wip: scheduler, more component

packages/runtime-core/src/scheduler.ts

@@ -0,0 +1,74 @@
+const queue: Array<() => void> = []
+const postFlushCbs: Array<() => void> = []
+const p = Promise.resolve()
+
+let isFlushing = false
+
+export function nextTick(fn?: () => void): Promise<void> {
+  return fn ? p.then(fn) : p
+}
+
+export function queueJob(job: () => void, onError?: (err: Error) => void) {
+  if (queue.indexOf(job) === -1) {
+    queue.push(job)
+    if (!isFlushing) {
+      const p = nextTick(flushJobs)
+      if (onError) p.catch(onError)
+    }
+  }
+}
+
+export function queuePostFlushCb(cb: () => void) {
+  if (postFlushCbs.indexOf(cb) === -1) {
+    postFlushCbs.push(cb)
+  }
+}
+
+export function flushPostFlushCbs() {
+  const cbs = postFlushCbs.slice()
+  let i = cbs.length
+  postFlushCbs.length = 0
+  // post flush cbs are flushed in reverse since they are queued top-down
+  // but should fire bottom-up
+  while (i--) {
+    cbs[i]()
+  }
+}
+
+const RECURSION_LIMIT = 100
+type JobCountMap = Map<Function, number>
+
+function flushJobs(seenJobs?: JobCountMap) {
+  isFlushing = true
+  let job
+  if (__DEV__) {
+    seenJobs = seenJobs || new Map()
+  }
+  while ((job = queue.shift())) {
+    if (__DEV__) {
+      const seen = seenJobs as JobCountMap
+      if (!seen.has(job)) {
+        seen.set(job, 1)
+      } else {
+        const count = seen.get(job) as number
+        if (count > RECURSION_LIMIT) {
+          throw new Error(
+            'Maximum recursive updates exceeded. ' +
+              "You may have code that is mutating state in your component's " +
+              'render function or updated hook.'
+          )
+        } else {
+          seen.set(job, count + 1)
+        }
+      }
+    }
+    job()
+  }
+  flushPostFlushCbs()
+  isFlushing = false
+  // some postFlushCb queued jobs!
+  // keep flushing until it drains.
+  if (queue.length) {
+    flushJobs(seenJobs)
+  }
+}