Cmake多级目录编译

以下面的C++程序多级目录为例：

根目录的CMakelists.txt示例代码如下所示：

cmake_minimum_required(VERSION 3.0.0)
project(cppjson VERSION 0.1.0)

# The default include directory
include_directories(./)

# home directory source
aux_source_directory(. ROOT_SOURCE)

# sub directory source
add_subdirectory(json)

# build executable file
add_executable(main ${ROOT_SOURCE} ${PARSER_SRC})

子目录的CMakelists.txt示例代码如下所示：

# sub directory source
aux_source_directory(${CMAKE_CURRENT_SOURCE_DIR} PARSER_SRC)
set(PARSER_SRC ${PARSER_SRC} PARENT_SCOPE)