add finalizing_ostream

src/io/finalizing_ostream.hpp

@@ -0,0 +1,47 @@
+#pragma once
+
+#include <memory>
+#include <ostream>
+#include <functional>
+
+class finalizing_ostream final : public std::ostream {
+public:
+    finalizing_ostream(
+        std::unique_ptr<std::ostream> inner,
+        std::function<void(std::unique_ptr<std::ostream>)> on_destruction
+    )
+        : std::ostream(inner->rdbuf()),
+          innerStream(std::move(inner)),
+          onDestruction(on_destruction) {
+    }
+
+    finalizing_ostream(const finalizing_ostream&) = delete;
+    finalizing_ostream& operator=(const finalizing_ostream&) = delete;
+
+    finalizing_ostream(finalizing_ostream&& other) noexcept
+        : std::ostream(std::move(other)),
+          innerStream(std::move(other.innerStream)),
+          onDestruction(std::move(other.onDestruction)) {
+        other.onDestruction = nullptr;
+    }
+
+    finalizing_ostream& operator=(finalizing_ostream&& other) noexcept {
+        if (this != &other) {
+            std::ostream::operator=(std::move(other));
+            innerStream = std::move(other.innerStream);
+            onDestruction = std::move(other.onDestruction);
+            other.onDestruction = nullptr;
+        }
+        return *this;
+    }
+
+    ~finalizing_ostream() {
+        if (onDestruction) {
+            onDestruction(std::move(innerStream));
+        }
+    }
+
+private:
+    std::unique_ptr<std::ostream> innerStream;
+    std::function<void(std::unique_ptr<std::ostream>)> onDestruction;
+};