feat: reorganize CMake configuration and add third-party library setup for Asio and EnTT

Signed-off-by: szdytom <szdytom@qq.com>

CMakeLists.txt

@@ -1,9 +1,11 @@
 cmake_minimum_required(VERSION 3.27)
 project(instructed LANGUAGES CXX)
 
-# Set C++ standard
+# Optionally build examples
-set(CMAKE_CXX_STANDARD 23)
+option(BUILD_EXAMPLES "Build example programs" ON)
-set(CMAKE_CXX_STANDARD_REQUIRED ON)
+
+# Load third-party libraries
+add_subdirectory(third_party)
 
 # Add tilemap library and examples
 add_subdirectory(tilemap)

third_party/CMakeLists.txt

@@ -0,0 +1,11 @@
+cmake_minimum_required(VERSION 3.27)
+
+set(ISTD_THIRD_PARTY_LIBS
+    entt
+    asio
+)
+
+foreach(lib IN LISTS ISTD_THIRD_PARTY_LIBS)
+    include(${CMAKE_CURRENT_LIST_DIR}/${lib}.cmake)
+endforeach()
+

third_party/asio.cmake

@@ -0,0 +1,12 @@
+cmake_minimum_required(VERSION 3.27)
+cmake_policy(VERSION 3.27)
+include(FetchContent)
+
+message(STATUS "Downloading Asio(Standalone)...")
+# Asio (Standalone) third-party library setup
+FetchContent_Declare(
+	asio
+	URL "https://github.com/chriskohlhoff/asio/archive/refs/tags/asio-1-34-2.zip"
+)
+FetchContent_MakeAvailable(asio)
+message(STATUS "Asio ready")

third_party/entt.cmake

@@ -0,0 +1,12 @@
+cmake_minimum_required(VERSION 3.27)
+cmake_policy(VERSION 3.27)
+include(FetchContent)
+
+# EnTT third-party library setup
+message(STATUS "Downloading EnTT...")
+FetchContent_Declare(
+	EnTT
+	URL "https://github.com/skypjack/entt/archive/refs/tags/v3.15.0.zip"
+)
+FetchContent_MakeAvailable(EnTT)
+message(STATUS "EnTT ready")

tilemap/CMakeLists.txt

@@ -26,8 +26,6 @@ add_library(istd_tilemap ${ISTD_TILEMAP_SRC})
 target_compile_features(istd_tilemap PUBLIC cxx_std_23)
 target_include_directories(istd_tilemap PUBLIC include)
 
-# Optionally build examples
-option(BUILD_EXAMPLES "Build example programs" ON)
 if(BUILD_EXAMPLES)
 	add_subdirectory(examples)
 endif()