1 1
/* @flow */
2 2 3 -
import Watcher from '../observer/watcher'
4 3
import Dep from '../observer/dep'
4 +
import Watcher from '../observer/watcher'
5 5 6 6
import {
7 7
set,
@@ -108,53 +108,62 @@ function initData (vm: Component) {
108 108
observe(data, true /* asRootData */)
109 109
}
110 110 111 +
const computedWatcherOptions = { lazy: true }
112 + 113 +
function initComputed (vm: Component, computed: Object) {
114 +
const watchers = vm._computedWatchers = Object.create(null)
115 + 116 +
for (const key in computed) {
117 +
const userDef = computed[key]
118 +
const getter = typeof userDef === 'function' ? userDef : userDef.get
119 +
// create internal watcher for the computed property.
120 +
watchers[key] = new Watcher(vm, getter, noop, computedWatcherOptions)
121 + 122 +
// component-defined computed properties are already defined on the
123 +
// component prototype. We only need to define on-the-fly computed
124 +
// properties here.
125 +
if (!(key in vm)) {
126 +
defineComputed(vm, key, userDef)
127 +
}
128 +
}
129 +
}
130 + 111 131
const computedSharedDefinition = {
112 132
enumerable: true,
113 133
configurable: true,
114 134
get: noop,
115 135
set: noop
116 136
}
117 137 118 -
function initComputed (vm: Component, computed: Object) {
119 -
for (const key in computed) {
120 -
/* istanbul ignore if */
121 -
if (process.env.NODE_ENV !== 'production' && key in vm) {
122 -
warn(
123 -
`existing instance property "${key}" will be ` +
124 -
`overwritten by a computed property with the same name.`,
125 -
vm
126 -
)
127 -
}
128 -
const userDef = computed[key]
129 -
if (typeof userDef === 'function') {
130 -
computedSharedDefinition.get = makeComputedGetter(userDef, vm)
131 -
computedSharedDefinition.set = noop
132 -
} else {
133 -
computedSharedDefinition.get = userDef.get
134 -
? userDef.cache !== false
135 -
? makeComputedGetter(userDef.get, vm)
136 -
: bind(userDef.get, vm)
137 -
: noop
138 -
computedSharedDefinition.set = userDef.set
139 -
? bind(userDef.set, vm)
140 -
: noop
141 -
}
142 -
Object.defineProperty(vm, key, computedSharedDefinition)
138 +
export function defineComputed (target: any, key: string, userDef: Object | Function) {
139 +
if (typeof userDef === 'function') {
140 +
computedSharedDefinition.get = createComputedGetter(key)
141 +
computedSharedDefinition.set = noop
142 +
} else {
143 +
computedSharedDefinition.get = userDef.get
144 +
? userDef.cache !== false
145 +
? createComputedGetter(key)
146 +
: userDef.get
147 +
: noop
148 +
computedSharedDefinition.set = userDef.set
149 +
? userDef.set
150 +
: noop
143 151
}
152 +
Object.defineProperty(target, key, computedSharedDefinition)
144 153
}
145 154 146 -
function makeComputedGetter (getter: Function, owner: Component): Function {
147 -
const watcher = new Watcher(owner, getter, noop, {
148 -
lazy: true
149 -
})
155 +
function createComputedGetter (key) {
150 156
return function computedGetter () {
151 -
if (watcher.dirty) {
152 -
watcher.evaluate()
153 -
}
154 -
if (Dep.target) {
155 -
watcher.depend()
157 +
const watcher = this._computedWatchers && this._computedWatchers[key]
158 +
if (watcher) {
159 +
if (watcher.dirty) {
160 +
watcher.evaluate()
161 +
}
162 +
if (Dep.target) {
163 +
watcher.depend()
164 +
}
165 +
return watcher.value
156 166
}
157 -
return watcher.value
158 167
}
159 168
}
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