First repo code

src/data/entities.rs

@@ -1,11 +1,14 @@
 use crate::app::AppState;
 use crate::core::srs::{FADE_PER_DAY, MAX_SCORE, OrderMode, WordOpenMode};
 use crate::data::{INVALID_ID, Id};
+use crate::notification::MaybeError;
 use chrono::{DateTime, Utc};
 use log::info;
 use rayon::prelude::*;
 use rhai::{Engine, Scope};
 use std::collections::HashMap;
+use std::marker::PhantomData;
+use std::ops::{Deref, DerefMut};
 use std::time::Instant;
 
 #[derive(Clone, Debug)]
@@ -164,3 +167,50 @@ impl CardStatistics {
         (self.score as f32 * multiplier).max(1.0)
     }
 }
+
+#[derive(Clone)]
+pub struct Entity<E, R: Repository<E>> {
+    pub(crate) repo: R,
+    pub(crate) _phantom: PhantomData<E>,
+    pub(crate) inner: EntityInner,
+}
+
+#[derive(Clone)]
+pub(crate) struct EntityInner {
+    pub(crate) id: Id,
+    pub(crate) real: bool,
+}
+
+impl<E, R: Repository<E>> Entity<E, R> {
+    pub fn load(&self) -> EntityAccess<E, R> {
+        let clone = *self.clone();
+        let repo = &self.repo;
+        let value = repo.get(self.inner.id).unwrap();
+        EntityAccess { value, entity: clone, }
+    }
+}
+
+pub struct EntityAccess<E, R: Repository<E>> {
+    entity: Entity<E, R>,
+    value: E,
+}
+
+impl<E, R: Repository<E>> Deref for EntityAccess<E, R> {
+    type Target = E;
+
+    fn deref(&self) -> &Self::Target {
+        &self.value
+    }
+}
+
+impl<E, R: Repository<E>> DerefMut for EntityAccess<E, R> {
+    fn deref_mut(&mut self) -> &mut E {
+        &mut self.value
+    }
+}
+
+pub trait Repository<T> {
+    fn get(&self, id: Id) -> Option<T>;
+    fn create(&mut self, new: T) -> Entity<T, impl Repository<T>>;
+    fn save(&mut self, entity: EntityInner) -> MaybeError;
+}