mirror of https://github.com/vuejs/core.git
54 lines
1.1 KiB
TypeScript
54 lines
1.1 KiB
TypeScript
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// Used for memoizing trees inside render functions.
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//
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// Example (equivalent of v-once):
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//
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// render() {
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// return memoize(h('div', this.msg), this, 0)
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// }
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//
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// Memoize baesd on keys:
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//
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// render() {
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// return memoize(h('div', this.msg + this.count), this, 0, [this.msg])
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// }
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import { Component } from '../component'
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import { warn } from '../warning'
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const memoizeMap = new WeakMap()
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export function memoize(
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getter: () => any,
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instance: Component,
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id: number,
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keys?: any[]
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): any {
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if (__DEV__ && !Array.isArray(keys)) {
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warn(
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`keys passed to v-memo or memoize must be an array. Got ${String(keys)}`
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)
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}
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let storage = memoizeMap.get(instance)
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if (!storage) {
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storage = []
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memoizeMap.set(instance, storage)
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}
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const record = storage[id]
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if (!record) {
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const value = getter()
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storage[id] = [value, keys]
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return value
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} else {
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const [prevValue, prevKeys] = record
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record[1] = keys
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if (keys) {
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for (let i = 0; i < keys.length; i++) {
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if (keys[i] !== prevKeys[i]) {
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return (record[0] = getter())
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}
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}
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}
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return prevValue
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}
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}
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