chore: struct for storing cursor states

src/lib/cursor.rs

@@ -0,0 +1,56 @@
+use std::{collections::HashMap, sync::Mutex};
+
+use crate::proto::CursorMov;
+
+/// Note that this differs from any hashmap in its put method: no &mut!
+pub trait CursorStorage {
+	fn get(&self, id: &String) -> Option<Cursor>;
+	fn put(&self, id: String, val: Cursor);
+
+	fn update(&self, event: CursorMov) -> Option<Cursor> {
+		let mut cur = self.get(&event.user)?;
+		cur.buffer = event.path;
+		cur.start = (event.row, event.col).into();
+		self.put(event.user, cur.clone());
+		Some(cur)
+	}
+}
+
+#[derive(Copy, Clone)]
+pub struct Position {
+	row: i64,
+	col: i64,
+}
+
+impl From::<(i64, i64)> for Position {
+	fn from((row, col): (i64, i64)) -> Self {
+		Position { row, col }
+	}
+}
+
+#[derive(Clone)]
+pub struct Cursor {
+	buffer: String,
+	start: Position,
+	end:   Position,
+}
+
+pub struct CursorController {
+	users: Mutex<HashMap<String, Cursor>>,
+}
+
+impl CursorController {
+	pub fn new() -> Self {
+		CursorController { users: Mutex::new(HashMap::new()) }
+	}
+}
+
+impl CursorStorage for CursorController {
+	fn get(&self, id: &String) -> Option<Cursor> {
+		Some(self.users.lock().unwrap().get(id)?.clone())
+	}
+
+	fn put(&self, id: String, val: Cursor) {
+		self.users.lock().unwrap().insert(id, val);
+	}
+}