/* @flow */
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import { def } from 'core/util/lang'
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import { normalizeChildren } from 'core/vdom/helpers/normalize-children'
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import { emptyObject } from 'shared/util'
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import { isAsyncPlaceholder } from './is-async-placeholder'
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export function normalizeScopedSlots (
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slots: { [key: string]: Function } | void,
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normalSlots: { [key: string]: Array<VNode> },
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prevSlots?: { [key: string]: Function } | void
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): any {
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let res
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const hasNormalSlots = Object.keys(normalSlots).length > 0
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const isStable = slots ? !!slots.$stable : !hasNormalSlots
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const key = slots && slots.$key
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if (!slots) {
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res = {}
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} else if (slots._normalized) {
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// fast path 1: child component re-render only, parent did not change
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return slots._normalized
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} else if (
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isStable &&
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prevSlots &&
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prevSlots !== emptyObject &&
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key === prevSlots.$key &&
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!hasNormalSlots &&
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!prevSlots.$hasNormal
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) {
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// fast path 2: stable scoped slots w/ no normal slots to proxy,
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// only need to normalize once
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return prevSlots
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} else {
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res = {}
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for (const key in slots) {
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if (slots[key] && key[0] !== '$') {
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res[key] = normalizeScopedSlot(normalSlots, key, slots[key])
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}
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}
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}
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// expose normal slots on scopedSlots
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for (const key in normalSlots) {
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if (!(key in res)) {
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res[key] = proxyNormalSlot(normalSlots, key)
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}
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}
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// avoriaz seems to mock a non-extensible $scopedSlots object
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// and when that is passed down this would cause an error
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if (slots && Object.isExtensible(slots)) {
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(slots: any)._normalized = res
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}
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def(res, '$stable', isStable)
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def(res, '$key', key)
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def(res, '$hasNormal', hasNormalSlots)
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return res
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}
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function normalizeScopedSlot(normalSlots, key, fn) {
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const normalized = function () {
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let res = arguments.length ? fn.apply(null, arguments) : fn({})
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res = res && typeof res === 'object' && !Array.isArray(res)
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? [res] // single vnode
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: normalizeChildren(res)
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let vnode: ?VNode = res && res[0]
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return res && (
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!vnode ||
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(res.length === 1 && vnode.isComment && !isAsyncPlaceholder(vnode)) // #9658, #10391
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) ? undefined
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: res
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}
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// this is a slot using the new v-slot syntax without scope. although it is
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// compiled as a scoped slot, render fn users would expect it to be present
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// on this.$slots because the usage is semantically a normal slot.
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if (fn.proxy) {
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Object.defineProperty(normalSlots, key, {
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get: normalized,
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enumerable: true,
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configurable: true
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})
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}
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return normalized
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}
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function proxyNormalSlot(slots, key) {
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return () => slots[key]
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}
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