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
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
|
/*
* Copyright (c) 2021-2022, Linus Groh <linusg@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <LibJS/Runtime/AbstractOperations.h>
#include <LibJS/Runtime/Error.h>
#include <LibJS/Runtime/NativeFunction.h>
#include <LibJS/Runtime/PromiseCapability.h>
namespace JS {
NonnullGCPtr<PromiseCapability> PromiseCapability::create(VM& vm, GCPtr<Object> promise, GCPtr<FunctionObject> resolve, GCPtr<FunctionObject> reject)
{
return vm.heap().allocate_without_realm<PromiseCapability>(promise, resolve, reject);
}
PromiseCapability::PromiseCapability(GCPtr<Object> promise, GCPtr<FunctionObject> resolve, GCPtr<FunctionObject> reject)
: m_promise(promise)
, m_resolve(resolve)
, m_reject(reject)
{
}
void PromiseCapability::visit_edges(Cell::Visitor& visitor)
{
visitor.visit(m_promise);
visitor.visit(m_resolve);
visitor.visit(m_reject);
}
// 27.2.1.5 NewPromiseCapability ( C ), https://tc39.es/ecma262/#sec-newpromisecapability
ThrowCompletionOr<NonnullGCPtr<PromiseCapability>> new_promise_capability(VM& vm, Value constructor)
{
auto& realm = *vm.current_realm();
// 1. If IsConstructor(C) is false, throw a TypeError exception.
if (!constructor.is_constructor())
return vm.throw_completion<TypeError>(ErrorType::NotAConstructor, constructor.to_deprecated_string_without_side_effects());
// 2. NOTE: C is assumed to be a constructor function that supports the parameter conventions of the Promise constructor (see 27.2.3.1).
// 3. Let promiseCapability be the PromiseCapability Record { [[Promise]]: undefined, [[Resolve]]: undefined, [[Reject]]: undefined }.
auto promise_capability = PromiseCapability::create(vm, nullptr, nullptr, nullptr);
// 4. Let executorClosure be a new Abstract Closure with parameters (resolve, reject) that captures promiseCapability and performs the following steps when called:
// NOTE: Additionally to capturing the GC-allocated promise capability, we also create handles for
// the resolve and reject values to keep them alive within the closure, as it may outlive the former.
auto executor_closure = [&promise_capability, resolve_handle = make_handle({}), reject_handle = make_handle({})](auto& vm) mutable -> ThrowCompletionOr<Value> {
auto resolve = vm.argument(0);
auto reject = vm.argument(1);
// No idea what other engines say here.
// a. If promiseCapability.[[Resolve]] is not undefined, throw a TypeError exception.
if (!resolve_handle.is_null())
return vm.template throw_completion<TypeError>(ErrorType::GetCapabilitiesExecutorCalledMultipleTimes);
// b. If promiseCapability.[[Reject]] is not undefined, throw a TypeError exception.
if (!reject_handle.is_null())
return vm.template throw_completion<TypeError>(ErrorType::GetCapabilitiesExecutorCalledMultipleTimes);
// c. Set promiseCapability.[[Resolve]] to resolve.
resolve_handle = make_handle(resolve);
if (resolve.is_function())
promise_capability->set_resolve(resolve.as_function());
// d. Set promiseCapability.[[Reject]] to reject.
reject_handle = make_handle(reject);
if (reject.is_function())
promise_capability->set_reject(reject.as_function());
// e. Return undefined.
return js_undefined();
};
// 5. Let executor be CreateBuiltinFunction(executorClosure, 2, "", « »).
auto executor = NativeFunction::create(realm, move(executor_closure), 2, "");
// 6. Let promise be ? Construct(C, « executor »).
auto promise = TRY(construct(vm, constructor.as_function(), executor));
// 7. If IsCallable(promiseCapability.[[Resolve]]) is false, throw a TypeError exception.
// NOTE: We only assign a value in the executor closure if it is a function.
if (promise_capability->resolve() == nullptr)
return vm.throw_completion<TypeError>(ErrorType::NotAFunction, "Promise capability resolve value");
// 8. If IsCallable(promiseCapability.[[Reject]]) is false, throw a TypeError exception.
// NOTE: We only assign a value in the executor closure if it is a function.
if (promise_capability->reject() == nullptr)
return vm.throw_completion<TypeError>(ErrorType::NotAFunction, "Promise capability reject value");
// 9. Set promiseCapability.[[Promise]] to promise.
promise_capability->set_promise(*promise);
// 10. Return promiseCapability.
return promise_capability;
}
}
|
