FlatBuffer support

CMakeLists.txt

@@ -66,6 +66,13 @@ FetchContent_Declare(
 )
 FetchContent_MakeAvailable(sqlite3)
 
+FetchContent_Declare(FlatBuffers
+        GIT_REPOSITORY https://github.com/google/flatbuffers.git
+        GIT_TAG v25.2.10
+        GIT_SHALLOW ON
+)
+FetchContent_MakeAvailable(FlatBuffers)
+
 FetchContent_Declare(
         marvin
         GIT_REPOSITORY https://github.com/MeijisIrlnd/marvin.git
@@ -115,6 +122,7 @@ target_link_libraries(MostlyHarmless
         fmt::fmt-header-only
         nlohmann_json
         sqlite3::sqlite3
+        flatbuffers
         ${MOSTLY_HARMLESS_EXTRA_LIBS}
 )
 

cmake/mostly_harmless.cmake

@@ -108,9 +108,9 @@ function(mostly_harmless_add_plugin targetName)
             set(PLUGIN_NOTE_BUS_CONFIG "BusConfig::None")
         endif ()
     endif ()
-    if(NOT ${PLUGIN_NEEDS_AUDIO_OUT_BUS})
+    if (NOT ${PLUGIN_NEEDS_AUDIO_OUT_BUS})
         message(FATAL_ERROR "Plugins that don't support audio output are not supported yet!")
-    endif()
+    endif ()
     # AUDIO BUSSES
     if (${PLUGIN_NEEDS_AUDIO_IN_BUS})
         if (${PLUGIN_NEEDS_AUDIO_OUT_BUS})
@@ -258,3 +258,38 @@ function(mostly_harmless_add_plugin targetName)
         )
     endif ()
 endfunction()
+
+function(mostly_harmless_compile_flatbuffer_schemas)
+    set(SINGLE_VALUE_ARGS
+            "TARGET"
+            "INCLUDE_PREFIX"
+    )
+    set(MULTI_VALUE_ARGS
+            "SCHEMAS"
+            "LANGUAGES"
+    )
+    cmake_parse_arguments(ARG "" "${SINGLE_VALUE_ARGS}" "${MULTI_VALUE_ARGS}" ${ARGN})
+    if (NOT DEFINED ARG_TARGET)
+        message(FATAL_ERROR "A target is required!")
+    endif ()
+    if (NOT DEFINED ARG_INCLUDE_PREFIX)
+        message(FATAL_ERROR "An include prefix is required!")
+    endif ()
+    if (NOT DEFINED ARG_SCHEMAS)
+        message(FATAL_ERROR "At least one schema must be provided")
+    endif ()
+    if (NOT DEFINED ARG_LANGUAGES)
+        message(FATAL_ERROR "At least one language must be provided")
+    endif ()
+    foreach (language_string ${ARG_LANGUAGES})
+        set(LANGUAGE_FLAGS "${LANGUAGE_FLAGS}" "--${language_string}")
+    endforeach ()
+    set(FLAGS "${LANGUAGE_FLAGS}" "--gen-object-api")
+    flatbuffers_generate_headers(
+            TARGET ${ARG_TARGET}
+            INCLUDE_PREFIX ${ARG_INCLUDE_PREFIX}
+            SCHEMAS ${ARG_SCHEMAS}
+            BINARY_SCHEMAS_DIR ""
+            FLAGS ${FLAGS}
+    )
+endfunction()

docs/mostlyharmless_NamespaceDocs.h

@@ -46,6 +46,12 @@ namespace mostly_harmless {
         namespace directories {
 
         }
+        /**
+        \brief Serialisation and Deserialisation utils for FlatBuffers
+        */
+        namespace flat_buffers {
+
+        }
 
     }
     /**

include/mostly_harmless/CMakeLists.txt

@@ -26,6 +26,7 @@ set(MOSTLYHARMLESS_HEADERS
         ${CMAKE_CURRENT_SOURCE_DIR}/utils/mostlyharmless_OnScopeExit.h
         ${CMAKE_CURRENT_SOURCE_DIR}/utils/mostlyharmless_Proxy.h
         ${CMAKE_CURRENT_SOURCE_DIR}/utils/mostlyharmless_NoDenormals.h
+        ${CMAKE_CURRENT_SOURCE_DIR}/utils/mostlyharmless_FlatBuffers.h
         ${CMAKE_CURRENT_SOURCE_DIR}/data/mostlyharmless_DatabaseState.h
         ${CMAKE_CURRENT_SOURCE_DIR}/data/mostlyharmless_DatabasePropertyWatcher.h
         ${PLATFORM_HEADERS}

include/mostly_harmless/utils/mostlyharmless_FlatBuffers.h

@@ -0,0 +1,69 @@
+//
+// Created by Syl Morrison on 06/09/2025.
+//
+
+#ifndef MOSTLYHARMLESS_FLATBUFFERS_H
+#define MOSTLYHARMLESS_FLATBUFFERS_H
+#include <flatbuffers/flatbuffers.h>
+
+namespace mostly_harmless::utils::flat_buffers {
+    /**
+     * \brief Represents a flatbuffer autogenerated SomethingT type
+     **/
+    template<typename T>
+    concept FlatBufferType = std::is_base_of_v<flatbuffers::NativeTable, T>;
+
+
+    /**
+     * \brief Handles serialising or deserialising flat buffer data.
+     * Serialised data is tied to the lifecycle of a flatbuffer::FlatBufferBuilder - rather than requiring the user learn the ins and outs of the flatbuffer api,
+     * this class owns a FlatBufferBuilder.
+     * Subsequent calls to `serialise` will clear the builder's buffer, so if serialising multiple flat buffers in a loop, be sure to copy the serialised data into a
+     * concrete vector etc!
+     */
+    class Serialiser final {
+    public:
+        /**
+         * Constructor
+         * @param initialAllocSize The initial alloc size, to pass to the flatbuffer builder
+         */
+        explicit Serialiser(size_t initialAllocSize);
+
+        /**
+         * Given an autogenerated flatbuffer SomethingT type, serialises the data.
+         * As mentioned above, calling serialise will clear the internal builder's buffer, and the return value from this function's lifecycle is tied to that builder,
+         * so ensure you've done what you need to with the data before calling this function again!
+         * @tparam T An autogenerated flatbuffer YourTypeT type
+         * @param toSerialise The data you want to serialise
+         * @return A view into the resulting serialised buffer.
+         */
+        template<FlatBufferType T>
+        [[nodiscard]] std::span<std::uint8_t> serialise(T &toSerialise) {
+            using Underlying = typename T::TableType;
+            m_builder.Clear();
+            auto packed = Underlying::Pack(m_builder, &toSerialise);
+            m_builder.Finish(packed);
+            return {m_builder.GetBufferPointer(), m_builder.GetSize()};
+        }
+
+
+        /**
+         * Deserialises the given buffer into a flatbuffer autogenerated YourTypeT.
+         * In this case, the internal builder isn't used at all (hence being static), and the return value's lifecycle is tied to that of your input data.
+         * @tparam T A flatbuffer autogenerated YourTypeT
+         * @param toDeserialise A view into the data to deserialise
+         * @return A pointer to the resulting YourTypeT
+         */
+        template<FlatBufferType T>
+        [[nodiscard]] static T *deserialise(std::span<std::uint8_t> toDeserialise) {
+            using Underlying = typename T::TableType;
+            auto *root = flatbuffers::GetRoot<Underlying>(toDeserialise.data());
+            auto *res = root->UnPack();
+            return res;
+        }
+
+    private:
+        flatbuffers::FlatBufferBuilder m_builder;
+    };
+}
+#endif //MOSTLYHARMLESS_FLATBUFFERS_H

source/CMakeLists.txt

@@ -32,6 +32,7 @@ set(MOSTLYHARMLESS_SOURCES
         ${CMAKE_CURRENT_SOURCE_DIR}/utils/mostlyharmless_NoDenormals.cpp
         ${CMAKE_CURRENT_SOURCE_DIR}/utils/mostlyharmless_Hash.cpp
         ${CMAKE_CURRENT_SOURCE_DIR}/utils/mostlyharmless_Macros.cpp
+        ${CMAKE_CURRENT_SOURCE_DIR}/utils/mostlyharmless_FlatBuffers.cpp
         ${CMAKE_CURRENT_SOURCE_DIR}/data/mostlyharmless_DatabaseState.cpp
         ${CMAKE_CURRENT_SOURCE_DIR}/data/mostlyharmless_DatabasePropertyWatcher.cpp
         ${PLATFORM_SOURCES}

source/utils/mostlyharmless_FlatBuffers.cpp

@@ -0,0 +1,13 @@
+//
+// Created by Syl Morrison on 06/09/2025.
+//
+#include <mostly_harmless/utils/mostlyharmless_FlatBuffers.h>
+
+namespace mostly_harmless::utils::flat_buffers {
+    Serialiser::Serialiser(size_t initialAllocSize) : m_builder(initialAllocSize) {
+
+    }
+
+
+
+}