1 files changed, 91 insertions, 0 deletions
diff --git a/core/basic_state.rs b/core/basic_state.rs
new file mode 100644
index 000000000..54b9ee132
--- /dev/null
+++ b/core/basic_state.rs
@@ -0,0 +1,91 @@
+// Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
+
+use crate::BufVec;
+use crate::Op;
+use crate::OpId;
+use crate::OpRegistry;
+use crate::OpRouter;
+use crate::OpTable;
+use crate::ResourceTable;
+use std::cell::RefCell;
+use std::collections::HashMap;
+use std::rc::Rc;
+
+/// A minimal state struct for use by tests, examples etc. It contains
+/// an OpTable and ResourceTable, and implements the relevant traits
+/// for working with ops in the most straightforward way possible.
+#[derive(Default)]
+pub struct BasicState {
+  pub op_table: RefCell<OpTable<Self>>,
+  pub resource_table: RefCell<ResourceTable>,
+}
+
+impl BasicState {
+  pub fn new() -> Rc<Self> {
+    Default::default()
+  }
+}
+
+impl OpRegistry for BasicState {
+  fn get_op_catalog(self: Rc<Self>) -> HashMap<String, OpId> {
+    self.op_table.borrow().get_op_catalog()
+  }
+
+  fn register_op<F>(&self, name: &str, op_fn: F) -> OpId
+  where
+    F: Fn(Rc<Self>, BufVec) -> Op + 'static,
+  {
+    let mut op_table = self.op_table.borrow_mut();
+    let (op_id, prev) = op_table.insert_full(name.to_owned(), Rc::new(op_fn));
+    assert!(prev.is_none());
+    op_id
+  }
+}
+
+impl OpRouter for BasicState {
+  fn route_op(self: Rc<Self>, op_id: OpId, bufs: BufVec) -> Op {
+    let op_fn = self
+      .op_table
+      .borrow()
+      .get_index(op_id)
+      .map(|(_, op_fn)| op_fn.clone())
+      .unwrap();
+    (op_fn)(self, bufs)
+  }
+}
+
+#[test]
+fn test_basic_state_ops() {
+  let state = BasicState::new();
+
+  let foo_id = state.register_op("foo", |_, _| Op::Sync(b"oof!"[..].into()));
+  assert_eq!(foo_id, 1);
+
+  let bar_id = state.register_op("bar", |_, _| Op::Sync(b"rab!"[..].into()));
+  assert_eq!(bar_id, 2);
+
+  let state_ = state.clone();
+  let foo_res = state_.route_op(foo_id, Default::default());
+  assert!(matches!(foo_res, Op::Sync(buf) if &*buf == b"oof!"));
+
+  let state_ = state.clone();
+  let bar_res = state_.route_op(bar_id, Default::default());
+  assert!(matches!(bar_res, Op::Sync(buf) if &*buf == b"rab!"));
+
+  let catalog_res = state.route_op(0, Default::default());
+  let mut catalog_entries = match catalog_res {
+    Op::Sync(buf) => serde_json::from_slice::<HashMap<String, OpId>>(&buf)
+      .map(|map| map.into_iter().collect::<Vec<_>>())
+      .unwrap(),
+    _ => panic!("unexpected `Op` variant"),
+  };
+  catalog_entries.sort_by(|(_, id1), (_, id2)| id1.partial_cmp(id2).unwrap());
+  assert_eq!(
+    catalog_entries,
+    vec![
+      ("ops".to_owned(), 0),
+      ("foo".to_owned(), 1),
+      ("bar".to_owned(), 2)
+    ]
+  )
+}