CMakeLists.txt

cmake_minimum_required(VERSION 3.1)

##
## OPTIONS
##
option(BUILD_UNIT_TESTS "Build the unit tests" ON)

##
## HUNTER
##
option(HUNTER_ENABLED "Use hunter to manage dependencies" OFF)
if(HUNTER_ENABLED)
    include("cmake/HunterGate.cmake")
    HunterGate(
        URL "https://github.com/ruslo/hunter/archive/v0.19.156.tar.gz"
        SHA1 "8d5e4635b137365e0d1ade4d60accf4e2bb41f0d"
    )
endif()

##
## PROJECT
## name and version
##
project(inja LANGUAGES CXX VERSION 1.0.0)
set(INJA_VERSION ${PROJECT_VERSION})

##
## CONFIGURATION
##
# set(CMAKE_CXX_COMPILER g++-7)
set(CMAKE_CXX_STANDARD 11)
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wall")
set(INJA_SOURCE_DIR src)
set(INJA_HEADER_INSTALL_DIR include)

if(WIN32 AND MSVC AND MSVC_VERSION LESS 1900)
    message(FATAL_ERROR "[${PROJECT_NAME}] Visual Studio versions prior to 2015 do not support the noexcept keyword, which is used in the JSON library.")
endif()

##
## TESTS
## create and configure the unit test target
##
if(BUILD_UNIT_TESTS)
  enable_testing()
  add_subdirectory(test)
endif()

##
## TARGETS
## Build targets for the interface library
##
add_library(inja INTERFACE)
target_include_directories(inja INTERFACE
    $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/${INJA_SOURCE_DIR}>
    $<INSTALL_INTERFACE:${INJA_HEADER_INSTALL_DIR}>
)
if(HUNTER_ENABLED) # Use Hunter to manage dependencies
    # Add JSON package
    hunter_add_package(nlohmann_json)
    find_package(nlohmann_json CONFIG REQUIRED)
    # Add dependencies to target
    target_link_libraries(inja INTERFACE nlohmann_json)
else()
    target_include_directories(inja INTERFACE
        $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/test/thirdparty>
        $<INSTALL_INTERFACE:${INJA_HEADER_INSTALL_DIR}>
    )
endif()

##
## INSTALL
## install header files, generate and install cmake config files for find_package()
##
set(include_install_dir ${INJA_HEADER_INSTALL_DIR})
set(config_install_dir "lib/cmake/${PROJECT_NAME}")
set(generated_dir "${CMAKE_CURRENT_BINARY_DIR}/generated")
set(version_config "${generated_dir}/${PROJECT_NAME}ConfigVersion.cmake")
set(project_config "${generated_dir}/${PROJECT_NAME}Config.cmake")
set(TARGETS_EXPORT_NAME "${PROJECT_NAME}Targets")
set(namespace "${PROJECT_NAME}::")
include(CMakePackageConfigHelpers)

# Use:
#   * PROJECT_VERSION
write_basic_package_version_file(
    "${version_config}" COMPATIBILITY SameMajorVersion
)

# Use:
#   * TARGETS_EXPORT_NAME
#   * PROJECT_NAME
configure_package_config_file(
    "cmake/Config.cmake.in"
    "${project_config}"
    INSTALL_DESTINATION "${config_install_dir}"
)

install(
    TARGETS inja
    EXPORT "${TARGETS_EXPORT_NAME}"
    LIBRARY DESTINATION "lib"
    ARCHIVE DESTINATION "lib"
    RUNTIME DESTINATION "bin"
    INCLUDES DESTINATION "${include_install_dir}"
)

install(
    FILES ${INJA_SOURCE_DIR}/inja.hpp
    DESTINATION "${include_install_dir}"
)

install(
    FILES "${project_config}" "${version_config}"
    DESTINATION "${config_install_dir}"
)

install(
    EXPORT "${TARGETS_EXPORT_NAME}"
    NAMESPACE "${namespace}"
    DESTINATION "${config_install_dir}"
)