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diff --git a/serd/detail/Flags.hpp b/serd/detail/Flags.hpp
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+++ b/serd/detail/Flags.hpp
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+/*
+  Copyright 2019 David Robillard <http://drobilla.net>
+
+  Permission to use, copy, modify, and/or distribute this software for any
+  purpose with or without fee is hereby granted, provided that the above
+  copyright notice and this permission notice appear in all copies.
+
+  THIS SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+  WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+  MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+  ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+  WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+  ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+  OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+*/
+
+#ifndef SERD_DETAIL_FLAGS_HPP
+#define SERD_DETAIL_FLAGS_HPP
+
+#include "serd/serd.h"
+
+#include <type_traits>
+
+namespace serd {
+namespace detail {
+
+/**
+   Type-safe bit flags
+
+  This is a minimal interface for a type-safe bit flags field, which only
+  allows values from the given enum to be set.
+
+  @tparam Flag Enum class of flag values.
+*/
+template <typename Flag>
+class Flags
+{
+public:
+	static_assert(std::is_enum<Flag>::value, "");
+
+	using FlagUnderlyingType = typename std::underlying_type<Flag>::type;
+	using Value = typename std::make_unsigned<FlagUnderlyingType>::type;
+
+	constexpr Flags() noexcept : _value(0) {}
+	constexpr explicit Flags(const Value value) noexcept : _value{value} {}
+
+	// NOLINTNEXTLINE(hicpp-explicit-conversions)
+	constexpr Flags(const Flag f) noexcept
+	    : _value(static_cast<Value>(f))
+	{
+	}
+
+	constexpr Flags operator|(const Flag rhs) const noexcept
+	{
+		return Flags{_value | static_cast<Value>(rhs)};
+	}
+
+	constexpr Flags operator|(const Flags rhs) const noexcept
+	{
+		return Flags{_value | rhs._value};
+	}
+
+	// NOLINTNEXTLINE(hicpp-explicit-conversions)
+	constexpr operator Value() const noexcept { return _value; }
+
+private:
+	Value _value{};
+};
+
+} // namespace detail
+} // namespace serd
+
+#endif // SERD_DETAIL_FLAGS_HPP