Vue.js/dist/vue.runtime.js

/*!
 * Vue.js v2.0.5
 * (c) 2014-2016 Evan You
 * Released under the MIT License.
 */
(function (global, factory) {
  typeof exports === 'object' && typeof module !== 'undefined' ? module.exports = factory() :
  typeof define === 'function' && define.amd ? define(factory) :
  (global.Vue = factory());
}(this, (function () { 'use strict';

/*  */

/**
 * Convert a value to a string that is actually rendered.
 */
function _toString (val) {
  return val == null
    ? ''
    : typeof val === 'object'
      ? JSON.stringify(val, null, 2)
      : String(val)
}

/**
 * Convert a input value to a number for persistence.
 * If the conversion fails, return original string.
 */
function toNumber (val) {
  var n = parseFloat(val, 10);
  return (n || n === 0) ? n : val
}

/**
 * Make a map and return a function for checking if a key
 * is in that map.
 */
function makeMap (
  str,
  expectsLowerCase
) {
  var map = Object.create(null);
  var list = str.split(',');
  for (var i = 0; i < list.length; i++) {
    map[list[i]] = true;
  }
  return expectsLowerCase
    ? function (val) { return map[val.toLowerCase()]; }
    : function (val) { return map[val]; }
}

/**
 * Check if a tag is a built-in tag.
 */
var isBuiltInTag = makeMap('slot,component', true);

/**
 * Remove an item from an array
 */
function remove$1 (arr, item) {
  if (arr.length) {
    var index = arr.indexOf(item);
    if (index > -1) {
      return arr.splice(index, 1)
    }
  }
}

/**
 * Check whether the object has the property.
 */
var hasOwnProperty = Object.prototype.hasOwnProperty;
function hasOwn (obj, key) {
  return hasOwnProperty.call(obj, key)
}

/**
 * Check if value is primitive
 */
function isPrimitive (value) {
  return typeof value === 'string' || typeof value === 'number'
}

/**
 * Create a cached version of a pure function.
 */
function cached (fn) {
  var cache = Object.create(null);
  return function cachedFn (str) {
    var hit = cache[str];
    return hit || (cache[str] = fn(str))
  }
}

/**
 * Camelize a hyphen-delmited string.
 */
var camelizeRE = /-(\w)/g;
var camelize = cached(function (str) {
  return str.replace(camelizeRE, function (_, c) { return c ? c.toUpperCase() : ''; })
});

/**
 * Capitalize a string.
 */
var capitalize = cached(function (str) {
  return str.charAt(0).toUpperCase() + str.slice(1)
});

/**
 * Hyphenate a camelCase string.
 */
var hyphenateRE = /([^-])([A-Z])/g;
var hyphenate = cached(function (str) {
  return str
    .replace(hyphenateRE, '$1-$2')
    .replace(hyphenateRE, '$1-$2')
    .toLowerCase()
});

/**
 * Simple bind, faster than native
 */
function bind$1 (fn, ctx) {
  function boundFn (a) {
    var l = arguments.length;
    return l
      ? l > 1
        ? fn.apply(ctx, arguments)
        : fn.call(ctx, a)
      : fn.call(ctx)
  }
  // record original fn length
  boundFn._length = fn.length;
  return boundFn
}

/**
 * Convert an Array-like object to a real Array.
 */
function toArray (list, start) {
  start = start || 0;
  var i = list.length - start;
  var ret = new Array(i);
  while (i--) {
    ret[i] = list[i + start];
  }
  return ret
}

/**
 * Mix properties into target object.
 */
function extend (to, _from) {
  for (var key in _from) {
    to[key] = _from[key];
  }
  return to
}

/**
 * Quick object check - this is primarily used to tell
 * Objects from primitive values when we know the value
 * is a JSON-compliant type.
 */
function isObject (obj) {
  return obj !== null && typeof obj === 'object'
}

/**
 * Strict object type check. Only returns true
 * for plain JavaScript objects.
 */
var toString = Object.prototype.toString;
var OBJECT_STRING = '[object Object]';
function isPlainObject (obj) {
  return toString.call(obj) === OBJECT_STRING
}

/**
 * Merge an Array of Objects into a single Object.
 */
function toObject (arr) {
  var res = {};
  for (var i = 0; i < arr.length; i++) {
    if (arr[i]) {
      extend(res, arr[i]);
    }
  }
  return res
}

/**
 * Perform no operation.
 */
function noop () {}

/**
 * Always return false.
 */
var no = function () { return false; };

/**
 * Generate a static keys string from compiler modules.
 */
function genStaticKeys (modules) {
  return modules.reduce(function (keys, m) {
    return keys.concat(m.staticKeys || [])
  }, []).join(',')
}

/**
 * Check if two values are loosely equal - that is,
 * if they are plain objects, do they have the same shape?
 */
function looseEqual (a, b) {
  /* eslint-disable eqeqeq */
  return a == b || (
    isObject(a) && isObject(b)
      ? JSON.stringify(a) === JSON.stringify(b)
      : false
  )
  /* eslint-enable eqeqeq */
}

function looseIndexOf (arr, val) {
  for (var i = 0; i < arr.length; i++) {
    if (looseEqual(arr[i], val)) { return i }
  }
  return -1
}

/*  */

var config = {
  /**
   * Option merge strategies (used in core/util/options)
   */
  optionMergeStrategies: Object.create(null),

  /**
   * Whether to suppress warnings.
   */
  silent: false,

  /**
   * Whether to enable devtools
   */
  devtools: process.env.NODE_ENV !== 'production',

  /**
   * Error handler for watcher errors
   */
  errorHandler: null,

  /**
   * Ignore certain custom elements
   */
  ignoredElements: null,

  /**
   * Custom user key aliases for v-on
   */
  keyCodes: Object.create(null),

  /**
   * Check if a tag is reserved so that it cannot be registered as a
   * component. This is platform-dependent and may be overwritten.
   */
  isReservedTag: no,

  /**
   * Check if a tag is an unknown element.
   * Platform-dependent.
   */
  isUnknownElement: no,

  /**
   * Get the namespace of an element
   */
  getTagNamespace: noop,

  /**
   * Check if an attribute must be bound using property, e.g. value
   * Platform-dependent.
   */
  mustUseProp: no,

  /**
   * List of asset types that a component can own.
   */
  _assetTypes: [
    'component',
    'directive',
    'filter'
  ],

  /**
   * List of lifecycle hooks.
   */
  _lifecycleHooks: [
    'beforeCreate',
    'created',
    'beforeMount',
    'mounted',
    'beforeUpdate',
    'updated',
    'beforeDestroy',
    'destroyed',
    'activated',
    'deactivated'
  ],

  /**
   * Max circular updates allowed in a scheduler flush cycle.
   */
  _maxUpdateCount: 100,

  /**
   * Server rendering?
   */
  _isServer: process.env.VUE_ENV === 'server'
};

/*  */

/**
 * Check if a string starts with $ or _
 */
function isReserved (str) {
  var c = (str + '').charCodeAt(0);
  return c === 0x24 || c === 0x5F
}

/**
 * Define a property.
 */
function def (obj, key, val, enumerable) {
  Object.defineProperty(obj, key, {
    value: val,
    enumerable: !!enumerable,
    writable: true,
    configurable: true
  });
}

/**
 * Parse simple path.
 */
var bailRE = /[^\w.$]/;
function parsePath (path) {
  if (bailRE.test(path)) {
    return
  } else {
    var segments = path.split('.');
    return function (obj) {
      for (var i = 0; i < segments.length; i++) {
        if (!obj) { return }
        obj = obj[segments[i]];
      }
      return obj
    }
  }
}

/*  */
/* globals MutationObserver */

// can we use __proto__?
var hasProto = '__proto__' in {};

// Browser environment sniffing
var inBrowser =
  typeof window !== 'undefined' &&
  Object.prototype.toString.call(window) !== '[object Object]';

var UA = inBrowser && window.navigator.userAgent.toLowerCase();
var isIE = UA && /msie|trident/.test(UA);
var isIE9 = UA && UA.indexOf('msie 9.0') > 0;
var isEdge = UA && UA.indexOf('edge/') > 0;
var isAndroid = UA && UA.indexOf('android') > 0;
var isIOS = UA && /iphone|ipad|ipod|ios/.test(UA);

// detect devtools
var devtools = inBrowser && window.__VUE_DEVTOOLS_GLOBAL_HOOK__;

/* istanbul ignore next */
function isNative (Ctor) {
  return /native code/.test(Ctor.toString())
}

/**
 * Defer a task to execute it asynchronously.
 */
var nextTick = (function () {
  var callbacks = [];
  var pending = false;
  var timerFunc;

  function nextTickHandler () {
    pending = false;
    var copies = callbacks.slice(0);
    callbacks.length = 0;
    for (var i = 0; i < copies.length; i++) {
      copies[i]();
    }
  }

  // the nextTick behavior leverages the microtask queue, which can be accessed
  // via either native Promise.then or MutationObserver.
  // MutationObserver has wider support, however it is seriously bugged in
  // UIWebView in iOS >= 9.3.3 when triggered in touch event handlers. It
  // completely stops working after triggering a few times... so, if native
  // Promise is available, we will use it:
  /* istanbul ignore if */
  if (typeof Promise !== 'undefined' && isNative(Promise)) {
    var p = Promise.resolve();
    timerFunc = function () {
      p.then(nextTickHandler);
      // in problematic UIWebViews, Promise.then doesn't completely break, but
      // it can get stuck in a weird state where callbacks are pushed into the
      // microtask queue but the queue isn't being flushed, until the browser
      // needs to do some other work, e.g. handle a timer. Therefore we can
      // "force" the microtask queue to be flushed by adding an empty timer.
      if (isIOS) { setTimeout(noop); }
    };
  } else if (typeof MutationObserver !== 'undefined' && (
    isNative(MutationObserver) ||
    // PhantomJS and iOS 7.x
    MutationObserver.toString() === '[object MutationObserverConstructor]'
  )) {
    // use MutationObserver where native Promise is not available,
    // e.g. PhantomJS IE11, iOS7, Android 4.4
    var counter = 1;
    var observer = new MutationObserver(nextTickHandler);
    var textNode = document.createTextNode(String(counter));
    observer.observe(textNode, {
      characterData: true
    });
    timerFunc = function () {
      counter = (counter + 1) % 2;
      textNode.data = String(counter);
    };
  } else {
    // fallback to setTimeout
    /* istanbul ignore next */
    timerFunc = function () {
      setTimeout(nextTickHandler, 0);
    };
  }

  return function queueNextTick (cb, ctx) {
    var func = ctx
      ? function () { cb.call(ctx); }
      : cb;
    callbacks.push(func);
    if (!pending) {
      pending = true;
      timerFunc();
    }
  }
})();

var _Set;
/* istanbul ignore if */
if (typeof Set !== 'undefined' && isNative(Set)) {
  // use native Set when available.
  _Set = Set;
} else {
  // a non-standard Set polyfill that only works with primitive keys.
  _Set = (function () {
    function Set () {
      this.set = Object.create(null);
    }
    Set.prototype.has = function has (key) {
      return this.set[key] !== undefined
    };
    Set.prototype.add = function add (key) {
      this.set[key] = 1;
    };
    Set.prototype.clear = function clear () {
      this.set = Object.create(null);
    };

    return Set;
  }());
}

/* not type checking this file because flow doesn't play well with Proxy */

var hasProxy;
var proxyHandlers;
var initProxy;

if (process.env.NODE_ENV !== 'production') {
  var allowedGlobals = makeMap(
    'Infinity,undefined,NaN,isFinite,isNaN,' +
    'parseFloat,parseInt,decodeURI,decodeURIComponent,encodeURI,encodeURIComponent,' +
    'Math,Number,Date,Array,Object,Boolean,String,RegExp,Map,Set,JSON,Intl,' +
    'require' // for Webpack/Browserify
  );

  hasProxy =
    typeof Proxy !== 'undefined' &&
    Proxy.toString().match(/native code/);

  proxyHandlers = {
    has: function has (target, key) {
      var has = key in target;
      var isAllowed = allowedGlobals(key) || key.charAt(0) === '_';
      if (!has && !isAllowed) {
        warn(
          "Property or method \"" + key + "\" is not defined on the instance but " +
          "referenced during render. Make sure to declare reactive data " +
          "properties in the data option.",
          target
        );
      }
      return has || !isAllowed
    }
  };

  initProxy = function initProxy (vm) {
    if (hasProxy) {
      vm._renderProxy = new Proxy(vm, proxyHandlers);
    } else {
      vm._renderProxy = vm;
    }
  };
}

/*  */


var uid$2 = 0;

/**
 * A dep is an observable that can have multiple
 * directives subscribing to it.
 */
var Dep = function Dep () {
  this.id = uid$2++;
  this.subs = [];
};

Dep.prototype.addSub = function addSub (sub) {
  this.subs.push(sub);
};

Dep.prototype.removeSub = function removeSub (sub) {
  remove$1(this.subs, sub);
};

Dep.prototype.depend = function depend () {
  if (Dep.target) {
    Dep.target.addDep(this);
  }
};

Dep.prototype.notify = function notify () {
  // stablize the subscriber list first
  var subs = this.subs.slice();
  for (var i = 0, l = subs.length; i < l; i++) {
    subs[i].update();
  }
};

// the current target watcher being evaluated.
// this is globally unique because there could be only one
// watcher being evaluated at any time.
Dep.target = null;
var targetStack = [];

function pushTarget (_target) {
  if (Dep.target) { targetStack.push(Dep.target); }
  Dep.target = _target;
}

function popTarget () {
  Dep.target = targetStack.pop();
}

/*  */


var queue = [];
var has$1 = {};
var circular = {};
var waiting = false;
var flushing = false;
var index = 0;

/**
 * Reset the scheduler's state.
 */
function resetSchedulerState () {
  queue.length = 0;
  has$1 = {};
  if (process.env.NODE_ENV !== 'production') {
    circular = {};
  }
  waiting = flushing = false;
}

/**
 * Flush both queues and run the watchers.
 */
function flushSchedulerQueue () {
  flushing = true;

  // Sort queue before flush.
  // This ensures that:
  // 1. Components are updated from parent to child. (because parent is always
  //    created before the child)
  // 2. A component's user watchers are run before its render watcher (because
  //    user watchers are created before the render watcher)
  // 3. If a component is destroyed during a parent component's watcher run,
  //    its watchers can be skipped.
  queue.sort(function (a, b) { return a.id - b.id; });

  // do not cache length because more watchers might be pushed
  // as we run existing watchers
  for (index = 0; index < queue.length; index++) {
    var watcher = queue[index];
    var id = watcher.id;
    has$1[id] = null;
    watcher.run();
    // in dev build, check and stop circular updates.
    if (process.env.NODE_ENV !== 'production' && has$1[id] != null) {
      circular[id] = (circular[id] || 0) + 1;
      if (circular[id] > config._maxUpdateCount) {
        warn(
          'You may have an infinite update loop ' + (
            watcher.user
              ? ("in watcher with expression \"" + (watcher.expression) + "\"")
              : "in a component render function."
          ),
          watcher.vm
        );
        break
      }
    }
  }

  // devtool hook
  /* istanbul ignore if */
  if (devtools && config.devtools) {
    devtools.emit('flush');
  }

  resetSchedulerState();
}

/**
 * Push a watcher into the watcher queue.
 * Jobs with duplicate IDs will be skipped unless it's
 * pushed when the queue is being flushed.
 */
function queueWatcher (watcher) {
  var id = watcher.id;
  if (has$1[id] == null) {
    has$1[id] = true;
    if (!flushing) {
      queue.push(watcher);
    } else {
      // if already flushing, splice the watcher based on its id
      // if already past its id, it will be run next immediately.
      var i = queue.length - 1;
      while (i >= 0 && queue[i].id > watcher.id) {
        i--;
      }
      queue.splice(Math.max(i, index) + 1, 0, watcher);
    }
    // queue the flush
    if (!waiting) {
      waiting = true;
      nextTick(flushSchedulerQueue);
    }
  }
}

/*  */

var uid$1 = 0;

/**
 * A watcher parses an expression, collects dependencies,
 * and fires callback when the expression value changes.
 * This is used for both the $watch() api and directives.
 */
var Watcher = function Watcher (
  vm,
  expOrFn,
  cb,
  options
) {
  if ( options === void 0 ) options = {};

  this.vm = vm;
  vm._watchers.push(this);
  // options
  this.deep = !!options.deep;
  this.user = !!options.user;
  this.lazy = !!options.lazy;
  this.sync = !!options.sync;
  this.expression = expOrFn.toString();
  this.cb = cb;
  this.id = ++uid$1; // uid for batching
  this.active = true;
  this.dirty = this.lazy; // for lazy watchers
  this.deps = [];
  this.newDeps = [];
  this.depIds = new _Set();
  this.newDepIds = new _Set();
  // parse expression for getter
  if (typeof expOrFn === 'function') {
    this.getter = expOrFn;
  } else {
    this.getter = parsePath(expOrFn);
    if (!this.getter) {
      this.getter = function () {};
      process.env.NODE_ENV !== 'production' && warn(
        "Failed watching path: \"" + expOrFn + "\" " +
        'Watcher only accepts simple dot-delimited paths. ' +
        'For full control, use a function instead.',
        vm
      );
    }
  }
  this.value = this.lazy
    ? undefined
    : this.get();
};

/**
 * Evaluate the getter, and re-collect dependencies.
 */
Watcher.prototype.get = function get () {
  pushTarget(this);
  var value = this.getter.call(this.vm, this.vm);
  // "touch" every property so they are all tracked as
  // dependencies for deep watching
  if (this.deep) {
    traverse(value);
  }
  popTarget();
  this.cleanupDeps();
  return value
};

/**
 * Add a dependency to this directive.
 */
Watcher.prototype.addDep = function addDep (dep) {
  var id = dep.id;
  if (!this.newDepIds.has(id)) {
    this.newDepIds.add(id);
    this.newDeps.push(dep);
    if (!this.depIds.has(id)) {
      dep.addSub(this);
    }
  }
};

/**
 * Clean up for dependency collection.
 */
Watcher.prototype.cleanupDeps = function cleanupDeps () {
    var this$1 = this;

  var i = this.deps.length;
  while (i--) {
    var dep = this$1.deps[i];
    if (!this$1.newDepIds.has(dep.id)) {
      dep.removeSub(this$1);
    }
  }
  var tmp = this.depIds;
  this.depIds = this.newDepIds;
  this.newDepIds = tmp;
  this.newDepIds.clear();
  tmp = this.deps;
  this.deps = this.newDeps;
  this.newDeps = tmp;
  this.newDeps.length = 0;
};

/**
 * Subscriber interface.
 * Will be called when a dependency changes.
 */
Watcher.prototype.update = function update () {
  /* istanbul ignore else */
  if (this.lazy) {
    this.dirty = true;
  } else if (this.sync) {
    this.run();
  } else {
    queueWatcher(this);
  }
};

/**
 * Scheduler job interface.
 * Will be called by the scheduler.
 */
Watcher.prototype.run = function run () {
  if (this.active) {
    var value = this.get();
      if (
        value !== this.value ||
      // Deep watchers and watchers on Object/Arrays should fire even
      // when the value is the same, because the value may
      // have mutated.
      isObject(value) ||
      this.deep
    ) {
      // set new value
      var oldValue = this.value;
      this.value = value;
      if (this.user) {
        try {
          this.cb.call(this.vm, value, oldValue);
        } catch (e) {
          process.env.NODE_ENV !== 'production' && warn(
            ("Error in watcher \"" + (this.expression) + "\""),
            this.vm
          );
          /* istanbul ignore else */
          if (config.errorHandler) {
            config.errorHandler.call(null, e, this.vm);
          } else {
            throw e
          }
        }
      } else {
        this.cb.call(this.vm, value, oldValue);
      }
    }
  }
};

/**
 * Evaluate the value of the watcher.
 * This only gets called for lazy watchers.
 */
Watcher.prototype.evaluate = function evaluate () {
  this.value = this.get();
  this.dirty = false;
};

/**
 * Depend on all deps collected by this watcher.
 */
Watcher.prototype.depend = function depend () {
    var this$1 = this;

  var i = this.deps.length;
  while (i--) {
    this$1.deps[i].depend();
  }
};

/**
 * Remove self from all dependencies' subscriber list.
 */
Watcher.prototype.teardown = function teardown () {
    var this$1 = this;

  if (this.active) {
    // remove self from vm's watcher list
    // this is a somewhat expensive operation so we skip it
    // if the vm is being destroyed or is performing a v-for
    // re-render (the watcher list is then filtered by v-for).
    if (!this.vm._isBeingDestroyed && !this.vm._vForRemoving) {
      remove$1(this.vm._watchers, this);
    }
    var i = this.deps.length;
    while (i--) {
      this$1.deps[i].removeSub(this$1);
    }
    this.active = false;
  }
};

/**
 * Recursively traverse an object to evoke all converted
 * getters, so that every nested property inside the object
 * is collected as a "deep" dependency.
 */
var seenObjects = new _Set();
function traverse (val) {
  seenObjects.clear();
  _traverse(val, seenObjects);
}

function _traverse (val, seen) {
  var i, keys;
  var isA = Array.isArray(val);
  if ((!isA && !isObject(val)) || !Object.isExtensible(val)) {
    return
  }
  if (val.__ob__) {
    var depId = val.__ob__.dep.id;
    if (seen.has(depId)) {
      return
    }
    seen.add(depId);
  }
  if (isA) {
    i = val.length;
    while (i--) { _traverse(val[i], seen); }
  } else {
    keys = Object.keys(val);
    i = keys.length;
    while (i--) { _traverse(val[keys[i]], seen); }
  }
}

/*
 * not type checking this file because flow doesn't play well with
 * dynamically accessing methods on Array prototype
 */

var arrayProto = Array.prototype;
var arrayMethods = Object.create(arrayProto);[
  'push',
  'pop',
  'shift',
  'unshift',
  'splice',
  'sort',
  'reverse'
]
.forEach(function (method) {
  // cache original method
  var original = arrayProto[method];
  def(arrayMethods, method, function mutator () {
    var arguments$1 = arguments;

    // avoid leaking arguments:
    // http://jsperf.com/closure-with-arguments
    var i = arguments.length;
    var args = new Array(i);
    while (i--) {
      args[i] = arguments$1[i];
    }
    var result = original.apply(this, args);
    var ob = this.__ob__;
    var inserted;
    switch (method) {
      case 'push':
        inserted = args;
        break
      case 'unshift':
        inserted = args;
        break
      case 'splice':
        inserted = args.slice(2);
        break
    }
    if (inserted) { ob.observeArray(inserted); }
    // notify change
    ob.dep.notify();
    return result
  });
});

/*  */

var arrayKeys = Object.getOwnPropertyNames(arrayMethods);

/**
 * By default, when a reactive property is set, the new value is
 * also converted to become reactive. However when passing down props,
 * we don't want to force conversion because the value may be a nested value
 * under a frozen data structure. Converting it would defeat the optimization.
 */
var observerState = {
  shouldConvert: true,
  isSettingProps: false
};

/**
 * Observer class that are attached to each observed
 * object. Once attached, the observer converts target
 * object's property keys into getter/setters that
 * collect dependencies and dispatches updates.
 */
var Observer = function Observer (value) {
  this.value = value;
  this.dep = new Dep();
  this.vmCount = 0;
  def(value, '__ob__', this);
  if (Array.isArray(value)) {
    var augment = hasProto
      ? protoAugment
      : copyAugment;
    augment(value, arrayMethods, arrayKeys);
    this.observeArray(value);
  } else {
    this.walk(value);
  }
};

/**
 * Walk through each property and convert them into
 * getter/setters. This method should only be called when
 * value type is Object.
 */
Observer.prototype.walk = function walk (obj) {
  var keys = Object.keys(obj);
  for (var i = 0; i < keys.length; i++) {
    defineReactive$$1(obj, keys[i], obj[keys[i]]);
  }
};

/**
 * Observe a list of Array items.
 */
Observer.prototype.observeArray = function observeArray (items) {
  for (var i = 0, l = items.length; i < l; i++) {
    observe(items[i]);
  }
};

// helpers

/**
 * Augment an target Object or Array by intercepting
 * the prototype chain using __proto__
 */
function protoAugment (target, src) {
  /* eslint-disable no-proto */
  target.__proto__ = src;
  /* eslint-enable no-proto */
}

/**
 * Augment an target Object or Array by defining
 * hidden properties.
 *
 * istanbul ignore next
 */
function copyAugment (target, src, keys) {
  for (var i = 0, l = keys.length; i < l; i++) {
    var key = keys[i];
    def(target, key, src[key]);
  }
}

/**
 * Attempt to create an observer instance for a value,
 * returns the new observer if successfully observed,
 * or the existing observer if the value already has one.
 */
function observe (value) {
  if (!isObject(value)) {
    return
  }
  var ob;
  if (hasOwn(value, '__ob__') && value.__ob__ instanceof Observer) {
    ob = value.__ob__;
  } else if (
    observerState.shouldConvert &&
    !config._isServer &&
    (Array.isArray(value) || isPlainObject(value)) &&
    Object.isExtensible(value) &&
    !value._isVue
  ) {
    ob = new Observer(value);
  }
  return ob
}

/**
 * Define a reactive property on an Object.
 */
function defineReactive$$1 (
  obj,
  key,
  val,
  customSetter
) {
  var dep = new Dep();

  var property = Object.getOwnPropertyDescriptor(obj, key);
  if (property && property.configurable === false) {
    return
  }

  // cater for pre-defined getter/setters
  var getter = property && property.get;
  var setter = property && property.set;

  var childOb = observe(val);
  Object.defineProperty(obj, key, {
    enumerable: true,
    configurable: true,
    get: function reactiveGetter () {
      var value = getter ? getter.call(obj) : val;
      if (Dep.target) {
        dep.depend();
        if (childOb) {
          childOb.dep.depend();
        }
        if (Array.isArray(value)) {
          dependArray(value);
        }
      }
      return value
    },
    set: function reactiveSetter (newVal) {
      var value = getter ? getter.call(obj) : val;
      if (newVal === value) {
        return
      }
      if (process.env.NODE_ENV !== 'production' && customSetter) {
        customSetter();
      }
      if (setter) {
        setter.call(obj, newVal);
      } else {
        val = newVal;
      }
      childOb = observe(newVal);
      dep.notify();
    }
  });
}

/**
 * Set a property on an object. Adds the new property and
 * triggers change notification if the property doesn't
 * already exist.
 */
function set (obj, key, val) {
  if (Array.isArray(obj)) {
    obj.length = Math.max(obj.length, key);
    obj.splice(key, 1, val);
    return val
  }
  if (hasOwn(obj, key)) {
    obj[key] = val;
    return
  }
  var ob = obj.__ob__;
  if (obj._isVue || (ob && ob.vmCount)) {
    process.env.NODE_ENV !== 'production' && warn(
      'Avoid adding reactive properties to a Vue instance or its root $data ' +
      'at runtime - declare it upfront in the data option.'
    );
    return
  }
  if (!ob) {
    obj[key] = val;
    return
  }
  defineReactive$$1(ob.value, key, val);
  ob.dep.notify();
  return val
}

/**
 * Delete a property and trigger change if necessary.
 */
function del (obj, key) {
  var ob = obj.__ob__;
  if (obj._isVue || (ob && ob.vmCount)) {
    process.env.NODE_ENV !== 'production' && warn(
      'Avoid deleting properties on a Vue instance or its root $data ' +
      '- just set it to null.'
    );
    return
  }
  if (!hasOwn(obj, key)) {
    return
  }
  delete obj[key];
  if (!ob) {
    return
  }
  ob.dep.notify();
}

/**
 * Collect dependencies on array elements when the array is touched, since
 * we cannot intercept array element access like property getters.
 */
function dependArray (value) {
  for (var e = void 0, i = 0, l = value.length; i < l; i++) {
    e = value[i];
    e && e.__ob__ && e.__ob__.dep.depend();
    if (Array.isArray(e)) {
      dependArray(e);
    }
  }
}

/*  */

function initState (vm) {
  vm._watchers = [];
  initProps(vm);
  initData(vm);
  initComputed(vm);
  initMethods(vm);
  initWatch(vm);
}

function initProps (vm) {
  var props = vm.$options.props;
  if (props) {
    var propsData = vm.$options.propsData || {};
    var keys = vm.$options._propKeys = Object.keys(props);
    var isRoot = !vm.$parent;
    // root instance props should be converted
    observerState.shouldConvert = isRoot;
    var loop = function ( i ) {
      var key = keys[i];
      /* istanbul ignore else */
      if (process.env.NODE_ENV !== 'production') {
        defineReactive$$1(vm, key, validateProp(key, props, propsData, vm), function () {
          if (vm.$parent && !observerState.isSettingProps) {
            warn(
              "Avoid mutating a prop directly since the value will be " +
              "overwritten whenever the parent component re-renders. " +
              "Instead, use a data or computed property based on the prop's " +
              "value. Prop being mutated: \"" + key + "\"",
              vm
            );
          }
        });
      } else {
        defineReactive$$1(vm, key, validateProp(key, props, propsData, vm));
      }
    };

    for (var i = 0; i < keys.length; i++) loop( i );
    observerState.shouldConvert = true;
  }
}

function initData (vm) {
  var data = vm.$options.data;
  data = vm._data = typeof data === 'function'
    ? data.call(vm)
    : data || {};
  if (!isPlainObject(data)) {
    data = {};
    process.env.NODE_ENV !== 'production' && warn(
      'data functions should return an object.',
      vm
    );
  }
  // proxy data on instance
  var keys = Object.keys(data);
  var props = vm.$options.props;
  var i = keys.length;
  while (i--) {
    if (props && hasOwn(props, keys[i])) {
      process.env.NODE_ENV !== 'production' && warn(
        "The data property \"" + (keys[i]) + "\" is already declared as a prop. " +
        "Use prop default value instead.",
        vm
      );
    } else {
      proxy(vm, keys[i]);
    }
  }
  // observe data
  observe(data);
  data.__ob__ && data.__ob__.vmCount++;
}

var computedSharedDefinition = {
  enumerable: true,
  configurable: true,
  get: noop,
  set: noop
};

function initComputed (vm) {
  var<