1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
|
// This file was procedurally generated from the following sources:
// - src/dstr-binding/ary-ptrn-elem-id-iter-val-array-prototype.case
// - src/dstr-binding/default/gen-func-decl-dflt.template
/*---
description: Array destructuring uses overriden Array.prototype[Symbol.iterator] (generator function declaration (default parameter))
esid: sec-generator-function-definitions-runtime-semantics-instantiatefunctionobject
features: [Symbol.iterator, generators, destructuring-binding, default-parameters]
flags: [generated]
info: |
GeneratorDeclaration : function * ( FormalParameters ) { GeneratorBody }
[...]
2. Let F be GeneratorFunctionCreate(Normal, FormalParameters,
GeneratorBody, scope, strict).
[...]
9.2.1 [[Call]] ( thisArgument, argumentsList)
[...]
7. Let result be OrdinaryCallEvaluateBody(F, argumentsList).
[...]
9.2.1.3 OrdinaryCallEvaluateBody ( F, argumentsList )
1. Let status be FunctionDeclarationInstantiation(F, argumentsList).
[...]
9.2.12 FunctionDeclarationInstantiation(func, argumentsList)
[...]
23. Let iteratorRecord be Record {[[iterator]]:
CreateListIterator(argumentsList), [[done]]: false}.
24. If hasDuplicates is true, then
[...]
25. Else,
b. Let formalStatus be IteratorBindingInitialization for formals with
iteratorRecord and env as arguments.
[...]
Runtime Semantics: IteratorBindingInitialization
SingleNameBinding : BindingIdentifier Initializer_opt
1. Let bindingId be StringValue of BindingIdentifier.
2. Let lhs be ? ResolveBinding(bindingId, environment).
3. If iteratorRecord.[[Done]] is false, then
a. Let next be IteratorStep(iteratorRecord).
b. If next is an abrupt completion, set iteratorRecord.[[Done]] to true.
c. ReturnIfAbrupt(next).
d. If next is false, set iteratorRecord.[[Done]] to true.
e. Else,
i. Let v be IteratorValue(next).
ii. If v is an abrupt completion, set iteratorRecord.[[Done]] to true.
iii. ReturnIfAbrupt(v).
[...]
7. Return InitializeReferencedBinding(lhs, v).
---*/
Array.prototype[Symbol.iterator] = function* () {
if (this.length > 0) {
yield this[0];
}
if (this.length > 1) {
yield this[1];
}
if (this.length > 2) {
yield 42;
}
};
var callCount = 0;
function* f([x, y, z] = [1, 2, 3]) {
assert.sameValue(x, 1);
assert.sameValue(y, 2);
assert.sameValue(z, 42);
callCount = callCount + 1;
};
f().next();
assert.sameValue(callCount, 1, 'generator function invoked exactly once');
reportCompare(0, 0);
|
