Add minimal required interfaces

1 files changed, 39 insertions, 0 deletions

diff --git a/src/node.rs b/src/node.rs
new file mode 100644
index 0000000..b6a088b
--- /dev/null
+++ b/src/node.rs
@@ -0,0 +1,39 @@
+//
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this
+// file, You can obtain one at http://mozilla.org/MPL/2.0/.
+//
+
+use std::fmt::Debug;
+
+use crate::id::Id;
+
+use futures::future::Future;
+use futures::stream::Stream;
+
+/// A "Node" is an object of the (DA)Graph
+///
+/// In git-speak, this would be an "Object".
+///
+///
+/// # Equality
+///
+/// A node might be compared to another node. In git, for example, equality would be the equality
+/// of the nodes ids, because objects are non-mutable.
+///
+pub trait Node: Debug + PartialEq + Eq {
+    type Id: Id;
+    type NodePayload: Debug;
+    type Error: Debug;
+    type Payload: Future<Item = Self::NodePayload, Error = Self::Error>;
+
+    /// It should be trivial to get the Id of a Node.
+    fn id(&self) -> Self::Id;
+
+    /// Fetch the payload of the node.
+    fn payload(&self) -> Self::Payload;
+
+    /// Fetch the Ids of the parents of this node
+    fn parent_ids(&self) -> Stream<Item = Self::Id, Error = Self::Error>;
+}
+