CMakeLists.txt

cmake_minimum_required(VERSION 3.11)
# 3.11 minimum (FetchContent), 3.14 preferred

project(cmake_sandbox LANGUAGES CXX)

# Only do these if this is the main project, 
# and not if it is included through add_subdirectory.
if(CMAKE_PROJECT_NAME STREQUAL PROJECT_NAME)
  # Testing only available if this is the main app
  # Note this needs to be done in the main CMakeLists since it calls
  # enable_testing, which must be in the main CMakeLists.
  include(CTest)

  # CCache
  find_program(CCACHE_PROGRAM ccache)
  if(CCACHE_PROGRAM)
      set(CMAKE_CXX_COMPILER_LAUNCHER "${CCACHE_PROGRAM}")
      set(CMAKE_CUDA_COMPILER_LAUNCHER "${CCACHE_PROGRAM}") # CMake 3.9+
  endif()

  # Nicely support folders in IDEs
  # set_property(GLOBAL PROPERTY USE_FOLDERS ON)
endif()

# If this is the main project, set default build type to Debug. 
# Otherwise use Release.
set(default_build_type "Release")
if(CMAKE_PROJECT_NAME STREQUAL PROJECT_NAME)
  set(default_build_type "Debug")
endif()
if(NOT CMAKE_BUILD_TYPE AND NOT CMAKE_CONFIGURATION_TYPES)
  message(STATUS "Setting build type to '${default_build_type}' as none was specified.")
  set(CMAKE_BUILD_TYPE "${default_build_type}" CACHE
      STRING "Choose the type of build." FORCE)
  # Retain possible values of build type for cmake-gui.
  set_property(CACHE CMAKE_BUILD_TYPE PROPERTY STRINGS
    "Debug" "Release" "MinSizeRel" "RelWithDebInfo")
endif()

# Add this project's cmake modules to the CMAKE_MODULE_PATH
list(APPEND CMAKE_MODULE_PATH "${CMAKE_CURRENT_LIST_DIR}/cmake")

# Using FindEigen3.cmake in cmake/ folder
find_package(Eigen3 3.3 REQUIRED)

# FetchContent
include(FetchContent)
# FetchContent_MakeAvailable macro (included in CMake 3.14)
if(${CMAKE_VERSION} VERSION_LESS 3.14)
  macro(FetchContent_MakeAvailable NAME)
    FetchContent_GetProperties(${NAME})
    if(NOT ${NAME}_POPULATED)
      FetchContent_Populate(${NAME})
      add_subdirectory(${${NAME}_SOURCE_DIR} ${${NAME}_BINARY_DIR})
    endif()
  endmacro()
endif()

# Compiled library code is here.
add_subdirectory(src)

# Executable code is here.
add_subdirectory(examples)

# Test code is only built if this is the main project.
if(CMAKE_PROJECT_NAME STREQUAL PROJECT_NAME AND BUILD_TESTING)
  add_subdirectory(tests)
endif()