json/CMakeLists.txt
Axel Huebl f049836d68
CMake: Optional Install if Embedded
When adding this library as embedded library with private
"target link", e.g. only used inside private source files, the
library does not need to be installed when the main project gets
installed.

This adds an additional option `JSON_Install` similar to the
test-build control switch in order to skip installing headers and
CMake config files if requested.

Avoids using
```cmake
add_subdirectory(path/to/nlohmann_json EXCLUDE_FROM_ALL)
```

which has further side-effects:
https://cmake.org/cmake/help/v3.0/command/add_subdirectory.html
2018-11-02 10:18:00 +01:00

126 lines
3.9 KiB
CMake

cmake_minimum_required(VERSION 3.8)
##
## PROJECT
## name and version
##
project(nlohmann_json VERSION 3.4.0 LANGUAGES CXX)
##
## INCLUDE
##
##
include(ExternalProject)
##
## OPTIONS
##
option(JSON_BuildTests "Build the unit tests when BUILD_TESTING is enabled." ON)
option(JSON_Install "Install CMake targets during install step." ON)
option(JSON_MultipleHeaders "Use non-amalgamated version of the library." OFF)
##
## CONFIGURATION
##
set(NLOHMANN_JSON_TARGET_NAME ${PROJECT_NAME})
set(NLOHMANN_JSON_CONFIG_INSTALL_DIR "lib/cmake/${PROJECT_NAME}"
CACHE INTERNAL "")
set(NLOHMANN_JSON_INCLUDE_INSTALL_DIR "include")
set(NLOHMANN_JSON_TARGETS_EXPORT_NAME "${PROJECT_NAME}Targets")
set(NLOHMANN_JSON_CMAKE_CONFIG_TEMPLATE "cmake/config.cmake.in")
set(NLOHMANN_JSON_CMAKE_CONFIG_DIR "${CMAKE_CURRENT_BINARY_DIR}")
set(NLOHMANN_JSON_CMAKE_VERSION_CONFIG_FILE "${NLOHMANN_JSON_CMAKE_CONFIG_DIR}/${PROJECT_NAME}ConfigVersion.cmake")
set(NLOHMANN_JSON_CMAKE_PROJECT_CONFIG_FILE "${NLOHMANN_JSON_CMAKE_CONFIG_DIR}/${PROJECT_NAME}Config.cmake")
set(NLOHMANN_JSON_CMAKE_PROJECT_TARGETS_FILE "${NLOHMANN_JSON_CMAKE_CONFIG_DIR}/${PROJECT_NAME}Targets.cmake")
if (JSON_MultipleHeaders)
set(NLOHMANN_JSON_INCLUDE_BUILD_DIR "${PROJECT_SOURCE_DIR}/include/")
message(STATUS "Using the multi-header code from ${NLOHMANN_JSON_INCLUDE_BUILD_DIR}")
else()
set(NLOHMANN_JSON_INCLUDE_BUILD_DIR "${PROJECT_SOURCE_DIR}/single_include/")
message(STATUS "Using the single-header code from ${NLOHMANN_JSON_INCLUDE_BUILD_DIR}")
endif()
##
## TARGET
## create target and add include path
##
add_library(${NLOHMANN_JSON_TARGET_NAME} INTERFACE)
add_library(${PROJECT_NAME}::${NLOHMANN_JSON_TARGET_NAME} ALIAS ${NLOHMANN_JSON_TARGET_NAME})
target_compile_features(${NLOHMANN_JSON_TARGET_NAME} INTERFACE cxx_std_11)
target_include_directories(
${NLOHMANN_JSON_TARGET_NAME}
INTERFACE
$<BUILD_INTERFACE:${NLOHMANN_JSON_INCLUDE_BUILD_DIR}>
$<INSTALL_INTERFACE:include>
)
## add debug view definition file for msvc (natvis)
if (MSVC)
set(NLOHMANN_ADD_NATVIS TRUE)
set(NLOHMANN_NATVIS_FILE "nlohmann_json.natvis")
target_sources(
${NLOHMANN_JSON_TARGET_NAME}
INTERFACE
$<INSTALL_INTERFACE:${NLOHMANN_NATVIS_FILE}>
$<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/${NLOHMANN_NATVIS_FILE}>
)
endif()
##
## TESTS
## create and configure the unit test target
##
include(CTest) #adds option BUILD_TESTING (default ON)
if(BUILD_TESTING AND JSON_BuildTests)
enable_testing()
add_subdirectory(test)
endif()
##
## INSTALL
## install header files, generate and install cmake config files for find_package()
##
include(CMakePackageConfigHelpers)
write_basic_package_version_file(
${NLOHMANN_JSON_CMAKE_VERSION_CONFIG_FILE} COMPATIBILITY SameMajorVersion
)
configure_file(
${NLOHMANN_JSON_CMAKE_CONFIG_TEMPLATE}
${NLOHMANN_JSON_CMAKE_PROJECT_CONFIG_FILE}
@ONLY
)
if(JSON_Install)
install(
DIRECTORY ${NLOHMANN_JSON_INCLUDE_BUILD_DIR}
DESTINATION ${NLOHMANN_JSON_INCLUDE_INSTALL_DIR}
)
install(
FILES ${NLOHMANN_JSON_CMAKE_PROJECT_CONFIG_FILE} ${NLOHMANN_JSON_CMAKE_VERSION_CONFIG_FILE}
DESTINATION ${NLOHMANN_JSON_CONFIG_INSTALL_DIR}
)
if (NLOHMANN_ADD_NATVIS)
install(
FILES ${NLOHMANN_NATVIS_FILE}
DESTINATION .
)
endif()
export(
TARGETS ${NLOHMANN_JSON_TARGET_NAME}
NAMESPACE ${PROJECT_NAME}::
FILE ${NLOHMANN_JSON_CMAKE_PROJECT_TARGETS_FILE}
)
install(
TARGETS ${NLOHMANN_JSON_TARGET_NAME}
EXPORT ${NLOHMANN_JSON_TARGETS_EXPORT_NAME}
INCLUDES DESTINATION ${NLOHMANN_JSON_INCLUDE_INSTALL_DIR}
)
install(
EXPORT ${NLOHMANN_JSON_TARGETS_EXPORT_NAME}
NAMESPACE ${PROJECT_NAME}::
DESTINATION ${NLOHMANN_JSON_CONFIG_INSTALL_DIR}
)
endif()