littleReact/dist/react.development.js

/** @license React v16.2.0
 * react.development.js
 *
 * Copyright (c) 2013-present, Facebook, Inc.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 */

'use strict';



if (process.env.NODE_ENV !== "production") {
  (function() {
'use strict';

var _assign = require('object-assign');
var emptyObject = require('fbjs/lib/emptyObject');
var invariant = require('fbjs/lib/invariant');
var warning = require('fbjs/lib/warning');
var emptyFunction = require('fbjs/lib/emptyFunction');
var checkPropTypes = require('prop-types/checkPropTypes');

// TODO: this is special because it gets imported during build.

var ReactVersion = '16.2.0';

// The Symbol used to tag the ReactElement-like types. If there is no native Symbol
// nor polyfill, then a plain number is used for performance.
var hasSymbol = typeof Symbol === 'function' && Symbol['for'];

var REACT_ELEMENT_TYPE = hasSymbol ? Symbol['for']('react.element') : 0xeac7;
var REACT_CALL_TYPE = hasSymbol ? Symbol['for']('react.call') : 0xeac8;
var REACT_RETURN_TYPE = hasSymbol ? Symbol['for']('react.return') : 0xeac9;
var REACT_PORTAL_TYPE = hasSymbol ? Symbol['for']('react.portal') : 0xeaca;
var REACT_FRAGMENT_TYPE = hasSymbol ? Symbol['for']('react.fragment') : 0xeacb;

var MAYBE_ITERATOR_SYMBOL = typeof Symbol === 'function' && Symbol.iterator;
var FAUX_ITERATOR_SYMBOL = '@@iterator';

function getIteratorFn(maybeIterable) {
  if (maybeIterable === null || typeof maybeIterable === 'undefined') {
    return null;
  }
  var maybeIterator = MAYBE_ITERATOR_SYMBOL && maybeIterable[MAYBE_ITERATOR_SYMBOL] || maybeIterable[FAUX_ITERATOR_SYMBOL];
  if (typeof maybeIterator === 'function') {
    return maybeIterator;
  }
  return null;
}

/**
 * WARNING: DO NOT manually require this module.
 * This is a replacement for `invariant(...)` used by the error code system
 * and will _only_ be required by the corresponding babel pass.
 * It always throws.
 */

/**
 * Forked from fbjs/warning:
 * https://github.com/facebook/fbjs/blob/e66ba20ad5be433eb54423f2b097d829324d9de6/packages/fbjs/src/__forks__/warning.js
 *
 * Only change is we use console.warn instead of console.error,
 * and do nothing when 'console' is not supported.
 * This really simplifies the code.
 * ---
 * Similar to invariant but only logs a warning if the condition is not met.
 * This can be used to log issues in development environments in critical
 * paths. Removing the logging code for production environments will keep the
 * same logic and follow the same code paths.
 */

var lowPriorityWarning = function () {};

{
  var printWarning = function (format) {
    for (var _len = arguments.length, args = Array(_len > 1 ? _len - 1 : 0), _key = 1; _key < _len; _key++) {
      args[_key - 1] = arguments[_key];
    }

    var argIndex = 0;
    var message = 'Warning: ' + format.replace(/%s/g, function () {
      return args[argIndex++];
    });
    if (typeof console !== 'undefined') {
      console.warn(message);
    }
    try {
      // --- Welcome to debugging React ---
      // This error was thrown as a convenience so that you can use this stack
      // to find the callsite that caused this warning to fire.
      throw new Error(message);
    } catch (x) {}
  };

  lowPriorityWarning = function (condition, format) {
    if (format === undefined) {
      throw new Error('`warning(condition, format, ...args)` requires a warning ' + 'message argument');
    }
    if (!condition) {
      for (var _len2 = arguments.length, args = Array(_len2 > 2 ? _len2 - 2 : 0), _key2 = 2; _key2 < _len2; _key2++) {
        args[_key2 - 2] = arguments[_key2];
      }

      printWarning.apply(undefined, [format].concat(args));
    }
  };
}

var lowPriorityWarning$1 = lowPriorityWarning;

var didWarnStateUpdateForUnmountedComponent = {};

function warnNoop(publicInstance, callerName) {
  {
    var constructor = publicInstance.constructor;
    var componentName = constructor && (constructor.displayName || constructor.name) || 'ReactClass';
    var warningKey = componentName + '.' + callerName;
    if (didWarnStateUpdateForUnmountedComponent[warningKey]) {
      return;
    }
    warning(false, '%s(...): Can only update a mounted or mounting component. ' + 'This usually means you called %s() on an unmounted component. ' + 'This is a no-op.\n\nPlease check the code for the %s component.', callerName, callerName, componentName);
    didWarnStateUpdateForUnmountedComponent[warningKey] = true;
  }
}

/**
 * This is the abstract API for an update queue.
 */
var ReactNoopUpdateQueue = {
  /**
   * Checks whether or not this composite component is mounted.
   * @param {ReactClass} publicInstance The instance we want to test.
   * @return {boolean} True if mounted, false otherwise.
   * @protected
   * @final
   */
  isMounted: function (publicInstance) {
    return false;
  },

  /**
   * Forces an update. This should only be invoked when it is known with
   * certainty that we are **not** in a DOM transaction.
   *
   * You may want to call this when you know that some deeper aspect of the
   * component's state has changed but `setState` was not called.
   *
   * This will not invoke `shouldComponentUpdate`, but it will invoke
   * `componentWillUpdate` and `componentDidUpdate`.
   *
   * @param {ReactClass} publicInstance The instance that should rerender.
   * @param {?function} callback Called after component is updated.
   * @param {?string} callerName name of the calling function in the public API.
   * @internal
   */
  enqueueForceUpdate: function (publicInstance, callback, callerName) {
    warnNoop(publicInstance, 'forceUpdate');
  },

  /**
   * Replaces all of the state. Always use this or `setState` to mutate state.
   * You should treat `this.state` as immutable.
   *
   * There is no guarantee that `this.state` will be immediately updated, so
   * accessing `this.state` after calling this method may return the old value.
   *
   * @param {ReactClass} publicInstance The instance that should rerender.
   * @param {object} completeState Next state.
   * @param {?function} callback Called after component is updated.
   * @param {?string} callerName name of the calling function in the public API.
   * @internal
   */
  enqueueReplaceState: function (publicInstance, completeState, callback, callerName) {
    warnNoop(publicInstance, 'replaceState');
  },

  /**
   * Sets a subset of the state. This only exists because _pendingState is
   * internal. This provides a merging strategy that is not available to deep
   * properties which is confusing. TODO: Expose pendingState or don't use it
   * during the merge.
   *
   * @param {ReactClass} publicInstance The instance that should rerender.
   * @param {object} partialState Next partial state to be merged with state.
   * @param {?function} callback Called after component is updated.
   * @param {?string} Name of the calling function in the public API.
   * @internal
   */
  enqueueSetState: function (publicInstance, partialState, callback, callerName) {
    warnNoop(publicInstance, 'setState');
  }
};

/**
 * Base class helpers for the updating state of a component.
 */
function Component(props, context, updater) {
  this.props = props;
  this.context = context;
  this.refs = emptyObject;
  // We initialize the default updater but the real one gets injected by the
  // renderer.
  this.updater = updater || ReactNoopUpdateQueue;
}

Component.prototype.isReactComponent = {};

/**
 * Sets a subset of the state. Always use this to mutate
 * state. You should treat `this.state` as immutable.
 *
 * There is no guarantee that `this.state` will be immediately updated, so
 * accessing `this.state` after calling this method may return the old value.
 *
 * There is no guarantee that calls to `setState` will run synchronously,
 * as they may eventually be batched together.  You can provide an optional
 * callback that will be executed when the call to setState is actually
 * completed.
 *
 * When a function is provided to setState, it will be called at some point in
 * the future (not synchronously). It will be called with the up to date
 * component arguments (state, props, context). These values can be different
 * from this.* because your function may be called after receiveProps but before
 * shouldComponentUpdate, and this new state, props, and context will not yet be
 * assigned to this.
 *
 * @param {object|function} partialState Next partial state or function to
 *        produce next partial state to be merged with current state.
 * @param {?function} callback Called after state is updated.
 * @final
 * @protected
 */
Component.prototype.setState = function (partialState, callback) {
  !(typeof partialState === 'object' || typeof partialState === 'function' || partialState == null) ? invariant(false, 'setState(...): takes an object of state variables to update or a function which returns an object of state variables.') : void 0;
  this.updater.enqueueSetState(this, partialState, callback, 'setState');
};

/**
 * Forces an update. This should only be invoked when it is known with
 * certainty that we are **not** in a DOM transaction.
 *
 * You may want to call this when you know that some deeper aspect of the
 * component's state has changed but `setState` was not called.
 *
 * This will not invoke `shouldComponentUpdate`, but it will invoke
 * `componentWillUpdate` and `componentDidUpdate`.
 *
 * @param {?function} callback Called after update is complete.
 * @final
 * @protected
 */
Component.prototype.forceUpdate = function (callback) {
  this.updater.enqueueForceUpdate(this, callback, 'forceUpdate');
};

/**
 * Deprecated APIs. These APIs used to exist on classic React classes but since
 * we would like to deprecate them, we're not going to move them over to this
 * modern base class. Instead, we define a getter that warns if it's accessed.
 */
{
  var deprecatedAPIs = {
    isMounted: ['isMounted', 'Instead, make sure to clean up subscriptions and pending requests in ' + 'componentWillUnmount to prevent memory leaks.'],
    replaceState: ['replaceState', 'Refactor your code to use setState instead (see ' + 'https://github.com/facebook/react/issues/3236).']
  };
  var defineDeprecationWarning = function (methodName, info) {
    Object.defineProperty(Component.prototype, methodName, {
      get: function () {
        lowPriorityWarning$1(false, '%s(...) is deprecated in plain JavaScript React classes. %s', info[0], info[1]);
        return undefined;
      }
    });
  };
  for (var fnName in deprecatedAPIs) {
    if (deprecatedAPIs.hasOwnProperty(fnName)) {
      defineDeprecationWarning(fnName, deprecatedAPIs[fnName]);
    }
  }
}

/**
 * Base class helpers for the updating state of a component.
 */
function PureComponent(props, context, updater) {
  // Duplicated from Component.
  this.props = props;
  this.context = context;
  this.refs = emptyObject;
  // We initialize the default updater but the real one gets injected by the
  // renderer.
  this.updater = updater || ReactNoopUpdateQueue;
}

function ComponentDummy() {}
ComponentDummy.prototype = Component.prototype;
var pureComponentPrototype = PureComponent.prototype = new ComponentDummy();
pureComponentPrototype.constructor = PureComponent;
// Avoid an extra prototype jump for these methods.
_assign(pureComponentPrototype, Component.prototype);
pureComponentPrototype.isPureReactComponent = true;

function AsyncComponent(props, context, updater) {
  // Duplicated from Component.
  this.props = props;
  this.context = context;
  this.refs = emptyObject;
  // We initialize the default updater but the real one gets injected by the
  // renderer.
  this.updater = updater || ReactNoopUpdateQueue;
}

var asyncComponentPrototype = AsyncComponent.prototype = new ComponentDummy();
asyncComponentPrototype.constructor = AsyncComponent;
// Avoid an extra prototype jump for these methods.
_assign(asyncComponentPrototype, Component.prototype);
asyncComponentPrototype.unstable_isAsyncReactComponent = true;
asyncComponentPrototype.render = function () {
  return this.props.children;
};

/**
 * Keeps track of the current owner.
 *
 * The current owner is the component who should own any components that are
 * currently being constructed.
 */
var ReactCurrentOwner = {
  /**
   * @internal
   * @type {ReactComponent}
   */
  current: null
};

var hasOwnProperty = Object.prototype.hasOwnProperty;

var RESERVED_PROPS = {
  key: true,
  ref: true,
  __self: true,
  __source: true
};

var specialPropKeyWarningShown;
var specialPropRefWarningShown;

function hasValidRef(config) {
  {
    if (hasOwnProperty.call(config, 'ref')) {
      var getter = Object.getOwnPropertyDescriptor(config, 'ref').get;
      if (getter && getter.isReactWarning) {
        return false;
      }
    }
  }
  return config.ref !== undefined;
}

function hasValidKey(config) {
  {
    if (hasOwnProperty.call(config, 'key')) {
      var getter = Object.getOwnPropertyDescriptor(config, 'key').get;
      if (getter && getter.isReactWarning) {
        return false;
      }
    }
  }
  return config.key !== undefined;
}

function defineKeyPropWarningGetter(props, displayName) {
  var warnAboutAccessingKey = function () {
    if (!specialPropKeyWarningShown) {
      specialPropKeyWarningShown = true;
      warning(false, '%s: `key` is not a prop. Trying to access it will result ' + 'in `undefined` being returned. If you need to access the same ' + 'value within the child component, you should pass it as a different ' + 'prop. (https://fb.me/react-special-props)', displayName);
    }
  };
  warnAboutAccessingKey.isReactWarning = true;
  Object.defineProperty(props, 'key', {
    get: warnAboutAccessingKey,
    configurable: true
  });
}

function defineRefPropWarningGetter(props, displayName) {
  var warnAboutAccessingRef = function () {
    if (!specialPropRefWarningShown) {
      specialPropRefWarningShown = true;
      warning(false, '%s: `ref` is not a prop. Trying to access it will result ' + 'in `undefined` being returned. If you need to access the same ' + 'value within the child component, you should pass it as a different ' + 'prop. (https://fb.me/react-special-props)', displayName);
    }
  };
  warnAboutAccessingRef.isReactWarning = true;
  Object.defineProperty(props, 'ref', {
    get: warnAboutAccessingRef,
    configurable: true
  });
}

/**
 * Factory method to create a new React element. This no longer adheres to
 * the class pattern, so do not use new to call it. Also, no instanceof check
 * will work. Instead test $$typeof field against Symbol.for('react.element') to check
 * if something is a React Element.
 *
 * @param {*} type
 * @param {*} key
 * @param {string|object} ref
 * @param {*} self A *temporary* helper to detect places where `this` is
 * different from the `owner` when React.createElement is called, so that we
 * can warn. We want to get rid of owner and replace string `ref`s with arrow
 * functions, and as long as `this` and owner are the same, there will be no
 * change in behavior.
 * @param {*} source An annotation object (added by a transpiler or otherwise)
 * indicating filename, line number, and/or other information.
 * @param {*} owner
 * @param {*} props
 * @internal
 */
var ReactElement = function (type, key, ref, self, source, owner, props) {
  var element = {
    // This tag allow us to uniquely identify this as a React Element
    $$typeof: REACT_ELEMENT_TYPE,

    // Built-in properties that belong on the element
    type: type,
    key: key,
    ref: ref,
    props: props,

    // Record the component responsible for creating this element.
    _owner: owner
  };

  {
    // The validation flag is currently mutative. We put it on
    // an external backing store so that we can freeze the whole object.
    // This can be replaced with a WeakMap once they are implemented in
    // commonly used development environments.
    element._store = {};

    // To make comparing ReactElements easier for testing purposes, we make
    // the validation flag non-enumerable (where possible, which should
    // include every environment we run tests in), so the test framework
    // ignores it.
    Object.defineProperty(element._store, 'validated', {
      configurable: false,
      enumerable: false,
      writable: true,
      value: false
    });
    // self and source are DEV only properties.
    Object.defineProperty(element, '_self', {
      configurable: false,
      enumerable: false,
      writable: false,
      value: self
    });
    // Two elements created in two different places should be considered
    // equal for testing purposes and therefore we hide it from enumeration.
    Object.defineProperty(element, '_source', {
      configurable: false,
      enumerable: false,
      writable: false,
      value: source
    });
    if (Object.freeze) {
      Object.freeze(element.props);
      Object.freeze(element);
    }
  }

  return element;
};

/**
 * Create and return a new ReactElement of the given type.
 * See https://reactjs.org/docs/react-api.html#createelement
 */
function createElement(type, config, children) {
  var propName;

  // Reserved names are extracted
  var props = {};

  var key = null;
  var ref = null;
  var self = null;
  var source = null;

  if (config != null) {
    if (hasValidRef(config)) {
      ref = config.ref;
    }
    if (hasValidKey(config)) {
      key = '' + config.key;
    }

    self = config.__self === undefined ? null : config.__self;
    source = config.__source === undefined ? null : config.__source;
    // Remaining properties are added to a new props object
    for (propName in config) {
      if (hasOwnProperty.call(config, propName) && !RESERVED_PROPS.hasOwnProperty(propName)) {
        props[propName] = config[propName];
      }
    }
  }

  // Children can be more than one argument, and those are transferred onto
  // the newly allocated props object.
  var childrenLength = arguments.length - 2;
  if (childrenLength === 1) {
    props.children = children;
  } else if (childrenLength > 1) {
    var childArray = Array(childrenLength);
    for (var i = 0; i < childrenLength; i++) {
      childArray[i] = arguments[i + 2];
    }
    {
      if (Object.freeze) {
        Object.freeze(childArray);
      }
    }
    props.children = childArray;
  }

  // Resolve default props
  if (type && type.defaultProps) {
    var defaultProps = type.defaultProps;
    for (propName in defaultProps) {
      if (props[propName] === undefined) {
        props[propName] = defaultProps[propName];
      }
    }
  }
  {
    if (key || ref) {
      if (typeof props.$$typeof === 'undefined' || props.$$typeof !== REACT_ELEMENT_TYPE) {
        var displayName = typeof type === 'function' ? type.displayName || type.name || 'Unknown' : type;
        if (key) {
          defineKeyPropWarningGetter(props, displayName);
        }
        if (ref) {
          defineRefPropWarningGetter(props, displayName);
        }
      }
    }
  }
  return ReactElement(type, key, ref, self, source, ReactCurrentOwner.current, props);
}

/**
 * Return a function that produces ReactElements of a given type.
 * See https://reactjs.org/docs/react-api.html#createfactory
 */


function cloneAndReplaceKey(oldElement, newKey) {
  var newElement = ReactElement(oldElement.type, newKey, oldElement.ref, oldElement._self, oldElement._source, oldElement._owner, oldElement.props);

  return newElement;
}

/**
 * Clone and return a new ReactElement using element as the starting point.
 * See https://reactjs.org/docs/react-api.html#cloneelement
 */
function cloneElement(element, config, children) {
  var propName;

  // Original props are copied
  var props = _assign({}, element.props);

  // Reserved names are extracted
  var key = element.key;
  var ref = element.ref;
  // Self is preserved since the owner is preserved.
  var self = element._self;
  // Source is preserved since cloneElement is unlikely to be targeted by a
  // transpiler, and the original source is probably a better indicator of the
  // true owner.
  var source = element._source;

  // Owner will be preserved, unless ref is overridden
  var owner = element._owner;

  if (config != null) {
    if (hasValidRef(config)) {
      // Silently steal the ref from the parent.
      ref = config.ref;
      owner = ReactCurrentOwner.current;
    }
    if (hasValidKey(config)) {
      key = '' + config.key;
    }

    // Remaining properties override existing props
    var defaultProps;
    if (element.type && element.type.defaultProps) {
      defaultProps = element.type.defaultProps;
    }
    for (propName in config) {
      if (hasOwnProperty.call(config, propName) && !RESERVED_PROPS.hasOwnProperty(propName)) {
        if (config[propName] === undefined && defaultProps !== undefined) {
          // Resolve default props
          props[propName] = defaultProps[propName];
        } else {
          props[propName] = config[propName];
        }
      }
    }
  }

  // Children can be more than one argument, and those are transferred onto
  // the newly allocated props object.
  var childrenLength = arguments.length - 2;
  if (childrenLength === 1) {
    props.children = children;
  } else if (childrenLength > 1) {
    var childArray = Array(childrenLength);
    for (var i = 0; i < childrenLength; i++) {
      childArray[i] = arguments[i + 2];
    }
    props.children = childArray;
  }

  return ReactElement(element.type, key, ref, self, source, owner, props);
}

/**
 * Verifies the object is a ReactElement.
 * See https://reactjs.org/docs/react-api.html#isvalidelement
 * @param {?object} object
 * @return {boolean} True if `object` is a valid component.
 * @final
 */
function isValidElement(object) {
  return typeof object === 'object' && object !== null && object.$$typeof === REACT_ELEMENT_TYPE;
}

var ReactDebugCurrentFrame = {};

{
  // Component that is being worked on
  ReactDebugCurrentFrame.getCurrentStack = null;

  ReactDebugCurrentFrame.getStackAddendum = function () {
    var impl = ReactDebugCurrentFrame.getCurrentStack;
    if (impl) {
      return impl();
    }
    return null;
  };
}

var SEPARATOR = '.';
var SUBSEPARATOR = ':';

/**
 * Escape and wrap key so it is safe to use as a reactid
 *
 * @param {string} key to be escaped.
 * @return {string} the escaped key.
 */
function escape(key) {
  var escapeRegex = /[=:]/g;
  var escaperLookup = {
    '=': '=0',
    ':': '=2'
  };
  var escapedString = ('' + key).replace(escapeRegex, function (match) {
    return escaperLookup[match];
  });

  return '$' + escapedString;
}

/**
 * TODO: Test that a single child and an array with one item have the same key
 * pattern.
 */

var didWarnAboutMaps = false;

var userProvidedKeyEscapeRegex = /\/+/g;
function escapeUserProvidedKey(text) {
  return ('' + text).replace(userProvidedKeyEscapeRegex, '$&/');
}

var POOL_SIZE = 10;
var traverseContextPool = [];
function getPooledTraverseContext(mapResult, keyPrefix, mapFunction, mapContext) {
  if (traverseContextPool.length) {
    var traverseContext = traverseContextPool.pop();
    traverseContext.result = mapResult;
    traverseContext.keyPrefix = keyPrefix;
    traverseContext.func = mapFunction;
    traverseContext.context = mapContext;
    traverseContext.count = 0;
    return traverseContext;
  } else {
    return {
      result: mapResult,
      keyPrefix: keyPrefix,
      func: mapFunction,
      context: mapContext,
      count: 0
    };
  }
}

function releaseTraverseContext(traverseContext) {
  traverseContext.result = null;
  traverseContext.keyPrefix = null;
  traverseContext.func = null;
  traverseContext.context = null;
  traverseContext.count = 0;
  if (traverseContextPool.length < POOL_SIZE) {
    traverseContextPool.push(traverseContext);
  }
}

/**
 * @param {?*} children Children tree container.
 * @param {!string} nameSoFar Name of the key path so far.
 * @param {!function} callback Callback to invoke with each child found.
 * @param {?*} traverseContext Used to pass information throughout the traversal
 * process.
 * @return {!number} The number of children in this subtree.
 */
function traverseAllChildrenImpl(children, nameSoFar, callback, traverseContext) {
  var type = typeof children;

  if (type === 'undefined' || type === 'boolean') {
    // All of the above are perceived as null.
    children = null;
  }

  var invokeCallback = false;

  if (children === null) {
    invokeCallback = true;
  } else {
    switch (type) {
      case 'string':
      case 'number':
        invokeCallback = true;
        break;
      case 'object':
        switch (children.$$typeof) {
          case REACT_ELEMENT_TYPE:
          case REACT_CALL_TYPE:
          case REACT_RETURN_TYPE:
          case REACT_PORTAL_TYPE:
            invokeCallback = true;
        }
    }
  }

  if (invokeCallback) {
    callback(traverseContext, children,
    // If it's the only child, treat the name as if it was wrapped in an array
    // so that it's consistent if the number of children grows.
    nameSoFar === '' ? SEPARATOR + getComponentKey(children, 0) : nameSoFar);
    return 1;
  }

  var child;
  var nextName;
  var subtreeCount = 0; // Count of children found in the current subtree.
  var nextNamePrefix = nameSoFar === '' ? SEPARATOR : nameSoFar + SUBSEPARATOR;

  if (Array.isArray(children)) {
    for (var i = 0; i < children.length; i++) {
      child = children[i];
      nextName = nextNamePrefix + getComponentKey(child, i);
      subtreeCount += traverseAllChildrenImpl(child, nextName, callback, traverseContext);
    }
  } else {
    var iteratorFn = getIteratorFn(children);
    if (typeof iteratorFn === 'function') {
      {
        // Warn about using Maps as children
        if (iteratorFn === children.entries) {
          warning(didWarnAboutMaps, 'Using Maps as children is unsupported and will likely yield ' + 'unexpected results. Convert it to a sequence/iterable of keyed ' + 'ReactElements instead.%s', ReactDebugCurrentFrame.getStackAddendum());
          didWarnAboutMaps = true;
        }
      }

      var iterator = iteratorFn.call(children);
      var step;
      var ii = 0;
      while (!(step = iterator.next()).done) {
        child = step.value;
        nextName = nextNamePrefix + getComponentKey(child, ii++);
        subtreeCount += traverseAllChildrenImpl(child, nextName, callback, traverseContext);
      }
    } else if (type === 'object') {
      var addendum = '';
      {
        addendum = ' If you meant to render a collection of children, use an array ' + 'instead.' + ReactDebugCurrentFrame.getStackAddendum();
      }
      var childrenString = '' + children;
      invariant(false, 'Objects are not valid as a React child (found: %s).%s', childrenString === '[object Object]' ? 'object with keys {' + Object.keys(children).join(', ') + '}' : childrenString, addendum);
    }
  }

  return subtreeCount;
}

/**
 * Traverses children that are typically specified as `props.children`, but
 * might also be specified through attributes:
 *
 * - `traverseAllChildren(this.props.children, ...)`
 * - `traverseAllChildren(this.props.leftPanelChildren, ...)`
 *
 * The `traverseContext` is an optional argument that is passed through the
 * entire traversal. It can be used to store accumulations or anything else that
 * the callback might find relevant.
 *
 * @param {?*} children Children tree object.
 * @param {!function} callback To invoke upon traversing each child.
 * @param {?*} traverseContext Context for traversal.
 * @return {!number} The number of children in this subtree.
 */
function traverseAllChildren(children, callback, traverseContext) {
  if (children == null) {
    return 0;
  }

  return traverseAllChildrenImpl(children, '', callback, traverseContext);
}

/**
 * Generate a key string that identifies a component within a set.
 *
 * @param {*} component A component that could contain a manual key.
 * @param {number} index Index that is used if a manual key is not provided.
 * @return {string}
 */
function getComponentKey(component, index) {
  // Do some typechecking here since we call this blindly. We want to ensure
  // that we don't block potential future ES APIs.
  if (typeof component === 'object' && component !== null && component.key != null) {
    // Explicit key
    return escape(component.key);
  }
  // Implicit key determined by the index in the set
  return index.toString(36);
}

function forEachSingleChild(bookKeeping, child, name) {
  var func = bookKeeping.func,
      context = bookKeeping.context;

  func.call(context, child, bookKeeping.count++);
}

/**
 * Iterates through children that are typically specified as `props.children`.
 *
 * See https://reactjs.org/docs/react-api.html#react.children.foreach
 *
 * The provided forEachFunc(child, index) will be called for each
 * leaf child.
 *
 * @param {?*} children Children tree container.
 * @param {function(*, int)} forEachFunc
 * @param {*} forEachContext Context for forEachContext.
 */
function forEachChildren(children, forEachFunc, forEachContext) {
  if (children == null) {
    return children;
  }
  var traverseContext = getPooledTraverseContext(null, null, forEachFunc, forEachContext);
  traverseAllChildren(children, forEachSingleChild, traverseContext);
  releaseTraverseContext(traverseContext);
}

function mapSingleChildIntoContext(bookKeeping, child, childKey) {
  var result = bookKeeping.result,
      keyPrefix = bookKeeping.keyPrefix,
      func = bookKeeping.func,
      context = bookKeeping.context;


  var mappedChild = func.call(context, child, bookKeeping.count++);
  if (Array.isArray(mappedChild)) {
    mapIntoWithKeyPrefixInternal(mappedChild, result, childKey, emptyFunction.thatReturnsArgument);
  } else if (mappedChild != null) {
    if (isValidElement(mappedChild)) {
      mappedChild = cloneAndReplaceKey(mappedChild,
      // Keep both the (mapped) and old keys if they differ, just as
      // traverseAllChildren used to do for objects as children
      keyPrefix + (mappedChild.key && (!child || child.key !== mappedChild.key) ? escapeUserProvidedKey(mappedChild.key) + '/' : '') + childKey);
    }
    result.push(mappedChild);
  }
}

function mapIntoWithKeyPrefixInternal(children, array, prefix, func, context) {
  var escapedPrefix = '';
  if (prefix != null) {
    escapedPrefix = escapeUserProvidedKey(prefix) + '/';
  }
  var traverseContext = getPooledTraverseContext(array, escapedPrefix, func, context);
  traverseAllChildren(children, mapSingleChildIntoContext, traverseContext);
  releaseTraverseContext(traverseContext);
}

/**
 * Maps children that are typically specified as `props.children`.
 *
 * See https://reactjs.org/docs/react-api.html#react.children.map
 *
 * The provided mapFunction(child, key, index) will be called for each
 * leaf child.
 *
 * @param {?*} children Children tree container.
 * @param {function(*, int)} func The map function.
 * @param {*} context Context for mapFunction.
 * @return {object} Object containing the ordered map of results.
 */
function mapChildren(children, func, context) {
  if (children == null) {
    return children;
  }
  var result = [];
  mapIntoWithKeyPrefixInternal(children, result, null, func, context);
  return result;
}

/**
 * Count the number of children that are typically specified as
 * `props.children`.
 *
 * See https://reactjs.org/docs/react-api.html#react.children.count
 *
 * @param {?*} children Children tree container.
 * @return {number} The number of children.
 */
function countChildren(children, context) {
  return traverseAllChildren(children, emptyFunction.thatReturnsNull, null);
}

/**
 * Flatten a children object (typically specified as `props.children`) and
 * return an array with appropriately re-keyed children.
 *
 * See https://reactjs.org/docs/react-api.html#react.children.toarray
 */
function toArray(children) {
  var result = [];
  mapIntoWithKeyPrefixInternal(children, result, null, emptyFunction.thatReturnsArgument);
  return result;
}

/**
 * Returns the first child in a collection of children and verifies that there
 * is only one child in the collection.
 *
 * See https://reactjs.org/docs/react-api.html#react.children.only
 *
 * The current implementation of this function assumes that a single child gets
 * passed without a wrapper, but the purpose of this helper function is to
 * abstract away the particular structure of children.
 *
 * @param {?object} children Child collection structure.
 * @return {ReactElement} The first and only `ReactElement` contained in the
 * structure.
 */
function onlyChild(children) {
  !isValidElement(children) ? invariant(false, 'React.Children.only expected to receive a single React element child.') : void 0;
  return children;
}

var describeComponentFrame = function (name, source, ownerName) {
  return '\n    in ' + (name || 'Unknown') + (source ? ' (at ' + source.fileName.replace(/^.*[\\\/]/, '') + ':' + source.lineNumber + ')' : ownerName ? ' (created by ' + ownerName + ')' : '');
};

function getComponentName(fiber) {
  var type = fiber.type;

  if (typeof type === 'string') {
    return type;
  }
  if (typeof type === 'function') {
    return type.displayName || type.name;
  }
  return null;
}

/**
 * ReactElementValidator provides a wrapper around a element factory
 * which validates the props passed to the element. This is intended to be
 * used only in DEV and could be replaced by a static type checker for languages
 * that support it.
 */

{
  var currentlyValidatingElement = null;

  var propTypesMisspellWarningShown = false;

  var getDisplayName = function (element) {
    if (element == null) {
      return '#empty';
    } else if (typeof element === 'string' || typeof element === 'number') {
      return '#text';
    } else if (typeof element.type === 'string') {
      return element.type;
    } else if (element.type === REACT_FRAGMENT_TYPE) {
      return 'React.Fragment';
    } else {
      return element.type.displayName || element.type.name || 'Unknown';
    }
  };

  var getStackAddendum = function () {
    var stack = '';
    if (currentlyValidatingElement) {
      var name = getDisplayName(currentlyValidatingElement);
      var owner = currentlyValidatingElement._owner;
      stack += describeComponentFrame(name, currentlyValidatingElement._source, owner && getComponentName(owner));
    }
    stack += ReactDebugCurrentFrame.getStackAddendum() || '';
    return stack;
  };

  var VALID_FRAGMENT_PROPS = new Map([['children', true], ['key', true]]);
}

function getDeclarationErrorAddendum() {
  if (ReactCurrentOwner.current) {
    var name = getComponentName(ReactCurrentOwner.current);
    if (name) {
      return '\n\nCheck the render method of `' + name + '`.';
    }
  }
  return '';
}

function getSourceInfoErrorAddendum(elementProps) {
  if (elementProps !== null && elementProps !== undefined && elementProps.__source !== undefined) {
    var source = elementProps.__source;
    var fileName = source.fileName.replace(/^.*[\\\/]/, '');
    var lineNumber = source.lineNumber;
    return '\n\nCheck your code at ' + fileName + ':' + lineNumber + '.';
  }
  return '';
}

/**
 * Warn if there's no key explicitly set on dynamic arrays of children or
 * object keys are not valid. This allows us to keep track of children between
 * updates.
 */
var ownerHasKeyUseWarning = {};

function getCurrentComponentErrorInfo(parentType) {
  var info = getDeclarationErrorAddendum();

  if (!info) {
    var parentName = typeof parentType === 'string' ? parentType : parentType.displayName || parentType.name;
    if (parentName) {
      info = '\n\nCheck the top-level render call using <' + parentName + '>.';
    }
  }
  return info;
}

/**
 * Warn if the element doesn't have an explicit key assigned to it.
 * This element is in an array. The array could grow and shrink or be
 * reordered. All children that haven't already been validated are required to
 * have a "key" property assigned to it. Error statuses are cached so a warning
 * will only be shown once.
 *
 * @internal
 * @param {ReactElement} element Element that requires a key.
 * @param {*} parentType element's parent's type.
 */
function validateExplicitKey(element, parentType) {
  if (!element._store || element._store.validated || element.key != null) {
    return;
  }
  element._store.validated = true;

  var currentComponentErrorInfo = getCurrentComponentErrorInfo(parentType);
  if (ownerHasKeyUseWarning[currentComponentErrorInfo]) {
    return;
  }
  ownerHasKeyUseWarning[currentComponentErrorInfo] = true;

  // Usually the current owner is the offender, but if it accepts children as a
  // property, it may be the creator of the child that's responsible for
  // assigning it a key.
  var childOwner = '';
  if (element && element._owner && element._owner !== ReactCurrentOwner.current) {
    // Give the component that originally created this child.
    childOwner = ' It was passed a child from ' + getComponentName(element._owner) + '.';
  }

  currentlyValidatingElement = element;
  {
    warning(false, 'Each child in an array or iterator should have a unique "key" prop.' + '%s%s See https://fb.me/react-warning-keys for more information.%s', currentComponentErrorInfo, childOwner, getStackAddendum());
  }
  currentlyValidatingElement = null;
}

/**
 * Ensure that every element either is passed in a static location, in an
 * array with an explicit keys property defined, or in an object literal
 * with valid key property.
 *
 * @internal
 * @param {ReactNode} node Statically passed child of any type.
 * @param {*} parentType node's parent's type.
 */
function validateChildKeys(node, parentType) {
  if (typeof node !== 'object') {
    return;
  }
  if (Array.isArray(node)) {
    for (var i = 0; i < node.length; i++) {
      var child = node[i];
      if (isValidElement(child)) {
        validateExplicitKey(child, parentType);
      }
    }
  } else if (isValidElement(node)) {
    // This element was passed in a valid location.
    if (node._store) {
      node._store.validated = true;
    }
  } else if (node) {
    var iteratorFn = getIteratorFn(node);
    if (typeof iteratorFn === 'function') {
      // Entry iterators used to provide implicit keys,
      // but now we print a separate warning for them later.
      if (iteratorFn !== node.entries) {
        var iterator = iteratorFn.call(node);
        var step;
        while (!(step = iterator.next()).done) {
          if (isValidElement(step.value)) {
            validateExplicitKey(step.value, parentType);
          }
        }
      }
    }
  }
}

/**
 * Given an element, validate that its props follow the propTypes definition,
 * provided by the type.
 *
 * @param {ReactElement} element
 */
function validatePropTypes(element) {
  var componentClass = element.type;
  if (typeof componentClass !== 'function') {
    return;
  }
  var name = componentClass.displayName || componentClass.name;
  var propTypes = componentClass.propTypes;
  if (propTypes) {
    currentlyValidatingElement = element;
    checkPropTypes(propTypes, element.props, 'prop', name, getStackAddendum);
    currentlyValidatingElement = null;
  } else if (componentClass.PropTypes !== undefined && !propTypesMisspellWarningShown) {
    propTypesMisspellWarningShown = true;
    warning(false, 'Component %s declared `PropTypes` instead of `propTypes`. Did you misspell the property assignment?', name || 'Unknown');
  }
  if (typeof componentClass.getDefaultProps === 'function') {
    warning(componentClass.getDefaultProps.isReactClassApproved, 'getDefaultProps is only used on classic React.createClass ' + 'definitions. Use a static property named `defaultProps` instead.');
  }
}

/**
 * Given a fragment, validate that it can only be provided with fragment props
 * @param {ReactElement} fragment
 */
function validateFragmentProps(fragment) {
  currentlyValidatingElement = fragment;

  var _iteratorNormalCompletion = true;
  var _didIteratorError = false;
  var _iteratorError = undefined;

  try {
    for (var _iterator = Object.keys(fragment.props)[Symbol.iterator](), _step; !(_iteratorNormalCompletion = (_step = _iterator.next()).done); _iteratorNormalCompletion = true) {
      var key = _step.value;

      if (!VALID_FRAGMENT_PROPS.has(key)) {
        warning(false, 'Invalid prop `%s` supplied to `React.Fragment`. ' + 'React.Fragment can only have `key` and `children` props.%s', key, getStackAddendum());
        break;
      }
    }
  } catch (err) {
    _didIteratorError = true;
    _iteratorError = err;
  } finally {
    try {
      if (!_iteratorNormalCompletion && _iterator['return']) {
        _iterator['return']();
      }
    } finally {
      if (_didIteratorError) {
        throw _iteratorError;
      }
    }
  }

  if (fragment.ref !== null) {
    warning(false, 'Invalid attribute `ref` supplied to `React.Fragment`.%s', getStackAddendum());
  }

  currentlyValidatingElement = null;
}

function createElementWithValidation(type, props, children) {
  var validType = typeof type === 'string' || typeof type === 'function' || typeof type === 'symbol' || typeof type === 'number';
  // We warn in this case but don't throw. We expect the element creation to
  // succeed and there will likely be errors in render.
  if (!validType) {
    var info = '';
    if (type === undefined || typeof type === 'object' && type !== null && Object.keys(type).length === 0) {
      info += ' You likely forgot to export your component from the file ' + "it's defined in, or you might have mixed up default and named imports.";
    }

    var sourceInfo = getSourceInfoErrorAddendum(props);
    if (sourceInfo) {
      info += sourceInfo;
    } else {
      info += getDeclarationErrorAddendum();
    }

    info += getStackAddendum() || '';

    warning(false, 'React.createElement: type is invalid -- expected a string (for ' + 'built-in components) or a class/function (for composite ' + 'components) but got: %s.%s', type == null ? type : typeof type, info);
  }

  var element = createElement.apply(this, arguments);

  // The result can be nullish if a mock or a custom function is used.
  // TODO: Drop this when these are no longer allowed as the type argument.
  if (element == null) {
    return element;
  }

  // Skip key warning if the type isn't valid since our key validation logic
  // doesn't expect a non-string/function type and can throw confusing errors.
  // We don't want exception behavior to differ between dev and prod.
  // (Rendering will throw with a helpful message and as soon as the type is
  // fixed, the key warnings will appear.)
  if (validType) {
    for (var i = 2; i < arguments.length; i++) {
      validateChildKeys(arguments[i], type);
    }
  }

  if (typeof type === 'symbol' && type === REACT_FRAGMENT_TYPE) {
    validateFragmentProps(element);
  } else {
    validatePropTypes(element);
  }

  return element;
}

function createFactoryWithValidation(type) {
  var validatedFactory = createElementWithValidation.bind(null, type);
  // Legacy hook TODO: Warn if this is accessed
  validatedFactory.type = type;

  {
    Object.defineProperty(validatedFactory, 'type', {
      enumerable: false,
      get: function () {
        lowPriorityWarning$1(false, 'Factory.type is deprecated. Access the class directly ' + 'before passing it to createFactory.');
        Object.defineProperty(this, 'type', {
          value: type
        });
        return type;
      }
    });
  }

  return validatedFactory;
}

function cloneElementWithValidation(element, props, children) {
  var newElement = cloneElement.apply(this, arguments);
  for (var i = 2; i < arguments.length; i++) {
    validateChildKeys(arguments[i], newElement.type);
  }
  validatePropTypes(newElement);
  return newElement;
}

var React = {
  Children: {
    map: mapChildren,
    forEach: forEachChildren,
    count: countChildren,
    toArray: toArray,
    only: onlyChild
  },

  Component: Component,
  PureComponent: PureComponent,
  unstable_AsyncComponent: AsyncComponent,

  Fragment: REACT_FRAGMENT_TYPE,

  createElement: createElementWithValidation,
  cloneElement: cloneElementWithValidation,
  createFactory: createFactoryWithValidation,
  isValidElement: isValidElement,

  version: ReactVersion,

  __SECRET_INTERNALS_DO_NOT_USE_OR_YOU_WILL_BE_FIRED: {
    ReactCurrentOwner: ReactCurrentOwner,
    // Used by renderers to avoid bundling object-assign twice in UMD bundles:
    assign: _assign
  }
};

{
  _assign(React.__SECRET_INTERNALS_DO_NOT_USE_OR_YOU_WILL_BE_FIRED, {
    // These should not be included in production.
    ReactDebugCurrentFrame: ReactDebugCurrentFrame,
    // Shim for React DOM 16.0.0 which still destructured (but not used) this.
    // TODO: remove in React 17.0.
    ReactComponentTreeHook: {}
  });
}



var React$2 = Object.freeze({
	default: React
});

var React$3 = ( React$2 && React ) || React$2;

// TODO: decide on the top-level export form.
// This is hacky but makes it work with both Rollup and Jest.
var react = React$3['default'] ? React$3['default'] : React$3;

module.exports = react;
  })();
}