tor-browser

The Tor Browser
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star-rhs-iter-thrw-violation-rtrn-invoke.js (2924B)

      1 // Copyright (C) 2016 the V8 project authors. All rights reserved.
      2 // This code is governed by the BSD license found in the LICENSE file.
      3 /*---
      4 esid: sec-generator-function-definitions-runtime-semantics-evaluation
      5 es6id: 14.4.14
      6 description: >
      7  Abrupt completion returned after protocol violation (and a `return` method
      8  is defined)
      9 info: |
     10  YieldExpression : yield * AssignmentExpression
     11 
     12  1. Let exprRef be the result of evaluating AssignmentExpression.
     13  2. Let value be ? GetValue(exprRef).
     14  3. Let iterator be ? GetIterator(value).
     15  4. Let received be NormalCompletion(undefined).
     16  5. Repeat
     17     a. If received.[[Type]] is normal, then
     18        [...]
     19     b. Else if received.[[Type]] is throw, then
     20        i. Let throw be ? GetMethod(iterator, "throw").
     21        ii. If throw is not undefined, then
     22            [...]
     23        iii. Else,
     24             1. NOTE: If iterator does not have a throw method, this throw is
     25                going to terminate the yield* loop. But first we need to give
     26                iterator a chance to clean up.
     27             2. Perform ? IteratorClose(iterator, Completion{[[Type]]: normal,
     28                [[Value]]: empty, [[Target]]: empty}).
     29             3. NOTE: The next step throws a TypeError to indicate that there
     30                was a yield* protocol violation: iterator does not have a throw
     31                method.
     32             4. Throw a TypeError exception.
     33 
     34  7.4.6 IteratorClose
     35 
     36  1. Assert: Type(iterator) is Object.
     37  2. Assert: completion is a Completion Record.
     38  3. Let return be ? GetMethod(iterator, "return").
     39  4. If return is undefined, return Completion(completion).
     40  5. Let innerResult be Call(return, iterator, « »).
     41  6. If completion.[[Type]] is throw, return Completion(completion).
     42  7. If innerResult.[[Type]] is throw, return Completion(innerResult).
     43  8. If Type(innerResult.[[Value]]) is not Object, throw a TypeError exception.
     44  9. Return Completion(completion).
     45 features: [generators, Symbol.iterator]
     46 ---*/
     47 
     48 var badIter = {};
     49 var throwCount = 0;
     50 var thisValue, args;
     51 var poisonedReturn = {
     52  next: function() {
     53    return { done: false };
     54  },
     55  return: function() {
     56    thisValue = this;
     57    args = arguments;
     58    return 'this value has no effect on the protocol';
     59  }
     60 };
     61 Object.defineProperty(poisonedReturn, 'throw', {
     62  get: function() {
     63    throwCount += 1;
     64  }
     65 });
     66 badIter[Symbol.iterator] = function() {
     67  return poisonedReturn;
     68 };
     69 function* g() {
     70  try {
     71    yield * badIter;
     72  } catch (err) {
     73    caught = err;
     74  }
     75 }
     76 var iter = g();
     77 var caught;
     78 
     79 iter.next();
     80 iter.throw();
     81 
     82 assert.sameValue(throwCount, 1);
     83 assert.sameValue(thisValue, poisonedReturn, '"this" value');
     84 assert.sameValue(
     85  typeof args, 'object', 'method invoked, arguments object provided'
     86 );
     87 assert.sameValue(args.length, 0);
     88 assert.sameValue(typeof caught, 'object', 'object value thrown');
     89 assert.sameValue(caught.constructor, TypeError);
     90 
     91 reportCompare(0, 0);