vuex/dist/vuex.js

/**
 * vuex v4.0.0-alpha.1
 * (c) 2020 Evan You
 * @license MIT
 */
(function (global, factory) {
  typeof exports === 'object' && typeof module !== 'undefined' ? module.exports = factory(require('vue')) :
  typeof define === 'function' && define.amd ? define(['vue'], factory) :
  (global = global || self, global.Vuex = factory(global.Vue));
}(this, function (vue) { 'use strict';

  var storeKey = 'store';

  function useStore (key) {
    if ( key === void 0 ) key = null;

    return vue.inject(key !== null ? key : storeKey)
  }

  function applyMixin (app, store, injectKey) {
    app.provide(injectKey || storeKey, store);

    // TODO: Refactor this to use `provide/inject`. It's currently
    // not possible because Vue 3 doesn't work with `$` prefixed
    // `provide/inject` at the moment.
    app.mixin({
      beforeCreate: function beforeCreate () {
        if (!this.parent) {
          this.$store = typeof store === 'function' ? store() : store;
        } else {
          this.$store = this.parent.$options.$store;
        }
      }
    });
  }

  var target = typeof window !== 'undefined'
    ? window
    : typeof global !== 'undefined'
      ? global
      : {};
  var devtoolHook = target.__VUE_DEVTOOLS_GLOBAL_HOOK__;

  function devtoolPlugin (store) {
    if (!devtoolHook) { return }

    store._devtoolHook = devtoolHook;

    devtoolHook.emit('vuex:init', store);

    devtoolHook.on('vuex:travel-to-state', function (targetState) {
      store.replaceState(targetState);
    });

    store.subscribe(function (mutation, state) {
      devtoolHook.emit('vuex:mutation', mutation, state);
    });
  }

  /**
   * Get the first item that pass the test
   * by second argument function
   *
   * @param {Array} list
   * @param {Function} f
   * @return {*}
   */

  /**
   * forEach for object
   */
  function forEachValue (obj, fn) {
    Object.keys(obj).forEach(function (key) { return fn(obj[key], key); });
  }

  function isObject (obj) {
    return obj !== null && typeof obj === 'object'
  }

  function isPromise (val) {
    return val && typeof val.then === 'function'
  }

  function assert (condition, msg) {
    if (!condition) { throw new Error(("[vuex] " + msg)) }
  }

  function partial (fn, arg) {
    return function () {
      return fn(arg)
    }
  }

  // Base data struct for store's module, package with some attribute and method
  var Module = function Module (rawModule, runtime) {
    this.runtime = runtime;
    // Store some children item
    this._children = Object.create(null);
    // Store the origin module object which passed by programmer
    this._rawModule = rawModule;
    var rawState = rawModule.state;

    // Store the origin module's state
    this.state = (typeof rawState === 'function' ? rawState() : rawState) || {};
  };

  var prototypeAccessors = { namespaced: { configurable: true } };

  prototypeAccessors.namespaced.get = function () {
    return !!this._rawModule.namespaced
  };

  Module.prototype.addChild = function addChild (key, module) {
    this._children[key] = module;
  };

  Module.prototype.removeChild = function removeChild (key) {
    delete this._children[key];
  };

  Module.prototype.getChild = function getChild (key) {
    return this._children[key]
  };

  Module.prototype.update = function update (rawModule) {
    this._rawModule.namespaced = rawModule.namespaced;
    if (rawModule.actions) {
      this._rawModule.actions = rawModule.actions;
    }
    if (rawModule.mutations) {
      this._rawModule.mutations = rawModule.mutations;
    }
    if (rawModule.getters) {
      this._rawModule.getters = rawModule.getters;
    }
  };

  Module.prototype.forEachChild = function forEachChild (fn) {
    forEachValue(this._children, fn);
  };

  Module.prototype.forEachGetter = function forEachGetter (fn) {
    if (this._rawModule.getters) {
      forEachValue(this._rawModule.getters, fn);
    }
  };

  Module.prototype.forEachAction = function forEachAction (fn) {
    if (this._rawModule.actions) {
      forEachValue(this._rawModule.actions, fn);
    }
  };

  Module.prototype.forEachMutation = function forEachMutation (fn) {
    if (this._rawModule.mutations) {
      forEachValue(this._rawModule.mutations, fn);
    }
  };

  Object.defineProperties( Module.prototype, prototypeAccessors );

  var ModuleCollection = function ModuleCollection (rawRootModule) {
    // register root module (Vuex.Store options)
    this.register([], rawRootModule, false);
  };

  ModuleCollection.prototype.get = function get (path) {
    return path.reduce(function (module, key) {
      return module.getChild(key)
    }, this.root)
  };

  ModuleCollection.prototype.getNamespace = function getNamespace (path) {
    var module = this.root;
    return path.reduce(function (namespace, key) {
      module = module.getChild(key);
      return namespace + (module.namespaced ? key + '/' : '')
    }, '')
  };

  ModuleCollection.prototype.update = function update$1 (rawRootModule) {
    update([], this.root, rawRootModule);
  };

  ModuleCollection.prototype.register = function register (path, rawModule, runtime) {
      var this$1 = this;
      if ( runtime === void 0 ) runtime = true;

    {
      assertRawModule(path, rawModule);
    }

    var newModule = new Module(rawModule, runtime);
    if (path.length === 0) {
      this.root = newModule;
    } else {
      var parent = this.get(path.slice(0, -1));
      parent.addChild(path[path.length - 1], newModule);
    }

    // register nested modules
    if (rawModule.modules) {
      forEachValue(rawModule.modules, function (rawChildModule, key) {
        this$1.register(path.concat(key), rawChildModule, runtime);
      });
    }
  };

  ModuleCollection.prototype.unregister = function unregister (path) {
    var parent = this.get(path.slice(0, -1));
    var key = path[path.length - 1];
    if (!parent.getChild(key).runtime) { return }

    parent.removeChild(key);
  };

  function update (path, targetModule, newModule) {
    {
      assertRawModule(path, newModule);
    }

    // update target module
    targetModule.update(newModule);

    // update nested modules
    if (newModule.modules) {
      for (var key in newModule.modules) {
        if (!targetModule.getChild(key)) {
          {
            console.warn(
              "[vuex] trying to add a new module '" + key + "' on hot reloading, " +
              'manual reload is needed'
            );
          }
          return
        }
        update(
          path.concat(key),
          targetModule.getChild(key),
          newModule.modules[key]
        );
      }
    }
  }

  var functionAssert = {
    assert: function (value) { return typeof value === 'function'; },
    expected: 'function'
  };

  var objectAssert = {
    assert: function (value) { return typeof value === 'function' ||
      (typeof value === 'object' && typeof value.handler === 'function'); },
    expected: 'function or object with "handler" function'
  };

  var assertTypes = {
    getters: functionAssert,
    mutations: functionAssert,
    actions: objectAssert
  };

  function assertRawModule (path, rawModule) {
    Object.keys(assertTypes).forEach(function (key) {
      if (!rawModule[key]) { return }

      var assertOptions = assertTypes[key];

      forEachValue(rawModule[key], function (value, type) {
        assert(
          assertOptions.assert(value),
          makeAssertionMessage(path, key, type, value, assertOptions.expected)
        );
      });
    });
  }

  function makeAssertionMessage (path, key, type, value, expected) {
    var buf = key + " should be " + expected + " but \"" + key + "." + type + "\"";
    if (path.length > 0) {
      buf += " in module \"" + (path.join('.')) + "\"";
    }
    buf += " is " + (JSON.stringify(value)) + ".";
    return buf
  }

  // let Vue // bind on install

  function createStore (options) {
    return new Store(options)
  }

  var Store = function Store (options) {
    var this$1 = this;
    if ( options === void 0 ) options = {};

    // TODO: Bring back this one if needed.
    //
    // Auto install if it is not done yet and `window` has `Vue`.
    // To allow users to avoid auto-installation in some cases,
    // this code should be placed here. See #731
    // if (!Vue && typeof window !== 'undefined' && window.Vue) {
    // install(window.Vue)
    // }

    {
      // TODO: Maybe we can remove this depending on the new implementation.
      // assert(Vue, `must call Vue.use(Vuex) before creating a store instance.`)
      assert(typeof Promise !== 'undefined', "vuex requires a Promise polyfill in this browser.");
      assert(this instanceof Store, "store must be called with the new operator.");
    }

    var plugins = options.plugins; if ( plugins === void 0 ) plugins = [];
    var strict = options.strict; if ( strict === void 0 ) strict = false;

    // store internal state
    this._committing = false;
    this._actions = Object.create(null);
    this._actionSubscribers = [];
    this._mutations = Object.create(null);
    this._wrappedGetters = Object.create(null);
    this._modules = new ModuleCollection(options);
    this._modulesNamespaceMap = Object.create(null);
    this._subscribers = [];
    this._makeLocalGettersCache = Object.create(null);

    // bind commit and dispatch to self
    var store = this;
    var ref = this;
    var dispatch = ref.dispatch;
    var commit = ref.commit;
    this.dispatch = function boundDispatch (type, payload) {
      return dispatch.call(store, type, payload)
    };
    this.commit = function boundCommit (type, payload, options) {
      return commit.call(store, type, payload, options)
    };

    // strict mode
    this.strict = strict;

    var state = this._modules.root.state;

    // init root module.
    // this also recursively registers all sub-modules
    // and collects all module getters inside this._wrappedGetters
    installModule(this, state, [], this._modules.root);

    // initialize the store vm, which is responsible for the reactivity
    // (also registers _wrappedGetters as computed properties)
    resetStoreVM(this, state);

    // apply plugins
    plugins.forEach(function (plugin) { return plugin(this$1); });

    var useDevtools = options.devtools !== undefined ? options.devtools : /* Vue.config.devtools */ true;
    if (useDevtools) {
      devtoolPlugin(this);
    }
  };

  var prototypeAccessors$1 = { state: { configurable: true } };

  Store.prototype.install = function install (app, injectKey) {
    // TODO: Removing double install check for now. Maybe we can bring this
    // feature back again if needed.
    //
    // if (Vue && _Vue === Vue) {
    // if ("development" !== 'production') {
    //   console.error(
    //     '[vuex] already installed. Vue.use(Vuex) should be called only once.'
    //   )
    // }
    // return
    // }
    // Vue = _Vue

    applyMixin(app, this, injectKey);
  };

  prototypeAccessors$1.state.get = function () {
    return this._vm._data.$$state
  };

  prototypeAccessors$1.state.set = function (v) {
    {
      assert(false, "use store.replaceState() to explicit replace store state.");
    }
  };

  Store.prototype.commit = function commit (_type, _payload, _options) {
      var this$1 = this;

    // check object-style commit
    var ref = unifyObjectStyle(_type, _payload, _options);
      var type = ref.type;
      var payload = ref.payload;
      var options = ref.options;

    var mutation = { type: type, payload: payload };
    var entry = this._mutations[type];
    if (!entry) {
      {
        console.error(("[vuex] unknown mutation type: " + type));
      }
      return
    }
    this._withCommit(function () {
      entry.forEach(function commitIterator (handler) {
        handler(payload);
      });
    });

    this._subscribers
      .slice() // shallow copy to prevent iterator invalidation if subscriber synchronously calls unsubscribe
      .forEach(function (sub) { return sub(mutation, this$1.state); });

    if (
      options && options.silent
    ) {
      console.warn(
        "[vuex] mutation type: " + type + ". Silent option has been removed. " +
        'Use the filter functionality in the vue-devtools'
      );
    }
  };

  Store.prototype.dispatch = function dispatch (_type, _payload) {
      var this$1 = this;

    // check object-style dispatch
    var ref = unifyObjectStyle(_type, _payload);
      var type = ref.type;
      var payload = ref.payload;

    var action = { type: type, payload: payload };
    var entry = this._actions[type];
    if (!entry) {
      {
        console.error(("[vuex] unknown action type: " + type));
      }
      return
    }

    try {
      this._actionSubscribers
        .slice() // shallow copy to prevent iterator invalidation if subscriber synchronously calls unsubscribe
        .filter(function (sub) { return sub.before; })
        .forEach(function (sub) { return sub.before(action, this$1.state); });
    } catch (e) {
      {
        console.warn("[vuex] error in before action subscribers: ");
        console.error(e);
      }
    }

    var result = entry.length > 1
      ? Promise.all(entry.map(function (handler) { return handler(payload); }))
      : entry[0](payload);

    return result.then(function (res) {
      try {
        this$1._actionSubscribers
          .filter(function (sub) { return sub.after; })
          .forEach(function (sub) { return sub.after(action, this$1.state); });
      } catch (e) {
        {
          console.warn("[vuex] error in after action subscribers: ");
          console.error(e);
        }
      }
      return res
    })
  };

  Store.prototype.subscribe = function subscribe (fn) {
    return genericSubscribe(fn, this._subscribers)
  };

  Store.prototype.subscribeAction = function subscribeAction (fn) {
    var subs = typeof fn === 'function' ? { before: fn } : fn;
    return genericSubscribe(subs, this._actionSubscribers)
  };

  Store.prototype.watch = function watch$1 (getter, cb, options) {
      var this$1 = this;

    {
      assert(typeof getter === 'function', "store.watch only accepts a function.");
    }
    return vue.watch(function () { return getter(this$1.state, this$1.getters); }, cb, Object.assign({}, options))
  };

  Store.prototype.replaceState = function replaceState (state) {
      var this$1 = this;

    this._withCommit(function () {
      this$1._vm._data.$$state = state;
    });
  };

  Store.prototype.registerModule = function registerModule (path, rawModule, options) {
      if ( options === void 0 ) options = {};

    if (typeof path === 'string') { path = [path]; }

    {
      assert(Array.isArray(path), "module path must be a string or an Array.");
      assert(path.length > 0, 'cannot register the root module by using registerModule.');
    }

    this._modules.register(path, rawModule);
    installModule(this, this.state, path, this._modules.get(path), options.preserveState);
    // reset store to update getters...
    resetStoreVM(this, this.state);
  };

  Store.prototype.unregisterModule = function unregisterModule (path) {
      var this$1 = this;

    if (typeof path === 'string') { path = [path]; }

    {
      assert(Array.isArray(path), "module path must be a string or an Array.");
    }

    this._modules.unregister(path);
    this._withCommit(function () {
      var parentState = getNestedState(this$1.state, path.slice(0, -1));
      delete parentState[path[path.length - 1]];
    });
    resetStore(this);
  };

  Store.prototype.hotUpdate = function hotUpdate (newOptions) {
    this._modules.update(newOptions);
    resetStore(this, true);
  };

  Store.prototype._withCommit = function _withCommit (fn) {
    var committing = this._committing;
    this._committing = true;
    fn();
    this._committing = committing;
  };

  Object.defineProperties( Store.prototype, prototypeAccessors$1 );

  function genericSubscribe (fn, subs) {
    if (subs.indexOf(fn) < 0) {
      subs.push(fn);
    }
    return function () {
      var i = subs.indexOf(fn);
      if (i > -1) {
        subs.splice(i, 1);
      }
    }
  }

  function resetStore (store, hot) {
    store._actions = Object.create(null);
    store._mutations = Object.create(null);
    store._wrappedGetters = Object.create(null);
    store._modulesNamespaceMap = Object.create(null);
    var state = store.state;
    // init all modules
    installModule(store, state, [], store._modules.root, true);
    // reset vm
    resetStoreVM(store, state, hot);
  }

  function resetStoreVM (store, state, hot) {
    var oldVm = store._vm;

    // bind store public getters
    store.getters = {};
    // reset local getters cache
    store._makeLocalGettersCache = Object.create(null);
    var wrappedGetters = store._wrappedGetters;
    var computedObj = {};
    forEachValue(wrappedGetters, function (fn, key) {
      // TODO: Refactor following code and comment. We can simplify many things
      // using computed function.
      //
      // use computed to leverage its lazy-caching mechanism
      // direct inline function use will lead to closure preserving oldVm.
      // using partial to return function with only arguments preserved in closure environment.
      computedObj[key] = partial(fn, store);
      Object.defineProperty(store.getters, key, {
        get: function () { return vue.computed(function () { return computedObj[key](); }).value; },
        enumerable: true // for local getters
      });
    });

    // TODO: Bring back this if it's still needed.
    //
    // use a Vue instance to store the state tree
    // suppress warnings just in case the user has added
    // some funky global mixins
    // const silent = Vue.config.silent
    // Vue.config.silent = true

    // TODO: Refactor the code and remove this comment.
    //
    // New impl with reactive. Defining redundunt keys to make it as close as
    // the old impl api.
    store._vm = vue.reactive({
      _data: {
        $$state: state
      }
    });

    // TODO: Bring back maybe?
    //
    // Vue.config.silent = silent

    // enable strict mode for new vm
    if (store.strict) {
      enableStrictMode(store);
    }

    if (oldVm) {
      if (hot) {
        // dispatch changes in all subscribed watchers
        // to force getter re-evaluation for hot reloading.
        store._withCommit(function () {
          oldVm._data.$$state = null;
        });
      }
      // TODO: I think we don't need this anymore since we're not using vm?
      // Vue.nextTick(() => oldVm.$destroy())
    }
  }

  function installModule (store, rootState, path, module, hot) {
    var isRoot = !path.length;
    var namespace = store._modules.getNamespace(path);

    // register in namespace map
    if (module.namespaced) {
      if (store._modulesNamespaceMap[namespace] && "development" !== 'production') {
        console.error(("[vuex] duplicate namespace " + namespace + " for the namespaced module " + (path.join('/'))));
      }
      store._modulesNamespaceMap[namespace] = module;
    }

    // set state
    if (!isRoot && !hot) {
      var parentState = getNestedState(rootState, path.slice(0, -1));
      var moduleName = path[path.length - 1];
      store._withCommit(function () {
        {
          if (moduleName in parentState) {
            console.warn(
              ("[vuex] state field \"" + moduleName + "\" was overridden by a module with the same name at \"" + (path.join('.')) + "\"")
            );
          }
        }
        parentState[moduleName] = module.state;
      });
    }

    var local = module.context = makeLocalContext(store, namespace, path);

    module.forEachMutation(function (mutation, key) {
      var namespacedType = namespace + key;
      registerMutation(store, namespacedType, mutation, local);
    });

    module.forEachAction(function (action, key) {
      var type = action.root ? key : namespace + key;
      var handler = action.handler || action;
      registerAction(store, type, handler, local);
    });

    module.forEachGetter(function (getter, key) {
      var namespacedType = namespace + key;
      registerGetter(store, namespacedType, getter, local);
    });

    module.forEachChild(function (child, key) {
      installModule(store, rootState, path.concat(key), child, hot);
    });
  }

  /**
   * make localized dispatch, commit, getters and state
   * if there is no namespace, just use root ones
   */
  function makeLocalContext (store, namespace, path) {
    var noNamespace = namespace === '';

    var local = {
      dispatch: noNamespace ? store.dispatch : function (_type, _payload, _options) {
        var args = unifyObjectStyle(_type, _payload, _options);
        var payload = args.payload;
        var options = args.options;
        var type = args.type;

        if (!options || !options.root) {
          type = namespace + type;
          if (!store._actions[type]) {
            console.error(("[vuex] unknown local action type: " + (args.type) + ", global type: " + type));
            return
          }
        }

        return store.dispatch(type, payload)
      },

      commit: noNamespace ? store.commit : function (_type, _payload, _options) {
        var args = unifyObjectStyle(_type, _payload, _options);
        var payload = args.payload;
        var options = args.options;
        var type = args.type;

        if (!options || !options.root) {
          type = namespace + type;
          if (!store._mutations[type]) {
            console.error(("[vuex] unknown local mutation type: " + (args.type) + ", global type: " + type));
            return
          }
        }

        store.commit(type, payload, options);
      }
    };

    // getters and state object must be gotten lazily
    // because they will be changed by vm update
    Object.defineProperties(local, {
      getters: {
        get: noNamespace
          ? function () { return store.getters; }
          : function () { return makeLocalGetters(store, namespace); }
      },
      state: {
        get: function () { return getNestedState(store.state, path); }
      }
    });

    return local
  }

  function makeLocalGetters (store, namespace) {
    if (!store._makeLocalGettersCache[namespace]) {
      var gettersProxy = {};
      var splitPos = namespace.length;
      Object.keys(store.getters).forEach(function (type) {
        // skip if the target getter is not match this namespace
        if (type.slice(0, splitPos) !== namespace) { return }

        // extract local getter type
        var localType = type.slice(splitPos);

        // Add a port to the getters proxy.
        // Define as getter property because
        // we do not want to evaluate the getters in this time.
        Object.defineProperty(gettersProxy, localType, {
          get: function () { return store.getters[type]; },
          enumerable: true
        });
      });
      store._makeLocalGettersCache[namespace] = gettersProxy;
    }

    return store._makeLocalGettersCache[namespace]
  }

  function registerMutation (store, type, handler, local) {
    var entry = store._mutations[type] || (store._mutations[type] = []);
    entry.push(function wrappedMutationHandler (payload) {
      handler.call(store, local.state, payload);
    });
  }

  function registerAction (store, type, handler, local) {
    var entry = store._actions[type] || (store._actions[type] = []);
    entry.push(function wrappedActionHandler (payload) {
      var res = handler.call(store, {
        dispatch: local.dispatch,
        commit: local.commit,
        getters: local.getters,
        state: local.state,
        rootGetters: store.getters,
        rootState: store.state
      }, payload);
      if (!isPromise(res)) {
        res = Promise.resolve(res);
      }
      if (store._devtoolHook) {
        return res.catch(function (err) {
          store._devtoolHook.emit('vuex:error', err);
          throw err
        })
      } else {
        return res
      }
    });
  }

  function registerGetter (store, type, rawGetter, local) {
    if (store._wrappedGetters[type]) {
      {
        console.error(("[vuex] duplicate getter key: " + type));
      }
      return
    }
    store._wrappedGetters[type] = function wrappedGetter (store) {
      return rawGetter(
        local.state, // local state
        local.getters, // local getters
        store.state, // root state
        store.getters // root getters
      )
    };
  }

  function enableStrictMode (store) {
    vue.watch(function () { return store._vm._data.$$state; }, function () {
      {
        assert(store._committing, "do not mutate vuex store state outside mutation handlers.");
      }
    }, { deep: true, flush: 'sync' });
  }

  function getNestedState (state, path) {
    return path.reduce(function (state, key) { return state[key]; }, state)
  }

  function unifyObjectStyle (type, payload, options) {
    if (isObject(type) && type.type) {
      options = payload;
      payload = type;
      type = type.type;
    }

    {
      assert(typeof type === 'string', ("expects string as the type, but found " + (typeof type) + "."));
    }

    return { type: type, payload: payload, options: options }
  }

  /**
   * Reduce the code which written in Vue.js for getting the state.
   * @param {String} [namespace] - Module's namespace
   * @param {Object|Array} states # Object's item can be a function which accept state and getters for param, you can do something for state and getters in it.
   * @param {Object}
   */
  var mapState = normalizeNamespace(function (namespace, states) {
    var res = {};
    if (!isValidMap(states)) {
      console.error('[vuex] mapState: mapper parameter must be either an Array or an Object');
    }
    normalizeMap(states).forEach(function (ref) {
      var key = ref.key;
      var val = ref.val;

      res[key] = function mappedState () {
        var state = this.$store.state;
        var getters = this.$store.getters;
        if (namespace) {
          var module = getModuleByNamespace(this.$store, 'mapState', namespace);
          if (!module) {
            return
          }
          state = module.context.state;
          getters = module.context.getters;
        }
        return typeof val === 'function'
          ? val.call(this, state, getters)
          : state[val]
      };
      // mark vuex getter for devtools
      res[key].vuex = true;
    });
    return res
  });

  /**
   * Reduce the code which written in Vue.js for committing the mutation
   * @param {String} [namespace] - Module's namespace
   * @param {Object|Array} mutations # Object's item can be a function which accept `commit` function as the first param, it can accept anthor params. You can commit mutation and do any other things in this function. specially, You need to pass anthor params from the mapped function.
   * @return {Object}
   */
  var mapMutations = normalizeNamespace(function (namespace, mutations) {
    var res = {};
    if (!isValidMap(mutations)) {
      console.error('[vuex] mapMutations: mapper parameter must be either an Array or an Object');
    }
    normalizeMap(mutations).forEach(function (ref) {
      var key = ref.key;
      var val = ref.val;

      res[key] = function mappedMutation () {
        var args = [], len = arguments.length;
        while ( len-- ) args[ len ] = arguments[ len ];

        // Get the commit method from store
        var commit = this.$store.commit;
        if (namespace) {
          var module = getModuleByNamespace(this.$store, 'mapMutations', namespace);
          if (!module) {
            return
          }
          commit = module.context.commit;
        }
        return typeof val === 'function'
          ? val.apply(this, [commit].concat(args))
          : commit.apply(this.$store, [val].concat(args))
      };
    });
    return res
  });

  /**
   * Reduce the code which written in Vue.js for getting the getters
   * @param {String} [namespace] - Module's namespace
   * @param {Object|Array} getters
   * @return {Object}
   */
  var mapGetters = normalizeNamespace(function (namespace, getters) {
    var res = {};
    if (!isValidMap(getters)) {
      console.error('[vuex] mapGetters: mapper parameter must be either an Array or an Object');
    }
    normalizeMap(getters).forEach(function (ref) {
      var key = ref.key;
      var val = ref.val;

      // The namespace has been mutated by normalizeNamespace
      val = namespace + val;
      res[key] = function mappedGetter () {
        if (namespace && !getModuleByNamespace(this.$store, 'mapGetters', namespace)) {
          return
        }
        if (!(val in this.$store.getters)) {
          console.error(("[vuex] unknown getter: " + val));
          return
        }
        return this.$store.getters[val]
      };
      // mark vuex getter for devtools
      res[key].vuex = true;
    });
    return res
  });

  /**
   * Reduce the code which written in Vue.js for dispatch the action
   * @param {String} [namespace] - Module's namespace
   * @param {Object|Array} actions # Object's item can be a function which accept `dispatch` function as the first param, it can accept anthor params. You can dispatch action and do any other things in this function. specially, You need to pass anthor params from the mapped function.
   * @return {Object}
   */
  var mapActions = normalizeNamespace(function (namespace, actions) {
    var res = {};
    if (!isValidMap(actions)) {
      console.error('[vuex] mapActions: mapper parameter must be either an Array or an Object');
    }
    normalizeMap(actions).forEach(function (ref) {
      var key = ref.key;
      var val = ref.val;

      res[key] = function mappedAction () {
        var args = [], len = arguments.length;
        while ( len-- ) args[ len ] = arguments[ len ];

        // get dispatch function from store
        var dispatch = this.$store.dispatch;
        if (namespace) {
          var module = getModuleByNamespace(this.$store, 'mapActions', namespace);
          if (!module) {
            return
          }
          dispatch = module.context.dispatch;
        }
        return typeof val === 'function'
          ? val.apply(this, [dispatch].concat(args))
          : dispatch.apply(this.$store, [val].concat(args))
      };
    });
    return res
  });

  /**
   * Rebinding namespace param for mapXXX function in special scoped, and return them by simple object
   * @param {String} namespace
   * @return {Object}
   */
  var createNamespacedHelpers = function (namespace) { return ({
    mapState: mapState.bind(null, namespace),
    mapGetters: mapGetters.bind(null, namespace),
    mapMutations: mapMutations.bind(null, namespace),
    mapActions: mapActions.bind(null, namespace)
  }); };

  /**
   * Normalize the map
   * normalizeMap([1, 2, 3]) => [ { key: 1, val: 1 }, { key: 2, val: 2 }, { key: 3, val: 3 } ]
   * normalizeMap({a: 1, b: 2, c: 3}) => [ { key: 'a', val: 1 }, { key: 'b', val: 2 }, { key: 'c', val: 3 } ]
   * @param {Array|Object} map
   * @return {Object}
   */
  function normalizeMap (map) {
    if (!isValidMap(map)) {
      return []
    }
    return Array.isArray(map)
      ? map.map(function (key) { return ({ key: key, val: key }); })
      : Object.keys(map).map(function (key) { return ({ key: key, val: map[key] }); })
  }

  /**
   * Validate whether given map is valid or not
   * @param {*} map
   * @return {Boolean}
   */
  function isValidMap (map) {
    return Array.isArray(map) || isObject(map)
  }

  /**
   * Return a function expect two param contains namespace and map. it will normalize the namespace and then the param's function will handle the new namespace and the map.
   * @param {Function} fn
   * @return {Function}
   */
  function normalizeNamespace (fn) {
    return function (namespace, map) {
      if (typeof namespace !== 'string') {
        map = namespace;
        namespace = '';
      } else if (namespace.charAt(namespace.length - 1) !== '/') {
        namespace += '/';
      }
      return fn(namespace, map)
    }
  }

  /**
   * Search a special module from store by namespace. if module not exist, print error message.
   * @param {Object} store
   * @param {String} helper
   * @param {String} namespace
   * @return {Object}
   */
  function getModuleByNamespace (store, helper, namespace) {
    var module = store._modulesNamespaceMap[namespace];
    if (!module) {
      console.error(("[vuex] module namespace not found in " + helper + "(): " + namespace));
    }
    return module
  }

  var index = {
    version: '4.0.0-alpha.1',
    createStore: createStore,
    Store: Store,
    useStore: useStore,
    mapState: mapState,
    mapMutations: mapMutations,
    mapGetters: mapGetters,
    mapActions: mapActions,
    createNamespacedHelpers: createNamespacedHelpers
  };

  return index;

}));