import { currentBlock, isBlockTreeEnabled, VNode } from '../vnode' export function withMemo( memo: any[], render: () => VNode, cache: any[], index: number ) { const cached = cache[index] as VNode | undefined if (cached && isMemoSame(cached, memo)) { return cached } const ret = render() // shallow clone ret.memo = memo.slice() return (cache[index] = ret) } export function isMemoSame(cached: VNode, memo: any[]) { const prev: any[] = cached.memo! if (prev.length != memo.length) { return false } for (let i = 0; i < prev.length; i++) { if (prev[i] !== memo[i]) { return false } } // make sure to let parent block track it when returning cached if (isBlockTreeEnabled > 0 && currentBlock) { currentBlock.push(cached) } return true }