Change CanConnect logic: remove blanket direct feedthrough ban, and always check against the global precedence graph.

Author: Kagamihara Nadeshiko

__tests__/InvalidMutations.ts

@@ -38,11 +38,6 @@ class R1 extends Reactor {
       [this.in1],
       [this.in1, this.in2, this.out1, this.out2],
       function (this, __in1, __in2, __out1, __out2) {
-        test("expect error on creating creating direct feed through", () => {
-          expect(() => {
-            this.connect(__in2.asConnectable(), __out2.asConnectable());
-          }).toThrowError("New connection introduces direct feed through.");
-        });
         test("expect error when creating connection outside container", () => {
           expect(() => {
             this.connect(__out2.asConnectable(), __in2.asConnectable());

src/core/reactor.ts

@@ -1168,34 +1168,23 @@ export abstract class Reactor extends Component {
         return CanConnectResult.RT_CONNECTION_OUTSIDE_CONTAINER;
       }
 
-      // Take the local graph and merge in all the causality interfaces
-      // of contained reactors. Then:
-      const graph = new PrecedenceGraph<Port<unknown> | Reaction<Variable[]>>();
-      graph.addAll(this._dependencyGraph);
-
-      for (const r of this._getOwnReactors()) {
-        graph.addAll(r._getCausalityInterface());
+      /**
+       * TODO (axmmisaka): The following code is commented for multiple reasons:
+       * The causality interface check is not fully implemented so new checks are failing
+       * Second, direct feedthrough itself would not cause any problem *per se*.
+       * To ensure there is no cycle, the safest way is to check against the global dependency graph.
+       */
+
+      let app = this as Reactor;
+      while (app._getContainer() !== app) {
+        app = app._getContainer();
       }
-
-      // Add the new edge.
+      const graph = app._getPrecedenceGraph();
       graph.addEdge(src, dst);
-
-      // 1) check for loops
-      const hasCycle = graph.hasCycle();
-      if (hasCycle) {
+      if (graph.hasCycle()) {
         return CanConnectResult.RT_CYCLE;
       }
 
-      // 2) check for direct feed through.
-      // FIXME: This doesn't handle while direct feed thorugh cases.
-      if (
-        src instanceof InPort &&
-        dst instanceof OutPort &&
-        dst.getContainer() === src.getContainer()
-      ) {
-        return CanConnectResult.RT_DIRECT_FEED_THROUGH;
-      }
-
       return CanConnectResult.SUCCESS;
     }
   }