Add ZoneWriting basis

src/ZoneWriting/Writing/WritingFileStream.h

@@ -0,0 +1,15 @@
+#pragma once
+#include <ostream>
+
+#include "IWritingStream.h"
+
+class WritingFileStream final : public IWritingStream
+{
+    std::ostream& m_stream;
+
+public:
+    explicit WritingFileStream(std::ostream& stream);
+
+    void Write(const void* buffer, size_t length) override;
+    int64_t Pos() override;
+};