vuex/src/helpers.js

export const mapState = normalizeNamespace((namespace, states) => {
  const res = {}
  normalizeMap(states).forEach(({ key, val }) => {
    res[key] = function mappedState () {
      let state = this.$store.state
      let getters = this.$store.getters
      if (namespace) {
        const module = this.$store._modulesNamespaceMap[namespace]
        if (!module) {
          warnNamespace('mapState', namespace)
          return
        }
        state = module.context.state
        getters = module.context.getters
      }
      return typeof val === 'function'
        ? val.call(this, state, getters)
        : state[val]
    }
  })
  return res
})

export const mapMutations = normalizeNamespace((namespace, mutations) => {
  const res = {}
  normalizeMap(mutations).forEach(({ key, val }) => {
    val = namespace + val
    res[key] = function mappedMutation (...args) {
      return this.$store.commit.apply(this.$store, [val].concat(args))
    }
  })
  return res
})

export const mapGetters = normalizeNamespace((namespace, getters) => {
  const res = {}
  normalizeMap(getters).forEach(({ key, val }) => {
    val = namespace + val
    res[key] = function mappedGetter () {
      if (!(val in this.$store.getters)) {
        console.error(`[vuex] unknown getter: ${val}`)
      }
      return this.$store.getters[val]
    }
  })
  return res
})

export const mapActions = normalizeNamespace((namespace, actions) => {
  const res = {}
  normalizeMap(actions).forEach(({ key, val }) => {
    val = namespace + val
    res[key] = function mappedAction (...args) {
      return this.$store.dispatch.apply(this.$store, [val].concat(args))
    }
  })
  return res
})

function normalizeMap (map) {
  return Array.isArray(map)
    ? map.map(key => ({ key, val: key }))
    : Object.keys(map).map(key => ({ key, val: map[key] }))
}

function normalizeNamespace (fn) {
  return (namespace, map) => {
    if (typeof namespace !== 'string') {
      map = namespace
      namespace = ''
    } else if (namespace.charAt(namespace.length - 1) !== '/') {
      namespace += '/'
    }
    return fn(namespace, map)
  }
}

function warnNamespace (helper, namespace) {
  console.error(`[vuex] module namespace not found in ${helper}(): ${namespace}`)
}