[brief] Adds a way to temporarily switch working directories.

[detailed]
- RAII wrapper so the switch occurs upon destruction of the scope.
- Made it move-only so weird things can't happen.
- Also adds a wrapper namespace for filesystem so it's easier to deal
  with.

Author: marovira

include/zeus/filesystem.hpp

@@ -14,25 +14,25 @@
 #include <string>
 
 #if defined(ZEUS_PLATFORM_WINDOWS) || defined(ZEUS_PLATFORM_APPLE)
-#    include <filesystem>
+#    include <filesystem> // IWYU pragma: export
 #else
-#    include <experimental/filesystem>
+#    include <experimental/filesystem> // IWYU pragma: export
 #endif
 
 namespace zeus
 {
+#if defined(ZEUS_PLATFORM_WINDOWS) || defined(ZEUS_PLATFORM_APPLE)
+    namespace zeus_fs = std::filesystem;
+#else
+    namespace zeus_fs = std::experimental::filesystem;
+#endif
+
 #if !defined(ZEUS_PLATFORM_APPLE)
     inline std::time_t get_file_last_write(std::string filename)
     {
-#    if defined(ZEUS_PLATFORM_WINDOWS)
-        namespace fs = std::filesystem;
-#    else
-        namespace fs = std::experimental::filesystem;
-#    endif
-
-        const fs::path file_path{filename};
+        const zeus_fs::path file_path{filename};
         std::error_code code;
-        auto ftime = fs::last_write_time(file_path, code);
+        auto ftime = zeus_fs::last_write_time(file_path, code);
         if (code && current_build == BuildType::debug)
         {
             fmt::print(stderr, "warning: ({}): {}\n", code.value(), code.message());
@@ -49,13 +49,7 @@ namespace zeus
 
     inline std::string get_file_directory(std::string filename)
     {
-#if defined(ZEUS_PLATFORM_WINDOWS) || defined(ZEUS_PLATFORM_APPLE)
-        namespace fs = std::filesystem;
-#else
-        namespace fs = std::experimental::filesystem;
-#endif
-
-        const fs::path file_path{filename};
+        const zeus_fs::path file_path{filename};
         std::string root_dir;
         if (file_path.has_parent_path())
         {
@@ -64,4 +58,35 @@ namespace zeus
 
         return root_dir;
     }
+
+    class ChdirScope
+    {
+    public:
+        ChdirScope(zeus_fs::path const& target_path)
+        {
+            m_start_path = zeus_fs::current_path();
+            zeus_fs::current_path(target_path);
+        }
+
+        ChdirScope(ChdirScope const&) = delete;
+        ChdirScope(ChdirScope&&)      = default;
+
+        ~ChdirScope()
+        {
+            try
+            {
+                zeus_fs::current_path(m_start_path);
+            }
+            catch (zeus_fs::filesystem_error const&) // NOLINT(bugprone-empty-catch)
+            {
+                fmt::print("error: unable to switch back to {}", m_start_path.string());
+            }
+        }
+
+        ChdirScope& operator=(ChdirScope const&) = delete;
+        ChdirScope& operator=(ChdirScope&&)      = default;
+
+    private:
+        zeus_fs::path m_start_path;
+    };
 } // namespace zeus

test/filesystem_test.cpp

@@ -21,3 +21,27 @@ TEST_CASE("[filesystem] - get_file_directory: valid root")
     auto result = get_file_directory(file_path);
     REQUIRE(result == expected);
 }
+
+TEST_CASE("[filesystem] - ChdirScope")
+{
+    using zeus::ChdirScope;
+    namespace fs = zeus::zeus_fs;
+
+    const auto start_path = fs::current_path();
+    const auto new_path   = start_path / "test_dir";
+    auto cur_path         = start_path;
+    fs::create_directory(new_path);
+    REQUIRE(fs::exists(new_path));
+    REQUIRE(cur_path == start_path);
+
+    {
+        const auto _ = ChdirScope{new_path};
+        cur_path     = fs::current_path();
+        REQUIRE(cur_path == new_path);
+    }
+
+    cur_path = fs::current_path();
+    REQUIRE(cur_path == start_path);
+
+    fs::remove(new_path);
+}