Improve path splitting speed

And create a range closure so the components can be iterated without allocating a container.

CMakeLists.txt

@@ -279,6 +279,7 @@ find_package(LLVM MODULE COMPONENTS Demangle)
 find_package(lz4 REQUIRED)
 find_package(nlohmann_json 3.8 REQUIRED)
 find_package(Opus 1.3 MODULE)
+find_package(range-v3 REQUIRED)
 find_package(ZLIB 1.2 REQUIRED)
 find_package(zstd 1.5 REQUIRED)
 

src/common/fs/path_util.cpp

@@ -350,17 +350,11 @@ std::string_view RemoveTrailingSlash(std::string_view path) {
 }
 
 std::vector<std::string> SplitPathComponents(std::string_view filename) {
-    std::string copy(filename);
-    std::replace(copy.begin(), copy.end(), '\\', '/');
-    std::vector<std::string> out;
-
-    std::stringstream stream(copy);
-    std::string item;
-    while (std::getline(stream, item, '/')) {
-        out.push_back(std::move(item));
+    std::vector<std::string> copied_components;
+    for (std::string_view component : filename | split_path_components_view) {
+        copied_components.emplace_back(component);
     }
-
-    return out;
+    return copied_components;
 }
 
 std::string SanitizePath(std::string_view path_, DirectorySeparator directory_separator) {

src/common/fs/path_util.h

@@ -6,6 +6,10 @@
 #include <filesystem>
 #include <vector>
 
+#include <range/v3/view/remove_if.hpp>
+#include <range/v3/view/split_when.hpp>
+#include <range/v3/view/transform.hpp>
+
 #include "common/fs/fs_util.h"
 
 namespace Common::FS {
@@ -284,6 +288,23 @@ enum class DirectorySeparator {
     PlatformDefault,
 };
 
+// A range adaptor closure which splits the path on '/' or '\'
+// i.e. "C:\Users\Yuzu\Documents\save.bin" becomes {"C:", "Users", "Yuzu", "Documents", "save.bin" }
+constexpr auto split_path_components_view =
+    // Somehow split_when never made it into the standard
+    ranges::views::split_when([](auto cur, auto end) {
+        const char c = *cur;
+        bool do_split = c == '\\' || c == '/';
+        return std::make_pair(do_split, cur + (do_split ? 1 : 0));
+    }) |
+    // Convert from opaque range to std::string_view
+    ranges::views::transform([](auto&& chunk) {
+        return std::string_view{&*ranges::begin(chunk),
+                                static_cast<std::size_t>(ranges::distance(chunk))};
+    }) |
+    // Skip any empty segments like at the beginning and end of "/root/directory/"
+    ranges::views::remove_if(&std::string_view::empty);
+
 // Splits the path on '/' or '\' and put the components into a vector
 // i.e. "C:\Users\Yuzu\Documents\save.bin" becomes {"C:", "Users", "Yuzu", "Documents", "save.bin" }
 [[nodiscard]] std::vector<std::string> SplitPathComponents(std::string_view filename);

src/core/CMakeLists.txt

@@ -837,7 +837,7 @@ endif()
 create_target_directory_groups(core)
 
 target_link_libraries(core PUBLIC common PRIVATE audio_core network video_core)
-target_link_libraries(core PUBLIC Boost::headers PRIVATE fmt::fmt nlohmann_json::nlohmann_json mbedtls Opus::opus)
+target_link_libraries(core PUBLIC Boost::headers PRIVATE fmt::fmt nlohmann_json::nlohmann_json mbedtls Opus::opus range-v3)
 if (MINGW)
     target_link_libraries(core PRIVATE ${MSWSOCK_LIBRARY})
 endif()

src/core/file_sys/vfs.cpp

@@ -200,31 +200,32 @@ std::string VfsFile::GetFullPath() const {
 }
 
 VirtualFile VfsDirectory::GetFileRelative(std::string_view path) const {
-    auto vec = Common::FS::SplitPathComponents(path);
-    vec.erase(std::remove_if(vec.begin(), vec.end(), [](const auto& str) { return str.empty(); }),
-              vec.end());
-    if (vec.empty()) {
+    auto&& component_view = path | Common::FS::split_path_components_view;
+    auto next_component = component_view.begin();
+    if (next_component == component_view.end()) {
         return nullptr;
     }
 
-    if (vec.size() == 1) {
-        return GetFile(vec[0]);
-    }
-
-    auto dir = GetSubdirectory(vec[0]);
-    for (std::size_t component = 1; component < vec.size() - 1; ++component) {
-        if (dir == nullptr) {
-            return nullptr;
-        }
-
-        dir = dir->GetSubdirectory(vec[component]);
+    std::string_view component = *next_component;
+    if (++next_component == component_view.end()) {
+        return GetFile(component);
     }
 
+    auto dir = GetSubdirectory(component);
     if (dir == nullptr) {
         return nullptr;
     }
+    component = *next_component;
 
-    return dir->GetFile(vec.back());
+    while (++next_component != component_view.end()) {
+        dir = dir->GetSubdirectory(component);
+        if (dir == nullptr) {
+            return nullptr;
+        }
+        component = *next_component;
+    }
+
+    return dir->GetFile(component);
 }
 
 VirtualFile VfsDirectory::GetFileAbsolute(std::string_view path) const {

vcpkg.json

@@ -24,6 +24,7 @@
         "fmt",
         "lz4",
         "nlohmann-json",
+        "range-v3",
         "zlib",
         "zstd"
     ],