summaryrefslogtreecommitdiffstats
path: root/js/src/builtin/Promise.h
blob: 4c48e8f4977b7c3d909373e7d8278c6667463080 (plain)
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
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
 * vim: set ts=8 sts=2 et sw=2 tw=80:
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#ifndef builtin_Promise_h
#define builtin_Promise_h

#include "jstypes.h"  // JS_PUBLIC_API

#include "js/RootingAPI.h"  // JS::{,Mutable}Handle
#include "js/TypeDecls.h"   // JS::HandleObjectVector

struct JS_PUBLIC_API JSContext;
class JS_PUBLIC_API JSObject;

namespace JS {
class CallArgs;
class Value;
}  // namespace JS

namespace js {

class AsyncFunctionGeneratorObject;
class AsyncGeneratorObject;
class PromiseObject;
class SavedFrame;

enum class CompletionKind : uint8_t;

enum class PromiseHandler : uint32_t {
  Identity = 0,
  Thrower,

  // ES2022 draft rev d03c1ec6e235a5180fa772b6178727c17974cb14
  //
  // Await in async function
  // https://tc39.es/ecma262/#await
  //
  // Step 3. fulfilledClosure Abstract Closure.
  // Step 5. rejectedClosure Abstract Closure.
  AsyncFunctionAwaitedFulfilled,
  AsyncFunctionAwaitedRejected,

  // Await in async generator
  // https://tc39.es/ecma262/#await
  //
  // Step 3. fulfilledClosure Abstract Closure.
  // Step 5. rejectedClosure Abstract Closure.
  AsyncGeneratorAwaitedFulfilled,
  AsyncGeneratorAwaitedRejected,

  // AsyncGeneratorAwaitReturn ( generator )
  // https://tc39.es/ecma262/#sec-asyncgeneratorawaitreturn
  //
  // Step 7. fulfilledClosure Abstract Closure.
  // Step 9. rejectedClosure Abstract Closure.
  AsyncGeneratorAwaitReturnFulfilled,
  AsyncGeneratorAwaitReturnRejected,

  // AsyncGeneratorUnwrapYieldResumption
  // https://tc39.es/ecma262/#sec-asyncgeneratorunwrapyieldresumption
  //
  // Steps 3-5 for awaited.[[Type]] handling.
  AsyncGeneratorYieldReturnAwaitedFulfilled,
  AsyncGeneratorYieldReturnAwaitedRejected,

  // AsyncFromSyncIteratorContinuation ( result, promiseCapability )
  // https://tc39.es/ecma262/#sec-asyncfromsynciteratorcontinuation
  //
  // Steps 7. unwrap Abstract Closure.
  AsyncFromSyncIteratorValueUnwrapDone,
  AsyncFromSyncIteratorValueUnwrapNotDone,

  // One past the maximum allowed PromiseHandler value.
  Limit
};

// Promise.prototype.then.
extern bool Promise_then(JSContext* cx, unsigned argc, JS::Value* vp);

// Promise[Symbol.species].
extern bool Promise_static_species(JSContext* cx, unsigned argc, JS::Value* vp);

// Promise.resolve.
extern bool Promise_static_resolve(JSContext* cx, unsigned argc, JS::Value* vp);

/**
 * Unforgeable version of the JS builtin Promise.all.
 *
 * Takes a HandleValueVector of Promise objects and returns a promise that's
 * resolved with an array of resolution values when all those promises have
 * been resolved, or rejected with the rejection value of the first rejected
 * promise.
 *
 * Asserts that all objects in the `promises` vector are, maybe wrapped,
 * instances of `Promise` or a subclass of `Promise`.
 */
[[nodiscard]] JSObject* GetWaitForAllPromise(JSContext* cx,
                                             JS::HandleObjectVector promises);

/**
 * Enqueues resolve/reject reactions in the given Promise's reactions lists
 * as though by calling the original value of Promise.prototype.then, and
 * without regard to any Promise subclassing used in `promiseObj` itself.
 */
[[nodiscard]] PromiseObject* OriginalPromiseThen(
    JSContext* cx, JS::Handle<JSObject*> promiseObj,
    JS::Handle<JSObject*> onFulfilled, JS::Handle<JSObject*> onRejected);

enum class UnhandledRejectionBehavior { Ignore, Report };

/**
 * React to[0] `unwrappedPromise` (which may not be from the current realm) as
 * if by using a fresh promise created for the provided nullable fulfill/reject
 * IsCallable objects.
 *
 * However, no dependent Promise will be created, and mucking with `Promise`,
 * `Promise.prototype.then`, and `Promise[Symbol.species]` will not alter this
 * function's behavior.
 *
 * If `unwrappedPromise` rejects and `onRejected_` is null, handling is
 * determined by `behavior`.  If `behavior == Report`, a fresh Promise will be
 * constructed and rejected on the fly (and thus will be reported as unhandled).
 * But if `behavior == Ignore`, the rejection is ignored and is not reported as
 * unhandled.
 *
 * Note: Reactions pushed using this function contain a null `promise` field.
 * That field is only ever used by devtools, which have to treat these reactions
 * specially.
 *
 * 0. The sense of "react" here is the sense of the term as defined by Web IDL:
 *    https://heycam.github.io/webidl/#dfn-perform-steps-once-promise-is-settled
 */
[[nodiscard]] extern bool ReactToUnwrappedPromise(
    JSContext* cx, JS::Handle<PromiseObject*> unwrappedPromise,
    JS::Handle<JSObject*> onFulfilled_, JS::Handle<JSObject*> onRejected_,
    UnhandledRejectionBehavior behavior);

/**
 * PromiseResolve ( C, x )
 *
 * The abstract operation PromiseResolve, given a constructor and a value,
 * returns a new promise resolved with that value.
 */
[[nodiscard]] JSObject* PromiseResolve(JSContext* cx,
                                       JS::Handle<JSObject*> constructor,
                                       JS::Handle<JS::Value> value);

/**
 * Reject |promise| with the value of the current pending exception.
 *
 * |promise| must be from the current realm.  Callers must enter the realm of
 * |promise| if they are not already in it.
 */
[[nodiscard]] bool RejectPromiseWithPendingError(
    JSContext* cx, JS::Handle<PromiseObject*> promise);

/**
 * Create the promise object which will be used as the return value of an async
 * function.
 */
[[nodiscard]] PromiseObject* CreatePromiseObjectForAsync(JSContext* cx);

/**
 * Returns true if the given object is a promise created by
 * either CreatePromiseObjectForAsync function or async generator's method.
 */
[[nodiscard]] bool IsPromiseForAsyncFunctionOrGenerator(JSObject* promise);

[[nodiscard]] bool AsyncFunctionReturned(
    JSContext* cx, JS::Handle<PromiseObject*> resultPromise,
    JS::Handle<JS::Value> value);

[[nodiscard]] bool AsyncFunctionThrown(
    JSContext* cx, JS::Handle<PromiseObject*> resultPromise,
    JS::Handle<JS::Value> reason,
    JS::Handle<SavedFrame*> unwrappedRejectionStack = nullptr);

// Start awaiting `value` in an async function (, but doesn't suspend the
// async function's execution!). Returns the async function's result promise.
[[nodiscard]] JSObject* AsyncFunctionAwait(
    JSContext* cx, JS::Handle<AsyncFunctionGeneratorObject*> genObj,
    JS::Handle<JS::Value> value);

// If the await operation can be skipped and the resolution value for `val` can
// be acquired, stored the resolved value to `resolved` and `true` to
// `*canSkip`.  Otherwise, stores `false` to `*canSkip`.
[[nodiscard]] bool CanSkipAwait(JSContext* cx, JS::Handle<JS::Value> val,
                                bool* canSkip);
[[nodiscard]] bool ExtractAwaitValue(JSContext* cx, JS::Handle<JS::Value> val,
                                     JS::MutableHandle<JS::Value> resolved);

bool AsyncFromSyncIteratorMethod(JSContext* cx, JS::CallArgs& args,
                                 CompletionKind completionKind);

// Callback for describing promise reaction records, for use with
// PromiseObject::getReactionRecords.
struct PromiseReactionRecordBuilder {
  // A reaction record created by a call to 'then' or 'catch', with functions to
  // call on resolution or rejection, and the promise that will be settled
  // according to the result of calling them.
  //
  // Note that resolve, reject, and result may not be same-compartment with cx,
  // or with the promise we're inspecting. This function presents the values
  // exactly as they appear in the reaction record. They may also be wrapped or
  // unwrapped.
  //
  // Some reaction records refer to internal resolution or rejection functions
  // that are not naturally represented as debuggee JavaScript functions. In
  // this case, resolve and reject may be nullptr.
  [[nodiscard]] virtual bool then(JSContext* cx, JS::Handle<JSObject*> resolve,
                                  JS::Handle<JSObject*> reject,
                                  JS::Handle<JSObject*> result) = 0;

  // A reaction record created when one native promise is resolved to another.
  // The 'promise' argument is the promise that will be settled in the same way
  // the promise this reaction record is attached to is settled.
  //
  // Note that promise may not be same-compartment with cx. This function
  // presents the promise exactly as it appears in the reaction record.
  [[nodiscard]] virtual bool direct(
      JSContext* cx, JS::Handle<PromiseObject*> unwrappedPromise) = 0;

  // A reaction record that resumes an asynchronous function suspended at an
  // await expression. The 'generator' argument is the generator object
  // representing the call.
  //
  // Note that generator may not be same-compartment with cx. This function
  // presents the generator exactly as it appears in the reaction record.
  [[nodiscard]] virtual bool asyncFunction(
      JSContext* cx,
      JS::Handle<AsyncFunctionGeneratorObject*> unwrappedGenerator) = 0;

  // A reaction record that resumes an asynchronous generator suspended at an
  // await expression. The 'generator' argument is the generator object
  // representing the call.
  //
  // Note that generator may not be same-compartment with cx. This function
  // presents the generator exactly as it appears in the reaction record.
  [[nodiscard]] virtual bool asyncGenerator(
      JSContext* cx, JS::Handle<AsyncGeneratorObject*> unwrappedGenerator) = 0;
};

[[nodiscard]] PromiseObject* CreatePromiseObjectForAsyncGenerator(
    JSContext* cx);

[[nodiscard]] bool ResolvePromiseInternal(JSContext* cx,
                                          JS::Handle<JSObject*> promise,
                                          JS::Handle<JS::Value> resolutionVal);
[[nodiscard]] bool RejectPromiseInternal(
    JSContext* cx, JS::Handle<PromiseObject*> promise,
    JS::Handle<JS::Value> reason,
    JS::Handle<SavedFrame*> unwrappedRejectionStack = nullptr);

[[nodiscard]] bool InternalAsyncGeneratorAwait(
    JSContext* cx, JS::Handle<AsyncGeneratorObject*> generator,
    JS::Handle<JS::Value> value, PromiseHandler onFulfilled,
    PromiseHandler onRejected);

bool IsPromiseWithDefaultResolvingFunction(PromiseObject* promise);
void SetAlreadyResolvedPromiseWithDefaultResolvingFunction(
    PromiseObject* promise);

}  // namespace js

#endif  // builtin_Promise_h