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array-elem-trlg-iter-rest-rtrn-close.js (3039B)

      1 // This file was procedurally generated from the following sources:
      2 // - src/dstr-assignment/array-elem-trlg-iter-rest-rtrn-close.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 thisValue = null;
     51 var args = null;
     52 var iterable = {};
     53 var x;
     54 var iterator = {
     55  next: function() {
     56    nextCount += 1;
     57    // Set an upper-bound to limit unnecessary iteration in non-conformant
     58    // implementations
     59    return { done: nextCount > 10 };
     60  },
     61  return: function() {
     62    returnCount += 1;
     63    thisValue = this;
     64    args = arguments;
     65    return {};
     66  }
     67 };
     68 var iter, result;
     69 iterable[Symbol.iterator] = function() {
     70  return iterator;
     71 };
     72 
     73 function* g() {
     74 
     75 var counter = 0;
     76 
     77 for ([ x , ...{}[yield] ] of [iterable]) {
     78  unreachable += 1;
     79  counter += 1;
     80 }
     81 
     82 assert.sameValue(counter, 1);
     83 
     84 }
     85 
     86 iter = g();
     87 iter.next();
     88 result = iter.return(999);
     89 
     90 assert.sameValue(nextCount, 1);
     91 assert.sameValue(returnCount, 1);
     92 assert.sameValue(unreachable, 0, 'Unreachable statement was not executed');
     93 assert.sameValue(result.value, 999);
     94 assert(result.done, 'Iterator correctly closed');
     95 assert.sameValue(thisValue, iterator, 'correct `this` value');
     96 assert(!!args, 'arguments object provided');
     97 assert.sameValue(args.length, 0, 'zero arguments specified');
     98 
     99 reportCompare(0, 0);