Adding FetchContent for everest-cmake (#85)

* Added fetch_content for everest-cmake. If no everest-cmake is found, everest-cmake will be download via fetch_content
* Updating README.md: One sentence to everest-cmake and fetch content and adding one block describing which dependencies should be installed

Signed-off-by: Sebastian Lukas <sebastian.lukas@pionix.de>

Author: SebaLukas

CMakeLists.txt

@@ -6,12 +6,25 @@ project(iso15118
 	LANGUAGES CXX C
 )
 
-find_package(everest-cmake 0.1 REQUIRED
+find_package(everest-cmake 0.5
     PATHS ../everest-cmake
 )
 
 find_package(OpenSSL 3 REQUIRED)
 
+if (NOT everest-cmake_FOUND)
+    message(STATUS "Retrieving everest-cmake using FetchContent")
+    include(FetchContent)
+    FetchContent_Declare(
+        everest-cmake
+        GIT_REPOSITORY https://github.com/EVerest/everest-cmake.git
+        GIT_TAG        v0.5.0
+    )
+    FetchContent_MakeAvailable(everest-cmake)
+    set(everest-cmake_DIR "${everest-cmake_SOURCE_DIR}")
+    include("${everest-cmake_SOURCE_DIR}/everest-cmake-config.cmake")
+endif()
+
 # options
 option(${PROJECT_NAME}_BUILD_TESTING "Build unit tests, used if included as dependency" OFF)
 option(BUILD_TESTING "Build unit tests, used if standalone project" OFF)

README.md

@@ -46,7 +46,23 @@ ISO15118 support is distributed accross multiple repositories and modules in EVe
 Dependencies
 ------------
 
-To build this library you need [everest-cmake](https://github.com/EVerest/everest-cmake) checkout in the same directory as libiso15118.
+To build this library you need [everest-cmake](https://github.com/EVerest/everest-cmake) checkout in the same directory as libiso15118. If no `everest-cmake` is available, it is retrieved via FetchContent.
+
+For Debian GNU/Linux 12 you will need the following dependencies:
+
+```bash
+sudo apt update
+sudo apt install build-essential cmake libssl-dev
+```
+
+For Fedora 41+ you will need the following dependencies:
+
+```bash
+sudo dnf update
+sudo dnf install gcc gcc-c++ git make cmake openssl-devel 
+```
+
+OpenSSL version 3.0 or above is required. The build system `ninja` is optional. 
 
 Getting started
 ---------------