Function eventEmitterEdges

src/resolution/callback-synthesizer.ts:282–338

Phase 2: string-keyed EventEmitter channels (on('e', fn) ↔ emit('e')).

(ctx: ResolutionContext, onYield: MaybeYield)

/** Phase 2: string-keyed EventEmitter channels (on('e', fn) ↔ emit('e')). */
async function eventEmitterEdges(ctx: ResolutionContext, onYield: MaybeYield): Promise<Edge[]> {
  const emitsByEvent = new Map<string, Set<string>>();          // event → dispatcher node ids
  const handlersByEvent = new Map<string, Map<string, string>>(); // event → handler id → registration site (file:line)

  let scanned = 0;
  for (const file of ctx.getAllFiles()) {
    if ((++scanned & 255) === 0) await onYield(); // #1091: yield mid-scan on huge graphs
    const content = ctx.readFile(file);
    if (!content) continue;
    const hasEmit = content.includes('.emit(') || content.includes('.fire(') || content.includes('.dispatchEvent(');
    const hasOn = content.includes('.on(') || content.includes('.once(') || content.includes('.addListener(');
    if (!hasEmit && !hasOn) continue;
    const nodesInFile = ctx.getNodesInFile(file);
    const lineOf = (idx: number) => content.slice(0, idx).split('\n').length;

    if (hasEmit) {
      EMIT_RE.lastIndex = 0;
      let m: RegExpExecArray | null;
      while ((m = EMIT_RE.exec(content))) {
        const disp = enclosingFn(nodesInFile, lineOf(m.index));
        if (!disp) continue;
        const set = emitsByEvent.get(m[1]!) ?? new Set<string>();
        set.add(disp.id); emitsByEvent.set(m[1]!, set);
      }
    }
    if (hasOn) {
      ON_RE.lastIndex = 0;
      let m: RegExpExecArray | null;
      while ((m = ON_RE.exec(content))) {
        const handlerName = m[2] || m[3];
        if (!handlerName) continue;
        const handler = ctx.getNodesByName(handlerName).find((n) => n.kind === 'function' || n.kind === 'method');
        if (!handler) continue;
        const map = handlersByEvent.get(m[1]!) ?? new Map<string, string>();
        map.set(handler.id, `${file}:${lineOf(m.index)}`); handlersByEvent.set(m[1]!, map);
      }
    }
  }

  const edges: Edge[] = [];
  const seen = new Set<string>();
  for (const [event, dispatchers] of emitsByEvent) {
    const handlers = handlersByEvent.get(event);
    if (!handlers) continue;
    // Precision guard: a generic event name with many handlers/dispatchers can't
    // be matched without receiver-type info (Phase 3) — skip rather than over-link.
    if (dispatchers.size > EVENT_FANOUT_CAP || handlers.size > EVENT_FANOUT_CAP) continue;
    for (const d of dispatchers) for (const [h, registeredAt] of handlers) {
      if (d === h) continue;
      const key = `${d}>${h}`;
      if (seen.has(key)) continue;
      seen.add(key);
      edges.push({ source: d, target: h, kind: 'calls', provenance: 'heuristic', metadata: { synthesizedBy: 'event-emitter', event, registeredAt } });
    }
  }
  return edges;
}