tor-browser

The Tor Browser
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star-rhs-iter-rtrn-res-done-no-value.js (2861B)

      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  `value` property is not accessed when iteration is incomplete
      8 info: |
      9  YieldExpression : yield * AssignmentExpression
     10 
     11  1. Let exprRef be the result of evaluating AssignmentExpression.
     12  2. Let value be ? GetValue(exprRef).
     13  3. Let iterator be ? GetIterator(value).
     14  4. Let received be NormalCompletion(undefined).
     15  5. Repeat
     16     a. If received.[[Type]] is normal, then
     17        [...]
     18     b. Else if received.[[Type]] is throw, then
     19        [...]
     20     c. Else,
     21        i. Assert: received.[[Type]] is return.
     22        ii. Let return be ? GetMethod(iterator, "return").
     23        iii. If return is undefined, return Completion(received).
     24        iv. Let innerReturnResult be ? Call(return, iterator, «
     25            received.[[Value]] »).
     26        v. If Type(innerReturnResult) is not Object, throw a TypeError
     27           exception.
     28        vi. Let done be ? IteratorComplete(innerReturnResult).
     29        vii. If done is true, then
     30             1. Let value be ? IteratorValue(innerReturnResult).
     31             2. Return Completion{[[Type]]: return, [[Value]]: value,
     32                [[Target]]: empty}.
     33        viii. Let received be GeneratorYield(innerReturnResult).
     34 
     35  7.4.3 IteratorComplete
     36 
     37  1. Assert: Type(iterResult) is Object.
     38  2. Return ToBoolean(? Get(iterResult, "done")).
     39 features: [generators, Symbol.iterator]
     40 ---*/
     41 
     42 var badIter = {};
     43 var callCount = 0;
     44 var spyValue = Object.defineProperty({ done: false }, 'value', {
     45  get: function() {
     46    callCount += 1;
     47  }
     48 });
     49 badIter[Symbol.iterator] = function() {
     50  return {
     51    next: function() {
     52      return { done: false };
     53    },
     54    return: function() {
     55      return spyValue;
     56    }
     57  };
     58 };
     59 var normalCompletion = false;
     60 var errorCompletion = false;
     61 var delegationComplete = false;
     62 function* g() {
     63  try {
     64    yield * badIter;
     65    normalCompletion = true;
     66  } catch (_) {
     67    errorCompletion = true;
     68  } finally {
     69    delegationComplete = true;
     70  }
     71 }
     72 var iter = g();
     73 
     74 iter.next();
     75 assert.sameValue(callCount, 0, 'access count (first iteration)');
     76 assert.sameValue(
     77  delegationComplete, false, 'delegation ongoing (first iteration)'
     78 );
     79 
     80 iter.return();
     81 assert.sameValue(callCount, 0, 'access count (second iteration)');
     82 assert.sameValue(
     83  delegationComplete, false, 'delegation ongoing (second iteration)'
     84 );
     85 
     86 spyValue.done = true;
     87 iter.return();
     88 assert.sameValue(callCount, 1, 'access count (final iteration)');
     89 assert.sameValue(delegationComplete, true, 'delegation complete');
     90 assert.sameValue(normalCompletion, false, 'completion was abrupt');
     91 assert.sameValue(errorCompletion, false, 'completion was not of type "throw"');
     92 
     93 reportCompare(0, 0);