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// Copyright (C) 2016 the V8 project authors. All rights reserved.
// This code is governed by the BSD license found in the LICENSE file.
/*---
esid: sec-generator-function-definitions-runtime-semantics-evaluation
es6id: 14.4.14
description: >
Abrupt completion returned after protocol violation (and a `return` method
is defined)
info: |
YieldExpression : yield * AssignmentExpression
1. Let exprRef be the result of evaluating AssignmentExpression.
2. Let value be ? GetValue(exprRef).
3. Let iterator be ? GetIterator(value).
4. Let received be NormalCompletion(undefined).
5. Repeat
a. If received.[[Type]] is normal, then
[...]
b. Else if received.[[Type]] is throw, then
i. Let throw be ? GetMethod(iterator, "throw").
ii. If throw is not undefined, then
[...]
iii. Else,
1. NOTE: If iterator does not have a throw method, this throw is
going to terminate the yield* loop. But first we need to give
iterator a chance to clean up.
2. Perform ? IteratorClose(iterator, Completion{[[Type]]: normal,
[[Value]]: empty, [[Target]]: empty}).
3. NOTE: The next step throws a TypeError to indicate that there
was a yield* protocol violation: iterator does not have a throw
method.
4. Throw a TypeError exception.
7.4.6 IteratorClose
1. Assert: Type(iterator) is Object.
2. Assert: completion is a Completion Record.
3. Let return be ? GetMethod(iterator, "return").
4. If return is undefined, return Completion(completion).
5. Let innerResult be Call(return, iterator, « »).
6. If completion.[[Type]] is throw, return Completion(completion).
7. If innerResult.[[Type]] is throw, return Completion(innerResult).
8. If Type(innerResult.[[Value]]) is not Object, throw a TypeError exception.
9. Return Completion(completion).
features: [generators, Symbol.iterator]
---*/
var badIter = {};
var throwCount = 0;
var thisValue, args;
var poisonedReturn = {
next: function() {
return { done: false };
},
return: function() {
thisValue = this;
args = arguments;
return 'this value has no effect on the protocol';
}
};
Object.defineProperty(poisonedReturn, 'throw', {
get: function() {
throwCount += 1;
}
});
badIter[Symbol.iterator] = function() {
return poisonedReturn;
};
function* g() {
try {
yield * badIter;
} catch (err) {
caught = err;
}
}
var iter = g();
var caught;
iter.next();
iter.throw();
assert.sameValue(throwCount, 1);
assert.sameValue(thisValue, poisonedReturn, '"this" value');
assert.sameValue(
typeof args, 'object', 'method invoked, arguments object provided'
);
assert.sameValue(args.length, 0);
assert.sameValue(typeof caught, 'object', 'object value thrown');
assert.sameValue(caught.constructor, TypeError);
reportCompare(0, 0);
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