import {
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warn,
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remove,
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isObject,
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parsePath,
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_Set as Set,
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handleError,
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invokeWithErrorHandling,
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noop,
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isFunction
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} from '../util/index'
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import { traverse } from './traverse'
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import { queueWatcher } from './scheduler'
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import Dep, { pushTarget, popTarget, DepTarget } from './dep'
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import { DebuggerEvent, DebuggerOptions } from 'v3/debug'
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import type { SimpleSet } from '../util/index'
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import type { Component } from 'types/component'
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import { activeEffectScope, recordEffectScope } from 'v3/reactivity/effectScope'
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let uid = 0
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/**
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* @internal
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*/
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export interface WatcherOptions extends DebuggerOptions {
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deep?: boolean
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user?: boolean
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lazy?: boolean
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sync?: boolean
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before?: Function
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}
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/**
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* A watcher parses an expression, collects dependencies,
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* and fires callback when the expression value changes.
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* This is used for both the $watch() api and directives.
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* @internal
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*/
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export default class Watcher implements DepTarget {
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vm?: Component | null
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expression: string
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cb: Function
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id: number
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deep: boolean
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user: boolean
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lazy: boolean
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sync: boolean
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dirty: boolean
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active: boolean
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deps: Array<Dep>
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newDeps: Array<Dep>
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depIds: SimpleSet
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newDepIds: SimpleSet
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before?: Function
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onStop?: Function
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noRecurse?: boolean
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getter: Function
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value: any
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post: boolean
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// dev only
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onTrack?: ((event: DebuggerEvent) => void) | undefined
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onTrigger?: ((event: DebuggerEvent) => void) | undefined
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constructor(
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vm: Component | null,
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expOrFn: string | (() => any),
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cb: Function,
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options?: WatcherOptions | null,
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isRenderWatcher?: boolean
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) {
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recordEffectScope(
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this,
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// if the active effect scope is manually created (not a component scope),
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// prioritize it
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activeEffectScope && !activeEffectScope._vm
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? activeEffectScope
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: vm
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? vm._scope
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: undefined
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)
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if ((this.vm = vm) && isRenderWatcher) {
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vm._watcher = this
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}
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// options
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if (options) {
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this.deep = !!options.deep
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this.user = !!options.user
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this.lazy = !!options.lazy
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this.sync = !!options.sync
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this.before = options.before
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if (__DEV__) {
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this.onTrack = options.onTrack
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this.onTrigger = options.onTrigger
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}
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} else {
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this.deep = this.user = this.lazy = this.sync = false
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}
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this.cb = cb
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this.id = ++uid // uid for batching
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this.active = true
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this.post = false
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this.dirty = this.lazy // for lazy watchers
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this.deps = []
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this.newDeps = []
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this.depIds = new Set()
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this.newDepIds = new Set()
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this.expression = __DEV__ ? expOrFn.toString() : ''
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// parse expression for getter
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if (isFunction(expOrFn)) {
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this.getter = expOrFn
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} else {
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this.getter = parsePath(expOrFn)
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if (!this.getter) {
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this.getter = noop
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__DEV__ &&
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warn(
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`Failed watching path: "${expOrFn}" ` +
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'Watcher only accepts simple dot-delimited paths. ' +
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'For full control, use a function instead.',
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vm
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)
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}
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}
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this.value = this.lazy ? undefined : this.get()
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}
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/**
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* Evaluate the getter, and re-collect dependencies.
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*/
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get() {
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pushTarget(this)
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let value
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const vm = this.vm
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try {
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value = this.getter.call(vm, vm)
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} catch (e: any) {
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if (this.user) {
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handleError(e, vm, `getter for watcher "${this.expression}"`)
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} else {
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throw e
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}
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} finally {
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// "touch" every property so they are all tracked as
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// dependencies for deep watching
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if (this.deep) {
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traverse(value)
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}
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popTarget()
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this.cleanupDeps()
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}
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return value
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}
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/**
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* Add a dependency to this directive.
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*/
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addDep(dep: Dep) {
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const id = dep.id
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if (!this.newDepIds.has(id)) {
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this.newDepIds.add(id)
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this.newDeps.push(dep)
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if (!this.depIds.has(id)) {
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dep.addSub(this)
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}
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}
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}
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/**
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* Clean up for dependency collection.
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*/
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cleanupDeps() {
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let i = this.deps.length
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while (i--) {
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const dep = this.deps[i]
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if (!this.newDepIds.has(dep.id)) {
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dep.removeSub(this)
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}
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}
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let tmp: any = this.depIds
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this.depIds = this.newDepIds
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this.newDepIds = tmp
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this.newDepIds.clear()
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tmp = this.deps
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this.deps = this.newDeps
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this.newDeps = tmp
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this.newDeps.length = 0
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}
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/**
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* Subscriber interface.
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* Will be called when a dependency changes.
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*/
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update() {
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/* istanbul ignore else */
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if (this.lazy) {
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this.dirty = true
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} else if (this.sync) {
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this.run()
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} else {
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queueWatcher(this)
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}
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}
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/**
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* Scheduler job interface.
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* Will be called by the scheduler.
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*/
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run() {
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if (this.active) {
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const value = this.get()
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if (
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value !== this.value ||
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// Deep watchers and watchers on Object/Arrays should fire even
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// when the value is the same, because the value may
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// have mutated.
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isObject(value) ||
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this.deep
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) {
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// set new value
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const oldValue = this.value
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this.value = value
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if (this.user) {
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const info = `callback for watcher "${this.expression}"`
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invokeWithErrorHandling(
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this.cb,
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this.vm,
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[value, oldValue],
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this.vm,
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info
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)
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} else {
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this.cb.call(this.vm, value, oldValue)
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}
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}
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}
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}
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/**
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* Evaluate the value of the watcher.
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* This only gets called for lazy watchers.
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*/
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evaluate() {
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this.value = this.get()
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this.dirty = false
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}
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/**
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* Depend on all deps collected by this watcher.
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*/
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depend() {
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let i = this.deps.length
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while (i--) {
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this.deps[i].depend()
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}
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}
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/**
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* Remove self from all dependencies' subscriber list.
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*/
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teardown() {
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if (this.vm && !this.vm._isBeingDestroyed) {
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remove(this.vm._scope.effects, this)
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}
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if (this.active) {
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let i = this.deps.length
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while (i--) {
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this.deps[i].removeSub(this)
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}
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this.active = false
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if (this.onStop) {
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this.onStop()
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}
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}
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}
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}
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