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iterator-create-proxy.js
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iterator-create-proxy.js
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'use strict';
var call = require('../internals/function-call');
var anObject = require('../internals/an-object');
var create = require('../internals/object-create');
var createNonEnumerableProperty = require('../internals/create-non-enumerable-property');
var defineBuiltIns = require('../internals/define-built-ins');
var wellKnownSymbol = require('../internals/well-known-symbol');
var InternalStateModule = require('../internals/internal-state');
var getMethod = require('../internals/get-method');
var IteratorPrototype = require('../internals/iterators-core').IteratorPrototype;
var ITERATOR_PROXY = 'IteratorProxy';
var setInternalState = InternalStateModule.set;
var getInternalState = InternalStateModule.getterFor(ITERATOR_PROXY);
var TO_STRING_TAG = wellKnownSymbol('toStringTag');
module.exports = function (nextHandler, IS_ITERATOR) {
var IteratorProxy = function Iterator(record, state) {
if (state) {
state.iterator = record.iterator;
state.next = record.next;
} else state = record;
state.type = ITERATOR_PROXY;
state.done = false;
state.ignoreArg = !IS_ITERATOR;
setInternalState(this, state);
};
IteratorProxy.prototype = defineBuiltIns(create(IteratorPrototype), {
next: function next(arg) {
var state = getInternalState(this);
var args = arguments.length ? [state.ignoreArg ? undefined : arg] : IS_ITERATOR ? [] : [undefined];
state.ignoreArg = false;
var result = state.done ? undefined : call(nextHandler, state, args);
return { done: state.done, value: result };
},
'return': function (value) {
var state = getInternalState(this);
var iterator = state.iterator;
state.done = true;
var $$return = getMethod(iterator, 'return');
return { done: true, value: $$return ? anObject(call($$return, iterator, value)).value : value };
},
'throw': function (value) {
var state = getInternalState(this);
var iterator = state.iterator;
state.done = true;
var $$throw = getMethod(iterator, 'throw');
if ($$throw) return call($$throw, iterator, value);
throw value;
}
});
if (!IS_ITERATOR) {
createNonEnumerableProperty(IteratorProxy.prototype, TO_STRING_TAG, 'Generator');
}
return IteratorProxy;
};