MegEngine/cmake/protobuf.cmake

function(PROTOBUF_GENERATE_CPP_WITH_ROOT SRCS HDRS ROOT_DIR)
    if(NOT ARGN)
        message(SEND_ERROR "Error: PROTOBUF_GENERATE_CPP_WITH_ROOT() called without any proto files")
        return()
    endif()

    set(${SRCS})
    set(${HDRS})
    foreach(FIL ${ARGN})
        set(ABS_FIL ${ROOT_DIR}/${FIL})
        get_filename_component(FIL_WE ${FIL} NAME_WE)
        get_filename_component(FIL_DIR ${ABS_FIL} PATH)
        file(RELATIVE_PATH REL_DIR ${ROOT_DIR} ${FIL_DIR})

        list(APPEND ${SRCS} "${CMAKE_CURRENT_BINARY_DIR}/${FIL_WE}.pb.cc")
        list(APPEND ${HDRS} "${CMAKE_CURRENT_BINARY_DIR}/${FIL_WE}.pb.h")

        add_custom_command(
            OUTPUT "${CMAKE_CURRENT_BINARY_DIR}/${FIL_WE}.pb.cc"
                   "${CMAKE_CURRENT_BINARY_DIR}/${FIL_WE}.pb.h"
            COMMAND ${PROTOBUF_PROTOC_EXECUTABLE}
            ARGS --cpp_out ${CMAKE_CURRENT_BINARY_DIR} -I ${FIL_DIR} ${ABS_FIL} -I ${PROTOBUF_INCLUDE_DIRS}
            DEPENDS ${ABS_FIL} libprotobuf
            COMMENT "Running C++ protocol buffer compiler on ${FIL}"
            VERBATIM)
    endforeach()

    set_source_files_properties(${${SRCS}} ${${HDRS}} PROPERTIES GENERATED TRUE)
    set(${SRCS} ${${SRCS}} PARENT_SCOPE)
    set(${HDRS} ${${HDRS}} PARENT_SCOPE)
endfunction()

if(MGE_USE_SYSTEM_LIB)
    find_package(Protobuf)
    if(Protobuf_FOUND)
        add_library(libprotobuf INTERFACE)
        target_link_libraries(libprotobuf INTERFACE ${Protobuf_LIBRARIES})
        target_include_directories(libprotobuf INTERFACE ${Protobuf_INCLUDE_DIRS})
        get_filename_component(Protobuf_ROOT ${Protobuf_INCLUDE_DIR} DIRECTORY)
        set(PROTOBUF_ROOT ${Protobuf_ROOT})
        set(PROTOBUF_PROTOC_EXECUTABLE ${Protobuf_PROTOC_EXECUTABLE})
        set(PROTOBUF_INCLUDE_DIRS ${Protobuf_INCLUDE_DIRS})
        return()
    endif()
endif()


include(ExternalProject)
include(GNUInstallDirs)

set(PROTOBUF_DIR "${PROJECT_SOURCE_DIR}/third_party/protobuf" CACHE STRING "protobuf directory")
set(PROTOBUF_BUILD_DIR ${PROJECT_BINARY_DIR}/third_party/protobuf)

if(${CMAKE_BUILD_TYPE} STREQUAL "Debug")
    set(PROTOBUF_LIB ${PROTOBUF_BUILD_DIR}/${CMAKE_INSTALL_LIBDIR}/libprotobufd.a)
else()
    set(PROTOBUF_LIB ${PROTOBUF_BUILD_DIR}/${CMAKE_INSTALL_LIBDIR}/libprotobuf.a)
endif()
set(PROTOBUF_PROTOC_EXECUTABLE ${PROTOBUF_BUILD_DIR}/bin/protoc)

ExternalProject_add(
    protobuf
    SOURCE_DIR ${PROTOBUF_DIR}/cmake
    PREFIX ${PROTOBUF_BUILD_DIR}
    CMAKE_ARGS -DCMAKE_C_COMPILER_LAUNCHER=${CMAKE_C_COMPILER_LAUNCHER} -DCMAKE_CXX_COMPILER_LAUNCHER=${CMAKE_CXX_COMPILER_LAUNCHER} -DCMAKE_BUILD_TYPE=${CMAKE_BUILD_TYPE} -DCMAKE_INSTALL_PREFIX=${PROTOBUF_BUILD_DIR} -Dprotobuf_BUILD_EXAMPLES=OFF -Dprotobuf_BUILD_TESTS=OFF -DBUILD_SHARED_LIBS=OFF -DCMAKE_POSITION_INDEPENDENT_CODE=ON
    BUILD_BYPRODUCTS ${PROTOBUF_LIB} ${PROTOBUF_PROTOC_EXECUTABLE}
)

set(PROTOBUF_INC ${PROTOBUF_BUILD_DIR}/include)
file(MAKE_DIRECTORY ${PROTOBUF_INC})

add_library(libprotobuf STATIC IMPORTED GLOBAL)
add_dependencies(libprotobuf protobuf)
set_target_properties(
    libprotobuf PROPERTIES
    IMPORTED_LOCATION ${PROTOBUF_LIB}
    INTERFACE_INCLUDE_DIRECTORIES ${PROTOBUF_BUILD_DIR}/include
)

add_executable(protoc IMPORTED GLOBAL)
add_dependencies(protoc protobuf)
set_target_properties(
    protoc PROPERTIES
    IMPORTED_LOCATION ${PROTOBUF_BUILD_DIR}/bin/protoc
)

set(PROTOBUF_ROOT ${PROTOBUF_BUILD_DIR})
set(PROTOBUF_PROTOC_EXECUTABLE protoc)
set(PROTOBUF_INCLUDE_DIRS ${PROTOBUF_BUILD_DIR}/include)