Local and shared state

1 files changed, 55 insertions, 0 deletions

diff --git a/include/erebos/state.h b/include/erebos/state.h
new file mode 100644
index 0000000..543e03c
--- /dev/null
+++ b/include/erebos/state.h
@@ -0,0 +1,55 @@
+#pragma once
+
+#include <erebos/identity.h>
+#include <erebos/uuid.h>
+
+#include <optional>
+
+namespace erebos {
+
+using std::optional;
+using std::vector;
+
+class LocalState
+{
+public:
+	LocalState();
+	explicit LocalState(const Ref &);
+	static LocalState load(const Ref & ref) { return LocalState(ref); }
+	Ref store(const Storage &) const;
+
+	static const UUID headTypeId;
+
+	const optional<Identity> & identity() const;
+	LocalState identity(const Identity &) const;
+
+	template<class T> optional<T> shared() const;
+	template<class T> LocalState shared(const vector<Stored<T>> &) const;
+	template<class T> LocalState shared(const Stored<T> & x) const { return shared({ x }); };
+	template<class T> LocalState shared(const Storage & st, const T & x)
+	{ return updateShared(T::sharedTypeId, x.store(st)); }
+
+private:
+	vector<Ref> lookupShared(UUID) const;
+	LocalState updateShared(UUID, const vector<Ref> &) const;
+
+	struct Priv;
+	std::shared_ptr<Priv> p;
+};
+
+template<class T>
+optional<T> LocalState::shared() const
+{
+	return T::load(lookupShared(T::sharedTypeId));
+}
+
+template<class T>
+LocalState LocalState::shared(const vector<Stored<T>> & v) const
+{
+	vector<Ref> refs;
+	for (const auto x : v)
+		refs.push_back(x.ref());
+	return updateShared(T::sharedTypeId, refs);
+}
+
+}