Implement file handling improvements with Unreal compatibility and enhanced read/write methods

cpp/src/Private/sweepstore/utils/file_handle.cpp

@@ -0,0 +1,110 @@
+#include "sweepstore/utils/file_handle.h"
+
+// Constructor
+SweepstoreFileHandle::SweepstoreFileHandle(const std::string& p, std::ios::openmode mode)
+    : path(p)
+#ifdef WITH_UNREAL
+{
+    IPlatformFile& platformFile = FPlatformFileManager::Get().GetPlatformFile();
+
+    // Map std::ios flags to Unreal flags
+    bool read = (mode & std::ios::in) != 0;
+    bool write = (mode & std::ios::out) != 0;
+
+    if (read && write) {
+        unrealHandle = platformFile.OpenReadWrite(*FString(path.c_str()), true);
+    } else if (write) {
+        unrealHandle = platformFile.OpenWrite(*FString(path.c_str()), false, false);
+    } else {
+        unrealHandle = platformFile.OpenRead(*FString(path.c_str()), false);
+    }
+
+    if (!unrealHandle) {
+        throw std::runtime_error("Failed to open file: " + path);
+    }
+}
+#else
+    , stream(std::make_unique<std::fstream>(p, mode))
+{
+    if (!stream->is_open()) {
+        throw std::runtime_error("Failed to open file: " + path);
+    }
+}
+#endif
+
+// isOpen
+bool SweepstoreFileHandle::isOpen() const {
+#ifdef WITH_UNREAL
+    return unrealHandle != nullptr;
+#else
+    return stream && stream->is_open();
+#endif
+}
+
+// close
+void SweepstoreFileHandle::close() {
+#ifdef WITH_UNREAL
+    if (unrealHandle) {
+        delete unrealHandle;
+        unrealHandle = nullptr;
+    }
+#else
+    if (stream) {
+        stream->close();
+    }
+#endif
+}
+
+// readSeek
+void SweepstoreFileHandle::readSeek(std::streampos pos, std::ios::seekdir dir) {
+#ifdef WITH_UNREAL
+    // Unreal doesn't have separate read/write pointers, so just seek
+    int64 unrealPos = static_cast<int64>(pos);
+    if (dir == std::ios::beg) {
+        unrealHandle->Seek(unrealPos);
+    } else if (dir == std::ios::cur) {
+        unrealHandle->Seek(unrealHandle->Tell() + unrealPos);
+    } else if (dir == std::ios::end) {
+        unrealHandle->SeekFromEnd(unrealPos);
+    }
+#else
+    #ifdef _WIN32
+        // On Windows, flush output and sync to invalidate input buffer
+        stream->flush();
+        stream->seekp(pos, dir);  // Sync put pointer
+    #endif
+    stream->seekg(pos, dir);
+#endif
+}
+
+// writeSeek
+void SweepstoreFileHandle::writeSeek(std::streampos pos, std::ios::seekdir dir) {
+#ifdef WITH_UNREAL
+    // Same as readSeek for Unreal
+    readSeek(pos, dir);
+#else
+    #ifdef _WIN32
+        stream->flush();  // Flush any pending writes
+    #endif
+    stream->seekp(pos, dir);
+#endif
+}
+
+// readBytes
+void SweepstoreFileHandle::readBytes(char* buffer, std::streamsize size) {
+#ifdef WITH_UNREAL
+    unrealHandle->Read(reinterpret_cast<uint8*>(buffer), size);
+#else
+    stream->read(buffer, size);
+#endif
+}
+
+// writeBytes
+void SweepstoreFileHandle::writeBytes(const char* buffer, std::streamsize size) {
+#ifdef WITH_UNREAL
+    unrealHandle->Write(reinterpret_cast<const uint8*>(buffer), size);
+    unrealHandle->Flush();  // Unreal requires explicit flush
+#else
+    stream->write(buffer, size);
+#endif
+}