CMake 秘籍(四)(4)https://developer.aliyun.com/article/1525216
准备就绪
文件树结构与前两个配方非常相似。我们用 Fortran 源代码替换了 C++,在这种情况下,我们没有头文件:
. ├── CMakeLists.txt ├── external │ ├── CMakeLists.txt │ ├── conversion.f90 │ └── README.md ├── src │ ├── CMakeLists.txt │ ├── evolution │ │ ├── ancestors.f90 │ │ ├── CMakeLists.txt │ │ ├── empty.f90 │ │ └── evolution.f90 │ ├── initial │ │ ├── CMakeLists.txt │ │ └── initial.f90 │ ├── io │ │ ├── CMakeLists.txt │ │ └── io.f90 │ ├── main.f90 │ └── parser │ ├── CMakeLists.txt │ └── parser.f90 └── tests ├── CMakeLists.txt └── test.f90
主程序在src/main.f90
中:
program example use parser, only: get_arg_as_int use conversion, only: binary_representation use initial, only: initial_distribution use io, only: print_row use evolution, only: evolve implicit none integer :: num_steps integer :: length integer :: rule_decimal integer :: rule_binary(8) integer, allocatable :: row(:) integer :: step ! parse arguments num_steps = get_arg_as_int(1) length = get_arg_as_int(2) rule_decimal = get_arg_as_int(3) ! print information about parameters print *, "number of steps: ", num_steps print *, "length: ", length print *, "rule: ", rule_decimal ! obtain binary representation for the rule rule_binary = binary_representation(rule_decimal) ! create initial distribution allocate(row(length)) call initial_distribution(row) ! print initial configuration call print_row(row) ! the system evolves, print each step do step = 1, num_steps call evolve(row, rule_binary) call print_row(row) end do deallocate(row) end program
与之前的配方一样,我们将conversion
模块放在external/conversion.f90
中:
module conversion implicit none public binary_representation private contains pure function binary_representation(n_decimal) integer, intent(in) :: n_decimal integer :: binary_representation(8) integer :: pos integer :: n binary_representation = 0 pos = 8 n = n_decimal do while (n > 0) binary_representation(pos) = mod(n, 2) n = (n - binary_representation(pos))/2 pos = pos - 1 end do end function end module
evolution
库,它实现了时间步长,被人工分为三个文件。大部分内容收集在src/evolution/evolution.f90
:
module evolution implicit none public evolve private contains subroutine not_visible() ! no-op call to demonstrate private/public visibility call empty_subroutine_no_interface() end subroutine pure subroutine evolve(row, rule_binary) use ancestors, only: compute_ancestors integer, intent(inout) :: row(:) integer, intent(in) :: rule_binary(8) integer :: i integer :: left, center, right integer :: ancestry integer, allocatable :: new_row(:) allocate(new_row(size(row))) do i = 1, size(row) left = i - 1 center = i right = i + 1 if (left < 1) left = left + size(row) if (right > size(row)) right = right - size(row) ancestry = compute_ancestors(row, left, center, right) new_row(i) = rule_binary(ancestry) end do row = new_row deallocate(new_row) end subroutine end module
祖先的计算在src/evolution/ancestors.f90
中执行:
module ancestors implicit none public compute_ancestors private contains pure integer function compute_ancestors(row, left, center, right) result(i) integer, intent(in) :: row(:) integer, intent(in) :: left, center, right i = 4*row(left) + 2*row(center) + 1*row(right) i = 8 - i end function end module
我们还在src/evolution/empty.f90
中有一个“空”模块:
module empty implicit none public empty_subroutine private contains subroutine empty_subroutine() end subroutine end module subroutine empty_subroutine_no_interface() use empty, only: empty_subroutine call empty_subroutine() end subroutine
我们将在下一节解释这些选择。
起始条件的代码位于src/initial/initial.f90
:
module initial implicit none public initial_distribution private contains pure subroutine initial_distribution(row) integer, intent(out) :: row(:) row = 0 row(size(row)/2) = 1 end subroutine end module
src/io/io.f90
文件包含一个打印行的函数:
module io implicit none public print_row private contains subroutine print_row(row) integer, intent(in) :: row(:) character(size(row)) :: line integer :: i do i = 1, size(row) if (row(i) == 1) then line(i:i) = '*' else line(i:i) = ' ' end if end do print *, line end subroutine end module
src/parser/parser.f90
文件解析命令行参数:
module parser implicit none public get_arg_as_int private contains integer function get_arg_as_int(n) result(i) integer, intent(in) :: n character(len=32) :: arg call get_command_argument(n, arg) read(arg , *) i end function end module
最后,我们有测试源文件在tests/test.f90
:
program test use evolution, only: evolve implicit none integer :: row(9) integer :: expected_result(9) integer :: rule_binary(8) integer :: i ! test rule 90 row = (/0, 1, 0, 1, 0, 1, 0, 1, 0/) rule_binary = (/0, 1, 0, 1, 1, 0, 1, 0/) call evolve(row, rule_binary) expected_result = (/1, 0, 0, 0, 0, 0, 0, 0, 1/) do i = 1, 9 if (row(i) /= expected_result(i)) then print *, 'ERROR: test for rule 90 failed' call exit(1) end if end do ! test rule 222 row = (/0, 0, 0, 0, 1, 0, 0, 0, 0/) rule_binary = (/1, 1, 0, 1, 1, 1, 1, 0/) call evolve(row, rule_binary) expected_result = (/0, 0, 0, 1, 1, 1, 0, 0, 0/) do i = 1, 9 if (row(i) /= expected_result(i)) then print *, 'ERROR: test for rule 222 failed' call exit(1) end if end do end program
如何做到这一点
我们现在将讨论相应的 CMake 结构:
- 顶层的
CMakeLists.txt
与第 7 个配方类似;我们只将CXX
替换为Fortran
并删除 C++11 要求:
cmake_minimum_required(VERSION 3.5 FATAL_ERROR) project(recipe-09 LANGUAGES Fortran) include(GNUInstallDirs) set(CMAKE_ARCHIVE_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/${CMAKE_INSTALL_LIBDIR}) set(CMAKE_LIBRARY_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/${CMAKE_INSTALL_LIBDIR}) set(CMAKE_RUNTIME_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/${CMAKE_INSTALL_BINDIR}) # defines targets and sources add_subdirectory(src) # contains an "external" library we will link to add_subdirectory(external) # enable testing and define tests enable_testing() add_subdirectory(tests)
- 目标和源文件在
src/CMakeLists.txt
中定义(除了conversion
目标):
add_executable(automata main.f90) add_subdirectory(evolution) add_subdirectory(initial) add_subdirectory(io) add_subdirectory(parser) target_link_libraries(automata PRIVATE conversion evolution initial io parser )
转换
库在external/CMakeLists.txt
中定义:
add_library(conversion "") target_sources(conversion PUBLIC ${CMAKE_CURRENT_LIST_DIR}/conversion.f90 )
src/CMakeLists.txt
文件添加了进一步的子目录,这些子目录又包含CMakeLists.txt
文件。它们的结构都类似;例如,src/initial/CMakeLists.txt
包含以下内容:
add_library(initial "") target_sources(initial PUBLIC ${CMAKE_CURRENT_LIST_DIR}/initial.f90 )
- 例外是
src/evolution/CMakeLists.txt
中的evolution
库,我们将其分为三个源文件:
add_library(evolution "") target_sources(evolution PRIVATE empty.f90 PUBLIC ${CMAKE_CURRENT_LIST_DIR}/ancestors.f90 ${CMAKE_CURRENT_LIST_DIR}/evolution.f90 )
- 单元测试在
tests/CMakeLists.txt
中注册:
add_executable(fortran_test test.f90) target_link_libraries(fortran_test evolution) add_test( NAME test_evolution COMMAND $<TARGET_FILE:fortran_test> )
- 配置和构建项目会产生以下输出:
$ mkdir -p build $ cd build $ cmake .. $ cmake --build . Scanning dependencies of target conversion [ 4%] Building Fortran object external/CMakeFiles/conversion.dir/conversion.f90.o [ 8%] Linking Fortran static library ../lib64/libconversion.a [ 8%] Built target conversion Scanning dependencies of target evolution [ 12%] Building Fortran object src/evolution/CMakeFiles/evolution.dir/ancestors.f90.o [ 16%] Building Fortran object src/evolution/CMakeFiles/evolution.dir/empty.f90.o [ 20%] Building Fortran object src/evolution/CMakeFiles/evolution.dir/evolution.f90.o [ 25%] Linking Fortran static library ../../lib64/libevolution.a [ 25%] Built target evolution Scanning dependencies of target initial [ 29%] Building Fortran object src/initial/CMakeFiles/initial.dir/initial.f90.o [ 33%] Linking Fortran static library ../../lib64/libinitial.a [ 33%] Built target initial Scanning dependencies of target io [ 37%] Building Fortran object src/io/CMakeFiles/io.dir/io.f90.o [ 41%] Linking Fortran static library ../../lib64/libio.a [ 41%] Built target io Scanning dependencies of target parser [ 45%] Building Fortran object src/parser/CMakeFiles/parser.dir/parser.f90.o [ 50%] Linking Fortran static library ../../lib64/libparser.a [ 50%] Built target parser Scanning dependencies of target example [ 54%] Building Fortran object src/CMakeFiles/example.dir/__/external/conversion.f90.o [ 58%] Building Fortran object src/CMakeFiles/example.dir/evolution/ancestors.f90.o [ 62%] Building Fortran object src/CMakeFiles/example.dir/evolution/evolution.f90.o [ 66%] Building Fortran object src/CMakeFiles/example.dir/initial/initial.f90.o [ 70%] Building Fortran object src/CMakeFiles/example.dir/io/io.f90.o [ 75%] Building Fortran object src/CMakeFiles/example.dir/parser/parser.f90.o [ 79%] Building Fortran object src/CMakeFiles/example.dir/main.f90.o [ 83%] Linking Fortran executable ../bin/example [ 83%] Built target example Scanning dependencies of target fortran_test [ 87%] Building Fortran object tests/CMakeFiles/fortran_test.dir/__/src/evolution/ancestors.f90.o [ 91%] Building Fortran object tests/CMakeFiles/fortran_test.dir/__/src/evolution/evolution.f90.o [ 95%] Building Fortran object tests/CMakeFiles/fortran_test.dir/test.f90.o [100%] Linking Fortran executable
- 最后,我们运行单元测试:
$ ctest Running tests... Start 1: test_evolution 1/1 Test #1: test_evolution ................... Passed 0.00 sec 100% tests passed, 0 tests failed out of 1
它是如何工作的
按照第 7 个配方,使用add_subdirectory
限制范围,我们将从下至上讨论 CMake 结构,从定义每个库的单独CMakeLists.txt
文件开始,例如src/evolution/CMakeLists.txt
:
add_library(evolution "") target_sources(evolution PRIVATE
empty.f90 PUBLIC ${CMAKE_CURRENT_LIST_DIR}/ancestors.f90 ${CMAKE_CURRENT_LIST_DIR}/evolution.f90 )
这些单独的CMakeLists.txt
文件尽可能接近源文件定义库,遵循与前两个配方相同的推理:了解此库的代码开发人员,可能对 CMake 框架的了解有限,只需要编辑此目录中的文件:分而治之。
我们首先使用add_library
定义库的名称,然后定义其源文件和包含目录,以及它们的目标可见性。在这种情况下,ancestors.f90
和evolution.f90
都是PUBLIC
,因为它们的模块接口被库外部访问,而empty.f90
的模块接口没有被库外部访问,因此我们将此源文件标记为PRIVATE
。
向上移动一级,库在src/CMakeLists.txt
中组装:
add_executable(automata main.f90) add_subdirectory(evolution) add_subdirectory(initial) add_subdirectory(io) add_subdirectory(parser) target_link_libraries(automata PRIVATE conversion evolution initial io parser )
反过来,此文件在顶层的CMakeLists.txt
中被引用。这意味着我们使用CMakeLists.txt
文件的树构建了我们的项目库树,使用add_subdirectory
添加。如第 7 个配方,使用add_subdirectory
限制范围所述,这种方法可以扩展到大型项目,无需在目录之间携带源文件列表的全局变量,并且具有隔离作用域和命名空间的额外好处。
将此 Fortran 示例与 C++版本(配方 7)进行比较,我们可以注意到,在 Fortran 情况下,我们不得不做的 CMake 工作较少;我们不需要使用target_include_directories
,因为没有头文件,接口是通过生成的 Fortran 模块文件进行通信的。此外,我们也不必担心源文件在target_sources
中列出的顺序,也不必在库之间施加任何显式依赖关系!CMake 能够从源文件依赖关系中推断出 Fortran 模块依赖关系。结合使用target_sources
与PRIVATE
和PUBLIC
,我们可以以紧凑且稳健的方式表达接口。
还有更多内容。
在本配方中,我们没有指定 Fortran 模块文件应放置的目录,并保持了这种透明性。可以通过设置CMAKE_Fortran_MODULE_DIRECTORY
CMake 变量来指定模块文件的位置。请注意,也可以将其设置为目标属性,即Fortran_MODULE_DIRECTORY
,从而实现更精细的控制。请参阅cmake.org/cmake/help/v3.5/prop_tgt/Fortran_MODULE_DIRECTORY.html
。