45 lines
1.2 KiB
TypeScript
45 lines
1.2 KiB
TypeScript
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import { autorun, stop } from './index'
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import { Autorun, activeAutorunStack } from './autorun'
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export interface ComputedGetter {
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(): any
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stop: () => void
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}
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export function computed(getter: Function, context?: any): ComputedGetter {
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let dirty: boolean = true
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let value: any = undefined
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const runner = autorun(() => getter.call(context, context), {
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lazy: true,
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scheduler: () => {
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dirty = true
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}
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})
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const computedGetter = (() => {
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if (dirty) {
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value = runner()
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dirty = false
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}
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// When computed autoruns are accessed in a parent autorun, the parent
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// should track all the dependencies the computed property has tracked.
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// This should also apply for chained computed properties.
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trackChildRun(runner)
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return value
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}) as ComputedGetter
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computedGetter.stop = () => stop(runner)
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return computedGetter
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}
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function trackChildRun(childRunner: Autorun) {
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const parentRunner = activeAutorunStack[activeAutorunStack.length - 1]
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if (parentRunner) {
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for (let i = 0; i < childRunner.deps.length; i++) {
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const dep = childRunner.deps[i]
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if (!dep.has(parentRunner)) {
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dep.add(parentRunner)
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parentRunner.deps.push(dep)
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}
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}
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}
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}
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