OLD | NEW |
---|---|
1 // Copyright 2016 the V8 project authors. All rights reserved. | 1 // Copyright 2016 the V8 project authors. All rights reserved. |
2 // Use of this source code is governed by a BSD-style license that can be | 2 // Use of this source code is governed by a BSD-style license that can be |
3 // found in the LICENSE file. | 3 // found in the LICENSE file. |
4 | 4 |
5 (function(global, utils, extrasUtils) { | 5 (function(global, utils, extrasUtils) { |
6 | 6 |
7 "use strict"; | 7 "use strict"; |
8 | 8 |
9 %CheckIsBootstrapping(); | 9 %CheckIsBootstrapping(); |
10 | 10 |
11 // ------------------------------------------------------------------- | 11 // ------------------------------------------------------------------- |
12 // Imports | 12 // Imports |
13 | 13 |
14 var AsyncFunctionNext; | 14 var AsyncFunctionNext; |
15 var AsyncFunctionThrow; | 15 var AsyncFunctionThrow; |
16 var GlobalPromise; | 16 var GlobalPromise; |
17 var IsPromise; | |
17 var NewPromiseCapability; | 18 var NewPromiseCapability; |
18 var PerformPromiseThen; | 19 var PerformPromiseThen; |
19 var PromiseCastResolved; | 20 var PromiseCreate; |
20 var RejectPromise; | 21 var RejectPromise; |
22 var ResolvePromise; | |
21 | 23 |
22 utils.Import(function(from) { | 24 utils.Import(function(from) { |
23 AsyncFunctionNext = from.AsyncFunctionNext; | 25 AsyncFunctionNext = from.AsyncFunctionNext; |
24 AsyncFunctionThrow = from.AsyncFunctionThrow; | 26 AsyncFunctionThrow = from.AsyncFunctionThrow; |
27 IsPromise = from.IsPromise; | |
25 GlobalPromise = from.GlobalPromise; | 28 GlobalPromise = from.GlobalPromise; |
26 NewPromiseCapability = from.NewPromiseCapability; | 29 NewPromiseCapability = from.NewPromiseCapability; |
27 PromiseCastResolved = from.PromiseCastResolved; | 30 PromiseCreate = from.PromiseCreate; |
28 PerformPromiseThen = from.PerformPromiseThen; | 31 PerformPromiseThen = from.PerformPromiseThen; |
29 RejectPromise = from.RejectPromise; | 32 RejectPromise = from.RejectPromise; |
33 ResolvePromise = from.ResolvePromise; | |
30 }); | 34 }); |
31 | 35 |
36 var promiseAwaitHandlerSymbol = utils.ImportNow("promise_await_handler_symbol"); | |
37 var promiseHandledHintSymbol = | |
38 utils.ImportNow("promise_handled_hint_symbol"); | |
39 | |
32 // ------------------------------------------------------------------- | 40 // ------------------------------------------------------------------- |
33 | 41 |
34 function AsyncFunctionAwait(generator, value) { | 42 function PromiseCastResolved(value) { |
35 // Promise.resolve(value).then( | 43 if (IsPromise(value)) { |
44 return value; | |
45 } else { | |
46 var promise = PromiseCreate(); | |
47 ResolvePromise(promise, value); | |
48 return promise; | |
49 } | |
50 } | |
51 | |
52 // ES#abstract-ops-async-function-await | |
53 // AsyncFunctionAwait ( value ) | |
54 // Shared logic for the core of await. The parser desugars | |
jgruber
2016/09/12 09:29:00
Thanks, these comments are very helpful.
| |
55 // await awaited | |
56 // into | |
57 // yield AsyncFunctionAwait{Caught,Uncaught}(.generator, awaited) | |
58 // The 'awaited' parameter is the value; the generator stands in | |
59 // for the asyncContext, and mark is metadata for debugging | |
60 function AsyncFunctionAwait(generator, awaited, mark) { | |
61 // Promise.resolve(awaited).then( | |
36 // value => AsyncFunctionNext(value), | 62 // value => AsyncFunctionNext(value), |
37 // error => AsyncFunctionThrow(error) | 63 // error => AsyncFunctionThrow(error) |
38 // ); | 64 // ); |
39 var promise = PromiseCastResolved(value); | 65 var promise = PromiseCastResolved(awaited); |
40 | 66 |
41 var onFulfilled = | 67 var onFulfilled = |
42 (sentValue) => %_Call(AsyncFunctionNext, generator, sentValue); | 68 (sentValue) => %_Call(AsyncFunctionNext, generator, sentValue); |
43 var onRejected = | 69 var onRejected = |
44 (sentError) => %_Call(AsyncFunctionThrow, generator, sentError); | 70 (sentError) => %_Call(AsyncFunctionThrow, generator, sentError); |
45 | 71 |
46 // false debugEvent to avoid redundant ExceptionEvents | 72 if (mark && DEBUG_IS_ACTIVE && IsPromise(awaited)) { |
73 // Mark the reject handler callback such that it does not influence | |
74 // catch prediction. | |
75 SET_PRIVATE(onRejected, promiseAwaitHandlerSymbol, true); | |
76 } | |
77 | |
78 // Just forwarding the exception, so no debugEvent for throwawayCapability | |
47 var throwawayCapability = NewPromiseCapability(GlobalPromise, false); | 79 var throwawayCapability = NewPromiseCapability(GlobalPromise, false); |
48 return PerformPromiseThen(promise, onFulfilled, onRejected, | 80 return PerformPromiseThen(promise, onFulfilled, onRejected, |
49 throwawayCapability); | 81 throwawayCapability); |
50 } | 82 } |
51 | 83 |
84 // Called by the parser from the desugaring of 'await' when catch | |
85 // prediction indicates no locally surrounding catch block | |
86 function AsyncFunctionAwaitUncaught(generator, awaited) { | |
87 // TODO(littledan): Install a dependency edge from awaited to outerPromise | |
88 return AsyncFunctionAwait(generator, awaited, true); | |
89 } | |
90 | |
91 // Called by the parser from the desugaring of 'await' when catch | |
92 // prediction indicates that there is a locally surrounding catch block | |
93 function AsyncFunctionAwaitCaught(generator, awaited) { | |
94 if (DEBUG_IS_ACTIVE && IsPromise(awaited)) { | |
95 SET_PRIVATE(awaited, promiseHandledHintSymbol, true); | |
96 } | |
97 return AsyncFunctionAwait(generator, awaited, false); | |
98 } | |
99 | |
52 // How the parser rejects promises from async/await desugaring | 100 // How the parser rejects promises from async/await desugaring |
53 function RejectPromiseNoDebugEvent(promise, reason) { | 101 function RejectPromiseNoDebugEvent(promise, reason) { |
54 return RejectPromise(promise, reason, false); | 102 return RejectPromise(promise, reason, false); |
55 } | 103 } |
56 | 104 |
57 %InstallToContext([ | 105 %InstallToContext([ |
58 "async_function_await", AsyncFunctionAwait, | 106 "async_function_await_caught", AsyncFunctionAwaitCaught, |
107 "async_function_await_uncaught", AsyncFunctionAwaitUncaught, | |
59 "reject_promise_no_debug_event", RejectPromiseNoDebugEvent, | 108 "reject_promise_no_debug_event", RejectPromiseNoDebugEvent, |
60 ]); | 109 ]); |
61 | 110 |
62 }) | 111 }) |
OLD | NEW |