From 8ebcba11d103ebe8ab259b311e874e1bac05dfd3 Mon Sep 17 00:00:00 2001
From: Spartan322 <Megacake1234@gmail.com>
Date: Fri, 18 Aug 2023 16:37:30 -0400
Subject: Add BasicCallbackOStreamBuffer for callback streaming Add
 CallbackStreamBuffer for char Add CallbackWStreamBuffer for wchar_t Add
 BasicCallbackStream Add CallbackStream for char Add CallbackWStream for
 wchar_t

---
 .../openvic-dataloader/detail/CallbackOStream.hpp  | 100 +++++++++++++++++++++
 1 file changed, 100 insertions(+)
 create mode 100644 include/openvic-dataloader/detail/CallbackOStream.hpp

diff --git a/include/openvic-dataloader/detail/CallbackOStream.hpp b/include/openvic-dataloader/detail/CallbackOStream.hpp
new file mode 100644
index 0000000..641d53f
--- /dev/null
+++ b/include/openvic-dataloader/detail/CallbackOStream.hpp
@@ -0,0 +1,100 @@
+#pragma once
+
+#include <cstring>
+#include <functional>
+#include <ostream>
+#include <type_traits>
+
+namespace ovdl::detail {
+	template<typename Callback, class CHAR_T, class traits = std::char_traits<CHAR_T>>
+	class BasicCallbackStreamBuffer : public std::basic_streambuf<CHAR_T, traits> {
+	public:
+		using base_type = std::basic_streambuf<CHAR_T, traits>;
+		using callback_type = Callback;
+		using char_type = typename base_type::char_type;
+		using int_type = typename base_type::int_type;
+
+		BasicCallbackStreamBuffer(Callback cb, void* user_data = nullptr)
+			: _callback(cb),
+			  _user_data(user_data) {}
+
+	protected:
+		std::streamsize xsputn(const char_type* s, std::streamsize n) override {
+			if constexpr (std::is_same_v<void, typename decltype(std::function { _callback })::result_type>) {
+				_callback(s, n, _user_data);
+				return n;
+			} else {
+				return _callback(s, n, _user_data); // returns the number of characters successfully written.
+			}
+		};
+
+		int_type overflow(int_type ch) override {
+			if constexpr (std::is_same_v<void, typename decltype(std::function { _callback })::result_type>) {
+				_callback(&ch, 1, _user_data);
+				return 1;
+			} else {
+				return _callback(&ch, 1, _user_data); // returns the number of characters successfully written.
+			}
+		}
+
+	private:
+		Callback _callback;
+		void* _user_data;
+	};
+
+	template<typename Callback>
+	class CallbackStreamBuffer : public BasicCallbackStreamBuffer<Callback, char> {
+	public:
+		using base_type = BasicCallbackStreamBuffer<Callback, char>;
+		using callback_type = Callback;
+		using char_type = typename base_type::char_type;
+		using int_type = typename base_type::int_type;
+
+		CallbackStreamBuffer(Callback cb, void* user_data = nullptr) : base_type(cb, user_data) {}
+	};
+
+	template<typename Callback>
+	class CallbackWStreamBuffer : public BasicCallbackStreamBuffer<Callback, wchar_t> {
+	public:
+		using base_type = BasicCallbackStreamBuffer<Callback, wchar_t>;
+		using callback_type = Callback;
+		using char_type = typename base_type::char_type;
+		using int_type = typename base_type::int_type;
+
+		CallbackWStreamBuffer(Callback cb, void* user_data = nullptr) : base_type(cb, user_data) {}
+	};
+
+	template<typename Callback, class CHAR_T, class traits = std::char_traits<CHAR_T>>
+	class BasicCallbackStream : public std::basic_ostream<CHAR_T, traits> {
+	public:
+		using base_type = std::basic_ostream<CHAR_T, traits>;
+
+		BasicCallbackStream(Callback cb, void* user_data = nullptr)
+			: m_sbuf(cb, user_data),
+			  std::basic_ios<CHAR_T, traits>(&m_sbuf),
+			  std::basic_ostream<CHAR_T, traits>(&m_sbuf) {
+			std::basic_ios<CHAR_T, traits>::init(&m_sbuf);
+		}
+
+	private:
+		BasicCallbackStreamBuffer<Callback, CHAR_T, traits> m_sbuf;
+	};
+
+	template<typename Callback>
+	class CallbackStream : public BasicCallbackStream<Callback, char> {
+	public:
+		using base_type = BasicCallbackStream<Callback, char>;
+
+		CallbackStream(Callback cb, void* user_data = nullptr) : base_type(cb, user_data) {
+		}
+	};
+
+	template<typename Callback>
+	class CallbackWStream : public BasicCallbackStream<Callback, wchar_t> {
+	public:
+		using base_type = BasicCallbackStream<Callback, wchar_t>;
+
+		CallbackWStream(Callback cb, void* user_data = nullptr) : base_type(cb, user_data) {
+		}
+	};
+}
\ No newline at end of file
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