Merge pull request #8134 from JosJuice/filesystem-string-view

DiscIO: Use std::string_view in FileSystem::FindFileInfo

1 files changed, 46 insertions, 5 deletions

diff --git a/Source/Core/DiscIO/FileSystemGCWii.cpp b/Source/Core/DiscIO/FileSystemGCWii.cpp
index a7826c9ab1..c4e8d4a48e 100644
--- a/Source/Core/DiscIO/FileSystemGCWii.cpp
+++ b/Source/Core/DiscIO/FileSystemGCWii.cpp
@@ -6,10 +6,12 @@
 #include <cinttypes>
 #include <cstddef>
 #include <cstring>
+#include <locale>
 #include <map>
 #include <memory>
 #include <optional>
 #include <string>
+#include <string_view>
 #include <vector>
 
 #include "Common/CommonFuncs.h"
@@ -118,6 +120,43 @@ std::string FileInfoGCWii::GetName() const
   return SHIFTJISToUTF8(reinterpret_cast<const char*>(m_fst + GetNameOffset()));
 }
 
+bool FileInfoGCWii::NameCaseInsensitiveEquals(std::string_view other) const
+{
+  // For speed, this function avoids allocating new strings, except when we are comparing
+  // non-ASCII characters with non-ASCII characters, which is a rare case.
+
+  const char* this_ptr = reinterpret_cast<const char*>(m_fst + GetNameOffset());
+  const char* other_ptr = other.data();
+
+  for (size_t i = 0; i < other.size(); ++i, ++this_ptr, ++other_ptr)
+  {
+    if (*this_ptr == '\0')
+    {
+      // A null byte in this is always a terminator and a null byte in other is never a terminator,
+      // so if we reach this case, this is shorter than other
+      return false;
+    }
+    else if (static_cast<unsigned char>(*this_ptr) >= 0x80 &&
+             static_cast<unsigned char>(*other_ptr) >= 0x80)
+    {
+      // other is in UTF-8 and this is in Shift-JIS, so we convert so that we can compare correctly
+      const std::string this_utf8 = SHIFTJISToUTF8(this_ptr);
+      return std::equal(this_utf8.cbegin(), this_utf8.cend(), other.cbegin() + i, other.cend(),
+                        [](char a, char b) {
+                          return std::tolower(a, std::locale::classic()) ==
+                                 std::tolower(b, std::locale::classic());
+                        });
+    }
+    else if (std::tolower(*this_ptr, std::locale::classic()) !=
+             std::tolower(*other_ptr, std::locale::classic()))
+    {
+      return false;
+    }
+  }
+
+  return *this_ptr == '\0';  // If we're not at a null byte, this is longer than other
+}
+
 std::string FileInfoGCWii::GetPath() const
 {
   // The root entry doesn't have a name
@@ -257,7 +296,7 @@ const FileInfo& FileSystemGCWii::GetRoot() const
   return m_root;
 }
 
-std::unique_ptr<FileInfo> FileSystemGCWii::FindFileInfo(const std::string& path) const
+std::unique_ptr<FileInfo> FileSystemGCWii::FindFileInfo(std::string_view path) const
 {
   if (!IsValid())
     return nullptr;
@@ -265,7 +304,7 @@ std::unique_ptr<FileInfo> FileSystemGCWii::FindFileInfo(const std::string& path)
   return FindFileInfo(path, m_root);
 }
 
-std::unique_ptr<FileInfo> FileSystemGCWii::FindFileInfo(const std::string& path,
+std::unique_ptr<FileInfo> FileSystemGCWii::FindFileInfo(std::string_view path,
                                                         const FileInfo& file_info) const
 {
   // Given a path like "directory1/directory2/fileA.bin", this function will
@@ -276,12 +315,14 @@ std::unique_ptr<FileInfo> FileSystemGCWii::FindFileInfo(const std::string& path,
     return file_info.clone();  // We're done
 
   const size_t name_end = path.find('/', name_start);
-  const std::string name = path.substr(name_start, name_end - name_start);
-  const std::string rest_of_path = (name_end != std::string::npos) ? path.substr(name_end + 1) : "";
+  const std::string_view name = path.substr(name_start, name_end - name_start);
+  const std::string_view rest_of_path =
+      (name_end != std::string::npos) ? path.substr(name_end + 1) : "";
 
   for (const FileInfo& child : file_info)
   {
-    if (!strcasecmp(child.GetName().c_str(), name.c_str()))
+    // We need case insensitive comparison since some games have OPENING.BNR instead of opening.bnr
+    if (child.NameCaseInsensitiveEquals(name))
     {
       // A match is found. The rest of the path is passed on to finish the search.
       std::unique_ptr<FileInfo> result = FindFileInfo(rest_of_path, child);