chore: initial state component definition

src/state.rs

@@ -50,6 +50,20 @@ pub const BOS_VERSION: u8 = 1;
 /// Magic number for the BESS file format.
 pub const BESS_MAGIC: u32 = 0x53534542;
 
+/// Represents a component that is able to store and retrieve
+/// the state of its internal structure.
+/// 
+/// This trait is used to define the behavior of the state
+/// components that are used to store the emulator state.
+/// 
+/// Ideally each of Game Boy's components should implement
+/// this trait to allow the state to be saved and restored
+/// in a consistent way.
+pub trait StateComponent {
+    fn get_state(&self) -> Result<Vec<u8>, Error>;
+    fn set_state(&mut self, data: &[u8]) -> Result<(), Error>;
+}
+
 #[cfg_attr(feature = "wasm", wasm_bindgen)]
 pub enum SaveStateFormat {
     /// Boytacean Save Compressed format (BOSC).