Add generic StreamWithBuffer owning the underlying buffer

components/files/constrainedfilestream.cpp

@@ -2,12 +2,6 @@
 
 namespace Files
 {
-    ConstrainedFileStream::ConstrainedFileStream(std::unique_ptr<ConstrainedFileStreamBuf> buf)
-        : std::istream(buf.get())
-        , mBuf(std::move(buf))
-    {
-    }
-
     IStreamPtr openConstrainedFileStream(const std::string& filename, std::size_t start, std::size_t length)
     {
         return std::make_shared<ConstrainedFileStream>(std::make_unique<ConstrainedFileStreamBuf>(filename, start, length));

components/files/constrainedfilestream.hpp

@@ -2,6 +2,7 @@
 #define OPENMW_CONSTRAINEDFILESTREAM_H
 
 #include "constrainedfilestreambuf.hpp"
+#include "streamwithbuffer.hpp"
 
 #include <istream>
 #include <memory>
@@ -12,14 +13,7 @@ namespace Files
 {
 
 /// A file stream constrained to a specific region in the file, specified by the 'start' and 'length' parameters.
-class ConstrainedFileStream final : public std::istream
-{
-public:
-    explicit ConstrainedFileStream(std::unique_ptr<ConstrainedFileStreamBuf> buf);
-
-private:
-    std::unique_ptr<ConstrainedFileStreamBuf> mBuf;
-};
+using ConstrainedFileStream = StreamWithBuffer<ConstrainedFileStreamBuf>;
 
 typedef std::shared_ptr<std::istream> IStreamPtr;
 

components/files/streamwithbuffer.hpp

@@ -0,0 +1,23 @@
+#ifndef OPENMW_COMPONENTS_FILES_STREAMWITHBUFFER_H
+#define OPENMW_COMPONENTS_FILES_STREAMWITHBUFFER_H
+
+#include <istream>
+#include <memory>
+
+namespace Files
+{
+    template <class Buffer>
+    class StreamWithBuffer final : public std::istream
+    {
+        public:
+            explicit StreamWithBuffer(std::unique_ptr<Buffer>&& buffer)
+                : std::istream(buffer.get())
+                , mBuffer(std::move(buffer))
+            {}
+
+        private:
+            std::unique_ptr<Buffer> mBuffer;
+    };
+}
+
+#endif