vmap/libs/property.h

#ifndef INCLUDED_IMPORTEXPORT_H
#define INCLUDED_IMPORTEXPORT_H

#include "generic/callback.h"
#include "string/string.h"

template<class T>
struct Property {
	// todo: just return T, don't use continuation passing style
	Callback<void(const Callback<void(T)> &returnz)> get;
	Callback<void(T value)> set;
};

// implementation

template<class Self, class T = Self>
struct PropertyImpl {
	static void Export(const Self &self, const Callback<void(T)> &returnz) {
		returnz(self);
	}

	static void Import(Self &self, T value) {
		self = value;
	}
};

namespace detail {

template<class I>
using propertyimpl_self = typename std::remove_reference<get_argument<decltype(&I::Import), 0> >::type;

template<class I>
using propertyimpl_other = get_argument<decltype(&I::Import), 1>;

template<class I>
using propertyimpl_other_free = get_argument<decltype(&I::Import), 0>;

}

// adaptor

template<
	class Self,
	class T = Self,
	class I = PropertyImpl<Self, T>
	>
struct PropertyAdaptor {
	using Type = Self;
	using Other = T;

	using Get = ConstReferenceCaller<Self, void (const Callback<void (T)> &), I::Export>;
	using Set = ReferenceCaller<Self, void (T), I::Import>;
};

template<
	class T,
	class I
	>
struct PropertyAdaptorFree {
	using Other = T;

	using Get = FreeCaller<void (const Callback<void (T)> &), I::Export>;
	using Set = FreeCaller<void (T), I::Import>;
};

// explicit full

template<class A>
Property<typename A::Other> make_property(typename A::Type &self) {
	return {typename A::Get(self), typename A::Set(self)};
}

template<class A>
Property<typename A::Other> make_property() {
	return {typename A::Get(), typename A::Set()};
}

// explicit impl

template<class I, class Self = detail::propertyimpl_self<I>, class T = detail::propertyimpl_other<I> >
using property_impl = PropertyAdaptor<Self, T, I>;

template<class I, class Self, class T = detail::propertyimpl_other<I> >
Property<T> make_property(Self &self) {
	return make_property<property_impl<I> >(self);
}

template<class I, class T = detail::propertyimpl_other_free<I> >
using property_impl_free = PropertyAdaptorFree<T, I>;

template<class I, class T = detail::propertyimpl_other_free<I> >
Property<T> make_property() {
	return make_property<property_impl_free<I> >();
}

// implicit

template<class Self, class T = Self>
Property<T> make_property(Self &self) {
	return make_property<PropertyAdaptor<Self, T> >(self);
}

// chain

template<typename DST, typename SRC, typename X, typename A>
struct make_property_chain_I_1 {
	static void ExportThunk(const Callback<void(DST)> &self, SRC value) {
		PropertyImpl<SRC, DST>::Export(value, self);
	}

	static void Export(const X &self, const Callback<void(DST)> &returnz) {
		A::Get::thunk_(self, ConstReferenceCaller<Callback<void(DST)>, void(SRC), ExportThunk>(returnz));
	}

	static void Import(X &self, DST value) {
		SRC out;
		PropertyImpl<SRC, DST>::Import(out, value);
		A::Set::thunk_(self, out);
	}
};

template<class I_Outer, class I_Inner>
Property<detail::propertyimpl_other<I_Outer> > make_property_chain(detail::propertyimpl_self<I_Inner> &it) {
	using DST = detail::propertyimpl_other<I_Outer>;
	using SRC = detail::propertyimpl_self<I_Outer>;
	using X = detail::propertyimpl_self<I_Inner>;

	using A = property_impl<I_Inner>;
	using I = make_property_chain_I_1<DST, SRC, X, A>;
	return make_property<PropertyAdaptor<X, DST, I> >(it);
}

template<typename DST, typename SRC, typename A>
struct make_property_chain_I_2 {
	static void ExportThunk(const Callback<void(DST)> &self, SRC value) {
		PropertyImpl<SRC, DST>::Export(value, self);
	}

	static void Export(const Callback<void(DST)> &returnz) {
		A::Get::thunk_(nullptr, ConstReferenceCaller<Callback<void(DST)>, void(SRC), ExportThunk>(returnz));
	}

	static void Import(DST value) {
		SRC out;
		PropertyImpl<SRC, DST>::Import(out, value);
		A::Set::thunk_(nullptr, out);
	}
};

template<class I_Outer, class I_Inner>
Property<detail::propertyimpl_other<I_Outer> > make_property_chain() {
	using DST = detail::propertyimpl_other<I_Outer>;
	using SRC = detail::propertyimpl_self<I_Outer>;

	using A = property_impl_free<I_Inner>;
	using I = make_property_chain_I_2<DST, SRC, A>;
	return make_property<PropertyAdaptorFree<DST, I> >();
}

// specializations

template<>
struct PropertyImpl<CopiedString, const char *> {
	static void Export(const CopiedString &self, const Callback<void(const char *)> &returnz) {
		returnz(self.c_str());
	}

	static void Import(CopiedString &self, const char *value) {
		self = value;
	}
};

#endif