refactor: make event-loop-yielder more concise

src/highlighter.ts

@@ -1,5 +1,5 @@
 import { TextBuffer, LanguageMode } from "atom"
-import { EventLoopYielder, maxTimeError } from "./utils/event-loop-yielder"
+import { eventLoopYielder, maxTimeError } from "./utils/event-loop-yielder"
 
 declare module "atom" {
   interface GrammarRegistry {
@@ -25,7 +25,7 @@ declare module "atom" {
 }
 
 export async function highlightTreeSitter(sourceCode: string, scopeName: string) {
-  const eventLoopYielder = new EventLoopYielder(100, 5000)
+  const yielder = eventLoopYielder(100, 5000)
   const buf = new TextBuffer()
   try {
     const grammar = atom.grammars.grammarForId(scopeName)
@@ -49,7 +49,7 @@ export async function highlightTreeSitter(sourceCode: string, scopeName: string)
         const nextPos = iter.getPosition()
         res.push(escapeHTML(buf.getTextInRange([pos, nextPos])))
 
-        if (!(await eventLoopYielder.yield())) {
+        if (!(await yielder())) {
           console.error(maxTimeError("Atom-IDE-Markdown-Service: Highlighter", 5))
           break
         }

src/utils/event-loop-yielder.ts

@@ -1,34 +1,21 @@
 /**
- * A class to allow the JavaScript event loop continue for a given interval between each iteration of a CPU intensive loop
- * If the time spent in the loop reaches the given maxTime, the operation is killed
+ * A helper to allow the JavaScript event loop continue for a given interval between each
+ * iteration of a CPU intensive loop. If the time spent in the loop reaches the given
+ * maxTime, the operation is killed.
+ *
+ * @returns An async function to call inside your heavy loop. It will return `false` if
+ *     the operation has exceeded the given max time (`true` otherwise).
  */
-export class EventLoopYielder {
-  private delayMs: number
-  private maxTimeMs: number
-  private started: number
-  private lastYield: number
-
-  constructor(delayMs: number, maxTimeMs: number) {
-    this.delayMs = delayMs
-    this.maxTimeMs = maxTimeMs
-    this.started = performance.now()
-    this.lastYield = this.started
-  }
-
-  /**
-   * Call yield method inside your heavy loop
-   * @returns it will be `false` if the operation has exceeded the given max time (`true` otherwise).
-   */
-  public async yield(): Promise<boolean> {
+export function eventLoopYielder(delayMs: number, maxTimeMs: number) {
+  const started = performance.now()
+  let lastYield = started
+  return async function (): Promise<boolean> {
     const now = performance.now()
-    if (now - this.lastYield > this.delayMs) {
+    if (now - lastYield > delayMs) {
       await new Promise(setImmediate)
-      this.lastYield = now
-    }
-    if (now - this.started > this.maxTimeMs) {
-      return false
+      lastYield = now
     }
-    return true
+    return now - started <= maxTimeMs
   }
 }