fix: walker was visiting states multiple times

Author: ColinEberhardt

assembly/__tests__/capture-group.spec.ts

@@ -33,3 +33,9 @@ it("should not return captured values for non-matching alternations", () => {
   expect(match.matches[1]).toBe("");
   expect(match.matches[2]).toBe("b");
 });
+
+it("repeated capture groups should return the last match", () => {
+  const match = exec("([a-c])+", "ac");
+  expect(match.matches[0]).toBe("ac");
+  expect(match.matches[1]).toBe("c");
+});

assembly/nfa/walker.ts

@@ -5,8 +5,8 @@ export function walker(
   visitor: (state: State) => void,
   visited: State[] = []
 ): void {
-  visitor(state);
   if (visited.includes(state)) return;
+  visitor(state);
   visited.push(state);
   const nextStates = state.transitions;
   for (let i = 0, len = nextStates.length; i < len; i++) {