diff --git a/services/inputflinger/reader/include/InputReader.h b/services/inputflinger/reader/include/InputReader.h
index 7e701c5..6f8c289 100644
--- a/services/inputflinger/reader/include/InputReader.h
+++ b/services/inputflinger/reader/include/InputReader.h
@@ -157,6 +157,7 @@
         void setLastKeyDownTimestamp(nsecs_t when) REQUIRES(mReader->mLock)
                 REQUIRES(mLock) override;
         nsecs_t getLastKeyDownTimestamp() REQUIRES(mReader->mLock) REQUIRES(mLock) override;
+        KeyboardClassifier& getKeyboardClassifier() override;
     } mContext;
 
     friend class ContextImpl;
@@ -176,6 +177,10 @@
 
     // The next stage that should receive the events generated inside InputReader.
     InputListenerInterface& mNextListener;
+
+    // Classifier for keyboard/keyboard-like devices
+    std::unique_ptr<KeyboardClassifier> mKeyboardClassifier;
+
     // As various events are generated inside InputReader, they are stored inside this list. The
     // list can only be accessed with the lock, so the events inside it are well-ordered.
     // Once the reader is done working, these events will be swapped into a temporary storage and
diff --git a/services/inputflinger/reader/include/InputReaderContext.h b/services/inputflinger/reader/include/InputReaderContext.h
index 907a49f..e0e0ac2 100644
--- a/services/inputflinger/reader/include/InputReaderContext.h
+++ b/services/inputflinger/reader/include/InputReaderContext.h
@@ -17,6 +17,7 @@
 #pragma once
 
 #include <input/InputDevice.h>
+#include <input/KeyboardClassifier.h>
 #include "NotifyArgs.h"
 
 #include <vector>
@@ -64,6 +65,8 @@
 
     virtual void setLastKeyDownTimestamp(nsecs_t when) = 0;
     virtual nsecs_t getLastKeyDownTimestamp() = 0;
+
+    virtual KeyboardClassifier& getKeyboardClassifier() = 0;
 };
 
 } // namespace android