WIP: Add C++ bindings

1 files changed, 127 insertions, 0 deletions

diff --git a/serd/detail/Optional.hpp b/serd/detail/Optional.hpp
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+++ b/serd/detail/Optional.hpp
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+/*
+  Copyright 2019-2020 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_OPTIONAL_HPP
+#define SERD_DETAIL_OPTIONAL_HPP
+
+#include <cassert>
+#include <cstddef>
+#include <utility>
+
+namespace serd {
+namespace detail {
+
+struct ConstructNullOptional
+{
+};
+
+/**
+   A simple optional wrapper around a wrapped type with a pointer-like API
+
+   This works like a typical optional type, but only works with Wrapper types,
+   and exploits the fact that these are interally just pointers to avoid adding
+   space overhead for an "is_set" flag, like a generic optional class would.
+
+   Types must explicitly opt-in to being optional by providing a constructor
+   that takes a single ContructNullOptional argument.  This constructor should
+   only be used by the Optional implementation, which guarantees that such an
+   object will not be used except by calling its cobj() method.
+*/
+template <typename T>
+class Optional
+{
+public:
+	using CType = typename T::CType;
+
+	Optional() : _value(nullptr) {}
+
+	// NOLINTNEXTLINE(hicpp-explicit-conversions, modernize-pass-by-value)
+	Optional(const T& value) : _value(value) {}
+
+	// NOLINTNEXTLINE(hicpp-explicit-conversions)
+	Optional(T&& value) : _value(std::move(value)) {}
+
+	template <typename U,
+	          typename = typename std::enable_if<
+	                  std::is_convertible<U, T>::value>::type>
+	// NOLINTNEXTLINE(hicpp-explicit-conversions)
+	Optional(U&& value) : _value(std::forward<U>(value))
+	{
+	}
+
+	void reset() { _value = T{nullptr}; }
+
+	const T& operator*() const
+	{
+		assert(_value.cobj());
+		return _value;
+	}
+
+	T& operator*()
+	{
+		assert(_value.cobj());
+		return _value;
+	}
+
+	const T* operator->() const
+	{
+		assert(_value.cobj());
+		return &_value;
+	}
+
+	T* operator->()
+	{
+		assert(_value.cobj());
+		return &_value;
+	}
+
+	bool operator==(const Optional& optional)
+	{
+		return (!*this && !optional) ||
+		       (*this && optional && _value == optional._value);
+	}
+
+	bool operator!=(const Optional& optional) { return !operator==(optional); }
+
+	explicit operator bool() const { return _value.cobj(); }
+	bool     operator!() const { return !_value.cobj(); }
+
+	inline CType*       cobj() { return _value.cobj(); }
+	inline const CType* cobj() const { return _value.cobj(); }
+
+private:
+	T _value;
+};
+
+} // namespace detail
+
+template <class T>
+constexpr detail::Optional<T>
+make_optional(T&& value)
+{
+	return detail::Optional<T>{std::forward<T>(value)};
+}
+
+template <class T, class... Args>
+constexpr detail::Optional<T>
+make_optional(Args&&... args)
+{
+	return detail::Optional<T>{std::forward<Args>(args)...};
+}
+
+} // namespace serd
+
+#endif // SERD_DETAIL_OPTIONAL_HPP