| 1 | /** |
| 2 | * Copyright (c) Meta Platforms, Inc. and affiliates. |
| 3 | * |
| 4 | * This source code is licensed under the MIT license found in the |
| 5 | * LICENSE file in the root directory of this source tree. |
| 6 | * |
| 7 | * @flow |
| 8 | */ |
| 9 | |
| 10 | import type {ReactClientValue} from 'react-server/src/ReactFlightServer'; |
| 11 | |
| 12 | export type ServerReference<T: Function> = T & { |
| 13 | $$typeof: symbol, |
| 14 | $$id: string, |
| 15 | $$bound: null | Array<ReactClientValue>, |
| 16 | $$location?: Error, |
| 17 | }; |
| 18 | |
| 19 | // eslint-disable-next-line no-unused-vars |
| 20 | export type ClientReference<T> = { |
| 21 | $$typeof: symbol, |
| 22 | $$id: string, |
| 23 | $$async: boolean, |
| 24 | }; |
| 25 | |
| 26 | const CLIENT_REFERENCE_TAG = Symbol.for('react.client.reference'); |
| 27 | const SERVER_REFERENCE_TAG = Symbol.for('react.server.reference'); |
| 28 | |
| 29 | export function isClientReference(reference: Object): boolean { |
| 30 | return reference.$$typeof === CLIENT_REFERENCE_TAG; |
| 31 | } |
| 32 | |
| 33 | export function isServerReference(reference: Object): boolean { |
| 34 | return reference.$$typeof === SERVER_REFERENCE_TAG; |
| 35 | } |
| 36 | |
| 37 | export function registerClientReference<T>( |
| 38 | proxyImplementation: any, |
| 39 | id: string, |
| 40 | exportName: string, |
| 41 | ): ClientReference<T> { |
| 42 | return registerClientReferenceImpl( |
| 43 | proxyImplementation, |
| 44 | id + '#' + exportName, |
| 45 | false, |
| 46 | ); |
| 47 | } |
| 48 | |
| 49 | function registerClientReferenceImpl<T>( |
| 50 | proxyImplementation: any, |
| 51 | id: string, |
| 52 | async: boolean, |
| 53 | ): ClientReference<T> { |
| 54 | return Object.defineProperties(proxyImplementation, { |
| 55 | $$typeof: {value: CLIENT_REFERENCE_TAG}, |
| 56 | $$id: {value: id}, |
| 57 | $$async: {value: async}, |
| 58 | }); |
| 59 | } |
| 60 | |
| 61 | // $FlowFixMe[method-unbinding] |
| 62 | const FunctionBind = Function.prototype.bind; |
| 63 | // $FlowFixMe[method-unbinding] |
| 64 | const ArraySlice = Array.prototype.slice; |
| 65 | function bind(this: ServerReference<any>): any { |
| 66 | // $FlowFixMe[incompatible-type] |
| 67 | const newFn = FunctionBind.apply(this, arguments); |
| 68 | if (this.$$typeof === SERVER_REFERENCE_TAG) { |
| 69 | if (__DEV__) { |
| 70 | const thisBind = arguments[0]; |
| 71 | if (thisBind != null) { |
| 72 | console.error( |
| 73 | 'Cannot bind "this" of a Server Action. Pass null or undefined as the first argument to .bind().', |
| 74 | ); |
| 75 | } |
| 76 | } |
| 77 | const args = ArraySlice.call(arguments, 1); |
| 78 | const $$typeof = {value: SERVER_REFERENCE_TAG}; |
| 79 | const $$id = {value: this.$$id}; |
| 80 | const $$bound = {value: this.$$bound ? this.$$bound.concat(args) : args}; |
| 81 | return Object.defineProperties( |
| 82 | newFn as any, |
| 83 | (__DEV__ |
| 84 | ? { |
| 85 | $$typeof, |
| 86 | $$id, |
| 87 | $$bound, |
| 88 | $$location: { |
| 89 | value: this.$$location, |
| 90 | configurable: true, |
| 91 | }, |
| 92 | bind: {value: bind, configurable: true}, |
| 93 | } |
| 94 | : { |
| 95 | $$typeof, |
| 96 | $$id, |
| 97 | $$bound, |
| 98 | bind: {value: bind, configurable: true}, |
| 99 | }) as PropertyDescriptorMap, |
| 100 | ); |
| 101 | } |
| 102 | return newFn; |
| 103 | } |
| 104 | |
| 105 | const serverReferenceToString = { |
| 106 | value: () => 'function () { [omitted code] }', |
| 107 | configurable: true, |
| 108 | writable: true, |
| 109 | }; |
| 110 | |
| 111 | export function registerServerReference<T: Function>( |
| 112 | reference: T, |
| 113 | id: string, |
| 114 | exportName: null | string, |
| 115 | ): ServerReference<T> { |
| 116 | const $$typeof = {value: SERVER_REFERENCE_TAG}; |
| 117 | const $$id = { |
| 118 | value: exportName === null ? id : id + '#' + exportName, |
| 119 | configurable: true, |
| 120 | }; |
| 121 | const $$bound = {value: null, configurable: true}; |
| 122 | return Object.defineProperties( |
| 123 | reference as any, |
| 124 | __DEV__ |
| 125 | ? ({ |
| 126 | $$typeof, |
| 127 | $$id, |
| 128 | $$bound, |
| 129 | $$location: { |
| 130 | value: Error('react-stack-top-frame'), |
| 131 | configurable: true, |
| 132 | }, |
| 133 | bind: {value: bind, configurable: true}, |
| 134 | toString: serverReferenceToString, |
| 135 | } as PropertyDescriptorMap) |
| 136 | : ({ |
| 137 | $$typeof, |
| 138 | $$id, |
| 139 | $$bound, |
| 140 | bind: {value: bind, configurable: true}, |
| 141 | toString: serverReferenceToString, |
| 142 | } as PropertyDescriptorMap), |
| 143 | ); |
| 144 | } |
| 145 | |
| 146 | const PROMISE_PROTOTYPE = Promise.prototype; |
| 147 | |
| 148 | const deepProxyHandlers: Proxy$traps<mixed> = { |
| 149 | get: function ( |
| 150 | target: Function, |
| 151 | name: string | symbol, |
| 152 | receiver: Proxy<Function>, |
| 153 | ) { |
| 154 | switch (name) { |
| 155 | // These names are read by the Flight runtime if you end up using the exports object. |
| 156 | case '$$typeof': |
| 157 | // These names are a little too common. We should probably have a way to |
| 158 | // have the Flight runtime extract the inner target instead. |
| 159 | return target.$$typeof; |
| 160 | case '$$id': |
| 161 | return target.$$id; |
| 162 | case '$$async': |
| 163 | return target.$$async; |
| 164 | case 'name': |
| 165 | return target.name; |
| 166 | case 'displayName': |
| 167 | return undefined; |
| 168 | // We need to special case this because createElement reads it if we pass this |
| 169 | // reference. |
| 170 | case 'defaultProps': |
| 171 | return undefined; |
| 172 | // React looks for debugInfo on thenables. |
| 173 | case '_debugInfo': |
| 174 | return undefined; |
| 175 | // Avoid this attempting to be serialized. |
| 176 | case 'toJSON': |
| 177 | return undefined; |
| 178 | case Symbol.toPrimitive: |
| 179 | // $FlowFixMe[prop-missing] |
| 180 | return Object.prototype[Symbol.toPrimitive]; |
| 181 | case Symbol.toStringTag: |
| 182 | // $FlowFixMe[prop-missing] |
| 183 | return Object.prototype[Symbol.toStringTag]; |
| 184 | case 'Provider': |
| 185 | // Context.Provider === Context in React, so return the same reference. |
| 186 | // This allows server components to render <ClientContext.Provider> |
| 187 | // which will be serialized and executed on the client. |
| 188 | return receiver; |
| 189 | case 'then': |
| 190 | throw new Error( |
| 191 | `Cannot await or return from a thenable. ` + |
| 192 | `You cannot await a client module from a server component.`, |
| 193 | ); |
| 194 | } |
| 195 | // eslint-disable-next-line react-internal/safe-string-coercion |
| 196 | const expression = String(target.name) + '.' + String(name); |
| 197 | throw new Error( |
| 198 | `Cannot access ${expression} on the server. ` + |
| 199 | 'You cannot dot into a client module from a server component. ' + |
| 200 | 'You can only pass the imported name through.', |
| 201 | ); |
| 202 | }, |
| 203 | set: function () { |
| 204 | throw new Error('Cannot assign to a client module from a server module.'); |
| 205 | }, |
| 206 | }; |
| 207 | |
| 208 | function getReference(target: Function, name: string | symbol): $FlowFixMe { |
| 209 | switch (name) { |
| 210 | // These names are read by the Flight runtime if you end up using the exports object. |
| 211 | case '$$typeof': |
| 212 | return target.$$typeof; |
| 213 | case '$$id': |
| 214 | return target.$$id; |
| 215 | case '$$async': |
| 216 | return target.$$async; |
| 217 | case 'name': |
| 218 | return target.name; |
| 219 | // We need to special case this because createElement reads it if we pass this |
| 220 | // reference. |
| 221 | case 'defaultProps': |
| 222 | return undefined; |
| 223 | // React looks for debugInfo on thenables. |
| 224 | case '_debugInfo': |
| 225 | return undefined; |
| 226 | // Avoid this attempting to be serialized. |
| 227 | case 'toJSON': |
| 228 | return undefined; |
| 229 | case Symbol.toPrimitive: |
| 230 | // $FlowFixMe[prop-missing] |
| 231 | return Object.prototype[Symbol.toPrimitive]; |
| 232 | case Symbol.toStringTag: |
| 233 | // $FlowFixMe[prop-missing] |
| 234 | return Object.prototype[Symbol.toStringTag]; |
| 235 | case '__esModule': |
| 236 | // Something is conditionally checking which export to use. We'll pretend to be |
| 237 | // an ESM compat module but then we'll check again on the client. |
| 238 | const moduleId = target.$$id; |
| 239 | target.default = registerClientReferenceImpl( |
| 240 | function () { |
| 241 | throw new Error( |
| 242 | `Attempted to call the default export of ${moduleId} from the server ` + |
| 243 | `but it's on the client. It's not possible to invoke a client function from ` + |
| 244 | `the server, it can only be rendered as a Component or passed to props of a ` + |
| 245 | `Client Component.`, |
| 246 | ); |
| 247 | } as any, |
| 248 | target.$$id + '#', |
| 249 | target.$$async, |
| 250 | ); |
| 251 | return true; |
| 252 | case 'then': |
| 253 | if (target.then) { |
| 254 | // Use a cached value |
| 255 | return target.then; |
| 256 | } |
| 257 | if (!target.$$async) { |
| 258 | // If this module is expected to return a Promise (such as an AsyncModule) then |
| 259 | // we should resolve that with a client reference that unwraps the Promise on |
| 260 | // the client. |
| 261 | |
| 262 | const clientReference: ClientReference<any> = |
| 263 | registerClientReferenceImpl({} as any, target.$$id, true); |
| 264 | // $FlowFixMe[incompatible-variance] |
| 265 | // $FlowFixMe[incompatible-type] |
| 266 | const proxy = new Proxy(clientReference, proxyHandlers); |
| 267 | |
| 268 | // Treat this as a resolved Promise for React's use() |
| 269 | target.status = 'fulfilled'; |
| 270 | target.value = proxy; |
| 271 | |
| 272 | const then = (target.then = registerClientReferenceImpl( |
| 273 | function then(resolve, reject: any) { |
| 274 | // Expose to React. |
| 275 | return Promise.resolve(resolve(proxy)); |
| 276 | } as any, |
| 277 | // If this is not used as a Promise but is treated as a reference to a `.then` |
| 278 | // export then we should treat it as a reference to that name. |
| 279 | target.$$id + '#then', |
| 280 | false, |
| 281 | )); |
| 282 | return then; |
| 283 | } else { |
| 284 | // Since typeof .then === 'function' is a feature test we'd continue recursing |
| 285 | // indefinitely if we return a function. Instead, we return an object reference |
| 286 | // if we check further. |
| 287 | return undefined; |
| 288 | } |
| 289 | } |
| 290 | if (typeof name === 'symbol') { |
| 291 | throw new Error( |
| 292 | 'Cannot read Symbol exports. Only named exports are supported on a client module ' + |
| 293 | 'imported on the server.', |
| 294 | ); |
| 295 | } |
| 296 | let cachedReference = target[name]; |
| 297 | if (!cachedReference) { |
| 298 | const reference: ClientReference<any> = registerClientReferenceImpl( |
| 299 | function () { |
| 300 | throw new Error( |
| 301 | // eslint-disable-next-line react-internal/safe-string-coercion |
| 302 | `Attempted to call ${String(name)}() from the server but ${String(name)} is on the client. ` + |
| 303 | `It's not possible to invoke a client function from the server, it can ` + |
| 304 | `only be rendered as a Component or passed to props of a Client Component.`, |
| 305 | ); |
| 306 | } as any, |
| 307 | target.$$id + '#' + name, |
| 308 | target.$$async, |
| 309 | ); |
| 310 | Object.defineProperty(reference as any, 'name', {value: name}); |
| 311 | cachedReference = target[name] = new Proxy(reference, deepProxyHandlers); |
| 312 | } |
| 313 | return cachedReference; |
| 314 | } |
| 315 | |
| 316 | const proxyHandlers = { |
| 317 | get: function ( |
| 318 | target: Function, |
| 319 | name: string | symbol, |
| 320 | receiver: Proxy<Function>, |
| 321 | ): $FlowFixMe { |
| 322 | return getReference(target, name); |
| 323 | }, |
| 324 | getOwnPropertyDescriptor: function ( |
| 325 | target: Function, |
| 326 | name: string | symbol, |
| 327 | ): $FlowFixMe { |
| 328 | let descriptor = Object.getOwnPropertyDescriptor(target, name); |
| 329 | if (!descriptor) { |
| 330 | descriptor = { |
| 331 | value: getReference(target, name), |
| 332 | writable: false, |
| 333 | configurable: false, |
| 334 | enumerable: false, |
| 335 | }; |
| 336 | Object.defineProperty(target, name, descriptor); |
| 337 | } |
| 338 | return descriptor; |
| 339 | }, |
| 340 | getPrototypeOf(target: Function): Object { |
| 341 | // Pretend to be a Promise in case anyone asks. |
| 342 | return PROMISE_PROTOTYPE; |
| 343 | }, |
| 344 | set: function (): empty { |
| 345 | throw new Error('Cannot assign to a client module from a server module.'); |
| 346 | }, |
| 347 | }; |
| 348 | |
| 349 | export function createClientModuleProxy<T>( |
| 350 | moduleId: string, |
| 351 | ): ClientReference<T> { |
| 352 | const clientReference: ClientReference<T> = registerClientReferenceImpl( |
| 353 | {} as any, |
| 354 | // Represents the whole Module object instead of a particular import. |
| 355 | moduleId, |
| 356 | false, |
| 357 | ); |
| 358 | // $FlowFixMe[incompatible-variance] |
| 359 | // $FlowFixMe[incompatible-type] |
| 360 | // $FlowFixMe[incompatible-exact] |
| 361 | return new Proxy(clientReference, proxyHandlers); |
| 362 | } |