vue/dist/vue.common.js

'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 (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 (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(',')
}

/*  */

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
    }
  }
}

/*  */

/* global MutationObserver */
// can we use __proto__?
var hasProto = '__proto__' in {}

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

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

// UA sniffing for working around browser-specific quirks
var UA = inBrowser && window.navigator.userAgent.toLowerCase()
var isIos = UA && /(iphone|ipad|ipod|ios)/i.test(UA)
var iosVersionMatch = UA && isIos && UA.match(/os ([\d_]+)/)
var iosVersion = iosVersionMatch && iosVersionMatch[1].split('_')

// MutationObserver is unreliable in iOS 9.3 UIWebView
// detecting it by checking presence of IndexedDB
// ref #3027
var hasMutationObserverBug =
  iosVersion &&
  Number(iosVersion[0]) >= 9 &&
  Number(iosVersion[1]) >= 3 &&
  !window.indexedDB

/**
 * Defer a task to execute it asynchronously. Ideally this
 * should be executed as a microtask, so we leverage
 * MutationObserver if it's available, and fallback to
 * setTimeout(0).
 *
 * @param {Function} cb
 * @param {Object} ctx
 */
var nextTick = (function () {
  var callbacks = []
  var pending = false
  var timerFunc
  function nextTickHandler () {
    pending = false
    var copies = callbacks.slice(0)
    callbacks = []
    for (var i = 0; i < copies.length; i++) {
      copies[i]()
    }
  }

  /* istanbul ignore else */
  if (typeof MutationObserver !== 'undefined' && !hasMutationObserverBug) {
    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 {
    // webpack attempts to inject a shim for setImmediate
    // if it is used as a global, so we have to work around that to
    // avoid bundling unnecessary code.
    var context = inBrowser
      ? window
      : typeof global !== 'undefined' ? global : {}
    timerFunc = context.setImmediate || setTimeout
  }
  return function (cb, ctx) {
    var func = ctx
      ? function () { cb.call(ctx) }
      : cb
    callbacks.push(func)
    if (pending) return
    pending = true
    timerFunc(nextTickHandler, 0)
  }
})()

var _Set
/* istanbul ignore if */
if (typeof Set !== 'undefined' && /native code/.test(Set.toString())) {
  // 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(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 = {}
var circular = {}
var waiting = false
var flushing = false
var index = 0

/**
 * Reset the scheduler's state.
 */
function resetSchedulerState () {
  queue.length = 0
  has = {}
  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[id] = null
    watcher.run()
    // in dev build, check and stop circular updates.
    if (process.env.NODE_ENV !== 'production' && has[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[id] == null) {
    has[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' subcriber 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(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, seen) {
  var i, keys
  if (!seen) {
    seen = seenObjects
    seen.clear()
  }
  var isA = Array.isArray(val)
  var isO = isObject(val)
  if ((isA || isO) && Object.isExtensible(val)) {
    if (val.__ob__) {
      var depId = val.__ob__.dep.id
      if (seen.has(depId)) {
        return
      } else {
        seen.add(depId)
      }
    }
    if (isA) {
      i = val.length
      while (i--) traverse(val[i], seen)
    } else if (isO) {
      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)

/**
 * Intercept mutating methods and emit events
 */
;[
  '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(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 (
  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)) {
          for (var e, i = 0, l = value.length; i < l; i++) {
            e = value[i]
            e && e.__ob__ && e.__ob__.dep.depend()
          }
        }
      }
      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.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(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()
}

/*  */

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

function initProps (vm) {
  var props = vm.$options.props
  var propsData = vm.$options.propsData
  if (props) {
    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(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(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 computed = vm.$options.computed
  if (computed) {
    for (var key in computed) {
      var userDef = computed[key]
      if (typeof userDef === 'function') {
        computedSharedDefinition.get = makeComputedGetter(userDef, vm)
        computedSharedDefinition.set = noop
      } else {
        computedSharedDefinition.get = userDef.get
          ? userDef.cache !== false
            ? makeComputedGetter(userDef.get, vm)
            : bind(userDef.get, vm)
          : noop
        computedSharedDefinition.set = userDef.set
          ? bind(userDef.set, vm)
          : noop
      }
      Object.defineProperty(vm, key, computedSharedDefinition)
    }
  }
}

function makeComputedGetter (getter, owner) {
  var watcher = new Watcher(owner, getter, noop, {
    lazy: true
  })
  return function computedGetter () {
    if (watcher.dirty) {
      watcher.evaluate()
    }
    if (Dep.target) {
      watcher.depend()
    }
    return watcher.value
  }
}

function initMethods (vm) {
  var methods = vm.$options.methods
  if (methods) {
    for (var key in methods) {
      if (methods[key] != null) {
        vm[key] = bind(methods[key], vm)
      } else if (process.env.NODE_ENV !== 'production') {
        warn(("Method \"" + key + "\" is undefined in options."), vm)
      }
    }
  }
}

function initWatch (vm) {
  var watch = vm.$options.watch
  if (watch) {
    for (var key in watch) {
      var handler = watch[key]
      if (Array.isArray(handler)) {
        for (var i = 0; i < handler.length; i++) {
          createWatcher(vm, key, handler[i])
        }
      } else {
        createWatcher(vm, key, handler)
      }
    }
  }
}

function createWatcher (vm, key, handler) {
  var options
  if (isPlainObject(handler)) {
    options = handler
    handler = handler.handler
  }
  if (typeof handler === 'string') {
    handler = vm[handler]
  }
  vm.$watch(key, handler, options)
}

function stateMixin (Vue) {
  // flow somehow has problems with directly declared definition object
  // when using Object.defineProperty, so we have to procedurally build up
  // the object here.
  var dataDef = {}
  dataDef.get = function () {
    return this._data
  }
  if (process.env.NODE_ENV !== 'production') {
    dataDef.set = function (newData) {
      warn(
        'Avoid replacing instance root $data. ' +
        'Use nested data properties instead.',
        this
      )
    }
  }
  Object.defineProperty(Vue.prototype, '$data', dataDef)

  Vue.prototype.$set = set
  Vue.prototype.$delete = del

  Vue.prototype.$watch = function (
    expOrFn,
    cb,
    options
  ) {
    var vm = this
    options = options || {}
    options.user = true
    var watcher = new Watcher(vm, expOrFn, cb, options)
    if (options.immediate) {
      cb.call(vm, watcher.value)
    }
    return function unwatchFn () {
      watcher.teardown()
    }
  }
}

function proxy (vm, key) {
  if (!isReserved(key)) {
    Object.defineProperty(vm, key, {
      configurable: true,
      enumerable: true,
      get: function proxyGetter () {
        return vm._data[key]
      },
      set: function proxySetter (val) {
        vm._data[key] = val
      }
    })
  }
}

/*  */

var VNode = function VNode (
  tag,
  data,
  children,
  text,
  elm,
  ns,
  context,
  componentOptions
) {
  this.tag = tag
  this.data = data
  this.children = children
  this.text = text
  this.elm = elm
  this.ns = ns
  this.context = context
  this.key = data && data.key
  this.componentOptions = componentOptions
  this.child = undefined
  this.parent = undefined
  this.raw = false
  this.isStatic = false
  this.isRootInsert = true
  this.isComment = false
  this.isCloned = false
  // apply construct hook.
  // this is applied during render, before patch happens.
  // unlike other hooks, this is applied on both client and server.
  var constructHook = data && data.hook && data.hook.construct
  if (constructHook) {
    constructHook(this)
  }
};

var emptyVNode = function () {
  var node = new VNode()
  node.text = ''
  node.isComment = true
  return node
}

// optimized shallow clone
// used for static nodes and slot nodes because they may be reused across
// multiple renders, cloning them avoids errors when DOM manipulations rely
// on their elm reference.
function cloneVNode (vnode) {
  var cloned = new VNode(
    vnode.tag,
    vnode.data,
    vnode.children,
    vnode.text,
    vnode.elm,
    vnode.ns,
    vnode.context,
    vnode.componentOptions
  )
  cloned.isStatic = vnode.isStatic
  cloned.key = vnode.key
  cloned.isCloned = true
  return cloned
}

function cloneVNodes (vnodes) {
  var res = new Array(vnodes.length)
  for (var i = 0; i < vnodes.length; i++) {
    res[i] = cloneVNode(vnodes[i])
  }
  return res
}

/*  */

function normalizeChildren (
  children,
  ns,
  nestedIndex
) {
  if (isPrimitive(children)) {
    return [createTextVNode(children)]
  }
  if (Array.isArray(children)) {
    var res = []
    for (var i = 0, l = children.length; i < l; i++) {
      var c = children[i]
      var last = res[res.length - 1]
      //  nested
      if (Array.isArray(c)) {
        res.push.apply(res, normalizeChildren(c, ns, i))
      } else if (isPrimitive(c)) {
        if (last && last.text) {
          last.text += String(c)
        } else if (c !== '') {
          // convert primitive to vnode
          res.push(createTextVNode(c))
        }
      } else if (c instanceof VNode) {
        if (c.text && last && last.text) {
          last.text += c.text
        } else {
          // inherit parent namespace
          if (ns) {
            applyNS(c, ns)
          }
          // default key for nested array children (likely generated by v-for)
          if (c.key == null && nestedIndex != null) {
            c.key = "__vlist_" + nestedIndex + "_" + i + "__"
          }
          res.push(c)
        }
      }
    }
    return res
  }
}

function createTextVNode (val) {
  return new VNode(undefined, undefined, undefined, String(val))
}

function applyNS (vnode, ns) {
  if (vnode.tag && !vnode.ns) {
    vnode.ns = ns
    if (vnode.children) {
      for (var i = 0, l = vnode.children.length; i < l; i++) {
        applyNS(vnode.children[i], ns)
      }
    }
  }
}

function getFirstComponentChild (children) {
  return children && children.filter(function (c) { return c && c.componentOptions; })[0]
}

function mergeVNodeHook (def, key, hook) {
  var oldHook = def[key]
  if (oldHook) {
    var injectedHash = def.__injected || (def.__injected = {})
    if (!injectedHash[key]) {
      injectedHash[key] = true
      def[key] = function () {
        oldHook.apply(this, arguments)
        hook.apply(this, arguments)
      }
    }
  } else {
    def[key] = hook
  }
}

function updateListeners (
  on,
  oldOn,
  add,
  remove
) {
  var name, cur, old, fn, event, capture
  for (name in on) {
    cur = on[name]
    old = oldOn[name]
    if (!cur) {
      process.env.NODE_ENV !== 'production' && warn(
        ("Handler for event \"" + name + "\" is undefined.")
      )
    } else if (!old) {
      capture = name.charAt(0) === '!'
      event = capture ? name.slice(1) : name
      if (Array.isArray(cur)) {
        add(event, (cur.invoker = arrInvoker(cur)), capture)
      } else {
        if (!cur.invoker) {
          fn = cur
          cur = on[name] = {}
          cur.fn = fn
          cur.invoker = fnInvoker(cur)
        }
        add(event, cur.invoker, capture)
      }
    } else if (cur !== old) {
      if (Array.isArray(old)) {
        old.length = cur.length
        for (var i = 0; i < old.length; i++) old[i] = cur[i]
        on[name] = old
      } else {
        old.fn = cur
        on[name] = old
      }
    }
  }
  for (name in oldOn) {
    if (!on[name]) {
      event = name.charAt(0) === '!' ? name.slice(1) : name
      remove(event, oldOn[name].invoker)
    }
  }
}

function arrInvoker (arr) {
  return function (ev) {
    var arguments$1 = arguments;

    var single = arguments.length === 1
    for (var i = 0; i < arr.length; i++) {
      single ? arr[i](ev) : arr[i].apply(null, arguments$1)
    }
  }
}

function fnInvoker (o) {
  return function (ev) {
    var single = arguments.length === 1
    single ? o.fn(ev) : o.fn.apply(null, arguments)
  }
}

/*  */

var activeInstance = null

function initLifecycle (vm) {
  var options = vm.$options

  // locate first non-abstract parent
  var parent = options.parent
  if (parent && !options.abstract) {
    while (parent.$options.abstract && parent.$parent) {
      parent = parent.$parent
    }
    parent.$children.push(vm)
  }

  vm.$parent = parent
  vm.$root = parent ? parent.$root : vm

  vm.$children = []
  vm.$refs = {}

  vm._watcher = null
  vm._inactive = false
  vm._isMounted = false
  vm._isDestroyed = false
  vm._isBeingDestroyed = false
}

function lifecycleMixin (Vue) {
  Vue.prototype._mount = function (
    el,
    hydrating
  ) {
    var vm = this
    vm.$el = el
    if (!vm.$options.render) {
      vm.$options.render = emptyVNode
      if (process.env.NODE_ENV !== 'production') {
        /* istanbul ignore if */
        if (vm.$options.template) {
          warn(
            'You are using the runtime-only build of Vue where the template ' +
            'option is not available. Either pre-compile the templates into ' +
            'render functions, or use the compiler-included build.',
            vm
          )
        } else {
          warn(
            'Failed to mount component: template or render function not defined.',
            vm
          )
        }
      }
    }
    callHook(vm, 'beforeMount')
    vm._watcher = new Watcher(vm, function () {
      vm._update(vm._render(), hydrating)
    }, noop)
    hydrating = false
    // root instance, call mounted on self
    // mounted is called for child components in its inserted hook
    if (vm.$root === vm) {
      vm._isMounted = true
      callHook(vm, 'mounted')
    }
    return vm
  }

  Vue.prototype._update = function (vnode, hydrating) {
    var vm = this
    if (vm._isMounted) {
      callHook(vm, 'beforeUpdate')
    }
    var prevEl = vm.$el
    var prevActiveInstance = activeInstance
    activeInstance = vm
    var prevVnode = vm._vnode
    vm._vnode = vnode
    if (!prevVnode) {
      // Vue.prototype.__patch__ is injected in entry points
      // based on the rendering backend used.
      vm.$el = vm.__patch__(vm.$el, vnode, hydrating)
    } else {
      vm.$el = vm.__patch__(prevVnode, vnode)
    }
    activeInstance = prevActiveInstance
    // update __vue__ reference
    if (prevEl) {
      prevEl.__vue__ = null
    }
    if (vm.$el) {
      vm.$el.__vue__ = vm
    }
    // if parent is an HOC, update its $el as well
    if (vm.$vnode && vm.$parent && vm.$vnode === vm.$parent._vnode) {
      vm.$parent.$el = vm.$el
    }
    if (vm._isMounted) {
      callHook(vm, 'updated')
    }
  }

  Vue.prototype._updateFromParent = function (
    propsData,
    listeners,
    parentVnode,
    renderChildren
  ) {
    var vm = this
    var hasChildren = !!(vm.$options._renderChildren || renderChildren)
    vm.$options._parentVnode = parentVnode
    vm.$options._renderChildren = renderChildren
    // update props
    if (propsData && vm.$options.props) {
      observerState.shouldConvert = false
      if (process.env.NODE_ENV !== 'production') {
        observerState.isSettingProps = true
      }
      var propKeys = vm.$options._propKeys || []
      for (var i = 0; i < propKeys.length; i++) {
        var key = propKeys[i]
        vm[key] = validateProp(key, vm.$options.props, propsData, vm)
      }
      observerState.shouldConvert = true
      if (process.env.NODE_ENV !== 'production') {
        observerState.isSettingProps = false
      }
    }
    // update listeners
    if (listeners) {
      var oldListeners = vm.$options._parentListeners
      vm.$options._parentListeners = listeners
      vm._updateListeners(listeners, oldListeners)
    }
    // resolve slots + force update if has children
    if (hasChildren) {
      vm.$slots = resolveSlots(renderChildren)
      vm.$forceUpdate()
    }
  }

  Vue.prototype.$forceUpdate = function () {
    var vm = this
    if (vm._watcher) {
      vm._watcher.update()
    }
  }

  Vue.prototype.$destroy = function () {
    var vm = this
    if (vm._isBeingDestroyed) {
      return
    }
    callHook(vm, 'beforeDestroy')
    vm._isBeingDestroyed = true
    // remove self from parent
    var parent = vm.$parent
    if (parent && !parent._isBeingDestroyed && !vm.$options.abstract) {
      remove(parent.$children, vm)
    }
    // teardown watchers
    if (vm._watcher) {
      vm._watcher.teardown()
    }
    var i = vm._watchers.length
    while (i--) {
      vm._watchers[i].teardown()
    }
    // remove reference from data ob
    // frozen object may not have observer.
    if (vm._data.__ob__) {
      vm._data.__ob__.vmCount--
    }
    // call the last hook...
    vm._isDestroyed = true
    callHook(vm, 'destroyed')
    // turn off all instance listeners.
    vm.$off()
    // remove __vue__ reference
    if (vm.$el) {
      vm.$el.__vue__ = null
    }
  }
}

function callHook (vm, hook) {
  var handlers = vm.$options[hook]
  if (handlers) {
    for (var i = 0, j = handlers.length; i < j; i++) {
      handlers[i].call(vm)
    }
  }
  vm.$emit('hook:' + hook)
}

/*  */

var hooks = { init: init, prepatch: prepatch, insert: insert, destroy: destroy }
var hooksToMerge = Object.keys(hooks)

function createComponent (
  Ctor,
  data,
  context,
  children,
  tag
) {
  if (!Ctor) {
    return
  }

  if (isObject(Ctor)) {
    Ctor = Vue.extend(Ctor)
  }

  if (typeof Ctor !== 'function') {
    if (process.env.NODE_ENV !== 'production') {
      warn(("Invalid Component definition: " + (String(Ctor))), context)
    }
    return
  }

  // async component
  if (!Ctor.cid) {
    if (Ctor.resolved) {
      Ctor = Ctor.resolved
    } else {
      Ctor = resolveAsyncComponent(Ctor, function () {
        // it's ok to queue this on every render because
        // $forceUpdate is buffered by the scheduler.
        context.$forceUpdate()
      })
      if (!Ctor) {
        // return nothing if this is indeed an async component
        // wait for the callback to trigger parent update.
        return
      }
    }
  }

  data = data || {}

  // extract props
  var propsData = extractProps(data, Ctor)

  // functional component
  if (Ctor.options.functional) {
    return createFunctionalComponent(Ctor, propsData, data, context, children)
  }

  // extract listeners, since these needs to be treated as
  // child component listeners instead of DOM listeners
  var listeners = data.on
  // replace with listeners with .native modifier
  data.on = data.nativeOn

  if (Ctor.options.abstract) {
    // abstract components do not keep anything
    // other than props & listeners
    data = {}
  }

  // merge component management hooks onto the placeholder node
  mergeHooks(data)

  // return a placeholder vnode
  var name = Ctor.options.name || tag
  var vnode = new VNode(
    ("vue-component-" + (Ctor.cid) + (name ? ("-" + name) : '')),
    data, undefined, undefined, undefined, undefined, context,
    { Ctor: Ctor, propsData: propsData, listeners: listeners, tag: tag, children: children }
  )
  return vnode
}

function createFunctionalComponent (
  Ctor,
  propsData,
  data,
  context,
  children
) {
  var props = {}
  var propOptions = Ctor.options.props
  if (propOptions) {
    for (var key in propOptions) {
      props[key] = validateProp(key, propOptions, propsData)
    }
  }
  return Ctor.options.render.call(
    null,
    context.$createElement,
    {
      props: props,
      data: data,
      parent: context,
      children: normalizeChildren(children),
      slots: function () { return resolveSlots(children); }
    }
  )
}

function createComponentInstanceForVnode (
  vnode, // we know it's MountedComponentVNode but flow doesn't
  parent // activeInstance in lifecycle state
) {
  var vnodeComponentOptions = vnode.componentOptions
  var options = {
    _isComponent: true,
    parent: parent,
    propsData: vnodeComponentOptions.propsData,
    _componentTag: vnodeComponentOptions.tag,
    _parentVnode: vnode,
    _parentListeners: vnodeComponentOptions.listeners,
    _renderChildren: vnodeComponentOptions.children
  }
  // check inline-template render functions
  var inlineTemplate = vnode.data.inlineTemplate
  if (inlineTemplate) {
    options.render = inlineTemplate.render
    options.staticRenderFns = inlineTemplate.staticRenderFns
  }
  return new vnodeComponentOptions.Ctor(options)
}

function init (vnode, hydrating) {
  if (!vnode.child || vnode.child._isDestroyed) {
    var child = vnode.child = createComponentInstanceForVnode(vnode, activeInstance)
    child.$mount(hydrating ? vnode.elm : undefined, hydrating)
  }
}

function prepatch (
  oldVnode,
  vnode
) {
  var options = vnode.componentOptions
  var child = vnode.child = oldVnode.child
  child._updateFromParent(
    options.propsData, // updated props
    options.listeners, // updated listeners
    vnode, // new parent vnode
    options.children // new children
  )
}

function insert (vnode) {
  if (!vnode.child._isMounted) {
    vnode.child._isMounted = true
    callHook(vnode.child, 'mounted')
  }
  if (vnode.data.keepAlive) {
    vnode.child._inactive = false
    callHook(vnode.child, 'activated')
  }
}

function destroy (vnode) {
  if (!vnode.child._isDestroyed) {
    if (!vnode.data.keepAlive) {
      vnode.child.$destroy()
    } else {
      vnode.child._inactive = true
      callHook(vnode.child, 'deactivated')
    }
  }
}

function resolveAsyncComponent (
  factory,
  cb
) {
  if (factory.requested) {
    // pool callbacks
    factory.pendingCallbacks.push(cb)
  } else {
    factory.requested = true
    var cbs = factory.pendingCallbacks = [cb]
    var sync = true

    var resolve = function (res) {
      if (isObject(res)) {
        res = Vue.extend(res)
      }
      // cache resolved
      factory.resolved = res
      // invoke callbacks only if this is not a synchronous resolve
      // (async resolves are shimmed as synchronous during SSR)
      if (!sync) {
        for (var i = 0, l = cbs.length; i < l; i++) {
          cbs[i](res)
        }
      }
    }

    var reject = function (reason) {
      process.env.NODE_ENV !== 'production' && warn(
        "Failed to resolve async component: " + (String(factory)) +
        (reason ? ("\nReason: " + reason) : '')
      )
    }

    var res = factory(resolve, reject)

    // handle promise
    if (res && typeof res.then === 'function' && !factory.resolved) {
      res.then(resolve, reject)
    }

    sync = false
    // return in case resolved synchronously
    return factory.resolved
  }
}

function extractProps (data, Ctor) {
  // we are only extrating raw values here.
  // validation and default values are handled in the child
  // component itself.
  var propOptions = Ctor.options.props
  if (!propOptions) {
    return
  }
  var res = {}
  var attrs = data.attrs;
  var props = data.props;
  var domProps = data.domProps;
  if (attrs || props || domProps) {
    for (var key in propOptions) {
      var altKey = hyphenate(key)
      checkProp(res, props, key, altKey, true) ||
      checkProp(res, attrs, key, altKey) ||
      checkProp(res, domProps, key, altKey)
    }
  }
  return res
}

function checkProp (
  res,
  hash,
  key,
  altKey,
  preserve
) {
  if (hash) {
    if (hasOwn(hash, key)) {
      res[key] = hash[key]
      if (!preserve) {
        delete hash[key]
      }
      return true
    } else if (hasOwn(hash, altKey)) {
      res[key] = hash[altKey]
      if (!preserve) {
        delete hash[altKey]
      }
      return true
    }
  }
  return false
}

function mergeHooks (data) {
  if (!data.hook) {
    data.hook = {}
  }
  for (var i = 0; i < hooksToMerge.length; i++) {
    var key = hooksToMerge[i]
    var fromParent = data.hook[key]
    var ours = hooks[key]
    data.hook[key] = fromParent ? mergeHook$1(ours, fromParent) : ours
  }
}

function mergeHook$1 (a, b) {
  // since all hooks have at most two args, use fixed args
  // to avoid having to use fn.apply().
  return function (_, __) {
    a(_, __)
    b(_, __)
  }
}

/*  */

// wrapper function for providing a more flexible interface
// without getting yelled at by flow
function createElement (
  tag,
  data,
  children
) {
  if (data && (Array.isArray(data) || typeof data !== 'object')) {
    children = data
    data = undefined
  }
  // make sure to use real instance instead of proxy as context
  return _createElement(this._self, tag, data, children)
}

function _createElement (
  context,
  tag,
  data,
  children
) {
  if (data && data.__ob__) {
    process.env.NODE_ENV !== 'production' && warn(
      "Avoid using observed data object as vnode data: " + (JSON.stringify(data)) + "\n" +
      'Always create fresh vnode data objects in each render!',
      context
    )
    return
  }
  if (!tag) {
    // in case of component :is set to falsy value
    return emptyVNode()
  }
  if (typeof tag === 'string') {
    var Ctor
    var ns = config.getTagNamespace(tag)
    if (config.isReservedTag(tag)) {
      // platform built-in elements
      return new VNode(
        tag, data, normalizeChildren(children, ns),
        undefined, undefined, ns, context
      )
    } else if ((Ctor = resolveAsset(context.$options, 'components', tag))) {
      // component
      return createComponent(Ctor, data, context, children, tag)
    } else {
      // unknown or unlisted namespaced elements
      // check at runtime because it may get assigned a namespace when its
      // parent normalizes children
      return new VNode(
        tag, data, normalizeChildren(children, ns),
        undefined, undefined, ns, context
      )
    }
  } else {
    // direct component options / constructor
    return createComponent(tag, data, context, children)
  }
}

/*  */

function initRender (vm) {
  vm.$vnode = null // the placeholder node in parent tree
  vm._vnode = null // the root of the child tree
  vm._staticTrees = null
  vm.$slots = resolveSlots(vm.$options._renderChildren)
  // bind the public createElement fn to this instance
  // so that we get proper render context inside it.
  vm.$createElement = bind(createElement, vm)
  if (vm.$options.el) {
    vm.$mount(vm.$options.el)
  }
}

function renderMixin (Vue) {
  Vue.prototype.$nextTick = function (fn) {
    nextTick(fn, this)
  }

  Vue.prototype._render = function () {
    var vm = this
    var ref = vm.$options;
    var render = ref.render;
    var staticRenderFns = ref.staticRenderFns;
    var _parentVnode = ref._parentVnode;

    if (vm._isMounted) {
      // clone slot nodes on re-renders
      for (var key in vm.$slots) {
        vm.$slots[key] = cloneVNodes(vm.$slots[key])
      }
    }

    if (staticRenderFns && !vm._staticTrees) {
      vm._staticTrees = []
    }
    // set parent vnode. this allows render functions to have access
    // to the data on the placeholder node.
    vm.$vnode = _parentVnode
    // render self
    var vnode
    try {
      vnode = render.call(vm._renderProxy, vm.$createElement)
    } catch (e) {
      if (process.env.NODE_ENV !== 'production') {
        warn(("Error when rendering " + (formatComponentName(vm)) + ":"))
      }
      /* istanbul ignore else */
      if (config.errorHandler) {
        config.errorHandler.call(null, e, vm)
      } else {
        if (config._isServer) {
          throw e
        } else {
          setTimeout(function () { throw e }, 0)
        }
      }
      // return previous vnode to prevent render error causing blank component
      vnode = vm._vnode
    }
    // return empty vnode in case the render function errored out
    if (!(vnode instanceof VNode)) {
      if (process.env.NODE_ENV !== 'production' && Array.isArray(vnode)) {
        warn(
          'Multiple root nodes returned from render function. Render function ' +
          'should return a single root node.',
          vm
        )
      }
      vnode = emptyVNode()
    }
    // set parent
    vnode.parent = _parentVnode
    return vnode
  }

  // shorthands used in render functions
  Vue.prototype._h = createElement
  // toString for mustaches
  Vue.prototype._s = _toString
  // number conversion
  Vue.prototype._n = toNumber
  // empty vnode
  Vue.prototype._e = emptyVNode

  // render static tree by index
  Vue.prototype._m = function renderStatic (
    index,
    isInFor
  ) {
    var tree = this._staticTrees[index]
    // if has already-rendered static tree and not inside v-for,
    // we can reuse the same tree by doing a shallow clone.
    if (tree && !isInFor) {
      return Array.isArray(tree)
        ? cloneVNodes(tree)
        : cloneVNode(tree)
    }
    // otherwise, render a fresh tree.
    tree = this._staticTrees[index] = this.$options.staticRenderFns[index].call(this._renderProxy)
    if (Array.isArray(tree)) {
      for (var i = 0; i < tree.length; i++) {
        tree[i].isStatic = true
        tree[i].key = "__static__" + index + "_" + i
      }
    } else {
      tree.isStatic = true
      tree.key = "__static__" + index
    }
    return tree
  }

  // filter resolution helper
  var identity = function (_) { return _; }
  Vue.prototype._f = function resolveFilter (id) {
    return resolveAsset(this.$options, 'filters', id, true) || identity
  }

  // render v-for
  Vue.prototype._l = function renderList (
    val,
    render
  ) {
    var ret, i, l, keys, key
    if (Array.isArray(val)) {
      ret = new Array(val.length)
      for (i = 0, l = val.length; i < l; i++) {
        ret[i] = render(val[i], i)
      }
    } else if (typeof val === 'number') {
      ret = new Array(val)
      for (i = 0; i < val; i++) {
        ret[i] = render(i + 1, i)
      }
    } else if (isObject(val)) {
      keys = Object.keys(val)
      ret = new Array(keys.length)
      for (i = 0, l = keys.length; i < l; i++) {
        key = keys[i]
        ret[i] = render(val[key], key, i)
      }
    }
    return ret
  }

  // renderSlot
  Vue.prototype._t = function (
    name,
    fallback
  ) {
    var slotNodes = this.$slots[name]
    // warn duplicate slot usage
    if (slotNodes && process.env.NODE_ENV !== 'production') {
      slotNodes._rendered && warn(
        "Duplicate presence of slot \"" + name + "\" found in the same render tree " +
        "- this will likely cause render errors.",
        this
      )
      slotNodes._rendered = true
    }
    return slotNodes || fallback
  }

  // apply v-bind object
  Vue.prototype._b = function bindProps (
    vnode,
    value,
    asProp) {
    if (value) {
      if (!isObject(value)) {
        process.env.NODE_ENV !== 'production' && warn(
          'v-bind without argument expects an Object or Array value',
          this
        )
      } else {
        if (Array.isArray(value)) {
          value = toObject(value)
        }
        var data = vnode.data
        for (var key in value) {
          if (key === 'class' || key === 'style') {
            data[key] = value[key]
          } else {
            var hash = asProp || config.mustUseProp(key)
              ? data.domProps || (data.domProps = {})
              : data.attrs || (data.attrs = {})
            hash[key] = value[key]
          }
        }
      }
    }
  }

  // expose v-on keyCodes
  Vue.prototype._k = function getKeyCodes (key) {
    return config.keyCodes[key]
  }
}

function resolveSlots (
  renderChildren
) {
  var slots = {}
  if (!renderChildren) {
    return slots
  }
  var children = normalizeChildren(renderChildren) || []
  var defaultSlot = []
  var name, child
  for (var i = 0, l = children.length; i < l; i++) {
    child = children[i]
    if (child.data && (name = child.data.slot)) {
      delete child.data.slot
      var slot = (slots[name] || (slots[name] = []))
      if (child.tag === 'template') {
        slot.push.apply(slot, child.children)
      } else {
        slot.push(child)
      }
    } else {
      defaultSlot.push(child)
    }
  }
  // ignore single whitespace
  if (defaultSlot.length && !(
    defaultSlot.length === 1 &&
    (defaultSlot[0].text === ' ' || defaultSlot[0].isComment)
  )) {
    slots.default = defaultSlot
  }
  return slots
}

/*  */

function initEvents (vm) {
  vm._events = Object.create(null)
  // init parent attached events
  var listeners = vm.$options._parentListeners
  var on = bind(vm.$on, vm)
  var off = bind(vm.$off, vm)
  vm._updateListeners = function (listeners, oldListeners) {
    updateListeners(listeners, oldListeners || {}, on, off)
  }
  if (listeners) {
    vm._updateListeners(listeners)
  }
}

function eventsMixin (Vue) {
  Vue.prototype.$on = function (event, fn) {
    var vm = this
    ;(vm._events[event] || (vm._events[event] = [])).push(fn)
    return vm
  }

  Vue.prototype.$once = function (event, fn) {
    var vm = this
    function on () {
      vm.$off(event, on)
      fn.apply(vm, arguments)
    }
    on.fn = fn
    vm.$on(event, on)
    return vm
  }

  Vue.prototype.$off = function (event, fn) {
    var vm = this
    // all
    if (!arguments.length) {
      vm._events = Object.create(null)
      return vm
    }
    // specific event
    var cbs = vm._events[event]
    if (!cbs) {
      return vm
    }
    if (arguments.length === 1) {
      vm._events[event] = null
      return vm
    }
    // specific handler
    var cb
    var i = cbs.length
    while (i--) {
      cb = cbs[i]
      if (cb === fn || cb.fn === fn) {
        cbs.splice(i, 1)
        break
      }
    }
    return vm
  }

  Vue.prototype.$emit = function (event) {
    var vm = this
    var cbs = vm._events[event]
    if (cbs) {
      cbs = cbs.length > 1 ? toArray(cbs) : cbs
      var args = toArray(arguments, 1)
      for (var i = 0, l = cbs.length; i < l; i++) {
        cbs[i].apply(vm, args)
      }
    }
    return vm
  }
}

/*  */

var uid = 0

function initMixin (Vue) {
  Vue.prototype._init = function (options) {
    var vm = this
    // a uid
    vm._uid = uid++
    // a flag to avoid this being observed
    vm._isVue = true
    // merge options
    if (options && options._isComponent) {
      // optimize internal component instantiation
      // since dynamic options merging is pretty slow, and none of the
      // internal component options needs special treatment.
      initInternalComponent(vm, options)
    } else {
      vm.$options = mergeOptions(
        resolveConstructorOptions(vm),
        options || {},
        vm
      )
    }
    /* istanbul ignore else */
    if (process.env.NODE_ENV !== 'production') {
      initProxy(vm)
    } else {
      vm._renderProxy = vm
    }
    // expose real self
    vm._self = vm
    initLifecycle(vm)
    initEvents(vm)
    callHook(vm, 'beforeCreate')
    initState(vm)
    callHook(vm, 'created')
    initRender(vm)
  }

  function initInternalComponent (vm, options) {
    var opts = vm.$options = Object.create(resolveConstructorOptions(vm))
    // doing this because it's faster than dynamic enumeration.
    opts.parent = options.parent
    opts.propsData = options.propsData
    opts._parentVnode = options._parentVnode
    opts._parentListeners = options._parentListeners
    opts._renderChildren = options._renderChildren
    opts._componentTag = options._componentTag
    if (options.render) {
      opts.render = options.render
      opts.staticRenderFns = options.staticRenderFns
    }
  }

  function resolveConstructorOptions (vm) {
    var Ctor = vm.constructor
    var options = Ctor.options
    if (Ctor.super) {
      var superOptions = Ctor.super.options
      var cachedSuperOptions = Ctor.superOptions
      if (superOptions !== cachedSuperOptions) {
        // super option changed
        Ctor.superOptions = superOptions
        options = Ctor.options = mergeOptions(superOptions, Ctor.extendOptions)
        if (options.name) {
          options.components[options.name] = Ctor
        }
      }
    }
    return options
  }
}

function Vue (options) {
  this._init(options)
}

initMixin(Vue)
stateMixin(Vue)
eventsMixin(Vue)
lifecycleMixin(Vue)
renderMixin(Vue)

var warn
var formatComponentName

if (process.env.NODE_ENV !== 'production') {
  var hasConsole = typeof console !== 'undefined'

  warn = function (msg, vm) {
    if (hasConsole && (!config.silent)) {
      console.error("[Vue warn]: " + msg + " " + (
        vm ? formatLocation(formatComponentName(vm)) : ''
      ))
    }
  }

  formatComponentName = function (vm) {
    if (vm.$root === vm) {
      return 'root instance'
    }
    var name = vm._isVue
      ? vm.$options.name || vm.$options._componentTag
      : vm.name
    return name ? ("component <" + name + ">") : "anonymous component"
  }

  var formatLocation = function (str) {
    if (str === 'anonymous component') {
      str += " - use the \"name\" option for better debugging messages."
    }
    return ("(found in " + str + ")")
  }
}

/*  */

/**
 * Option overwriting strategies are functions that handle
 * how to merge a parent option value and a child option
 * value into the final value.
 */
var strats = config.optionMergeStrategies

/**
 * Options with restrictions
 */
if (process.env.NODE_ENV !== 'production') {
  strats.el = strats.propsData = function (parent, child, vm, key) {
    if (!vm) {
      warn(
        "option \"" + key + "\" can only be used during instance " +
        'creation with the `new` keyword.'
      )
    }
    return defaultStrat(parent, child)
  }

  strats.name = function (parent, child, vm) {
    if (vm && child) {
      warn(
        'options "name" can only be used as a component definition option, ' +
        'not during instance creation.'
      )
    }
    return defaultStrat(parent, child)
  }
}

/**
 * Helper that recursively merges two data objects together.
 */
function mergeData (to, from) {
  var key, toVal, fromVal
  for (key in from) {
    toVal = to[key]
    fromVal = from[key]
    if (!hasOwn(to, key)) {
      set(to, key, fromVal)
    } else if (isObject(toVal) && isObject(fromVal)) {
      mergeData(toVal, fromVal)
    }
  }
  return to
}

/**
 * Data
 */
strats.data = function (
  parentVal,
  childVal,
  vm
) {
  if (!vm) {
    // in a Vue.extend merge, both should be functions
    if (!childVal) {
      return parentVal
    }
    if (typeof childVal !== 'function') {
      process.env.NODE_ENV !== 'production' && warn(
        'The "data" option should be a function ' +
        'that returns a per-instance value in component ' +
        'definitions.',
        vm
      )
      return parentVal
    }
    if (!parentVal) {
      return childVal
    }
    // when parentVal & childVal are both present,
    // we need to return a function that returns the
    // merged result of both functions... no need to
    // check if parentVal is a function here because
    // it has to be a function to pass previous merges.
    return function mergedDataFn () {
      return mergeData(
        childVal.call(this),
        parentVal.call(this)
      )
    }
  } else if (parentVal || childVal) {
    return function mergedInstanceDataFn () {
      // instance merge
      var instanceData = typeof childVal === 'function'
        ? childVal.call(vm)
        : childVal
      var defaultData = typeof parentVal === 'function'
        ? parentVal.call(vm)
        : undefined
      if (instanceData) {
        return mergeData(instanceData, defaultData)
      } else {
        return defaultData
      }
    }
  }
}

/**
 * Hooks and param attributes are merged as arrays.
 */
function mergeHook (
  parentVal,
  childVal
) {
  return childVal
    ? parentVal
      ? parentVal.concat(childVal)
      : Array.isArray(childVal)
        ? childVal
        : [childVal]
    : parentVal
}

config._lifecycleHooks.forEach(function (hook) {
  strats[hook] = mergeHook
})

/**
 * Assets
 *
 * When a vm is present (instance creation), we need to do
 * a three-way merge between constructor options, instance
 * options and parent options.
 */
function mergeAssets (parentVal, childVal) {
  var res = Object.create(parentVal || null)
  return childVal
    ? extend(res, childVal)
    : res
}

config._assetTypes.forEach(function (type) {
  strats[type + 's'] = mergeAssets
})

/**
 * Watchers.
 *
 * Watchers hashes should not overwrite one
 * another, so we merge them as arrays.
 */
strats.watch = function (parentVal, childVal) {
  /* istanbul ignore if */
  if (!childVal) return parentVal
  if (!parentVal) return childVal
  var ret = {}
  extend(ret, parentVal)
  for (var key in childVal) {
    var parent = ret[key]
    var child = childVal[key]
    if (parent && !Array.isArray(parent)) {
      parent = [parent]
    }
    ret[key] = parent
      ? parent.concat(child)
      : [child]
  }
  return ret
}

/**
 * Other object hashes.
 */
strats.props =
strats.methods =
strats.computed = function (parentVal, childVal) {
  if (!childVal) return parentVal
  if (!parentVal) return childVal
  var ret = Object.create(null)
  extend(ret, parentVal)
  extend(ret, childVal)
  return ret
}

/**
 * Default strategy.
 */
var defaultStrat = function (parentVal, childVal) {
  return childVal === undefined
    ? parentVal
    : childVal
}

/**
 * Make sure component options get converted to actual
 * constructors.
 */
function normalizeComponents (options) {
  if (options.components) {
    var components = options.components
    var def
    for (var key in components) {
      var lower = key.toLowerCase()
      if (isBuiltInTag(lower) || config.isReservedTag(lower)) {
        process.env.NODE_ENV !== 'production' && warn(
          'Do not use built-in or reserved HTML elements as component ' +
          'id: ' + key
        )
        continue
      }
      def = components[key]
      if (isPlainObject(def)) {
        components[key] = Vue.extend(def)
      }
    }
  }
}

/**
 * Ensure all props option syntax are normalized into the
 * Object-based format.
 */
function normalizeProps (options) {
  var props = options.props
  if (!props) return
  var res = {}
  var i, val, name
  if (Array.isArray(props)) {
    i = props.length
    while (i--) {
      val = props[i]
      if (typeof val === 'string') {
        name = camelize(val)
        res[name] = { type: null }
      } else if (process.env.NODE_ENV !== 'production') {
        warn('props must be strings when using array syntax.')
      }
    }
  } else if (isPlainObject(props)) {
    for (var key in props) {
      val = props[key]
      name = camelize(key)
      res[name] = isPlainObject(val)
        ? val
        : { type: val }
    }
  }
  options.props = res
}

/**
 * Normalize raw function directives into object format.
 */
function normalizeDirectives (options) {
  var dirs = options.directives
  if (dirs) {
    for (var key in dirs) {
      var def = dirs[key]
      if (typeof def === 'function') {
        dirs[key] = { bind: def, update: def }
      }
    }
  }
}

/**
 * Merge two option objects into a new one.
 * Core utility used in both instantiation and inheritance.
 */
function mergeOptions (
  parent,
  child,
  vm
) {
  normalizeComponents(child)
  normalizeProps(child)
  normalizeDirectives(child)
  var extendsFrom = child.extends
  if (extendsFrom) {
    parent = typeof extendsFrom === 'function'
      ? mergeOptions(parent, extendsFrom.options, vm)
      : mergeOptions(parent, extendsFrom, vm)
  }
  if (child.mixins) {
    for (var i = 0, l = child.mixins.length; i < l; i++) {
      var mixin = child.mixins[i]
      if (mixin.prototype instanceof Vue) {
        mixin = mixin.options
      }
      parent = mergeOptions(parent, mixin, vm)
    }
  }
  var options = {}
  var key
  for (key in parent) {
    mergeField(key)
  }
  for (key in child) {
    if (!hasOwn(parent, key)) {
      mergeField(key)
    }
  }
  function mergeField (key) {
    var strat = strats[key] || defaultStrat
    options[key] = strat(parent[key], child[key], vm, key)
  }
  return options
}

/**
 * Resolve an asset.
 * This function is used because child instances need access
 * to assets defined in its ancestor chain.
 */
function resolveAsset (
  options,
  type,
  id,
  warnMissing
) {
  /* istanbul ignore if */
  if (typeof id !== 'string') {
    return
  }
  var assets = options[type]
  var res = assets[id] ||
    // camelCase ID
    assets[camelize(id)] ||
    // Pascal Case ID
    assets[capitalize(camelize(id))]
  if (process.env.NODE_ENV !== 'production' && warnMissing && !res) {
    warn(
      'Failed to resolve ' + type.slice(0, -1) + ': ' + id,
      options
    )
  }
  return res
}

/*  */

function validateProp (
  key,
  propOptions,
  propsData,
  vm
) {
  /* istanbul ignore if */
  if (!propsData) return
  var prop = propOptions[key]
  var absent = !hasOwn(propsData, key)
  var value = propsData[key]
  // handle boolean props
  if (getType(prop.type) === 'Boolean') {
    if (absent && !hasOwn(prop, 'default')) {
      value = false
    } else if (value === '' || value === hyphenate(key)) {
      value = true
    }
  }
  // check default value
  if (value === undefined) {
    value = getPropDefaultValue(vm, prop, key)
    // since the default value is a fresh copy,
    // make sure to observe it.
    var prevShouldConvert = observerState.shouldConvert
    observerState.shouldConvert = true
    observe(value)
    observerState.shouldConvert = prevShouldConvert
  }
  if (process.env.NODE_ENV !== 'production') {
    assertProp(prop, key, value, vm, absent)
  }
  return value
}

/**
 * Get the default value of a prop.
 */
function getPropDefaultValue (vm, prop, name) {
  // no default, return undefined
  if (!hasOwn(prop, 'default')) {
    return undefined
  }
  var def = prop.default
  // warn against non-factory defaults for Object & Array
  if (isObject(def)) {
    process.env.NODE_ENV !== 'production' && warn(
      'Invalid default value for prop "' + name + '": ' +
      'Props with type Object/Array must use a factory function ' +
      'to return the default value.',
      vm
    )
  }
  // call factory function for non-Function types
  return typeof def === 'function' && prop.type !== Function
    ? def.call(vm)
    : def
}

/**
 * Assert whether a prop is valid.
 */
function assertProp (
  prop,
  name,
  value,
  vm,
  absent
) {
  if (prop.required && absent) {
    warn(
      'Missing required prop: "' + name + '"',
      vm
    )
    return
  }
  if (value == null && !prop.required) {
    return
  }
  var type = prop.type
  var valid = !type || type === true
  var expectedTypes = []
  if (type) {
    if (!Array.isArray(type)) {
      type = [type]
    }
    for (var i = 0; i < type.length && !valid; i++) {
      var assertedType = assertType(value, type[i])
      expectedTypes.push(assertedType.expectedType)
      valid = assertedType.valid
    }
  }
  if (!valid) {
    warn(
      'Invalid prop: type check failed for prop "' + name + '".' +
      ' Expected ' + expectedTypes.map(capitalize).join(', ') +
      ', got ' + Object.prototype.toString.call(value).slice(8, -1) + '.',
      vm
    )
    return
  }
  var validator = prop.validator
  if (validator) {
    if (!validator(value)) {
      warn(
        'Invalid prop: custom validator check failed for prop "' + name + '".',
        vm
      )
    }
  }
}

/**
 * Assert the type of a value
 */
function assertType (value, type) {
  var valid
  var expectedType = getType(type)
  if (expectedType === 'String') {
    valid = typeof value === (expectedType = 'string')
  } else if (expectedType === 'Number') {
    valid = typeof value === (expectedType = 'number')
  } else if (expectedType === 'Boolean') {
    valid = typeof value === (expectedType = 'boolean')
  } else if (expectedType === 'Function') {
    valid = typeof value === (expectedType = 'function')
  } else if (expectedType === 'Object') {
    valid = isPlainObject(value)
  } else if (expectedType === 'Array') {
    valid = Array.isArray(value)
  } else {
    valid = value instanceof type
  }
  return {
    valid: valid,
    expectedType: expectedType
  }
}

/**
 * Use function string name to check built-in types,
 * because a simple equality check will fail when running
 * across different vms / iframes.
 */
function getType (fn) {
  var match = fn && fn.toString().match(/^\s*function (\w+)/)
  return match && match[1]
}



var util = Object.freeze({
	defineReactive: defineReactive,
	_toString: _toString,
	toNumber: toNumber,
	makeMap: makeMap,
	isBuiltInTag: isBuiltInTag,
	remove: remove,
	hasOwn: hasOwn,
	isPrimitive: isPrimitive,
	cached: cached,
	camelize: camelize,
	capitalize: capitalize,
	hyphenate: hyphenate,
	bind: bind,
	toArray: toArray,
	extend: extend,
	isObject: isObject,
	isPlainObject: isPlainObject,
	toObject: toObject,
	noop: noop,
	no: no,
	genStaticKeys: genStaticKeys,
	isReserved: isReserved,
	def: def,
	parsePath: parsePath,
	hasProto: hasProto,
	inBrowser: inBrowser,
	devtools: devtools,
	UA: UA,
	nextTick: nextTick,
	get _Set () { return _Set; },
	mergeOptions: mergeOptions,
	resolveAsset: resolveAsset,
	get warn () { return warn; },
	get formatComponentName () { return formatComponentName; },
	validateProp: validateProp
});

/*  */

function initUse (Vue) {
  Vue.use = function (plugin) {
    /* istanbul ignore if */
    if (plugin.installed) {
      return
    }
    // additional parameters
    var args = toArray(arguments, 1)
    args.unshift(this)
    if (typeof plugin.install === 'function') {
      plugin.install.apply(plugin, args)
    } else {
      plugin.apply(null, args)
    }
    plugin.installed = true
    return this
  }
}

/*  */

function initMixin$1 (Vue) {
  Vue.mixin = function (mixin) {
    Vue.options = mergeOptions(Vue.options, mixin)
  }
}

/*  */

function initExtend (Vue) {
  /**
   * Each instance constructor, including Vue, has a unique
   * cid. This enables us to create wrapped "child
   * constructors" for prototypal inheritance and cache them.
   */
  Vue.cid = 0
  var cid = 1

  /**
   * Class inheritance
   */
  Vue.extend = function (extendOptions) {
    extendOptions = extendOptions || {}
    var Super = this
    var isFirstExtend = Super.cid === 0
    if (isFirstExtend && extendOptions._Ctor) {
      return extendOptions._Ctor
    }
    var name = extendOptions.name || Super.options.name
    if (process.env.NODE_ENV !== 'production') {
      if (!/^[a-zA-Z][\w-]*$/.test(name)) {
        warn(
          'Invalid component name: "' + name + '". Component names ' +
          'can only contain alphanumeric characaters and the hyphen.'
        )
        name = null
      }
    }
    var Sub = function VueComponent (options) {
      this._init(options)
    }
    Sub.prototype = Object.create(Super.prototype)
    Sub.prototype.constructor = Sub
    Sub.cid = cid++
    Sub.options = mergeOptions(
      Super.options,
      extendOptions
    )
    Sub['super'] = Super
    // allow further extension
    Sub.extend = Super.extend
    // create asset registers, so extended classes
    // can have their private assets too.
    config._assetTypes.forEach(function (type) {
      Sub[type] = Super[type]
    })
    // enable recursive self-lookup
    if (name) {
      Sub.options.components[name] = Sub
    }
    // keep a reference to the super options at extension time.
    // later at instantiation we can check if Super's options have
    // been updated.
    Sub.superOptions = Super.options
    Sub.extendOptions = extendOptions
    // cache constructor
    if (isFirstExtend) {
      extendOptions._Ctor = Sub
    }
    return Sub
  }
}

/*  */

function initAssetRegisters (Vue) {
  /**
   * Create asset registration methods.
   */
  config._assetTypes.forEach(function (type) {
    Vue[type] = function (
      id,
      definition
    ) {
      if (!definition) {
        return this.options[type + 's'][id]
      } else {
        /* istanbul ignore if */
        if (process.env.NODE_ENV !== 'production') {
          if (type === 'component' && config.isReservedTag(id)) {
            warn(
              'Do not use built-in or reserved HTML elements as component ' +
              'id: ' + id
            )
          }
        }
        if (type === 'component' && isPlainObject(definition)) {
          definition.name = definition.name || id
          definition = Vue.extend(definition)
        }
        if (type === 'directive' && typeof definition === 'function') {
          definition = { bind: definition, update: definition }
        }
        this.options[type + 's'][id] = definition
        return definition
      }
    }
  })
}

var KeepAlive = {
  name: 'keep-alive',
  abstract: true,
  created: function created () {
    this.cache = Object.create(null)
  },
  render: function render () {
    var vnode = getFirstComponentChild(this.$slots.default)
    if (vnode && vnode.componentOptions) {
      var opts = vnode.componentOptions
      var key = vnode.key == null
        // same constructor may get registered as different local components
        // so cid alone is not enough (#3269)
        ? opts.Ctor.cid + '::' + opts.tag
        : vnode.key
      if (this.cache[key]) {
        vnode.child = this.cache[key].child
      } else {
        this.cache[key] = vnode
      }
      vnode.data.keepAlive = true
    }
    return vnode
  },
  destroyed: function destroyed () {
    var this$1 = this;

    for (var key in this.cache) {
      var vnode = this$1.cache[key]
      callHook(vnode.child, 'deactivated')
      vnode.child.$destroy()
    }
  }
}

var builtInComponents = {
  KeepAlive: KeepAlive
}

/*  */

function initGlobalAPI (Vue) {
  // config
  var configDef = {}
  configDef.get = function () { return config; }
  if (process.env.NODE_ENV !== 'production') {
    configDef.set = function () {
      warn(
        'Do not replace the Vue.config object, set individual fields instead.'
      )
    }
  }
  Object.defineProperty(Vue, 'config', configDef)
  Vue.util = util
  Vue.set = set
  Vue.delete = del
  Vue.nextTick = nextTick

  Vue.options = Object.create(null)
  config._assetTypes.forEach(function (type) {
    Vue.options[type + 's'] = Object.create(null)
  })

  extend(Vue.options.components, builtInComponents)

  initUse(Vue)
  initMixin$1(Vue)
  initExtend(Vue)
  initAssetRegisters(Vue)
}

initGlobalAPI(Vue)

Object.defineProperty(Vue.prototype, '$isServer', {
  get: function () { return config._isServer; }
})

Vue.version = '2.0.0-rc.6'

/*  */

// attributes that should be using props for binding
var mustUseProp = makeMap('value,selected,checked,muted')

var isEnumeratedAttr = makeMap('contenteditable,draggable,spellcheck')

var isBooleanAttr = makeMap(
  'allowfullscreen,async,autofocus,autoplay,checked,compact,controls,declare,' +
  'default,defaultchecked,defaultmuted,defaultselected,defer,disabled,' +
  'enabled,formnovalidate,hidden,indeterminate,inert,ismap,itemscope,loop,multiple,' +
  'muted,nohref,noresize,noshade,novalidate,nowrap,open,pauseonexit,readonly,' +
  'required,reversed,scoped,seamless,selected,sortable,translate,' +
  'truespeed,typemustmatch,visible'
)

var isAttr = makeMap(
  'accept,accept-charset,accesskey,action,align,alt,async,autocomplete,' +
  'autofocus,autoplay,autosave,bgcolor,border,buffered,challenge,charset,' +
  'checked,cite,class,code,codebase,color,cols,colspan,content,http-equiv,' +
  'name,contenteditable,contextmenu,controls,coords,data,datetime,default,' +
  'defer,dir,dirname,disabled,download,draggable,dropzone,enctype,method,for,' +
  'form,formaction,headers,<th>,height,hidden,high,href,hreflang,http-equiv,' +
  'icon,id,ismap,itemprop,keytype,kind,label,lang,language,list,loop,low,' +
  'manifest,max,maxlength,media,method,GET,POST,min,multiple,email,file,' +
  'muted,name,novalidate,open,optimum,pattern,ping,placeholder,poster,' +
  'preload,radiogroup,readonly,rel,required,reversed,rows,rowspan,sandbox,' +
  'scope,scoped,seamless,selected,shape,size,type,text,password,sizes,span,' +
  'spellcheck,src,srcdoc,srclang,srcset,start,step,style,summary,tabindex,' +
  'target,title,type,usemap,value,width,wrap'
)

var xlinkNS = 'http://www.w3.org/1999/xlink'

var isXlink = function (name) {
  return name.charAt(5) === ':' && name.slice(0, 5) === 'xlink'
}

var getXlinkProp = function (name) {
  return isXlink(name) ? name.slice(6, name.length) : ''
}

var isFalsyAttrValue = function (val) {
  return val == null || val === false
}

/*  */

function genClassForVnode (vnode) {
  var data = vnode.data
  var parentNode = vnode
  var childNode = vnode
  while (childNode.child) {
    childNode = childNode.child._vnode
    if (childNode.data) {
      data = mergeClassData(childNode.data, data)
    }
  }
  while ((parentNode = parentNode.parent)) {
    if (parentNode.data) {
      data = mergeClassData(data, parentNode.data)
    }
  }
  return genClassFromData(data)
}

function mergeClassData (child, parent) {
  return {
    staticClass: concat(child.staticClass, parent.staticClass),
    class: child.class
      ? [child.class, parent.class]
      : parent.class
  }
}

function genClassFromData (data) {
  var dynamicClass = data.class
  var staticClass = data.staticClass
  if (staticClass || dynamicClass) {
    return concat(staticClass, stringifyClass(dynamicClass))
  }
  /* istanbul ignore next */
  return ''
}

function concat (a, b) {
  return a ? b ? (a + ' ' + b) : a : (b || '')
}

function stringifyClass (value) {
  var res = ''
  if (!value) {
    return res
  }
  if (typeof value === 'string') {
    return value
  }
  if (Array.isArray(value)) {
    var stringified
    for (var i = 0, l = value.length; i < l; i++) {
      if (value[i]) {
        if ((stringified = stringifyClass(value[i]))) {
          res += stringified + ' '
        }
      }
    }
    return res.slice(0, -1)
  }
  if (isObject(value)) {
    for (var key in value) {
      if (value[key]) res += key + ' '
    }
    return res.slice(0, -1)
  }
  /* istanbul ignore next */
  return res
}

/*  */

var namespaceMap = {
  svg: 'http://www.w3.org/2000/svg',
  math: 'http://www.w3.org/1998/Math/MathML'
}

var isHTMLTag = makeMap(
  'html,body,base,head,link,meta,style,title,' +
  'address,article,aside,footer,header,h1,h2,h3,h4,h5,h6,hgroup,nav,section,' +
  'div,dd,dl,dt,figcaption,figure,hr,img,li,main,ol,p,pre,ul,' +
  'a,b,abbr,bdi,bdo,br,cite,code,data,dfn,em,i,kbd,mark,q,rp,rt,rtc,ruby,' +
  's,samp,small,span,strong,sub,sup,time,u,var,wbr,area,audio,map,track,video,' +
  'embed,object,param,source,canvas,script,noscript,del,ins,' +
  'caption,col,colgroup,table,thead,tbody,td,th,tr,' +
  'button,datalist,fieldset,form,input,label,legend,meter,optgroup,option,' +
  'output,progress,select,textarea,' +
  'details,dialog,menu,menuitem,summary,' +
  'content,element,shadow,template'
)

var isUnaryTag = makeMap(
  'area,base,br,col,embed,frame,hr,img,input,isindex,keygen,' +
  'link,meta,param,source,track,wbr',
  true
)

// Elements that you can, intentionally, leave open
// (and which close themselves)
var canBeLeftOpenTag = makeMap(
  'colgroup,dd,dt,li,options,p,td,tfoot,th,thead,tr,source',
  true
)

// HTML5 tags https://html.spec.whatwg.org/multipage/indices.html#elements-3
// Phrasing Content https://html.spec.whatwg.org/multipage/dom.html#phrasing-content
var isNonPhrasingTag = makeMap(
  'address,article,aside,base,blockquote,body,caption,col,colgroup,dd,' +
  'details,dialog,div,dl,dt,fieldset,figcaption,figure,footer,form,' +
  'h1,h2,h3,h4,h5,h6,head,header,hgroup,hr,html,legend,li,menuitem,meta,' +
  'optgroup,option,param,rp,rt,source,style,summary,tbody,td,tfoot,th,thead,' +
  'title,tr,track',
  true
)

// this map is intentionally selective, only covering SVG elements that may
// contain child elements.
var isSVG = makeMap(
  'svg,animate,circle,clippath,cursor,defs,desc,ellipse,filter,font,' +
  'font-face,g,glyph,image,line,marker,mask,missing-glyph,path,pattern,' +
  'polygon,polyline,rect,switch,symbol,text,textpath,tspan,use,view',
  true
)

var isReservedTag = function (tag) {
  return isHTMLTag(tag) || isSVG(tag)
}

function getTagNamespace (tag) {
  if (isSVG(tag)) {
    return 'svg'
  }
  // basic support for MathML
  // note it doesn't support other MathML elements being component roots
  if (tag === 'math') {
    return 'math'
  }
}

var unknownElementCache = Object.create(null)
function isUnknownElement (tag) {
  /* istanbul ignore if */
  if (!inBrowser) {
    return true
  }
  if (isReservedTag(tag)) {
    return false
  }
  tag = tag.toLowerCase()
  /* istanbul ignore if */
  if (unknownElementCache[tag] != null) {
    return unknownElementCache[tag]
  }
  var el = document.createElement(tag)
  if (tag.indexOf('-') > -1) {
    // http://stackoverflow.com/a/28210364/1070244
    return (unknownElementCache[tag] = (
      el.constructor === window.HTMLUnknownElement ||
      el.constructor === window.HTMLElement
    ))
  } else {
    return (unknownElementCache[tag] = /HTMLUnknownElement/.test(el.toString()))
  }
}

/*  */

var UA$1 = inBrowser && window.navigator.userAgent.toLowerCase()
var isIE = UA$1 && /msie|trident/.test(UA$1)
var isIE9 = UA$1 && UA$1.indexOf('msie 9.0') > 0
var isAndroid = UA$1 && UA$1.indexOf('android') > 0

/**
 * Query an element selector if it's not an element already.
 */
function query (el) {
  if (typeof el === 'string') {
    var selector = el
    el = document.querySelector(el)
    if (!el) {
      process.env.NODE_ENV !== 'production' && warn(
        'Cannot find element: ' + selector
      )
      return document.createElement('div')
    }
  }
  return el
}

/*  */

function createElement$1 (tagName) {
  return document.createElement(tagName)
}

function createElementNS (namespace, tagName) {
  return document.createElementNS(namespaceMap[namespace], tagName)
}

function createTextNode (text) {
  return document.createTextNode(text)
}

function createComment (text) {
  return document.createComment(text)
}

function insertBefore (parentNode, newNode, referenceNode) {
  parentNode.insertBefore(newNode, referenceNode)
}

function removeChild (node, child) {
  node.removeChild(child)
}

function appendChild (node, child) {
  node.appendChild(child)
}

function parentNode (node) {
  return node.parentNode
}

function nextSibling (node) {
  return node.nextSibling
}

function tagName (node) {
  return node.tagName
}

function setTextContent (node, text) {
  node.textContent = text
}

function childNodes (node) {
  return node.childNodes
}

function setAttribute (node, key, val) {
  node.setAttribute(key, val)
}


var nodeOps = Object.freeze({
  createElement: createElement$1,
  createElementNS: createElementNS,
  createTextNode: createTextNode,
  createComment: createComment,
  insertBefore: insertBefore,
  removeChild: removeChild,
  appendChild: appendChild,
  parentNode: parentNode,
  nextSibling: nextSibling,
  tagName: tagName,
  setTextContent: setTextContent,
  childNodes: childNodes,
  setAttribute: setAttribute
});

/*  */

var ref = {
  create: function create (_, vnode) {
    registerRef(vnode)
  },
  update: function update (oldVnode, vnode) {
    if (oldVnode.data.ref !== vnode.data.ref) {
      registerRef(oldVnode, true)
      registerRef(vnode)
    }
  },
  destroy: function destroy (vnode) {
    registerRef(vnode, true)
  }
}

function registerRef (vnode, isRemoval) {
  var key = vnode.data.ref
  if (!key) return

  var vm = vnode.context
  var ref = vnode.child || vnode.elm
  var refs = vm.$refs
  if (isRemoval) {
    if (Array.isArray(refs[key])) {
      remove(refs[key], ref)
    } else if (refs[key] === ref) {
      refs[key] = undefined
    }
  } else {
    if (vnode.data.refInFor) {
      if (Array.isArray(refs[key])) {
        refs[key].push(ref)
      } else {
        refs[key] = [ref]
      }
    } else {
      refs[key] = ref
    }
  }
}

/**
 * Virtual DOM patching algorithm based on Snabbdom by
 * Simon Friis Vindum (@paldepind)
 * Licensed under the MIT License
 * https://github.com/paldepind/snabbdom/blob/master/LICENSE
 *
 * modified by Evan You (@yyx990803)
 *

/*
 * Not type-checking this because this file is perf-critical and the cost
 * of making flow understand it is not worth it.
 */

var emptyData = {}
var emptyNode = new VNode('', emptyData, [])
var hooks$1 = ['create', 'update', 'postpatch', 'remove', 'destroy']

function isUndef (s) {
  return s == null
}

function isDef (s) {
  return s != null
}

function sameVnode (vnode1, vnode2) {
  return (
    vnode1.key === vnode2.key &&
    vnode1.tag === vnode2.tag &&
    vnode1.isComment === vnode2.isComment &&
    !vnode1.data === !vnode2.data
  )
}

function createKeyToOldIdx (children, beginIdx, endIdx) {
  var i, key
  var map = {}
  for (i = beginIdx; i <= endIdx; ++i) {
    key = children[i].key
    if (isDef(key)) map[key] = i
  }
  return map
}

function createPatchFunction (backend) {
  var i, j
  var cbs = {}

  var modules = backend.modules;
  var nodeOps = backend.nodeOps;

  for (i = 0; i < hooks$1.length; ++i) {
    cbs[hooks$1[i]] = []
    for (j = 0; j < modules.length; ++j) {
      if (modules[j][hooks$1[i]] !== undefined) cbs[hooks$1[i]].push(modules[j][hooks$1[i]])
    }
  }

  function emptyNodeAt (elm) {
    return new VNode(nodeOps.tagName(elm).toLowerCase(), {}, [], undefined, elm)
  }

  function createRmCb (childElm, listeners) {
    function remove () {
      if (--remove.listeners === 0) {
        removeElement(childElm)
      }
    }
    remove.listeners = listeners
    return remove
  }

  function removeElement (el) {
    var parent = nodeOps.parentNode(el)
    nodeOps.removeChild(parent, el)
  }

  function createElm (vnode, insertedVnodeQueue, nested) {
    var i
    var data = vnode.data
    vnode.isRootInsert = !nested
    if (isDef(data)) {
      if (isDef(i = data.hook) && isDef(i = i.init)) i(vnode)
      // after calling the init hook, if the vnode is a child component
      // it should've created a child instance and mounted it. the child
      // component also has set the placeholder vnode's elm.
      // in that case we can just return the element and be done.
      if (isDef(i = vnode.child)) {
        initComponent(vnode, insertedVnodeQueue)
        return vnode.elm
      }
    }
    var children = vnode.children
    var tag = vnode.tag
    if (isDef(tag)) {
      if (process.env.NODE_ENV !== 'production') {
        if (
          !vnode.ns &&
          !(config.ignoredElements && config.ignoredElements.indexOf(tag) > -1) &&
          config.isUnknownElement(tag)
        ) {
          warn(
            'Unknown custom element: <' + tag + '> - did you ' +
            'register the component correctly? For recursive components, ' +
            'make sure to provide the "name" option.',
            vnode.context
          )
        }
      }
      vnode.elm = vnode.ns
        ? nodeOps.createElementNS(vnode.ns, tag)
        : nodeOps.createElement(tag)
      setScope(vnode)
      createChildren(vnode, children, insertedVnodeQueue)
      if (isDef(data)) {
        invokeCreateHooks(vnode, insertedVnodeQueue)
      }
    } else if (vnode.isComment) {
      vnode.elm = nodeOps.createComment(vnode.text)
    } else {
      vnode.elm = nodeOps.createTextNode(vnode.text)
    }
    return vnode.elm
  }

  function createChildren (vnode, children, insertedVnodeQueue) {
    if (Array.isArray(children)) {
      for (var i = 0; i < children.length; ++i) {
        nodeOps.appendChild(vnode.elm, createElm(children[i], insertedVnodeQueue, true))
      }
    } else if (isPrimitive(vnode.text)) {
      nodeOps.appendChild(vnode.elm, nodeOps.createTextNode(vnode.text))
    }
  }

  function isPatchable (vnode) {
    while (vnode.child) {
      vnode = vnode.child._vnode
    }
    return isDef(vnode.tag)
  }

  function invokeCreateHooks (vnode, insertedVnodeQueue) {
    for (var i$1 = 0; i$1 < cbs.create.length; ++i$1) {
      cbs.create[i$1](emptyNode, vnode)
    }
    i = vnode.data.hook // Reuse variable
    if (isDef(i)) {
      if (i.create) i.create(emptyNode, vnode)
      if (i.insert) insertedVnodeQueue.push(vnode)
    }
  }

  function initComponent (vnode, insertedVnodeQueue) {
    if (vnode.data.pendingInsert) {
      insertedVnodeQueue.push.apply(insertedVnodeQueue, vnode.data.pendingInsert)
    }
    vnode.elm = vnode.child.$el
    if (isPatchable(vnode)) {
      invokeCreateHooks(vnode, insertedVnodeQueue)
      setScope(vnode)
    } else {
      // empty component root.
      // skip all element-related modules except for ref (#3455)
      registerRef(vnode)
      // make sure to invoke the insert hook
      insertedVnodeQueue.push(vnode)
    }
  }

  // set scope id attribute for scoped CSS.
  // this is implemented as a special case to avoid the overhead
  // of going through the normal attribute patching process.
  function setScope (vnode) {
    var i
    if (isDef(i = vnode.context) && isDef(i = i.$options._scopeId)) {
      nodeOps.setAttribute(vnode.elm, i, '')
    }
    if (isDef(i = activeInstance) &&
        i !== vnode.context &&
        isDef(i = i.$options._scopeId)) {
      nodeOps.setAttribute(vnode.elm, i, '')
    }
  }

  function addVnodes (parentElm, before, vnodes, startIdx, endIdx, insertedVnodeQueue) {
    for (; startIdx <= endIdx; ++startIdx) {
      nodeOps.insertBefore(parentElm, createElm(vnodes[startIdx], insertedVnodeQueue), before)
    }
  }

  function invokeDestroyHook (vnode) {
    var i, j
    var data = vnode.data
    if (isDef(data)) {
      if (isDef(i = data.hook) && isDef(i = i.destroy)) i(vnode)
      for (i = 0; i < cbs.destroy.length; ++i) cbs.destroy[i](vnode)
    }
    if (isDef(i = vnode.child) && !data.keepAlive) {
      invokeDestroyHook(i._vnode)
    }
    if (isDef(i = vnode.children)) {
      for (j = 0; j < vnode.children.length; ++j) {
        invokeDestroyHook(vnode.children[j])
      }
    }
  }

  function removeVnodes (parentElm, vnodes, startIdx, endIdx) {
    for (; startIdx <= endIdx; ++startIdx) {
      var ch = vnodes[startIdx]
      if (isDef(ch)) {
        if (isDef(ch.tag)) {
          removeAndInvokeRemoveHook(ch)
          invokeDestroyHook(ch)
        } else { // Text node
          nodeOps.removeChild(parentElm, ch.elm)
        }
      }
    }
  }

  function removeAndInvokeRemoveHook (vnode, rm) {
    if (rm || isDef(vnode.data)) {
      var listeners = cbs.remove.length + 1
      if (!rm) {
        // directly removing
        rm = createRmCb(vnode.elm, listeners)
      } else {
        // we have a recursively passed down rm callback
        // increase the listeners count
        rm.listeners += listeners
      }
      // recursively invoke hooks on child component root node
      if (isDef(i = vnode.child) && isDef(i = i._vnode) && isDef(i.data)) {
        removeAndInvokeRemoveHook(i, rm)
      }
      for (i = 0; i < cbs.remove.length; ++i) {
        cbs.remove[i](vnode, rm)
      }
      if (isDef(i = vnode.data.hook) && isDef(i = i.remove)) {
        i(vnode, rm)
      } else {
        rm()
      }
    } else {
      removeElement(vnode.elm)
    }
  }

  function updateChildren (parentElm, oldCh, newCh, insertedVnodeQueue, removeOnly) {
    var oldStartIdx = 0
    var newStartIdx = 0
    var oldEndIdx = oldCh.length - 1
    var oldStartVnode = oldCh[0]
    var oldEndVnode = oldCh[oldEndIdx]
    var newEndIdx = newCh.length - 1
    var newStartVnode = newCh[0]
    var newEndVnode = newCh[newEndIdx]
    var oldKeyToIdx, idxInOld, elmToMove, before

    // removeOnly is a special flag used only by <transition-group>
    // to ensure removed elements stay in correct relative positions
    // during leaving transitions
    var canMove = !removeOnly

    while (oldStartIdx <= oldEndIdx && newStartIdx <= newEndIdx) {
      if (isUndef(oldStartVnode)) {
        oldStartVnode = oldCh[++oldStartIdx] // Vnode has been moved left
      } else if (isUndef(oldEndVnode)) {
        oldEndVnode = oldCh[--oldEndIdx]
      } else if (sameVnode(oldStartVnode, newStartVnode)) {
        patchVnode(oldStartVnode, newStartVnode, insertedVnodeQueue)
        oldStartVnode = oldCh[++oldStartIdx]
        newStartVnode = newCh[++newStartIdx]
      } else if (sameVnode(oldEndVnode, newEndVnode)) {
        patchVnode(oldEndVnode, newEndVnode, insertedVnodeQueue)
        oldEndVnode = oldCh[--oldEndIdx]
        newEndVnode = newCh[--newEndIdx]
      } else if (sameVnode(oldStartVnode, newEndVnode)) { // Vnode moved right
        patchVnode(oldStartVnode, newEndVnode, insertedVnodeQueue)
        canMove && nodeOps.insertBefore(parentElm, oldStartVnode.elm, nodeOps.nextSibling(oldEndVnode.elm))
        oldStartVnode = oldCh[++oldStartIdx]
        newEndVnode = newCh[--newEndIdx]
      } else if (sameVnode(oldEndVnode, newStartVnode)) { // Vnode moved left
        patchVnode(oldEndVnode, newStartVnode, insertedVnodeQueue)
        canMove && nodeOps.insertBefore(parentElm, oldEndVnode.elm, oldStartVnode.elm)
        oldEndVnode = oldCh[--oldEndIdx]
        newStartVnode = newCh[++newStartIdx]
      } else {
        if (isUndef(oldKeyToIdx)) oldKeyToIdx = createKeyToOldIdx(oldCh, oldStartIdx, oldEndIdx)
        idxInOld = isDef(newStartVnode.key) ? oldKeyToIdx[newStartVnode.key] : null
        if (isUndef(idxInOld)) { // New element
          nodeOps.insertBefore(parentElm, createElm(newStartVnode, insertedVnodeQueue), oldStartVnode.elm)
          newStartVnode = newCh[++newStartIdx]
        } else {
          elmToMove = oldCh[idxInOld]
          /* istanbul ignore if */
          if (process.env.NODE_ENV !== 'production' && !elmToMove) {
            warn(
              'It seems there are duplicate keys that is causing an update error. ' +
              'Make sure each v-for item has a unique key.'
            )
          }
          if (elmToMove.tag !== newStartVnode.tag) {
            // same key but different element. treat as new element
            nodeOps.insertBefore(parentElm, createElm(newStartVnode, insertedVnodeQueue), oldStartVnode.elm)
            newStartVnode = newCh[++newStartIdx]
          } else {
            patchVnode(elmToMove, newStartVnode, insertedVnodeQueue)
            oldCh[idxInOld] = undefined
            canMove && nodeOps.insertBefore(parentElm, newStartVnode.elm, oldStartVnode.elm)
            newStartVnode = newCh[++newStartIdx]
          }
        }
      }
    }
    if (oldStartIdx > oldEndIdx) {
      before = isUndef(newCh[newEndIdx + 1]) ? null : newCh[newEndIdx + 1].elm
      addVnodes(parentElm, before, newCh, newStartIdx, newEndIdx, insertedVnodeQueue)
    } else if (newStartIdx > newEndIdx) {
      removeVnodes(parentElm, oldCh, oldStartIdx, oldEndIdx)
    }
  }

  function patchVnode (oldVnode, vnode, insertedVnodeQueue, removeOnly) {
    if (oldVnode === vnode) {
      return
    }
    // reuse element for static trees.
    // note we only do this if the vnode is cloned -
    // if the new node is not cloned it means the render functions have been
    // reset by the hot-reload-api and we need to do a proper re-render.
    if (vnode.isStatic &&
        oldVnode.isStatic &&
        vnode.key === oldVnode.key &&
        vnode.isCloned) {
      vnode.elm = oldVnode.elm
      return
    }
    var i, hook
    var hasData = isDef(i = vnode.data)
    if (hasData && isDef(hook = i.hook) && isDef(i = hook.prepatch)) {
      i(oldVnode, vnode)
    }
    var elm = vnode.elm = oldVnode.elm
    var oldCh = oldVnode.children
    var ch = vnode.children
    if (hasData && isPatchable(vnode)) {
      for (i = 0; i < cbs.update.length; ++i) cbs.update[i](oldVnode, vnode)
      if (isDef(hook) && isDef(i = hook.update)) i(oldVnode, vnode)
    }
    if (isUndef(vnode.text)) {
      if (isDef(oldCh) && isDef(ch)) {
        if (oldCh !== ch) updateChildren(elm, oldCh, ch, insertedVnodeQueue, removeOnly)
      } else if (isDef(ch)) {
        if (isDef(oldVnode.text)) nodeOps.setTextContent(elm, '')
        addVnodes(elm, null, ch, 0, ch.length - 1, insertedVnodeQueue)
      } else if (isDef(oldCh)) {
        removeVnodes(elm, oldCh, 0, oldCh.length - 1)
      } else if (isDef(oldVnode.text)) {
        nodeOps.setTextContent(elm, '')
      }
    } else if (oldVnode.text !== vnode.text) {
      nodeOps.setTextContent(elm, vnode.text)
    }
    if (hasData) {
      for (i = 0; i < cbs.postpatch.length; ++i) cbs.postpatch[i](oldVnode, vnode)
      if (isDef(hook) && isDef(i = hook.postpatch)) i(oldVnode, vnode)
    }
  }

  function invokeInsertHook (vnode, queue, initial) {
    // delay insert hooks for component root nodes, invoke them after the
    // element is really inserted
    if (initial && vnode.parent) {
      vnode.parent.data.pendingInsert = queue
    } else {
      for (var i = 0; i < queue.length; ++i) {
        queue[i].data.hook.insert(queue[i])
      }
    }
  }

  var bailed = false
  function hydrate (elm, vnode, insertedVnodeQueue) {
    if (process.env.NODE_ENV !== 'production') {
      if (!assertNodeMatch(elm, vnode)) {
        return false
      }
    }
    vnode.elm = elm
    var tag = vnode.tag;
    var data = vnode.data;
    var children = vnode.children;
    if (isDef(data)) {
      if (isDef(i = data.hook) && isDef(i = i.init)) i(vnode, true /* hydrating */)
      if (isDef(i = vnode.child)) {
        // child component. it should have hydrated its own tree.
        initComponent(vnode, insertedVnodeQueue)
        return true
      }
    }
    if (isDef(tag)) {
      if (isDef(children)) {
        var childNodes = nodeOps.childNodes(elm)
        // empty element, allow client to pick up and populate children
        if (!childNodes.length) {
          createChildren(vnode, children, insertedVnodeQueue)
        } else {
          var childrenMatch = true
          if (childNodes.length !== children.length) {
            childrenMatch = false
          } else {
            for (var i$1 = 0; i$1 < children.length; i$1++) {
              if (!hydrate(childNodes[i$1], children[i$1], insertedVnodeQueue)) {
                childrenMatch = false
                break
              }
            }
          }
          if (!childrenMatch) {
            if (process.env.NODE_ENV !== 'production' &&
                typeof console !== 'undefined' &&
                !bailed) {
              bailed = true
              console.warn('Parent: ', elm)
              console.warn('Mismatching childNodes vs. VNodes: ', childNodes, children)
            }
            return false
          }
        }
      }
      if (isDef(data)) {
        invokeCreateHooks(vnode, insertedVnodeQueue)
      }
    }
    return true
  }

  function assertNodeMatch (node, vnode) {
    if (vnode.tag) {
      return (
        vnode.tag.indexOf('vue-component') === 0 ||
        vnode.tag === nodeOps.tagName(node).toLowerCase()
      )
    } else {
      return _toString(vnode.text) === node.data
    }
  }

  return function patch (oldVnode, vnode, hydrating, removeOnly) {
    var elm, parent
    var isInitialPatch = false
    var insertedVnodeQueue = []

    if (!oldVnode) {
      // empty mount, create new root element
      isInitialPatch = true
      createElm(vnode, insertedVnodeQueue)
    } else {
      var isRealElement = isDef(oldVnode.nodeType)
      if (!isRealElement && sameVnode(oldVnode, vnode)) {
        patchVnode(oldVnode, vnode, insertedVnodeQueue, removeOnly)
      } else {
        if (isRealElement) {
          // mounting to a real element
          // check if this is server-rendered content and if we can perform
          // a successful hydration.
          if (oldVnode.nodeType === 1 && oldVnode.hasAttribute('server-rendered')) {
            oldVnode.removeAttribute('server-rendered')
            hydrating = true
          }
          if (hydrating) {
            if (hydrate(oldVnode, vnode, insertedVnodeQueue)) {
              invokeInsertHook(vnode, insertedVnodeQueue, true)
              return oldVnode
            } else if (process.env.NODE_ENV !== 'production') {
              warn(
                'The client-side rendered virtual DOM tree is not matching ' +
                'server-rendered content. This is likely caused by incorrect ' +
                'HTML markup, for example nesting block-level elements inside ' +
                '<p>, or missing <tbody>. Bailing hydration and performing ' +
                'full client-side render.'
              )
            }
          }
          // either not server-rendered, or hydration failed.
          // create an empty node and replace it
          oldVnode = emptyNodeAt(oldVnode)
        }
        elm = oldVnode.elm
        parent = nodeOps.parentNode(elm)

        createElm(vnode, insertedVnodeQueue)

        // component root element replaced.
        // update parent placeholder node element.
        if (vnode.parent) {
          vnode.parent.elm = vnode.elm
          if (isPatchable(vnode)) {
            for (var i = 0; i < cbs.create.length; ++i) {
              cbs.create[i](emptyNode, vnode.parent)
            }
          }
        }

        if (parent !== null) {
          nodeOps.insertBefore(parent, vnode.elm, nodeOps.nextSibling(elm))
          removeVnodes(parent, [oldVnode], 0, 0)
        } else if (isDef(oldVnode.tag)) {
          invokeDestroyHook(oldVnode)
        }
      }
    }

    invokeInsertHook(vnode, insertedVnodeQueue, isInitialPatch)
    return vnode.elm
  }
}

/*  */

var directives = {
  create: function bindDirectives (oldVnode, vnode) {
    var hasInsert = false
    forEachDirective(oldVnode, vnode, function (def, dir) {
      callHook$1(def, dir, 'bind', vnode, oldVnode)
      if (def.inserted) {
        hasInsert = true
      }
    })
    if (hasInsert) {
      mergeVNodeHook(vnode.data.hook || (vnode.data.hook = {}), 'insert', function () {
        applyDirectives(oldVnode, vnode, 'inserted')
      })
    }
  },
  update: function updateDirectives (oldVnode, vnode) {
    applyDirectives(oldVnode, vnode, 'update')
    // if old vnode has directives but new vnode doesn't
    // we need to teardown the directives on the old one.
    if (oldVnode.data.directives && !vnode.data.directives) {
      applyDirectives(oldVnode, oldVnode, 'unbind')
    }
  },
  postpatch: function postupdateDirectives (oldVnode, vnode) {
    applyDirectives(oldVnode, vnode, 'componentUpdated')
  },
  destroy: function unbindDirectives (vnode) {
    applyDirectives(vnode, vnode, 'unbind')
  }
}

var emptyModifiers = Object.create(null)

function forEachDirective (
  oldVnode,
  vnode,
  fn
) {
  var dirs = vnode.data.directives
  if (dirs) {
    for (var i = 0; i < dirs.length; i++) {
      var dir = dirs[i]
      var def = resolveAsset(vnode.context.$options, 'directives', dir.name, true)
      if (def) {
        var oldDirs = oldVnode && oldVnode.data.directives
        if (oldDirs) {
          dir.oldValue = oldDirs[i].value
        }
        if (!dir.modifiers) {
          dir.modifiers = emptyModifiers
        }
        fn(def, dir)
      }
    }
  }
}

function applyDirectives (
  oldVnode,
  vnode,
  hook
) {
  forEachDirective(oldVnode, vnode, function (def, dir) {
    callHook$1(def, dir, hook, vnode, oldVnode)
  })
}

function callHook$1 (def, dir, hook, vnode, oldVnode) {
  var fn = def && def[hook]
  if (fn) {
    fn(vnode.elm, dir, vnode, oldVnode)
  }
}

var baseModules = [
  ref,
  directives
]

/*  */

function updateAttrs (oldVnode, vnode) {
  if (!oldVnode.data.attrs && !vnode.data.attrs) {
    return
  }
  var key, cur, old
  var elm = vnode.elm
  var oldAttrs = oldVnode.data.attrs || {}
  var attrs = vnode.data.attrs || {}
  // clone observed objects, as the user probably wants to mutate it
  if (attrs.__ob__) {
    attrs = vnode.data.attrs = extend({}, attrs)
  }

  for (key in attrs) {
    cur = attrs[key]
    old = oldAttrs[key]
    if (old !== cur) {
      setAttr(elm, key, cur)
    }
  }
  for (key in oldAttrs) {
    if (attrs[key] == null) {
      if (isXlink(key)) {
        elm.removeAttributeNS(xlinkNS, getXlinkProp(key))
      } else if (!isEnumeratedAttr(key)) {
        elm.removeAttribute(key)
      }
    }
  }
}

function setAttr (el, key, value) {
  if (isBooleanAttr(key)) {
    // set attribute for blank value
    // e.g. <option disabled>Select one</option>
    if (isFalsyAttrValue(value)) {
      el.removeAttribute(key)
    } else {
      el.setAttribute(key, key)
    }
  } else if (isEnumeratedAttr(key)) {
    el.setAttribute(key, isFalsyAttrValue(value) || value === 'false' ? 'false' : 'true')
  } else if (isXlink(key)) {
    if (isFalsyAttrValue(value)) {
      el.removeAttributeNS(xlinkNS, getXlinkProp(key))
    } else {
      el.setAttributeNS(xlinkNS, key, value)
    }
  } else {
    if (isFalsyAttrValue(value)) {
      el.removeAttribute(key)
    } else {
      el.setAttribute(key, value)
    }
  }
}

var attrs = {
  create: updateAttrs,
  update: updateAttrs
}

/*  */

function updateClass (oldVnode, vnode) {
  var el = vnode.elm
  var data = vnode.data
  var oldData = oldVnode.data
  if (!data.staticClass && !data.class &&
      (!oldData || (!oldData.staticClass && !oldData.class))) {
    return
  }

  var cls = genClassForVnode(vnode)

  // handle transition classes
  var transitionClass = el._transitionClasses
  if (transitionClass) {
    cls = concat(cls, stringifyClass(transitionClass))
  }

  // set the class
  if (cls !== el._prevClass) {
    el.setAttribute('class', cls)
    el._prevClass = cls
  }
}

var klass = {
  create: updateClass,
  update: updateClass
}

// skip type checking this file because we need to attach private properties
// to elements

function updateDOMListeners (oldVnode, vnode) {
  if (!oldVnode.data.on && !vnode.data.on) {
    return
  }
  var on = vnode.data.on || {}
  var oldOn = oldVnode.data.on || {}
  var add = vnode.elm._v_add || (vnode.elm._v_add = function (event, handler, capture) {
    vnode.elm.addEventListener(event, handler, capture)
  })
  var remove = vnode.elm._v_remove || (vnode.elm._v_remove = function (event, handler) {
    vnode.elm.removeEventListener(event, handler)
  })
  updateListeners(on, oldOn, add, remove)
}

var events = {
  create: updateDOMListeners,
  update: updateDOMListeners
}

/*  */

function updateDOMProps (oldVnode, vnode) {
  if (!oldVnode.data.domProps && !vnode.data.domProps) {
    return
  }
  var key, cur
  var elm = vnode.elm
  var oldProps = oldVnode.data.domProps || {}
  var props = vnode.data.domProps || {}
  // clone observed objects, as the user probably wants to mutate it
  if (props.__ob__) {
    props = vnode.data.domProps = extend({}, props)
  }

  for (key in oldProps) {
    if (props[key] == null) {
      elm[key] = undefined
    }
  }
  for (key in props) {
    // ignore children if the node has textContent or innerHTML,
    // as these will throw away existing DOM nodes and cause removal errors
    // on subsequent patches (#3360)
    if ((key === 'textContent' || key === 'innerHTML') && vnode.children) {
      vnode.children.length = 0
    }
    cur = props[key]
    if (key === 'value') {
      // store value as _value as well since
      // non-string values will be stringified
      elm._value = cur
      // avoid resetting cursor position when value is the same
      var strCur = cur == null ? '' : String(cur)
      if (elm.value !== strCur) {
        elm.value = strCur
      }
    } else {
      elm[key] = cur
    }
  }
}

var domProps = {
  create: updateDOMProps,
  update: updateDOMProps
}

/*  */

var prefixes = ['Webkit', 'Moz', 'ms']

var testEl
var normalize = cached(function (prop) {
  testEl = testEl || document.createElement('div')
  prop = camelize(prop)
  if (prop !== 'filter' && (prop in testEl.style)) {
    return prop
  }
  var upper = prop.charAt(0).toUpperCase() + prop.slice(1)
  for (var i = 0; i < prefixes.length; i++) {
    var prefixed = prefixes[i] + upper
    if (prefixed in testEl.style) {
      return prefixed
    }
  }
})

function updateStyle (oldVnode, vnode) {
  if ((!oldVnode.data || !oldVnode.data.style) && !vnode.data.style) {
    return
  }
  var cur, name
  var el = vnode.elm
  var oldStyle = oldVnode.data.style || {}
  var style = vnode.data.style || {}

  // handle string
  if (typeof style === 'string') {
    el.style.cssText = style
    return
  }

  var needClone = style.__ob__

  // handle array syntax
  if (Array.isArray(style)) {
    style = vnode.data.style = toObject(style)
  }

  // clone the style for future updates,
  // in case the user mutates the style object in-place.
  if (needClone) {
    style = vnode.data.style = extend({}, style)
  }

  for (name in oldStyle) {
    if (!style[name]) {
      el.style[normalize(name)] = ''
    }
  }
  for (name in style) {
    cur = style[name]
    if (cur !== oldStyle[name]) {
      // ie9 setting to null has no effect, must use empty string
      el.style[normalize(name)] = cur || ''
    }
  }
}

var style = {
  create: updateStyle,
  update: updateStyle
}

/*  */

/**
 * Add class with compatibility for SVG since classList is not supported on
 * SVG elements in IE
 */
function addClass (el, cls) {
  /* istanbul ignore else */
  if (el.classList) {
    if (cls.indexOf(' ') > -1) {
      cls.split(/\s+/).forEach(function (c) { return el.classList.add(c); })
    } else {
      el.classList.add(cls)
    }
  } else {
    var cur = ' ' + el.getAttribute('class') + ' '
    if (cur.indexOf(' ' + cls + ' ') < 0) {
      el.setAttribute('class', (cur + cls).trim())
    }
  }
}

/**
 * Remove class with compatibility for SVG since classList is not supported on
 * SVG elements in IE
 */
function removeClass (el, cls) {
  /* istanbul ignore else */
  if (el.classList) {
    if (cls.indexOf(' ') > -1) {
      cls.split(/\s+/).forEach(function (c) { return el.classList.remove(c); })
    } else {
      el.classList.remove(cls)
    }
  } else {
    var cur = ' ' + el.getAttribute('class') + ' '
    var tar = ' ' + cls + ' '
    while (cur.indexOf(tar) >= 0) {
      cur = cur.replace(tar, ' ')
    }
    el.setAttribute('class', cur.trim())
  }
}

/*  */

var hasTransition = inBrowser && !isIE9
var TRANSITION = 'transition'
var ANIMATION = 'animation'

// Transition property/event sniffing
var transitionProp = 'transition'
var transitionEndEvent = 'transitionend'
var animationProp = 'animation'
var animationEndEvent = 'animationend'
if (hasTransition) {
  /* istanbul ignore if */
  if (window.ontransitionend === undefined &&
    window.onwebkittransitionend !== undefined) {
    transitionProp = 'WebkitTransition'
    transitionEndEvent = 'webkitTransitionEnd'
  }
  if (window.onanimationend === undefined &&
    window.onwebkitanimationend !== undefined) {
    animationProp = 'WebkitAnimation'
    animationEndEvent = 'webkitAnimationEnd'
  }
}

var raf = (inBrowser && window.requestAnimationFrame) || setTimeout
function nextFrame (fn) {
  raf(function () {
    raf(fn)
  })
}

function addTransitionClass (el, cls) {
  (el._transitionClasses || (el._transitionClasses = [])).push(cls)
  addClass(el, cls)
}

function removeTransitionClass (el, cls) {
  if (el._transitionClasses) {
    remove(el._transitionClasses, cls)
  }
  removeClass(el, cls)
}

function whenTransitionEnds (
  el,
  expectedType,
  cb
) {
  var ref = getTransitionInfo(el, expectedType);
  var type = ref.type;
  var timeout = ref.timeout;
  var propCount = ref.propCount;
  if (!type) return cb()
  var event = type === TRANSITION ? transitionEndEvent : animationEndEvent
  var ended = 0
  var end = function () {
    el.removeEventListener(event, onEnd)
    cb()
  }
  var onEnd = function (e) {
    if (e.target === el) {
      if (++ended >= propCount) {
        end()
      }
    }
  }
  setTimeout(function () {
    if (ended < propCount) {
      end()
    }
  }, timeout + 1)
  el.addEventListener(event, onEnd)
}

var transformRE = /\b(transform|all)(,|$)/

function getTransitionInfo (el, expectedType) {
  var styles = window.getComputedStyle(el)
  var transitioneDelays = styles[transitionProp + 'Delay'].split(', ')
  var transitionDurations = styles[transitionProp + 'Duration'].split(', ')
  var transitionTimeout = getTimeout(transitioneDelays, transitionDurations)
  var animationDelays = styles[animationProp + 'Delay'].split(', ')
  var animationDurations = styles[animationProp + 'Duration'].split(', ')
  var animationTimeout = getTimeout(animationDelays, animationDurations)

  var type
  var timeout = 0
  var propCount = 0
  /* istanbul ignore if */
  if (expectedType === TRANSITION) {
    if (transitionTimeout > 0) {
      type = TRANSITION
      timeout = transitionTimeout
      propCount = transitionDurations.length
    }
  } else if (expectedType === ANIMATION) {
    if (animationTimeout > 0) {
      type = ANIMATION
      timeout = animationTimeout
      propCount = animationDurations.length
    }
  } else {
    timeout = Math.max(transitionTimeout, animationTimeout)
    type = timeout > 0
      ? transitionTimeout > animationTimeout
        ? TRANSITION
        : ANIMATION
      : null
    propCount = type
      ? type === TRANSITION
        ? transitionDurations.length
        : animationDurations.length
      : 0
  }
  var hasTransform =
    type === TRANSITION &&
    transformRE.test(styles[transitionProp + 'Property'])
  return {
    type: type,
    timeout: timeout,
    propCount: propCount,
    hasTransform: hasTransform
  }
}

function getTimeout (delays, durations) {
  return Math.max.apply(null, durations.map(function (d, i) {
    return toMs(d) + toMs(delays[i])
  }))
}

function toMs (s) {
  return Number(s.slice(0, -1)) * 1000
}

/*  */

function enter (vnode) {
  var el = vnode.elm

  // call leave callback now
  if (el._leaveCb) {
    el._leaveCb.cancelled = true
    el._leaveCb()
  }

  var data = resolveTransition(vnode.data.transition)
  if (!data) {
    return
  }

  /* istanbul ignore if */
  if (el._enterCb || el.nodeType !== 1) {
    return
  }

  var css = data.css;
  var type = data.type;
  var enterClass = data.enterClass;
  var enterActiveClass = data.enterActiveClass;
  var appearClass = data.appearClass;
  var appearActiveClass = data.appearActiveClass;
  var beforeEnter = data.beforeEnter;
  var enter = data.enter;
  var afterEnter = data.afterEnter;
  var enterCancelled = data.enterCancelled;
  var beforeAppear = data.beforeAppear;
  var appear = data.appear;
  var afterAppear = data.afterAppear;
  var appearCancelled = data.appearCancelled;

  // activeInstance will always be the <transition> component managing this
  // transition. One edge case to check is when the <transition> is placed
  // as the root node of a child component. In that case we need to check
  // <transition>'s parent for appear check.
  var transitionNode = activeInstance.$vnode
  var context = transitionNode && transitionNode.parent
    ? transitionNode.parent.context
    : activeInstance

  var isAppear = !context._isMounted || !vnode.isRootInsert

  if (isAppear && !appear && appear !== '') {
    return
  }

  var startClass = isAppear ? appearClass : enterClass
  var activeClass = isAppear ? appearActiveClass : enterActiveClass
  var beforeEnterHook = isAppear ? (beforeAppear || beforeEnter) : beforeEnter
  var enterHook = isAppear ? (typeof appear === 'function' ? appear : enter) : enter
  var afterEnterHook = isAppear ? (afterAppear || afterEnter) : afterEnter
  var enterCancelledHook = isAppear ? (appearCancelled || enterCancelled) : enterCancelled

  var expectsCSS = css !== false && !isIE9
  var userWantsControl =
    enterHook &&
    // enterHook may be a bound method which exposes
    // the length of original fn as _length
    (enterHook._length || enterHook.length) > 1

  var cb = el._enterCb = once(function () {
    if (expectsCSS) {
      removeTransitionClass(el, activeClass)
    }
    if (cb.cancelled) {
      if (expectsCSS) {
        removeTransitionClass(el, startClass)
      }
      enterCancelledHook && enterCancelledHook(el)
    } else {
      afterEnterHook && afterEnterHook(el)
    }
    el._enterCb = null
  })

  if (!vnode.data.show) {
    // remove pending leave element on enter by injecting an insert hook
    mergeVNodeHook(vnode.data.hook || (vnode.data.hook = {}), 'insert', function () {
      var parent = el.parentNode
      var pendingNode = parent && parent._pending && parent._pending[vnode.key]
      if (pendingNode && pendingNode.tag === vnode.tag && pendingNode.elm._leaveCb) {
        pendingNode.elm._leaveCb()
      }
      enterHook && enterHook(el, cb)
    })
  }

  // start enter transition
  beforeEnterHook && beforeEnterHook(el)
  if (expectsCSS) {
    addTransitionClass(el, startClass)
    addTransitionClass(el, activeClass)
    nextFrame(function () {
      removeTransitionClass(el, startClass)
      if (!cb.cancelled && !userWantsControl) {
        whenTransitionEnds(el, type, cb)
      }
    })
  }

  if (vnode.data.show) {
    enterHook && enterHook(el, cb)
  }

  if (!expectsCSS && !userWantsControl) {
    cb()
  }
}

function leave (vnode, rm) {
  var el = vnode.elm

  // call enter callback now
  if (el._enterCb) {
    el._enterCb.cancelled = true
    el._enterCb()
  }

  var data = resolveTransition(vnode.data.transition)
  if (!data) {
    return rm()
  }

  /* istanbul ignore if */
  if (el._leaveCb || el.nodeType !== 1) {
    return
  }

  var css = data.css;
  var type = data.type;
  var leaveClass = data.leaveClass;
  var leaveActiveClass = data.leaveActiveClass;
  var beforeLeave = data.beforeLeave;
  var leave = data.leave;
  var afterLeave = data.afterLeave;
  var leaveCancelled = data.leaveCancelled;
  var delayLeave = data.delayLeave;

  var expectsCSS = css !== false && !isIE9
  var userWantsControl =
    leave &&
    // leave hook may be a bound method which exposes
    // the length of original fn as _length
    (leave._length || leave.length) > 1

  var cb = el._leaveCb = once(function () {
    if (el.parentNode && el.parentNode._pending) {
      el.parentNode._pending[vnode.key] = null
    }
    if (expectsCSS) {
      removeTransitionClass(el, leaveActiveClass)
    }
    if (cb.cancelled) {
      if (expectsCSS) {
        removeTransitionClass(el, leaveClass)
      }
      leaveCancelled && leaveCancelled(el)
    } else {
      rm()
      afterLeave && afterLeave(el)
    }
    el._leaveCb = null
  })

  if (delayLeave) {
    delayLeave(performLeave)
  } else {
    performLeave()
  }

  function performLeave () {
    // the delayed leave may have already been cancelled
    if (cb.cancelled) {
      return
    }
    // record leaving element
    if (!vnode.data.show) {
      (el.parentNode._pending || (el.parentNode._pending = {}))[vnode.key] = vnode
    }
    beforeLeave && beforeLeave(el)
    if (expectsCSS) {
      addTransitionClass(el, leaveClass)
      addTransitionClass(el, leaveActiveClass)
      nextFrame(function () {
        removeTransitionClass(el, leaveClass)
        if (!cb.cancelled && !userWantsControl) {
          whenTransitionEnds(el, type, cb)
        }
      })
    }
    leave && leave(el, cb)
    if (!expectsCSS && !userWantsControl) {
      cb()
    }
  }
}

function resolveTransition (def) {
  if (!def) {
    return
  }
  /* istanbul ignore else */
  if (typeof def === 'object') {
    var res = {}
    if (def.css !== false) {
      extend(res, autoCssTransition(def.name || 'v'))
    }
    extend(res, def)
    return res
  } else if (typeof def === 'string') {
    return autoCssTransition(def)
  }
}

var autoCssTransition = cached(function (name) {
  return {
    enterClass: (name + "-enter"),
    leaveClass: (name + "-leave"),
    appearClass: (name + "-enter"),
    enterActiveClass: (name + "-enter-active"),
    leaveActiveClass: (name + "-leave-active"),
    appearActiveClass: (name + "-enter-active")
  }
})

function once (fn) {
  var called = false
  return function () {
    if (!called) {
      called = true
      fn()
    }
  }
}

var transition = inBrowser ? {
  create: function create (_, vnode) {
    if (!vnode.data.show) {
      enter(vnode)
    }
  },
  remove: function remove (vnode, rm) {
    /* istanbul ignore else */
    if (!vnode.data.show) {
      leave(vnode, rm)
    } else {
      rm()
    }
  }
} : {}

var platformModules = [
  attrs,
  klass,
  events,
  domProps,
  style,
  transition
]

/*  */

// the directive module should be applied last, after all
// built-in modules have been applied.
var modules = platformModules.concat(baseModules)

var patch = createPatchFunction({ nodeOps: nodeOps, modules: modules })

/**
 * Not type checking this file because flow doesn't like attaching
 * properties to Elements.
 */

var modelableTagRE = /^input|select|textarea|vue-component-[0-9]+(-[0-9a-zA-Z_\-]*)?$/

/* istanbul ignore if */
if (isIE9) {
  // http://www.matts411.com/post/internet-explorer-9-oninput/
  document.addEventListener('selectionchange', function () {
    var el = document.activeElement
    if (el && el.vmodel) {
      trigger(el, 'input')
    }
  })
}

var model = {
  bind: function bind (el, binding, vnode) {
    if (process.env.NODE_ENV !== 'production') {
      if (!modelableTagRE.test(vnode.tag)) {
        warn(
          "v-model is not supported on element type: <" + (vnode.tag) + ">. " +
          'If you are working with contenteditable, it\'s recommended to ' +
          'wrap a library dedicated for that purpose inside a custom component.',
          vnode.context
        )
      }
    }
    if (vnode.tag === 'select') {
      setSelected(el, binding, vnode.context)
    } else {
      if (!isAndroid) {
        el.addEventListener('compositionstart', onCompositionStart)
        el.addEventListener('compositionend', onCompositionEnd)
      }
      /* istanbul ignore if */
      if (isIE9) {
        el.vmodel = true
      }
    }
  },
  componentUpdated: function componentUpdated (el, binding, vnode) {
    if (vnode.tag === 'select') {
      setSelected(el, binding, vnode.context)
      // in case the options rendered by v-for have changed,
      // it's possible that the value is out-of-sync with the rendered options.
      // detect such cases and filter out values that no longer has a matchig
      // option in the DOM.
      var needReset = el.multiple
        ? binding.value.some(function (v) { return hasNoMatchingOption(v, el.options); })
        : hasNoMatchingOption(binding.value, el.options)
      if (needReset) {
        trigger(el, 'change')
      }
    }
  }
}

function setSelected (el, binding, vm) {
  var value = binding.value
  var isMultiple = el.multiple
  if (isMultiple && !Array.isArray(value)) {
    process.env.NODE_ENV !== 'production' && warn(
      "<select multiple v-model=\"" + (binding.expression) + "\"> " +
      "expects an Array value for its binding, but got " + (Object.prototype.toString.call(value).slice(8, -1)),
      vm
    )
    return
  }
  var selected, option
  for (var i = 0, l = el.options.length; i < l; i++) {
    option = el.options[i]
    if (isMultiple) {
      selected = value.indexOf(getValue(option)) > -1
      if (option.selected !== selected) {
        option.selected = selected
      }
    } else {
      if (getValue(option) === value) {
        if (el.selectedIndex !== i) {
          el.selectedIndex = i
        }
        return
      }
    }
  }
  if (!isMultiple) {
    el.selectedIndex = -1
  }
}

function hasNoMatchingOption (value, options) {
  for (var i = 0, l = options.length; i < l; i++) {
    if (getValue(options[i]) === value) {
      return false
    }
  }
  return true
}

function getValue (option) {
  return '_value' in option
    ? option._value
    : option.value || option.text
}

function onCompositionStart (e) {
  e.target.composing = true
}

function onCompositionEnd (e) {
  e.target.composing = false
  trigger(e.target, 'input')
}

function trigger (el, type) {
  var e = document.createEvent('HTMLEvents')
  e.initEvent(type, true, true)
  el.dispatchEvent(e)
}

/*  */

// recursively search for possible transition defined inside the component root
function locateNode (vnode) {
  return vnode.child && (!vnode.data || !vnode.data.transition)
    ? locateNode(vnode.child._vnode)
    : vnode
}

var show = {
  bind: function bind (el, ref, vnode) {
    var value = ref.value;

    vnode = locateNode(vnode)
    var transition = vnode.data && vnode.data.transition
    if (value && transition && !isIE9) {
      enter(vnode)
    }
    var originalDisplay = el.style.display === 'none' ? '' : el.style.display
    el.style.display = value ? originalDisplay : 'none'
    el.__vOriginalDisplay = originalDisplay
  },
  update: function update (el, ref, vnode) {
    var value = ref.value;
    var oldValue = ref.oldValue;

    /* istanbul ignore if */
    if (value === oldValue) return
    vnode = locateNode(vnode)
    var transition = vnode.data && vnode.data.transition
    if (transition && !isIE9) {
      if (value) {
        enter(vnode)
        el.style.display = el.__vOriginalDisplay
      } else {
        leave(vnode, function () {
          el.style.display = 'none'
        })
      }
    } else {
      el.style.display = value ? el.__vOriginalDisplay : 'none'
    }
  }
}

var platformDirectives = {
  model: model,
  show: show
}

/*  */

// Provides transition support for a single element/component.
// supports transition mode (out-in / in-out)

var transitionProps = {
  name: String,
  appear: Boolean,
  css: Boolean,
  mode: String,
  type: String,
  enterClass: String,
  leaveClass: String,
  enterActiveClass: String,
  leaveActiveClass: String,
  appearClass: String,
  appearActiveClass: String
}

// in case the child is also an abstract component, e.g. <keep-alive>
// we want to recrusively retrieve the real component to be rendered
function getRealChild (vnode) {
  var compOptions = vnode && vnode.componentOptions
  if (compOptions && compOptions.Ctor.options.abstract) {
    return getRealChild(getFirstComponentChild(compOptions.children))
  } else {
    return vnode
  }
}

function extractTransitionData (comp) {
  var data = {}
  var options = comp.$options
  // props
  for (var key in options.propsData) {
    data[key] = comp[key]
  }
  // events.
  // extract listeners and pass them directly to the transition methods
  var listeners = options._parentListeners
  for (var key$1 in listeners) {
    data[camelize(key$1)] = listeners[key$1].fn
  }
  return data
}

function placeholder (h, rawChild) {
  return /\d-keep-alive$/.test(rawChild.tag)
    ? h('keep-alive')
    : null
}

function hasParentTransition (vnode) {
  while ((vnode = vnode.parent)) {
    if (vnode.data.transition) {
      return true
    }
  }
}

var Transition = {
  name: 'transition',
  props: transitionProps,
  abstract: true,
  render: function render (h) {
    var this$1 = this;

    var children = this.$slots.default
    if (!children) {
      return
    }

    // filter out text nodes (possible whitespaces)
    children = children.filter(function (c) { return c.tag; })
    /* istanbul ignore if */
    if (!children.length) {
      return
    }

    // warn multiple elements
    if (process.env.NODE_ENV !== 'production' && children.length > 1) {
      warn(
        '<transition> can only be used on a single element. Use ' +
        '<transition-group> for lists.',
        this.$parent
      )
    }

    var mode = this.mode

    // warn invalid mode
    if (process.env.NODE_ENV !== 'production' &&
        mode && mode !== 'in-out' && mode !== 'out-in') {
      warn(
        'invalid <transition> mode: ' + mode,
        this.$parent
      )
    }

    var rawChild = children[0]

    // if this is a component root node and the component's
    // parent container node also has transition, skip.
    if (hasParentTransition(this.$vnode)) {
      return rawChild
    }

    // apply transition data to child
    // use getRealChild() to ignore abstract components e.g. keep-alive
    var child = getRealChild(rawChild)
    /* istanbul ignore if */
    if (!child) {
      return rawChild
    }

    if (this._leaving) {
      return placeholder(h, rawChild)
    }

    child.key = child.key == null
      ? ("__v" + (child.tag + this._uid) + "__")
      : child.key
    var data = (child.data || (child.data = {})).transition = extractTransitionData(this)
    var oldRawChild = this._vnode
    var oldChild = getRealChild(oldRawChild)

    // mark v-show
    // so that the transition module can hand over the control to the directive
    if (child.data.directives && child.data.directives.some(function (d) { return d.name === 'show'; })) {
      child.data.show = true
    }

    if (oldChild && oldChild.data && oldChild.key !== child.key) {
      // replace old child transition data with fresh one
      // important for dynamic transitions!
      var oldData = oldChild.data.transition = extend({}, data)

      // handle transition mode
      if (mode === 'out-in') {
        // return placeholder node and queue update when leave finishes
        this._leaving = true
        mergeVNodeHook(oldData, 'afterLeave', function () {
          this$1._leaving = false
          this$1.$forceUpdate()
        })
        return placeholder(h, rawChild)
      } else if (mode === 'in-out') {
        var delayedLeave
        var performLeave = function () { delayedLeave() }
        mergeVNodeHook(data, 'afterEnter', performLeave)
        mergeVNodeHook(data, 'enterCancelled', performLeave)
        mergeVNodeHook(oldData, 'delayLeave', function (leave) {
          delayedLeave = leave
        })
      }
    }

    return rawChild
  }
}

/*  */

// Provides transition support for list items.
// supports move transitions using the FLIP technique.

// Because the vdom's children update algorithm is "unstable" - i.e.
// it doesn't guarantee the relative positioning of removed elements,
// we force transition-group to update its children into two passes:
// in the first pass, we remove all nodes that need to be removed,
// triggering their leaving transition; in the second pass, we insert/move
// into the final disired state. This way in the second pass removed
// nodes will remain where they should be.

var props = extend({
  tag: String,
  moveClass: String
}, transitionProps)

delete props.mode

var TransitionGroup = {
  props: props,

  render: function render (h) {
    var tag = this.tag || this.$vnode.data.tag || 'span'
    var map = Object.create(null)
    var prevChildren = this.prevChildren = this.children
    var rawChildren = this.$slots.default || []
    var children = this.children = []
    var transitionData = extractTransitionData(this)

    for (var i = 0; i < rawChildren.length; i++) {
      var c = rawChildren[i]
      if (c.tag) {
        if (c.key != null && String(c.key).indexOf('__vlist') !== 0) {
          children.push(c)
          map[c.key] = c
          ;(c.data || (c.data = {})).transition = transitionData
        } else if (process.env.NODE_ENV !== 'production') {
          var opts = c.componentOptions
          var name = opts
            ? (opts.Ctor.options.name || opts.tag)
            : c.tag
          warn(("<transition-group> children must be keyed: <" + name + ">"))
        }
      }
    }

    if (prevChildren) {
      var kept = []
      var removed = []
      for (var i$1 = 0; i$1 < prevChildren.length; i$1++) {
        var c$1 = prevChildren[i$1]
        c$1.data.transition = transitionData
        c$1.data.pos = c$1.elm.getBoundingClientRect()
        if (map[c$1.key]) {
          kept.push(c$1)
        } else {
          removed.push(c$1)
        }
      }
      this.kept = h(tag, null, kept)
      this.removed = removed
    }

    return h(tag, null, children)
  },

  beforeUpdate: function beforeUpdate () {
    // force removing pass
    this.__patch__(
      this._vnode,
      this.kept,
      false, // hydrating
      true // removeOnly (!important, avoids unnecessary moves)
    )
    this._vnode = this.kept
  },

  updated: function updated () {
    var children = this.prevChildren
    var moveClass = this.moveClass || (this.name + '-move')
    if (!children.length || !this.hasMove(children[0].elm, moveClass)) {
      return
    }

    children.forEach(function (c) {
      /* istanbul ignore if */
      if (c.elm._moveCb) {
        c.elm._moveCb()
      }
      /* istanbul ignore if */
      if (c.elm._enterCb) {
        c.elm._enterCb()
      }
      var oldPos = c.data.pos
      var newPos = c.data.pos = c.elm.getBoundingClientRect()
      var dx = oldPos.left - newPos.left
      var dy = oldPos.top - newPos.top
      if (dx || dy) {
        c.data.moved = true
        var s = c.elm.style
        s.transform = s.WebkitTransform = "translate(" + dx + "px," + dy + "px)"
        s.transitionDuration = '0s'
      }
    })

    // force reflow to put everything in position
    var f = document.body.offsetHeight // eslint-disable-line

    children.forEach(function (c) {
      if (c.data.moved) {
        var el = c.elm
        var s = el.style
        addTransitionClass(el, moveClass)
        s.transform = s.WebkitTransform = s.transitionDuration = ''
        el._moveDest = c.data.pos
        el.addEventListener(transitionEndEvent, el._moveCb = function cb (e) {
          if (!e || /transform$/.test(e.propertyName)) {
            el.removeEventListener(transitionEndEvent, cb)
            el._moveCb = null
            removeTransitionClass(el, moveClass)
          }
        })
      }
    })
  },

  methods: {
    hasMove: function hasMove (el, moveClass) {
      /* istanbul ignore if */
      if (!hasTransition) {
        return false
      }
      if (this._hasMove != null) {
        return this._hasMove
      }
      addTransitionClass(el, moveClass)
      var info = getTransitionInfo(el)
      removeTransitionClass(el, moveClass)
      return (this._hasMove = info.hasTransform)
    }
  }
}

var platformComponents = {
  Transition: Transition,
  TransitionGroup: TransitionGroup
}

/*  */

// install platform specific utils
Vue.config.isUnknownElement = isUnknownElement
Vue.config.isReservedTag = isReservedTag
Vue.config.getTagNamespace = getTagNamespace
Vue.config.mustUseProp = mustUseProp

// install platform runtime directives & components
extend(Vue.options.directives, platformDirectives)
extend(Vue.options.components, platformComponents)

// install platform patch function
Vue.prototype.__patch__ = config._isServer ? noop : patch

// wrap mount
Vue.prototype.$mount = function (
  el,
  hydrating
) {
  el = el && !config._isServer ? query(el) : undefined
  return this._mount(el, hydrating)
}

// devtools global hook
/* istanbul ignore next */
setTimeout(function () {
  if (config.devtools) {
    if (devtools) {
      devtools.emit('init', Vue)
    } else if (
      process.env.NODE_ENV !== 'production' &&
      inBrowser && /Chrome\/\d+/.test(window.navigator.userAgent)
    ) {
      console.log(
        'Download the Vue Devtools for a better development experience:\n' +
        'https://github.com/vuejs/vue-devtools'
      )
    }
  }
}, 0)

module.exports = Vue;