core-js/modules/$.iter-define.js

Standard library

'use strict';
var LIBRARY         = require('./$.library')
  , $def            = require('./$.def')
  , $redef          = require('./$.redef')
  , hide            = require('./$.hide')
  , has             = require('./$.has')
  , SYMBOL_ITERATOR = require('./$.wks')('iterator')
  , Iterators       = require('./$.iterators')
  , BUGGY           = !([].keys && 'next' in [].keys()) // Safari has buggy iterators w/o `next`
  , FF_ITERATOR     = '@@iterator'
  , KEYS            = 'keys'
  , VALUES          = 'values';
var returnThis = function(){ return this; };
module.exports = function(Base, NAME, Constructor, next, DEFAULT, IS_SET, FORCE){
  require('./$.iter-create')(Constructor, NAME, next);
  var createMethod = function(kind){
    switch(kind){
      case KEYS: return function keys(){ return new Constructor(this, kind); };
      case VALUES: return function values(){ return new Constructor(this, kind); };
    } return function entries(){ return new Constructor(this, kind); };
  };
  var TAG      = NAME + ' Iterator'
    , proto    = Base.prototype
    , _native  = proto[SYMBOL_ITERATOR] || proto[FF_ITERATOR] || DEFAULT && proto[DEFAULT]
    , _default = _native || createMethod(DEFAULT)
    , methods, key;
  // Fix native
  if(_native){
    var IteratorPrototype = require('./$').getProto(_default.call(new Base));
    // Set @@toStringTag to native iterators
    require('./$.tag')(IteratorPrototype, TAG, true);
    // FF fix
    if(!LIBRARY && has(proto, FF_ITERATOR))hide(IteratorPrototype, SYMBOL_ITERATOR, returnThis);
  }
  // Define iterator
  if(!LIBRARY || FORCE)hide(proto, SYMBOL_ITERATOR, _default);
  // Plug for library
  Iterators[NAME] = _default;
  Iterators[TAG]  = returnThis;
  if(DEFAULT){
    methods = {
      keys:    IS_SET            ? _default : createMethod(KEYS),
      values:  DEFAULT == VALUES ? _default : createMethod(VALUES),
      entries: DEFAULT != VALUES ? _default : createMethod('entries')
    };
    if(FORCE)for(key in methods){
      if(!(key in proto))$redef(proto, key, methods[key]);
    } else $def($def.P + $def.F * BUGGY, NAME, methods);
  }
};