feat(reactivity): new effectScope API (#2195)

packages/reactivity/src/effectScope.ts

@@ -0,0 +1,81 @@
+import { ReactiveEffect } from './effect'
+import { warn } from './warning'
+
+let activeEffectScope: EffectScope | undefined
+const effectScopeStack: EffectScope[] = []
+
+export class EffectScope {
+  active = true
+  effects: (ReactiveEffect | EffectScope)[] = []
+  cleanups: (() => void)[] = []
+
+  constructor(detached = false) {
+    if (!detached) {
+      recordEffectScope(this)
+    }
+  }
+
+  run<T>(fn: () => T): T | undefined {
+    if (this.active) {
+      try {
+        this.on()
+        return fn()
+      } finally {
+        this.off()
+      }
+    } else if (__DEV__) {
+      warn(`cannot run an inactive effect scope.`)
+    }
+  }
+
+  on() {
+    if (this.active) {
+      effectScopeStack.push(this)
+      activeEffectScope = this
+    }
+  }
+
+  off() {
+    if (this.active) {
+      effectScopeStack.pop()
+      activeEffectScope = effectScopeStack[effectScopeStack.length - 1]
+    }
+  }
+
+  stop() {
+    if (this.active) {
+      this.effects.forEach(e => e.stop())
+      this.cleanups.forEach(cleanup => cleanup())
+      this.active = false
+    }
+  }
+}
+
+export function effectScope(detached?: boolean) {
+  return new EffectScope(detached)
+}
+
+export function recordEffectScope(
+  effect: ReactiveEffect | EffectScope,
+  scope?: EffectScope | null
+) {
+  scope = scope || activeEffectScope
+  if (scope && scope.active) {
+    scope.effects.push(effect)
+  }
+}
+
+export function getCurrentScope() {
+  return activeEffectScope
+}
+
+export function onScopeDispose(fn: () => void) {
+  if (activeEffectScope) {
+    activeEffectScope.cleanups.push(fn)
+  } else if (__DEV__) {
+    warn(
+      `onDispose() is called when there is no active effect scope ` +
+        ` to be associated with.`
+    )
+  }
+}