Add Eventuality back to processor primitives

Also splits crate into modules.

processor/primitives/src/block.rs

@@ -0,0 +1,40 @@
+use core::fmt::Debug;
+
+use group::{Group, GroupEncoding};
+
+use crate::{Id, ReceivedOutput};
+
+/// A block header from an external network.
+pub trait BlockHeader: Send + Sync + Sized + Clone + Debug {
+  /// The type used to identify blocks.
+  type Id: 'static + Id;
+  /// The ID of this block.
+  fn id(&self) -> Self::Id;
+  /// The ID of the parent block.
+  fn parent(&self) -> Self::Id;
+}
+
+/// A block from an external network.
+///
+/// A block is defined as a consensus event associated with a set of transactions. It is not
+/// necessary to literally define it as whatever the external network defines as a block. For
+/// external networks which finalize block(s), this block type should be a representation of all
+/// transactions within a period finalization (whether block or epoch).
+#[async_trait::async_trait]
+pub trait Block: Send + Sync + Sized + Clone + Debug {
+  /// The type used for this block's header.
+  type Header: BlockHeader;
+
+  /// The type used to represent keys on this external network.
+  type Key: Group + GroupEncoding;
+  /// The type used to represent addresses on this external network.
+  type Address;
+  /// The type used to represent received outputs on this external network.
+  type Output: ReceivedOutput<Self::Key, Self::Address>;
+
+  /// The ID of this block.
+  fn id(&self) -> <Self::Header as BlockHeader>::Id;
+
+  /// Scan all outputs within this block to find the outputs spendable by this key.
+  fn scan_for_outputs(&self, key: Self::Key) -> Vec<Self::Output>;
+}