[cpp]: update CMate and CMakefiles to allow FetchContent

cpp/CMakeLists.txt

@@ -1,40 +1,144 @@
+###
+#
+# Project
+# name and version
+#
+###
 cmake_minimum_required(VERSION 3.12 FATAL_ERROR)
 
 project(cucumber_messages VERSION 0.1.0 LANGUAGES C CXX)
 
+###
+#
+# Main project check
+#
+###
+set(cucumber_messages_MAIN_PROJECT OFF)
+
+if (CMAKE_CURRENT_SOURCE_DIR STREQUAL CMAKE_SOURCE_DIR)
+    set(cucumber_messages_MAIN_PROJECT ON)
+endif()
+
+###
+#
+# Options
+#
+###
+if(${CUCUMBER_MESSAGES_MAIN_PROJECT})
+    set(CUCUMBER_MESSAGES_BUILD_TESTS_INIT ON)
+    set(CUCUMBER_MESSAGES_EXPORT_COMPILE_INIT ON)
+else()
+    set(CUCUMBER_MESSAGES_BUILD_TESTS_INIT OFF)
+    set(CUCUMBER_MESSAGES_EXPORT_COMPILE_INIT OFF)
+endif()
+
+option(
+    CUCUMBER_MESSAGES_BUILD_TESTS
+    "Build the unit tests."
+    ${CUCUMBER_MESSAGES_BUILD_TESTS_INIT}
+)
+
+option(
+    CUCUMBER_MESSAGES_EXPORT_COMPILE
+    "Export compile commands."
+    ${CUCUMBER_MESSAGES_EXPORT_COMPILE_INIT}
+)
+
+option(
+    CUCUMBER_MESSAGES_FETCH_DEPS
+    "Fetch dependencies via FetchContent."
+    ${CUCUMBER_MESSAGES_FETCH_DEPS}
+)
+
+###
+#
+# Configuration
+#
+###
 include(GNUInstallDirs)
 
-set(CMAKE_CXX_STANDARD 20)
-set(CMAKE_CXX_STANDARD_REQUIRED ON)
-set(CMAKE_CXX_EXTENSIONS OFF)
-set(CMAKE_POSITION_INDEPENDENT_CODE ON)
+if (CMAKE_CXX_COMPILER_ID STREQUAL "MSVC")
+    add_compile_definitions(_CRT_SECURE_NO_WARNINGS _SCL_SECURE_NO_WARNINGS)
+endif()
+
+if(CUCUMBER_MESSAGES_EXPORT_COMPILE)
+    set(CMAKE_EXPORT_COMPILE_COMMANDS ON)
+endif()
+
+###
+#
+# CMake dependencies
+#
+###
+if(CUCUMBER_MESSAGES_FETCH_DEPS)
+    include(FetchContent)
+
+    FetchContent_Declare(
+        nlohmann_json
+        GIT_REPOSITORY https://github.com/nlohmann/json.git
+        GIT_TAG v3.11.3
+        OVERRIDE_FIND_PACKAGE
+    )
+
+    set(JSON_BuildTests "OFF")
+    set(JSON_Install "ON")
 
-if(WIN32)
-  add_definitions(-DUNICODE -D_UNICODE -DSTRICT -DNOMINMAX)
-  add_definitions(-D_CRT_SECURE_NO_WARNINGS -D_SCL_SECURE_NO_WARNINGS)
+    FetchContent_MakeAvailable(nlohmann_json)
 endif()
 
 find_package(nlohmann_json CONFIG REQUIRED)
 
+###
+#
+# Targets
+#
+###
 add_subdirectory(src/lib/messages)
 
+###
+#
+# Installation support
+#
+###
+include(CMakePackageConfigHelpers)
+
+configure_package_config_file(
+  "cmake/cucumber_messages-config.cmake.in"
+  "${PROJECT_BINARY_DIR}/cucumber_messages-config.cmake"
+  INSTALL_DESTINATION "${CMAKE_INSTALL_LIBDIR}/cmake/cucumber_messages"
+  PATH_VARS CMAKE_INSTALL_INCLUDEDIR CMAKE_INSTALL_LIBDIR
+)
+
+write_basic_package_version_file(
+  "${PROJECT_BINARY_DIR}/cucumber_messages-config-version.cmake"
+  COMPATIBILITY AnyNewerVersion
+)
+
 install(
     TARGETS
         cucumber_messages_lib
-    EXPORT cucumber_messages-config
+    EXPORT cucumber_messages-targets
     RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR}
     LIBRARY DESTINATION ${CMAKE_INSTALL_LIBDIR}
     ARCHIVE DESTINATION ${CMAKE_INSTALL_LIBDIR}
 )
 
 install(
-    EXPORT cucumber_messages-config
-    FILE cucumber_messages-config.cmake
+    EXPORT cucumber_messages-targets
+    FILE cucumber_messages-targets.cmake
     NAMESPACE cucumber::
-    DESTINATION ${CMAKE_INSTALL_LIBDIR}/cmake/cucumber_messages
+    DESTINATION "${CMAKE_INSTALL_LIBDIR}/cmake/cucumber_messages"
+)
+
+install(
+    FILES
+        "${PROJECT_BINARY_DIR}/cucumber_messages-config.cmake"
+        "${PROJECT_BINARY_DIR}/cucumber_messages-config-version.cmake"
+    DESTINATION "${CMAKE_INSTALL_LIBDIR}/cmake/cucumber_messages"
 )
 
+
 install(
-    DIRECTORY "${PROJECT_SOURCE_DIR}/include/messages/"
+    DIRECTORY "${PROJECT_SOURCE_DIR}/include/messages"
     DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}/cucumber
 )