refactor(runtime-core): extract component emit related logic into dedicated file

packages/runtime-core/src/componentEmits.ts

@@ -0,0 +1,93 @@
+import {
+  isArray,
+  isOn,
+  hasOwn,
+  EMPTY_OBJ,
+  capitalize,
+  hyphenate
+} from '@vue/shared'
+import { ComponentInternalInstance } from './component'
+import { callWithAsyncErrorHandling, ErrorCodes } from './errorHandling'
+
+export type ObjectEmitsOptions = Record<
+  string,
+  ((...args: any[]) => any) | null
+>
+export type EmitsOptions = ObjectEmitsOptions | string[]
+
+type UnionToIntersection<U> = (U extends any
+  ? (k: U) => void
+  : never) extends ((k: infer I) => void)
+  ? I
+  : never
+
+export type EmitFn<
+  Options = ObjectEmitsOptions,
+  Event extends keyof Options = keyof Options
+> = Options extends any[]
+  ? (event: Options[0], ...args: any[]) => unknown[]
+  : UnionToIntersection<
+      {
+        [key in Event]: Options[key] extends ((...args: infer Args) => any)
+          ? (event: key, ...args: Args) => unknown[]
+          : (event: key, ...args: any[]) => unknown[]
+      }[Event]
+    >
+
+export function emit(
+  instance: ComponentInternalInstance,
+  event: string,
+  ...args: any[]
+): any[] {
+  const props = instance.vnode.props || EMPTY_OBJ
+  let handler = props[`on${event}`] || props[`on${capitalize(event)}`]
+  // for v-model update:xxx events, also trigger kebab-case equivalent
+  // for props passed via kebab-case
+  if (!handler && event.indexOf('update:') === 0) {
+    event = hyphenate(event)
+    handler = props[`on${event}`] || props[`on${capitalize(event)}`]
+  }
+  if (handler) {
+    const res = callWithAsyncErrorHandling(
+      handler,
+      instance,
+      ErrorCodes.COMPONENT_EVENT_HANDLER,
+      args
+    )
+    return isArray(res) ? res : [res]
+  } else {
+    return []
+  }
+}
+
+export function normalizeEmitsOptions(
+  options: EmitsOptions | undefined
+): ObjectEmitsOptions | undefined {
+  if (!options) {
+    return
+  } else if (isArray(options)) {
+    if ((options as any)._n) {
+      return (options as any)._n
+    }
+    const normalized: ObjectEmitsOptions = {}
+    options.forEach(key => (normalized[key] = null))
+    Object.defineProperty(options, '_n', { value: normalized })
+    return normalized
+  } else {
+    return options
+  }
+}
+
+// Check if an incoming prop key is a declared emit event listener.
+// e.g. With `emits: { click: null }`, props named `onClick` and `onclick` are
+// both considered matched listeners.
+export function isEmitListener(
+  emits: ObjectEmitsOptions,
+  key: string
+): boolean {
+  return (
+    isOn(key) &&
+    (hasOwn(emits, key[2].toLowerCase() + key.slice(3)) ||
+      hasOwn(emits, key.slice(2)))
+  )
+}