ReactContext.js — react Source File

Architecture documentation for ReactContext.js, a javascript file in the react codebase. 2 imports, 1 dependents.

File javascript BabelCompiler 2 imports 1 dependents

Entity Profile

BabelCompiler→ ReactContext.js — react Source File

Dependency Diagram

graph LR
  c0f9756e_36f0_b861_899d_decc8aef8f64["ReactContext.js"]
  e1e1de60_2be4_0643_45fb_e2c306735427["ReactSymbols"]
  c0f9756e_36f0_b861_899d_decc8aef8f64 --> e1e1de60_2be4_0643_45fb_e2c306735427
  d8f20c67_f5fa_0f0a_c967_c41fd9ffce07["ReactTypes"]
  c0f9756e_36f0_b861_899d_decc8aef8f64 --> d8f20c67_f5fa_0f0a_c967_c41fd9ffce07
  ffdf54f0_7e34_f1e9_1504_9dbadb0fbac5["ReactClient.js"]
  ffdf54f0_7e34_f1e9_1504_9dbadb0fbac5 --> c0f9756e_36f0_b861_899d_decc8aef8f64
  style c0f9756e_36f0_b861_899d_decc8aef8f64 fill:#6366f1,stroke:#818cf8,color:#fff

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Source Code

/**
 * Copyright (c) Meta Platforms, Inc. and affiliates.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 *
 * @flow
 */

import {REACT_CONSUMER_TYPE, REACT_CONTEXT_TYPE} from 'shared/ReactSymbols';

import type {ReactContext} from 'shared/ReactTypes';

export function createContext<T>(defaultValue: T): ReactContext<T> {
  // TODO: Second argument used to be an optional `calculateChangedBits`
  // function. Warn to reserve for future use?

  const context: ReactContext<T> = {
    $$typeof: REACT_CONTEXT_TYPE,
    // As a workaround to support multiple concurrent renderers, we categorize
    // some renderers as primary and others as secondary. We only expect
    // there to be two concurrent renderers at most: React Native (primary) and
    // Fabric (secondary); React DOM (primary) and React ART (secondary).
    // Secondary renderers store their context values on separate fields.
    _currentValue: defaultValue,
    _currentValue2: defaultValue,
    // Used to track how many concurrent renderers this context currently
    // supports within in a single renderer. Such as parallel server rendering.
    _threadCount: 0,
    // These are circular
    Provider: (null: any),
    Consumer: (null: any),
  };

  context.Provider = context;
  context.Consumer = {
    $$typeof: REACT_CONSUMER_TYPE,
    _context: context,
  };
  if (__DEV__) {
    context._currentRenderer = null;
    context._currentRenderer2 = null;
  }

  return context;
}