Build Mmap.hh even if memory mapping is disabled

Build flag `ZK_ENABLE_MMAP` no longer excludes relevant header and implementation files from build
 -> Users of ZenKit can now use Mmap.hh by themselves even if `ZK_ENABLE_MMAP` is `OFF`

Author: Katharsas

CMakeLists.txt

@@ -10,7 +10,7 @@ option(ZK_BUILD_SHARED "ZenKit: Build a shared library." OFF)
 option(ZK_ENABLE_ASAN "ZenKit: Enable sanitizers in debug builds." ON)
 option(ZK_ENABLE_DEPRECATION "ZenKit: Enable deprecation warnings." ON)
 option(ZK_ENABLE_INSTALL "ZenKit: Enable CMake install target creation." ON)
-option(ZK_ENABLE_MMAP "ZenKit: Build ZenKit with memory-mapping support." ON)
+option(ZK_ENABLE_MMAP "ZenKit: Build ZenKit with memory-mapping if supported by platform." ON)
 option(ZK_ENABLE_FUTURE "ZenKit: Enable breaking changes to be release in a future version" OFF)
 
 add_subdirectory(vendor)
@@ -118,18 +118,28 @@ bs_select_cflags(${ZK_ENABLE_ASAN} _ZK_COMPILE_FLAGS _ZK_LINK_FLAGS)
 bs_check_posix_mmap(_ZK_HAS_MMAP_POSIX)
 bs_check_win32_mmap(_ZK_HAS_MMAP_WIN32)
 
-if (ZK_ENABLE_MMAP AND (_ZK_HAS_MMAP_POSIX OR _ZK_HAS_MMAP_WIN32))
-    if (_ZK_HAS_MMAP_POSIX)
-        message(STATUS "ZenKit: Building with POSIX memory mapping support")
-        list(APPEND _ZK_SOURCES src/MmapPosix.cc)
-        target_compile_definitions(zenkit PUBLIC _ZK_WITH_MMAP=1)
-    elseif (_ZK_HAS_MMAP_WIN32)
-        message(STATUS "ZenKit: Building with Windows memory mapping support")
-        list(APPEND _ZK_SOURCES src/MmapWin32.cc)
+if (_ZK_HAS_MMAP_POSIX OR _ZK_HAS_MMAP_WIN32)
+    target_compile_definitions(zenkit PUBLIC _ZK_MMAP_AVAILABLE=1)
+    if (ZK_ENABLE_MMAP)
+        message(STATUS "ZenKit: Memory mapping enabled")
         target_compile_definitions(zenkit PUBLIC _ZK_WITH_MMAP=1)
+    else ()
+        message(STATUS "ZenKit: Memory mapping disabled")
     endif ()
 else ()
-    message(WARNING "ZenKit: Building WITHOUT memory mapping support")
+    if (ZK_ENABLE_MMAP)
+        message(WARNING "ZenKit: Memory mapping enabled but not supported!")
+    else ()
+        message(STATUS "ZenKit: Memory mapping not supported")
+    endif ()
+endif ()
+
+if (_ZK_HAS_MMAP_POSIX)
+    message(STATUS "ZenKit: Building with POSIX memory mapping support")
+    list(APPEND _ZK_SOURCES src/MmapPosix.cc)
+elseif (_ZK_HAS_MMAP_WIN32)
+    message(STATUS "ZenKit: Building with Windows memory mapping support")
+    list(APPEND _ZK_SOURCES src/MmapWin32.cc)
 endif ()
 
 target_sources(zenkit PRIVATE ${_ZK_SOURCES} ${_ZK_HEADERS})

include/zenkit/Mmap.hh

@@ -4,7 +4,7 @@
 #include <filesystem>
 
 namespace zenkit {
-#ifdef _ZK_WITH_MMAP
+#ifdef _ZK_MMAP_AVAILABLE
 	class Mmap {
 	public:
 		explicit Mmap(std::filesystem::path const& path);