Refactor code to use abstract classes and PIMPL (#370)

* Refactor code to use abstract classes and PIMPL

This paves the way towards having multiple implementations at runtime. It also centralized
the defintions of the "base" or "implementation" classes (such as AdapterBase, PeripheralBase) so
that by explicitly deriving from these ABCs the interfaces of each implemetations are correct.

The public interface for "frontend" classes (the ones used by the library user) are unchanged. The main
differences are:

- They now include an "internal_" shared pointer (the PIMPL)
- Some logic is implemented in the frontend (i.e. checking that a peripheral is connected before
  invoking read_inner, write_inner, etc).
- The logic to detect if the instance is initialized is centralized into a private "operator->()"
- The "safe" classes no longer inherit from the non safe ones. They are castable, though, so most code
  should continue working unmodified.

An additional concept, with the associated classes is introduced, the "Backend". For the time being
this is not exposed in the public API. The idea is that all static methods in the Adapter will be moved
to the Backend as non-static methods and the Backend frontend class will have a static get_backends().
Note that in many cases having a "BackendIMPL.h" header is unncecessary and thus ommited.

* fixup! address review comments.

* fixup! actually add the changes to the commit doh!

* fixup! fixup2

simpleble/CMakeLists.txt

@@ -46,6 +46,7 @@ set(SIMPLEBLE_SRC
     ${CMAKE_CURRENT_SOURCE_DIR}/src/frontends/base/Service.cpp
     ${CMAKE_CURRENT_SOURCE_DIR}/src/frontends/base/Characteristic.cpp
     ${CMAKE_CURRENT_SOURCE_DIR}/src/frontends/base/Descriptor.cpp
+    ${CMAKE_CURRENT_SOURCE_DIR}/src/frontends/base/Backend.cpp
 
     ${CMAKE_CURRENT_SOURCE_DIR}/src/backends/common/ServiceBase.cpp
     ${CMAKE_CURRENT_SOURCE_DIR}/src/backends/common/CharacteristicBase.cpp
@@ -143,7 +144,7 @@ endif()
 list(APPEND PRIVATE_COMPILE_DEFINITIONS SIMPLEBLE_LOG_LEVEL=SIMPLEBLE_LOG_LEVEL_${SIMPLEBLE_LOG_LEVEL})
 list(APPEND PRIVATE_COMPILE_DEFINITIONS SIMPLEBLE_VERSION="${PROJECT_VERSION}")
 
-if(NOT SIMPLEBLE_TEST)
+if(NOT SIMPLEBLE_TEST AND NOT SIMPLEBLE_PLAIN)
     if(CMAKE_SYSTEM_NAME STREQUAL "Linux")
         set(SIMPLEBLE_BACKEND_LINUX ON)
     else()
@@ -186,7 +187,8 @@ if(SIMPLEBLE_PLAIN)
 
     target_sources(simpleble PRIVATE
         ${CMAKE_CURRENT_SOURCE_DIR}/src/backends/plain/AdapterPlain.cpp
-        ${CMAKE_CURRENT_SOURCE_DIR}/src/backends/plain/PeripheralPlain.cpp)
+        ${CMAKE_CURRENT_SOURCE_DIR}/src/backends/plain/PeripheralPlain.cpp
+        ${CMAKE_CURRENT_SOURCE_DIR}/src/backends/plain/BackendPlain.cpp)
 elseif(SIMPLEBLE_BACKEND_LINUX)
     message(STATUS "Linux Host Detected")
 
@@ -282,11 +284,10 @@ elseif(SIMPLEBLE_BACKEND_WINDOWS)
         list(APPEND PRIVATE_COMPILE_OPTIONS "/W1")
     endif()
 
-    target_include_directories(simpleble PRIVATE
-        ${CMAKE_CURRENT_SOURCE_DIR}/src/backends/windows)
     target_sources(simpleble PRIVATE
         ${CMAKE_CURRENT_SOURCE_DIR}/src/backends/windows/AdapterWindows.cpp
         ${CMAKE_CURRENT_SOURCE_DIR}/src/backends/windows/PeripheralWindows.cpp
+        ${CMAKE_CURRENT_SOURCE_DIR}/src/backends/windows/BackendWinRT.cpp
         ${CMAKE_CURRENT_SOURCE_DIR}/src/backends/windows/Utils.cpp)
 
 elseif(SIMPLEBLE_BACKEND_MACOS)
@@ -295,14 +296,13 @@ elseif(SIMPLEBLE_BACKEND_MACOS)
     list(APPEND PRIVATE_COMPILE_OPTIONS -fobjc-arc)
 
     target_link_libraries(simpleble PUBLIC "-framework Foundation" "-framework CoreBluetooth" ObjC)
-    target_include_directories(simpleble PRIVATE
-        ${CMAKE_CURRENT_SOURCE_DIR}/src/backends/macos)
     target_sources(simpleble PRIVATE
         ${CMAKE_CURRENT_SOURCE_DIR}/src/backends/macos/Utils.mm
         ${CMAKE_CURRENT_SOURCE_DIR}/src/backends/macos/AdapterMac.mm
         ${CMAKE_CURRENT_SOURCE_DIR}/src/backends/macos/AdapterBaseMacOS.mm
         ${CMAKE_CURRENT_SOURCE_DIR}/src/backends/macos/PeripheralMac.mm
-        ${CMAKE_CURRENT_SOURCE_DIR}/src/backends/macos/PeripheralBaseMacOS.mm)
+        ${CMAKE_CURRENT_SOURCE_DIR}/src/backends/macos/PeripheralBaseMacOS.mm
+        ${CMAKE_CURRENT_SOURCE_DIR}/src/backends/macos/BackendCoreBluetooth.mm)
 
     set_property(TARGET simpleble PROPERTY INSTALL_RPATH @loader_path)
     set_property(TARGET simpleble-c PROPERTY INSTALL_RPATH @loader_path)
@@ -319,11 +319,10 @@ elseif(SIMPLEBLE_BACKEND_ANDROID)
 
     # Specify the source files for the Android backend
     # NOTE: These files have been commented out and replaced by the PLAIN version in order to develop the Android wrapper code.
-    target_include_directories(simpleble PRIVATE
-        ${CMAKE_CURRENT_SOURCE_DIR}/src/backends/android)
     target_sources(simpleble PRIVATE
         ${CMAKE_CURRENT_SOURCE_DIR}/src/backends/android/AdapterAndroid.cpp
         ${CMAKE_CURRENT_SOURCE_DIR}/src/backends/android/PeripheralAndroid.cpp
+        ${CMAKE_CURRENT_SOURCE_DIR}/src/backends/android/BackendAndroid.cpp
         ${CMAKE_CURRENT_SOURCE_DIR}/src/backends/android/android/BluetoothDevice.cpp
         ${CMAKE_CURRENT_SOURCE_DIR}/src/backends/android/android/BluetoothGatt.cpp
         ${CMAKE_CURRENT_SOURCE_DIR}/src/backends/android/android/BluetoothGattService.cpp
@@ -335,9 +334,6 @@ elseif(SIMPLEBLE_BACKEND_ANDROID)
         ${CMAKE_CURRENT_SOURCE_DIR}/src/backends/android/bridge/ScanCallback.cpp
     )
 
-    target_include_directories(simpleble PRIVATE
-        ${CMAKE_CURRENT_SOURCE_DIR}/src/backends/plain)
-
     target_link_libraries(simpleble PUBLIC
         android
         nativehelper

simpleble/include/simpleble/Adapter.h

@@ -15,12 +15,30 @@ namespace SimpleBLE {
 
 class AdapterBase;
 
+/**
+ * Bluetooth Adapter.
+ *
+ * A default-constructed Adapter object is not initialized. Calling any method
+ * other than `initialized()` on an uninitialized Adapter will throw an exception
+ * of type `SimpleBLE::NotInitialized`.
+ *
+ * NOTE: This class is intended to be used by the user only. Library developers
+ * should use shared pointers to `AdapterBase` instead.
+ */
 class SIMPLEBLE_EXPORT Adapter {
   public:
     Adapter() = default;
     virtual ~Adapter() = default;
 
     bool initialized() const;
+
+    /**
+     * Retrieve the underlying OS object/handle.
+     *
+     * For certain compatibility with external libraries, we sometimes need to
+     * expose the actual OS handle to the user. This is particularly important
+     * for MacOS right now.
+     */
     void* underlying() const;
 
     std::string identifier();
@@ -42,11 +60,17 @@ class SIMPLEBLE_EXPORT Adapter {
     static bool bluetooth_enabled();
 
     /**
-     *  Fetches a list of all available adapters.
+     * Fetches a list of all available adapters from all available backends.
+     *
+     * This will cause backends to be instantiated/initialized and adapters
+     * too.
      */
     static std::vector<Adapter> get_adapters();
 
   protected:
+    AdapterBase* operator->();
+    const AdapterBase* operator->() const;
+
     std::shared_ptr<AdapterBase> internal_;
 };
 

simpleble/include/simpleble/AdapterSafe.h

@@ -4,14 +4,25 @@
 
 #include <simpleble/Adapter.h>
 #include <simpleble/PeripheralSafe.h>
+#include <memory>
+#include <optional>
+#include <vector>
 
 namespace SimpleBLE {
 
 namespace Safe {
 
-class SIMPLEBLE_EXPORT Adapter : public SimpleBLE::Adapter {
+/**
+ * Wrapper around the Adapter class that provides a noexcept interface.
+ *
+ * We use instances of this class directly and not through shared_ptr because
+ * this is just a wrapper around the Adapter class, which is already managed by
+ * shared_ptr.
+ */
+class SIMPLEBLE_EXPORT Adapter {
   public:
     Adapter(SimpleBLE::Adapter& adapter);
+    Adapter(SimpleBLE::Adapter&& adapter);
     virtual ~Adapter() = default;
 
     std::optional<std::string> identifier() noexcept;
@@ -32,6 +43,14 @@ class SIMPLEBLE_EXPORT Adapter : public SimpleBLE::Adapter {
 
     static std::optional<bool> bluetooth_enabled() noexcept;
     static std::optional<std::vector<SimpleBLE::Safe::Adapter>> get_adapters() noexcept;
+
+    /**
+     * Cast to the underlying adapter object.
+     */
+    operator SimpleBLE::Adapter() const noexcept;
+
+  protected:
+    SimpleBLE::Adapter internal_;
 };
 
 }  // namespace Safe

simpleble/include/simpleble/Characteristic.h

@@ -17,6 +17,8 @@ class SIMPLEBLE_EXPORT Characteristic {
     Characteristic() = default;
     virtual ~Characteristic() = default;
 
+    bool initialized() const;
+
     BluetoothUUID uuid();
     std::vector<Descriptor> descriptors();
     std::vector<std::string> capabilities();
@@ -28,6 +30,9 @@ class SIMPLEBLE_EXPORT Characteristic {
     bool can_indicate();
 
   protected:
+    CharacteristicBase *operator->();
+    const CharacteristicBase *operator->() const;
+
     std::shared_ptr<CharacteristicBase> internal_;
 };
 

simpleble/include/simpleble/Descriptor.h

@@ -16,9 +16,14 @@ class SIMPLEBLE_EXPORT Descriptor {
     Descriptor() = default;
     virtual ~Descriptor() = default;
 
+    bool initialized() const;
+
     BluetoothUUID uuid();
 
   protected:
+    DescriptorBase* operator->();
+    const DescriptorBase* operator->() const;
+
     std::shared_ptr<DescriptorBase> internal_;
 };
 

simpleble/include/simpleble/Peripheral.h

@@ -55,6 +55,8 @@ class SIMPLEBLE_EXPORT Peripheral {
     std::vector<Service> services();
     std::map<uint16_t, ByteArray> manufacturer_data();
 
+    /* Calling any of the methods below when the device is not connected will throw
+       Exception::NotConnected */
     // clang-format off
     ByteArray read(BluetoothUUID const& service, BluetoothUUID const& characteristic);
     void write_request(BluetoothUUID const& service, BluetoothUUID const& characteristic, ByteArray const& data);
@@ -71,6 +73,9 @@ class SIMPLEBLE_EXPORT Peripheral {
     void set_callback_on_disconnected(std::function<void()> on_disconnected);
 
   protected:
+    PeripheralBase* operator->();
+    const PeripheralBase* operator->() const;
+
     std::shared_ptr<PeripheralBase> internal_;
 };
 

simpleble/include/simpleble/PeripheralSafe.h

@@ -1,5 +1,6 @@
 #pragma once
 
+#include <memory>
 #include <optional>
 
 #include <simpleble/export.h>
@@ -11,9 +12,10 @@ namespace SimpleBLE {
 
 namespace Safe {
 
-class SIMPLEBLE_EXPORT Peripheral : public SimpleBLE::Peripheral {
+class SIMPLEBLE_EXPORT Peripheral {
   public:
     Peripheral(SimpleBLE::Peripheral& peripheral);
+    Peripheral(SimpleBLE::Peripheral&& peripheral);
     virtual ~Peripheral() = default;
 
     std::optional<std::string> identifier() noexcept;
@@ -47,6 +49,14 @@ class SIMPLEBLE_EXPORT Peripheral : public SimpleBLE::Peripheral {
 
     bool set_callback_on_connected(std::function<void()> on_connected) noexcept;
     bool set_callback_on_disconnected(std::function<void()> on_disconnected) noexcept;
+
+    /**
+     * Get the underlying peripheral object.
+     */
+    operator SimpleBLE::Peripheral() const noexcept;
+
+  protected:
+    SimpleBLE::Peripheral internal_;
 };
 
 }  // namespace Safe

simpleble/include/simpleble/Service.h

@@ -18,11 +18,16 @@ class SIMPLEBLE_EXPORT Service {
     Service() = default;
     virtual ~Service() = default;
 
+    bool initialized() const;
+
     BluetoothUUID uuid();
     ByteArray data();
     std::vector<Characteristic> characteristics();
 
   protected:
+    const ServiceBase* operator->() const;
+    ServiceBase* operator->();
+
     std::shared_ptr<ServiceBase> internal_;
 };
 

simpleble/src/CommonUtils.h

@@ -1,5 +1,8 @@
 #pragma once
 
+#include <algorithm>
+#include <vector>
+
 #include "LoggingInternal.h"
 
 #define SAFE_CALLBACK_CALL(cb, ...)                                                           \
@@ -50,4 +53,9 @@ auto values(const MAP& map) {
     return ValueCollector<MAP>{map};
 }
 
-}  // namespace SimpleBLE::util
+}  // namespace SimpleBLE::Util
+
+namespace SimpleBLE {
+template <typename T>
+using SharedPtrVector = std::vector<std::shared_ptr<T>>;
+}