1. /* @flow */
    3. import { isRegExp, remove } from 'shared/util'
    4. import { getFirstComponentChild } from 'core/vdom/helpers/index'
    6. type VNodeCache = { [key: string]: ?VNode };
    8. function getComponentName (opts: ?VNodeComponentOptions): ?string {
    9.   return opts && (opts.Ctor.options.name || opts.tag)
    10. }
    12. function matches (pattern: string | RegExp | Array<string>, name: string): boolean {
    13.   if (Array.isArray(pattern)) {
    14.     return pattern.indexOf(name) > -1
    15.   } else if (typeof pattern === 'string') {
    16.     return pattern.split(',').indexOf(name) > -1
    17.   } else if (isRegExp(pattern)) {
    18.     return pattern.test(name)
    19.   }
    20.   /* istanbul ignore next */
    21.   return false
    22. }
    24. function pruneCache (keepAliveInstance: any, filter: Function) {
    25.   const { cache, keys, _vnode } = keepAliveInstance
    26.   for (const key in cache) {
    27.     const cachedNode: ?VNode = cache[key]
    28.     if (cachedNode) {
    29.       const name: ?string = getComponentName(cachedNode.componentOptions)
    30.       if (name && !filter(name)) {
    31.         pruneCacheEntry(cache, key, keys, _vnode)
    32.       }
    33.     }
    34.   }
    35. }
    37. function pruneCacheEntry (
    38.   cache: VNodeCache,
    39.   key: string,
    40.   keys: Array<string>,
    41.   current?: VNode
    42. ) {
    43.   const cached = cache[key]
    44.   if (cached && (!current || cached.tag !== current.tag)) {
    45.     cached.componentInstance.$destroy()
    46.   }
    47.   cache[key] = null
    48.   remove(keys, key)
    49. }
    51. const patternTypes: Array<Function> = [String, RegExp, Array]
    53. export default {
    54.   name: 'keep-alive',
    55.   abstract: true,
    57.   props: {
    58.     include: patternTypes,
    59.     exclude: patternTypes,
    60.     max: [String, Number]
    61.   },
    63.   created () {
    64.     this.cache = Object.create(null)
    65.     this.keys = []
    66.   },
    68.   destroyed () {
    69.     for (const key in this.cache) {
    70.       pruneCacheEntry(this.cache, key, this.keys)
    71.     }
    72.   },
    74.   mounted () {
    75.     this.$watch('include', val => {
    76.       pruneCache(this, name => matches(val, name))
    77.     })
    78.     this.$watch('exclude', val => {
    79.       pruneCache(this, name => !matches(val, name))
    80.     })
    81.   },
    83.   render () {
    84.     const slot = this.$slots.default
    85.     const vnode: VNode = getFirstComponentChild(slot)
    86.     const componentOptions: ?VNodeComponentOptions = vnode && vnode.componentOptions
    87.     if (componentOptions) {
    88.       // check pattern
    89.       const name: ?string = getComponentName(componentOptions)
    90.       const { include, exclude } = this
    91.       if (
    92.         // not included
    93.         (include && (!name || !matches(include, name))) ||
    94.         // excluded
    95.         (exclude && name && matches(exclude, name))
    96.       ) {
    97.         return vnode
    98.       }
    100.       const { cache, keys } = this
    101.       const key: ?string = vnode.key == null
    102.         // same constructor may get registered as different local components
    103.         // so cid alone is not enough (#3269)
    104.         ? componentOptions.Ctor.cid + (componentOptions.tag ? `::${componentOptions.tag}` : '')
    105.         : vnode.key
    106.       if (cache[key]) {
    107.         vnode.componentInstance = cache[key].componentInstance
    108.         // make current key freshest
    109.         remove(keys, key)
    110.         keys.push(key)
    111.       } else {
    112.         cache[key] = vnode
    113.         keys.push(key)
    114.         // prune oldest entry
    115.         if (this.max && keys.length > parseInt(this.max)) {
    116.           pruneCacheEntry(cache, keys[0], keys, this._vnode)
    117.         }
    118.       }
    120.       vnode.data.keepAlive = true
    121.     }
    122.     return vnode || (slot && slot[0])
    123.   }
    124. }