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array-elem-trlg-iter-rest-rtrn-close-err.js (2746B)

      1 // This file was procedurally generated from the following sources:
      2 // - src/dstr-assignment/array-elem-trlg-iter-rest-rtrn-close-err.case
      3 // - src/dstr-assignment/default/for-of.template
      4 /*---
      5 description: IteratorClose is called when AssignmentRestEvaluation produces a "return" completion due to reference evaluation (For..of statement)
      6 esid: sec-for-in-and-for-of-statements-runtime-semantics-labelledevaluation
      7 features: [Symbol.iterator, generators, destructuring-binding]
      8 flags: [generated]
      9 info: |
     10    IterationStatement :
     11      for ( LeftHandSideExpression of AssignmentExpression ) Statement
     12 
     13    1. Let keyResult be the result of performing ? ForIn/OfHeadEvaluation(« »,
     14       AssignmentExpression, iterate).
     15    2. Return ? ForIn/OfBodyEvaluation(LeftHandSideExpression, Statement,
     16       keyResult, assignment, labelSet).
     17 
     18    13.7.5.13 Runtime Semantics: ForIn/OfBodyEvaluation
     19 
     20    [...]
     21    4. If destructuring is true and if lhsKind is assignment, then
     22       a. Assert: lhs is a LeftHandSideExpression.
     23       b. Let assignmentPattern be the parse of the source text corresponding to
     24          lhs using AssignmentPattern as the goal symbol.
     25    [...]
     26 
     27    ArrayAssignmentPattern :
     28        [ AssignmentElementList , Elisionopt AssignmentRestElementopt ]
     29 
     30    [...]
     31    7. If AssignmentRestElement is present, then
     32       a. Let status be the result of performing
     33          IteratorDestructuringAssignmentEvaluation of AssignmentRestElement
     34          with iteratorRecord as the argument.
     35    8. If iteratorRecord.[[done]] is false, return IteratorClose(iterator,
     36       status).
     37    9. Return Completion(status).
     38 
     39    7.4.6 IteratorClose( iterator, completion )
     40 
     41    [...]
     42    6. Let innerResult be Call(return, iterator, « »).
     43    7. If completion.[[type]] is throw, return Completion(completion).
     44    8. If innerResult.[[type]] is throw, return Completion(innerResult).
     45 
     46 ---*/
     47 var nextCount = 0;
     48 var returnCount = 0;
     49 var unreachable = 0;
     50 var x;
     51 var iterable = {};
     52 var iterator = {
     53  next: function() {
     54    nextCount += 1;
     55    // Set an upper-bound to limit unnecessary iteration in non-conformant
     56    // implementations
     57    return { done: nextCount > 10 };
     58  },
     59  return: function() {
     60    returnCount += 1;
     61 
     62    throw new Test262Error();
     63  }
     64 };
     65 var iter;
     66 iterable[Symbol.iterator] = function() {
     67  return iterator;
     68 };
     69 function* g() {
     70 
     71 var counter = 0;
     72 
     73 for ([ x , ...{}[yield] ] of [iterable]) {
     74  unreachable += 1;
     75  counter += 1;
     76 }
     77 
     78 assert.sameValue(counter, 1);
     79 
     80 }
     81 
     82 iter = g();
     83 iter.next();
     84 
     85 assert.throws(Test262Error, function() {
     86  iter.return();
     87 });
     88 
     89 assert.sameValue(nextCount, 1);
     90 assert.sameValue(returnCount, 1);
     91 assert.sameValue(unreachable, 0, 'Unreachable statement was not executed');
     92 
     93 reportCompare(0, 0);