build: Use external submodule for pre-Catalina filesystem support.

Grab the submodule, pass -DENABLE_FILESYSTEM_COMPAT:bool=on.

Only really valid for macOS 10.13 and 10.14, which both lack native
support for C++17 std::filesystem.

Fixes #156.

.gitmodules

@@ -0,0 +1,3 @@
+[submodule "filesystem"]
+	path = filesystem
+	url = https://github.com/gulrak/filesystem

CMakeLists.txt

@@ -46,6 +46,7 @@ if(NOT HEADERS_ONLY)
 
   option(ENABLE_PLUGINS "Build set of default external plugins" ON)
   option(ENABLE_INTEL_SIMD "Enable SIMD intrinsics for Intel processors" ON)
+  option(ENABLE_FILESYSTEM_COMPAT "Use compatibility shim for C++17 filesystem" OFF)
 
   if(CMAKE_CONFIGURATION_TYPES)
     set(CMAKE_CONFIGURATION_TYPES Debug Release RelWithDebInfo)
@@ -211,6 +212,9 @@ if(NOT HEADERS_ONLY)
   if(ENABLE_PLUGINS)
     add_subdirectory("plugins")
   endif()
+  if(ENABLE_FILESYSTEM_COMPAT)
+    add_subdirectory("filesystem")
+  endif()
 
 else()
 

avs_core/CMakeLists.txt

@@ -92,6 +92,11 @@ if (CMAKE_COMPILER_IS_GNUCXX AND CMAKE_CXX_COMPILER_VERSION VERSION_LESS 9)
     set(FSLIB "stdc++fs")
 endif()
 
+if (ENABLE_FILESYSTEM_COMPAT)
+    set(FSLIB "ghc_filesystem")
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -DFILESYSTEM_COMPAT")
+endif()
+
 # Windows DLL dependencies
 if (MSVC OR MINGW)
   target_link_libraries("AvsCore" "uuid" "winmm" "vfw32" "msacm32" "gdi32" "user32" "advapi32" "ole32" "imagehlp")

avs_core/core/PluginManager.cpp

@@ -5,10 +5,18 @@
 #include "strings.h"
 #include "InternalEnvironment.h"
 #include <cassert>
-#include <filesystem>
 #include "function.h"
 
+#ifndef FILESYSTEM_COMPAT
+#include <filesystem>
+
 namespace fs = std::filesystem;
+#else
+#include <ghc/filesystem.hpp>
+
+namespace fs = ghc::filesystem;
+#endif // FILESYSTEM_COMPAT
+
 #ifdef AVS_WINDOWS
   #include <avs/win.h>
 #else
@@ -628,7 +636,11 @@ void PluginManager::AutoloadPlugins()
 #else
     const char* binaryFilter = ".dll";
 #endif
+#ifndef FILESYSTEM_COMPAT
     for (auto& file : fs::directory_iterator(dir, std::filesystem::directory_options::skip_permission_denied | std::filesystem::directory_options::follow_directory_symlink, ec))
+#else
+    for (auto& file : fs::directory_iterator(dir, ghc::filesystem::directory_options::skip_permission_denied | ghc::filesystem::directory_options::follow_directory_symlink, ec))
+#endif
     {
       const bool extensionsMatch =
 #ifdef AVS_POSIX
@@ -663,7 +675,11 @@ void PluginManager::AutoloadPlugins()
     }
 
     const char* scriptFilter = ".avsi";
+#ifndef FILESYSTEM_COMPAT
     for (auto& file : fs::directory_iterator(dir, std::filesystem::directory_options::skip_permission_denied | std::filesystem::directory_options::follow_directory_symlink, ec)) // and not recursive_directory_iterator
+#else
+    for (auto& file : fs::directory_iterator(dir, ghc::filesystem::directory_options::skip_permission_denied | ghc::filesystem::directory_options::follow_directory_symlink, ec)) // and not recursive_directory_iterator
+#endif
     {
       const bool extensionsMatch =
 #ifdef AVS_POSIX

avs_core/core/info.cpp

@@ -25,12 +25,21 @@
 #include <fstream>
 #include <unordered_map>
 #include <array>
+#include <iomanip>
+
+#ifndef FILESYSTEM_COMPAT
 #include <filesystem>
+namespace fs = std::filesystem;
+
+#else
+#include <ghc/filesystem.hpp>
+
+namespace fs = ghc::filesystem;
+#endif // FILESYSTEM_COMPAT
+
 #include "fonts/fixedfonts.h"
 #include "strings.h"
 
-namespace fs = std::filesystem;
-
 // generate outline on-the-fly
 // consider: thicker outline for font sizes over 24?
 void BitmapFont::generateOutline(uint16_t* outlined, int fontindex) const
@@ -243,7 +252,11 @@ static BdfFont LoadBMF(std::string name, bool bold) {
   //std::ifstream ss("c:\\Download\\terminus-font-4.48\\terminus-font-4.48\\ter-u16n.bdf");
   std::ifstream ss;
   // explicite font file name
+#ifndef FILESYSTEM_COMPAT
   auto fname = std::filesystem::path(name);
+#else
+  auto fname = ghc::filesystem::path(name);
+#endif
 
   if (!fs::exists(name))
     return fnt;

avs_core/core/parser/script.cpp

@@ -40,9 +40,15 @@
 #include <cmath>
 #include <vector>
 #include <fstream>
+#ifndef FILESYSTEM_COMPAT
 #include <filesystem>
 
 namespace fs = std::filesystem;
+#else
+#include <ghc/filesystem.hpp>
+
+namespace fs = ghc::filesystem;
+#endif
 
 #ifdef AVS_WINDOWS
 #include <io.h>
@@ -582,9 +588,15 @@ AVSValue Import(AVSValue args, void*, IScriptEnvironment* env)
     }
 
 #else // adapted from AvxSynth
+#ifndef FILESYSTEM_COMPAT
     std::string file_part = std::filesystem::path(script_name).filename().string();
     std::string full_path = std::filesystem::path(script_name).remove_filename();
     std::string dir_part = std::filesystem::path(script_name).parent_path();
+#else
+    std::string file_part = ghc::filesystem::path(script_name).filename().string();
+    std::string full_path = ghc::filesystem::path(script_name).remove_filename();
+    std::string dir_part = ghc::filesystem::path(script_name).parent_path();
+#endif
 
     FILE* h = fopen(script_name, "r");
     if(NULL == h)