refactor(perf): faster checks for end nfa recursion loops

Author: ColinEberhardt

assembly/nfa/nfa.ts

@@ -24,9 +24,11 @@ export enum MatchResult {
   Ignore,
 }
 
+let _stateId: u32 = 0;
+
 /* eslint @typescript-eslint/no-empty-function: ["error", { "allow": ["constructors", "methods"] }] */
 export class State {
-  constructor(public transitions: State[] = []) {}
+  constructor(public transitions: State[] = [], public id: u32 = _stateId++) {}
 
   matches(input: string, position: u32): MatchResult {
     return MatchResult.Ignore;
@@ -40,7 +42,7 @@ export class GroupStartMarkerState extends State {
   // captures from the path through the NFA that reaches the end are flagged
   flagged: bool = false;
 
-  constructor(next: State, public id: i32) {
+  constructor(next: State, public groupId: i32) {
     super();
     this.transitions.push(next);
   }

assembly/regexp.ts

@@ -9,14 +9,16 @@ import { walker as astWalker, expandRepetitions } from "./parser/walker";
 function recursiveBacktrackingSearch(
   state: State,
   input: string,
-  visited: State[] = [],
+  visited: u32[] = [],
   position: i32 = 0
 ): string | null {
   // prevent endless loops when following epsilon transitions
-  if (visited.includes(state)) {
-    return null;
+  for (let i = 0, len = visited.length; i < len; i++) {
+    if (visited[i] == state.id) {
+      return null;
+    }
   }
-  visited.push(state);
+  visited.push(state.id);
 
   const matches = state.matches(input, position);
   if (matches == MatchResult.Match) {
@@ -92,11 +94,11 @@ function filterCaptures(groupMarkers: GroupStartMarkerState[]): string[] {
     return [];
   }
   const values = [first(groupMarkers).capture];
-  let currrentId = first(groupMarkers).id;
+  let currrentId = first(groupMarkers).groupId;
   for (let i = 0; i < groupMarkers.length; i++) {
     const gm = groupMarkers[i];
-    if (gm.id != currrentId) {
-      currrentId = gm.id;
+    if (gm.groupId != currrentId) {
+      currrentId = gm.groupId;
       values.push(gm.capture);
     } else {
       if (gm.flagged) {