build: modularize CMake configuration

CMakeLists.txt

@@ -1,59 +1,48 @@
-cmake_minimum_required(VERSION 3.20)
+cmake_minimum_required(VERSION 3.21)
+
 project(
 	cpp_request
+	VERSION 0.9.0
 	DESCRIPTION "A lightweight synchronous C++17 HTTP/1.1 client built on native sockets"
-	VERSION 0.1.0
-	LANGUAGES CXX C
+	LANGUAGES CXX
 )
 
-set(CMAKE_CXX_STANDARD 17)
-set(CMAKE_CXX_STANDARD_REQUIRED ON)
-set(CMAKE_CXX_EXTENSIONS OFF)
-set(CMAKE_EXPORT_COMPILE_COMMANDS ON)
+list(APPEND CMAKE_MODULE_PATH "${PROJECT_SOURCE_DIR}/cmake/modules")
 
-option(CPP_REQUEST_BUILD_BENCHMARKS "Build cpp_request benchmarks" OFF)
+include(options)
+cpp_request_setup_options()
 
-include(CTest)
-include(GNUInstallDirs)
-include(CMakePackageConfigHelpers)
-include(cmake/modules/output.cmake)
-include(cmake/modules/warning.cmake)
-include(cmake/modules/sanitizing.cmake)
-include(cmake/modules/optimizing.cmake)
+include(project-settings)
+cpp_request_setup_project()
 
 add_subdirectory(src)
-if(BUILD_TESTING)
+
+if(CPP_REQUEST_BUILD_TESTS)
+	include(testing)
 	add_subdirectory(tests)
 endif()
+
 if(CPP_REQUEST_BUILD_BENCHMARKS)
+	include(benchmarking)
 	add_subdirectory(benchmarks)
 endif()
-add_subdirectory(examples)
 
-set(CPP_REQUEST_INSTALL_CMAKEDIR "${CMAKE_INSTALL_LIBDIR}/cmake/cpp_request")
-
-configure_package_config_file(
-	${CMAKE_CURRENT_SOURCE_DIR}/cmake/cpp_requestConfig.cmake.in
-	${CMAKE_CURRENT_BINARY_DIR}/cpp_requestConfig.cmake
-	INSTALL_DESTINATION ${CPP_REQUEST_INSTALL_CMAKEDIR}
-)
+if(CPP_REQUEST_BUILD_EXAMPLES)
+	include(examples)
+	add_subdirectory(examples)
+endif()
 
-write_basic_package_version_file(
-	${CMAKE_CURRENT_BINARY_DIR}/cpp_requestConfigVersion.cmake
-	VERSION ${PROJECT_VERSION}
-	COMPATIBILITY SameMinorVersion
-)
+if(CPP_REQUEST_ENABLE_INSTALL)
+	include(install)
+	cpp_request_configure_install()
+endif()
 
-install(
-	EXPORT cpp_requestTargets
-	FILE cpp_requestTargets.cmake
-	NAMESPACE cpp_request::
-	DESTINATION ${CPP_REQUEST_INSTALL_CMAKEDIR}
-)
+if(PROJECT_IS_TOP_LEVEL AND CPP_REQUEST_ENABLE_CLANG_FORMAT)
+	include("${PROJECT_SOURCE_DIR}/cmake/tools/clang-format.cmake")
+	cpp_request_add_clang_format_targets()
+endif()
 
-install(
-	FILES
-		${CMAKE_CURRENT_BINARY_DIR}/cpp_requestConfig.cmake
-		${CMAKE_CURRENT_BINARY_DIR}/cpp_requestConfigVersion.cmake
-	DESTINATION ${CPP_REQUEST_INSTALL_CMAKEDIR}
-)
+if(PROJECT_IS_TOP_LEVEL AND CPP_REQUEST_ENABLE_DOXYGEN)
+	include("${PROJECT_SOURCE_DIR}/cmake/tools/doxygen.cmake")
+	cpp_request_add_doxygen_target(cpp_request_docs)
+endif()

benchmarks/CMakeLists.txt

@@ -1,26 +1,3 @@
-include(${PROJECT_SOURCE_DIR}/cmake/packages/google-benchmark.cmake)
-find_package(Threads REQUIRED)
-
-function(cpp_request_add_benchmark target source)
-	add_executable(${target} ${source})
-	target_include_directories(${target}
-		PRIVATE
-			${PROJECT_SOURCE_DIR}/src
-			${CMAKE_CURRENT_SOURCE_DIR}
-	)
-	target_link_libraries(${target}
-		PRIVATE
-			cpp_request::internal
-			benchmark::benchmark_main
-			Threads::Threads
-	)
-	target_compile_features(${target} PRIVATE cxx_std_17)
-
-	if(WIN32)
-		target_link_libraries(${target} PRIVATE ws2_32)
-	endif()
-endfunction()
-
 cpp_request_add_benchmark(
 	cpp_request_bench_request_serializer
 	request_serializer_benchmark.cpp

cmake/README.md

@@ -0,0 +1,27 @@
+# CMake structure
+
+`cpp_request` keeps the root `CMakeLists.txt` as an orchestrator. Project behavior is split by responsibility:
+
+- `modules/` — project options, target policy, tests, benchmarks, examples, and install/export rules.
+- `packages/` — development-only third-party discovery with `find_package()` first and `FetchContent` fallback.
+- `tools/` — optional developer tooling such as clang-format, clang-tidy, and Doxygen.
+- `templates/` — inputs for files generated into the build/install tree.
+
+Normal CMake configure must not modify files in the source tree. In particular, `vcpkg.json` is source-controlled input and is not generated by CMake.
+
+## Main options
+
+- `CPP_REQUEST_BUILD_TESTS`
+- `CPP_REQUEST_BUILD_BENCHMARKS`
+- `CPP_REQUEST_BUILD_EXAMPLES`
+- `CPP_REQUEST_ENABLE_INSTALL`
+- `CPP_REQUEST_ENABLE_WARNINGS`
+- `CPP_REQUEST_WARNINGS_AS_ERRORS`
+- `CPP_REQUEST_ENABLE_SANITIZERS`
+- `CPP_REQUEST_ENABLE_IPO`
+- `CPP_REQUEST_ENABLE_NATIVE_OPTIMIZATION`
+- `CPP_REQUEST_ENABLE_CLANG_TIDY`
+- `CPP_REQUEST_ENABLE_CLANG_FORMAT`
+- `CPP_REQUEST_ENABLE_DOXYGEN`
+
+Tests, examples, and install rules default on only when `cpp_request` is the top-level project. Benchmarks and developer tools are opt-in. For compatibility with conventional CMake callers, an explicitly supplied `BUILD_TESTING` value is used as the default for `CPP_REQUEST_BUILD_TESTS`.

cmake/modules/benchmarking.cmake

@@ -1,10 +1,28 @@
-include(${CMAKE_SOURCE_DIR}/cmake/packages/google-benchmark.cmake)
-
-function(add_benchmark_target name)
-	add_executable(${name} ${ARGN})
-	target_link_libraries(${name} 
-		PRIVATE 
+include_guard(GLOBAL)
+
+include("${PROJECT_SOURCE_DIR}/cmake/packages/google-benchmark.cmake")
+find_package(Threads REQUIRED)
+
+function(cpp_request_add_benchmark target source)
+	add_executable(${target} ${source})
+
+	target_include_directories(${target}
+		PRIVATE
+			${PROJECT_SOURCE_DIR}/src
+			${PROJECT_SOURCE_DIR}/benchmarks
+	)
+
+	target_link_libraries(${target}
+		PRIVATE
+			cpp_request::cpp_request
 			benchmark::benchmark_main
-			${PROJECT_NAME}::internal
+			Threads::Threads
 	)
-endfunction()
+
+	if(WIN32)
+		target_link_libraries(${target} PRIVATE ws2_32)
+	endif()
+
+	target_compile_features(${target} PRIVATE cxx_std_17)
+	cpp_request_configure_target(${target})
+endfunction()

cmake/modules/examples.cmake

@@ -0,0 +1,8 @@
+include_guard(GLOBAL)
+
+function(cpp_request_add_example target source)
+	add_executable(${target} ${source})
+	target_link_libraries(${target} PRIVATE cpp_request::cpp_request)
+	target_compile_features(${target} PRIVATE cxx_std_17)
+	cpp_request_configure_target(${target})
+endfunction()

cmake/modules/install.cmake

@@ -0,0 +1,51 @@
+include_guard(GLOBAL)
+
+include(CMakePackageConfigHelpers)
+
+function(cpp_request_configure_install)
+	set(
+		CPP_REQUEST_INSTALL_CMAKEDIR
+		"${CMAKE_INSTALL_LIBDIR}/cmake/cpp_request"
+	)
+
+	configure_package_config_file(
+		"${PROJECT_SOURCE_DIR}/cmake/templates/cpp_requestConfig.cmake.in"
+		"${PROJECT_BINARY_DIR}/cpp_requestConfig.cmake"
+		INSTALL_DESTINATION "${CPP_REQUEST_INSTALL_CMAKEDIR}"
+	)
+
+	write_basic_package_version_file(
+		"${PROJECT_BINARY_DIR}/cpp_requestConfigVersion.cmake"
+		VERSION "${PROJECT_VERSION}"
+		COMPATIBILITY SameMinorVersion
+	)
+
+	install(
+		TARGETS cpp_request
+		EXPORT cpp_requestTargets
+		ARCHIVE DESTINATION "${CMAKE_INSTALL_LIBDIR}"
+		LIBRARY DESTINATION "${CMAKE_INSTALL_LIBDIR}"
+		RUNTIME DESTINATION "${CMAKE_INSTALL_BINDIR}"
+		INCLUDES DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}"
+	)
+
+	install(
+		DIRECTORY "${PROJECT_SOURCE_DIR}/include/cpp_request"
+		DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}"
+		FILES_MATCHING PATTERN "*.hpp"
+	)
+
+	install(
+		EXPORT cpp_requestTargets
+		FILE cpp_requestTargets.cmake
+		NAMESPACE cpp_request::
+		DESTINATION "${CPP_REQUEST_INSTALL_CMAKEDIR}"
+	)
+
+	install(
+		FILES
+			"${PROJECT_BINARY_DIR}/cpp_requestConfig.cmake"
+			"${PROJECT_BINARY_DIR}/cpp_requestConfigVersion.cmake"
+		DESTINATION "${CPP_REQUEST_INSTALL_CMAKEDIR}"
+	)
+endfunction()

cmake/modules/optimizations.cmake

@@ -0,0 +1,30 @@
+include_guard(GLOBAL)
+
+function(cpp_request_apply_optimizations target)
+	if(CPP_REQUEST_ENABLE_NATIVE_OPTIMIZATION)
+		if(CMAKE_CXX_COMPILER_ID MATCHES "Clang|GNU")
+			target_compile_options(${target}
+				PRIVATE
+					$<$<CONFIG:Release>:-march=native>
+					$<$<CONFIG:Release>:-mtune=native>
+			)
+		else()
+			message(WARNING
+				"CPP_REQUEST_ENABLE_NATIVE_OPTIMIZATION currently supports Clang and GCC only"
+			)
+		endif()
+	endif()
+
+	if(CPP_REQUEST_ENABLE_IPO)
+		include(CheckIPOSupported)
+		check_ipo_supported(RESULT _cpp_request_ipo_supported OUTPUT _cpp_request_ipo_error)
+		if(_cpp_request_ipo_supported)
+			set_property(
+				TARGET ${target}
+				PROPERTY INTERPROCEDURAL_OPTIMIZATION_RELEASE TRUE
+			)
+		else()
+			message(WARNING "IPO is unavailable: ${_cpp_request_ipo_error}")
+		endif()
+	endif()
+endfunction()

cmake/modules/options.cmake

@@ -0,0 +1,44 @@
+include_guard(GLOBAL)
+
+function(cpp_request_setup_options)
+	set(_cpp_request_top_level_default OFF)
+	if(PROJECT_IS_TOP_LEVEL)
+		set(_cpp_request_top_level_default ON)
+	endif()
+
+	set(_cpp_request_test_default ${_cpp_request_top_level_default})
+	if(DEFINED BUILD_TESTING)
+		set(_cpp_request_test_default ${BUILD_TESTING})
+	endif()
+
+	option(
+		CPP_REQUEST_BUILD_TESTS
+		"Build cpp_request tests"
+		${_cpp_request_test_default}
+	)
+	option(
+		CPP_REQUEST_BUILD_BENCHMARKS
+		"Build cpp_request benchmarks"
+		OFF
+	)
+	option(
+		CPP_REQUEST_BUILD_EXAMPLES
+		"Build cpp_request examples"
+		${_cpp_request_top_level_default}
+	)
+	option(
+		CPP_REQUEST_ENABLE_INSTALL
+		"Enable cpp_request install and package export rules"
+		${_cpp_request_top_level_default}
+	)
+
+	option(CPP_REQUEST_ENABLE_WARNINGS "Enable compiler warnings" ON)
+	option(CPP_REQUEST_WARNINGS_AS_ERRORS "Treat compiler warnings as errors" OFF)
+	option(CPP_REQUEST_ENABLE_SANITIZERS "Enable AddressSanitizer and UndefinedBehaviorSanitizer" OFF)
+	option(CPP_REQUEST_ENABLE_IPO "Enable interprocedural optimization for Release builds" OFF)
+	option(CPP_REQUEST_ENABLE_NATIVE_OPTIMIZATION "Enable host-specific optimization for local Release builds" OFF)
+
+	option(CPP_REQUEST_ENABLE_CLANG_TIDY "Enable clang-tidy for cpp_request targets" OFF)
+	option(CPP_REQUEST_ENABLE_CLANG_FORMAT "Add clang-format helper targets" OFF)
+	option(CPP_REQUEST_ENABLE_DOXYGEN "Add the Doxygen documentation target" OFF)
+endfunction()