react-native/Libraries/BatchedBridge/NativeModules.js

/**
 * Copyright (c) 2015-present, Facebook, Inc.
 * All rights reserved.
 *
 * This source code is licensed under the BSD-style license found in the
 * LICENSE file in the root directory of this source tree. An additional grant
 * of patent rights can be found in the PATENTS file in the same directory.
 *
 * @providesModule NativeModules
 * @flow
 */
'use strict';

const BatchedBridge = require('BatchedBridge');

const invariant = require('fbjs/lib/invariant');

type ModuleConfig = [
  string, /* name */
  ?Object, /* constants */
  Array<string>, /* functions */
  Array<number>, /* promise method IDs */
  Array<number>, /* sync method IDs */
];

export type MethodType = 'async' | 'promise' | 'sync';

function genModule(config: ?ModuleConfig, moduleID: number): ?{name: string, module?: Object} {
  if (!config) {
    return null;
  }

  const [moduleName, constants, methods, promiseMethods, syncMethods] = config;
  invariant(!moduleName.startsWith('RCT') && !moduleName.startsWith('RK'),
    'Module name prefixes should\'ve been stripped by the native side ' +
    'but wasn\'t for ' + moduleName);

  if (!constants && !methods) {
    // Module contents will be filled in lazily later
    return { name: moduleName };
  }

  const module = {};
  methods && methods.forEach((methodName, methodID) => {
    const isPromise = promiseMethods && arrayContains(promiseMethods, methodID);
    const isSync = syncMethods && arrayContains(syncMethods, methodID);
    invariant(!isPromise || !isSync, 'Cannot have a method that is both async and a sync hook');
    const methodType = isPromise ? 'promise' : isSync ? 'sync' : 'async';
    module[methodName] = genMethod(moduleID, methodID, methodType);
  });
  Object.assign(module, constants);

  if (__DEV__) {
    BatchedBridge.createDebugLookup(moduleID, moduleName, methods);
  }

  return { name: moduleName, module };
}

// export this method as a global so we can call it from native
global.__fbGenNativeModule = genModule;

function loadModule(name: string, moduleID: number): ?Object {
  invariant(global.nativeRequireModuleConfig,
    'Can\'t lazily create module without nativeRequireModuleConfig');
  const config = global.nativeRequireModuleConfig(name);
  const info = genModule(config, moduleID);
  return info && info.module;
}

function genMethod(moduleID: number, methodID: number, type: MethodType) {
  let fn = null;
  if (type === 'promise') {
    fn = function(...args: Array<any>) {
      return new Promise((resolve, reject) => {
        BatchedBridge.enqueueNativeCall(moduleID, methodID, args,
          (data) => resolve(data),
          (errorData) => reject(createErrorFromErrorData(errorData)));
      });
    };
  } else if (type === 'sync') {
    fn = function(...args: Array<any>) {
      return global.nativeCallSyncHook(moduleID, methodID, args);
    };
  } else {
    fn = function(...args: Array<any>) {
      const lastArg = args.length > 0 ? args[args.length - 1] : null;
      const secondLastArg = args.length > 1 ? args[args.length - 2] : null;
      const hasSuccessCallback = typeof lastArg === 'function';
      const hasErrorCallback = typeof secondLastArg === 'function';
      hasErrorCallback && invariant(
        hasSuccessCallback,
        'Cannot have a non-function arg after a function arg.'
      );
      const onSuccess = hasSuccessCallback ? lastArg : null;
      const onFail = hasErrorCallback ? secondLastArg : null;
      const callbackCount = hasSuccessCallback + hasErrorCallback;
      args = args.slice(0, args.length - callbackCount);
      BatchedBridge.enqueueNativeCall(moduleID, methodID, args, onFail, onSuccess);
    };
  }
  fn.type = type;
  return fn;
}

function arrayContains<T>(array: Array<T>, value: T): boolean {
  return array.indexOf(value) !== -1;
}

function createErrorFromErrorData(errorData: {message: string}): Error {
  const {
    message,
    ...extraErrorInfo
  } = errorData;
  const error = new Error(message);
  (error:any).framesToPop = 1;
  return Object.assign(error, extraErrorInfo);
}

let NativeModules : {[moduleName: string]: Object} = {};
if (global.nativeModuleProxy) {
  NativeModules = global.nativeModuleProxy;
} else {
  const bridgeConfig = global.__fbBatchedBridgeConfig;
  invariant(bridgeConfig, '__fbBatchedBridgeConfig is not set, cannot invoke native modules');

  const defineLazyObjectProperty = require('defineLazyObjectProperty');
  (bridgeConfig.remoteModuleConfig || []).forEach((config: ModuleConfig, moduleID: number) => {
    // Initially this config will only contain the module name when running in JSC. The actual
    // configuration of the module will be lazily loaded.
    const info = genModule(config, moduleID);
    if (!info) {
      return;
    }

    if (info.module) {
      NativeModules[info.name] = info.module;
    }
    // If there's no module config, define a lazy getter
    else {
      defineLazyObjectProperty(NativeModules, info.name, {
        get: () => loadModule(info.name, moduleID)
      });
    }
  });
}

module.exports = NativeModules;