546 lines
22 KiB
JavaScript
546 lines
22 KiB
JavaScript
/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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"use strict";
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// eslint-disable-next-line no-undef
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const apiMetadata = require("../api-metadata.json");
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if (typeof globalThis.browser === "undefined" || Object.getPrototypeOf(globalThis.browser) !== Object.prototype) {
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const CHROME_SEND_MESSAGE_CALLBACK_NO_RESPONSE_MESSAGE = "The message port closed before a response was received.";
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const SEND_RESPONSE_DEPRECATION_WARNING = "Returning a Promise is the preferred way to send a reply from an onMessage/onMessageExternal listener, as the sendResponse will be removed from the specs (See https://developer.mozilla.org/docs/Mozilla/Add-ons/WebExtensions/API/runtime/onMessage)";
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// Wrapping the bulk of this polyfill in a one-time-use function is a minor
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// optimization for Firefox. Since Spidermonkey does not fully parse the
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// contents of a function until the first time it's called, and since it will
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// never actually need to be called, this allows the polyfill to be included
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// in Firefox nearly for free.
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const wrapAPIs = extensionAPIs => {
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// NOTE: apiMetadata is associated to the content of the api-metadata.json file
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// at build time by replacing the following "include" with the content of the
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// JSON file.
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if (Object.keys(apiMetadata).length === 0) {
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throw new Error("api-metadata.json has not been included in browser-polyfill");
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}
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/**
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* A WeakMap subclass which creates and stores a value for any key which does
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* not exist when accessed, but behaves exactly as an ordinary WeakMap
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* otherwise.
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*
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* @param {function} createItem
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* A function which will be called in order to create the value for any
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* key which does not exist, the first time it is accessed. The
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* function receives, as its only argument, the key being created.
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*/
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class DefaultWeakMap extends WeakMap {
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constructor(createItem, items = undefined) {
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super(items);
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this.createItem = createItem;
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}
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get(key) {
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if (!this.has(key)) {
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this.set(key, this.createItem(key));
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}
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return super.get(key);
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}
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}
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/**
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* Returns true if the given object is an object with a `then` method, and can
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* therefore be assumed to behave as a Promise.
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*
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* @param {*} value The value to test.
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* @returns {boolean} True if the value is thenable.
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*/
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const isThenable = value => {
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return value && typeof value === "object" && typeof value.then === "function";
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};
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/**
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* Creates and returns a function which, when called, will resolve or reject
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* the given promise based on how it is called:
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*
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* - If, when called, `chrome.runtime.lastError` contains a non-null object,
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* the promise is rejected with that value.
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* - If the function is called with exactly one argument, the promise is
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* resolved to that value.
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* - Otherwise, the promise is resolved to an array containing all of the
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* function's arguments.
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*
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* @param {object} promise
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* An object containing the resolution and rejection functions of a
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* promise.
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* @param {function} promise.resolve
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* The promise's resolution function.
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* @param {function} promise.reject
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* The promise's rejection function.
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* @param {object} metadata
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* Metadata about the wrapped method which has created the callback.
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* @param {boolean} metadata.singleCallbackArg
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* Whether or not the promise is resolved with only the first
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* argument of the callback, alternatively an array of all the
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* callback arguments is resolved. By default, if the callback
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* function is invoked with only a single argument, that will be
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* resolved to the promise, while all arguments will be resolved as
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* an array if multiple are given.
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*
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* @returns {function}
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* The generated callback function.
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*/
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const makeCallback = (promise, metadata) => {
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return (...callbackArgs) => {
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if (extensionAPIs.runtime.lastError) {
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promise.reject(new Error(extensionAPIs.runtime.lastError.message));
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} else if (metadata.singleCallbackArg ||
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(callbackArgs.length <= 1 && metadata.singleCallbackArg !== false)) {
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promise.resolve(callbackArgs[0]);
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} else {
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promise.resolve(callbackArgs);
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}
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};
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};
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const pluralizeArguments = (numArgs) => numArgs == 1 ? "argument" : "arguments";
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/**
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* Creates a wrapper function for a method with the given name and metadata.
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*
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* @param {string} name
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* The name of the method which is being wrapped.
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* @param {object} metadata
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* Metadata about the method being wrapped.
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* @param {integer} metadata.minArgs
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* The minimum number of arguments which must be passed to the
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* function. If called with fewer than this number of arguments, the
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* wrapper will raise an exception.
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* @param {integer} metadata.maxArgs
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* The maximum number of arguments which may be passed to the
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* function. If called with more than this number of arguments, the
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* wrapper will raise an exception.
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* @param {boolean} metadata.singleCallbackArg
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* Whether or not the promise is resolved with only the first
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* argument of the callback, alternatively an array of all the
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* callback arguments is resolved. By default, if the callback
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* function is invoked with only a single argument, that will be
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* resolved to the promise, while all arguments will be resolved as
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* an array if multiple are given.
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*
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* @returns {function(object, ...*)}
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* The generated wrapper function.
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*/
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const wrapAsyncFunction = (name, metadata) => {
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return function asyncFunctionWrapper(target, ...args) {
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if (args.length < metadata.minArgs) {
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throw new Error(`Expected at least ${metadata.minArgs} ${pluralizeArguments(metadata.minArgs)} for ${name}(), got ${args.length}`);
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}
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if (args.length > metadata.maxArgs) {
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throw new Error(`Expected at most ${metadata.maxArgs} ${pluralizeArguments(metadata.maxArgs)} for ${name}(), got ${args.length}`);
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}
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return new Promise((resolve, reject) => {
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if (metadata.fallbackToNoCallback) {
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// This API method has currently no callback on Chrome, but it return a promise on Firefox,
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// and so the polyfill will try to call it with a callback first, and it will fallback
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// to not passing the callback if the first call fails.
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try {
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target[name](...args, makeCallback({resolve, reject}, metadata));
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} catch (cbError) {
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console.warn(`${name} API method doesn't seem to support the callback parameter, ` +
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"falling back to call it without a callback: ", cbError);
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target[name](...args);
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// Update the API method metadata, so that the next API calls will not try to
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// use the unsupported callback anymore.
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metadata.fallbackToNoCallback = false;
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metadata.noCallback = true;
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resolve();
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}
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} else if (metadata.noCallback) {
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target[name](...args);
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resolve();
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} else {
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target[name](...args, makeCallback({resolve, reject}, metadata));
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}
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});
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};
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};
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/**
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* Wraps an existing method of the target object, so that calls to it are
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* intercepted by the given wrapper function. The wrapper function receives,
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* as its first argument, the original `target` object, followed by each of
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* the arguments passed to the original method.
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*
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* @param {object} target
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* The original target object that the wrapped method belongs to.
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* @param {function} method
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* The method being wrapped. This is used as the target of the Proxy
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* object which is created to wrap the method.
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* @param {function} wrapper
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* The wrapper function which is called in place of a direct invocation
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* of the wrapped method.
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*
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* @returns {Proxy<function>}
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* A Proxy object for the given method, which invokes the given wrapper
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* method in its place.
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*/
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const wrapMethod = (target, method, wrapper) => {
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return new Proxy(method, {
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apply(targetMethod, thisObj, args) {
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return wrapper.call(thisObj, target, ...args);
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},
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});
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};
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let hasOwnProperty = Function.call.bind(Object.prototype.hasOwnProperty);
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/**
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* Wraps an object in a Proxy which intercepts and wraps certain methods
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* based on the given `wrappers` and `metadata` objects.
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*
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* @param {object} target
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* The target object to wrap.
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*
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* @param {object} [wrappers = {}]
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* An object tree containing wrapper functions for special cases. Any
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* function present in this object tree is called in place of the
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* method in the same location in the `target` object tree. These
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* wrapper methods are invoked as described in {@see wrapMethod}.
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*
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* @param {object} [metadata = {}]
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* An object tree containing metadata used to automatically generate
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* Promise-based wrapper functions for asynchronous. Any function in
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* the `target` object tree which has a corresponding metadata object
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* in the same location in the `metadata` tree is replaced with an
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* automatically-generated wrapper function, as described in
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* {@see wrapAsyncFunction}
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*
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* @returns {Proxy<object>}
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*/
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const wrapObject = (target, wrappers = {}, metadata = {}) => {
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let cache = Object.create(null);
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let handlers = {
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has(proxyTarget, prop) {
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return prop in target || prop in cache;
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},
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get(proxyTarget, prop, receiver) {
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if (prop in cache) {
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return cache[prop];
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}
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if (!(prop in target)) {
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return undefined;
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}
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let value = target[prop];
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if (typeof value === "function") {
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// This is a method on the underlying object. Check if we need to do
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// any wrapping.
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if (typeof wrappers[prop] === "function") {
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// We have a special-case wrapper for this method.
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value = wrapMethod(target, target[prop], wrappers[prop]);
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} else if (hasOwnProperty(metadata, prop)) {
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// This is an async method that we have metadata for. Create a
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// Promise wrapper for it.
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let wrapper = wrapAsyncFunction(prop, metadata[prop]);
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value = wrapMethod(target, target[prop], wrapper);
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} else {
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// This is a method that we don't know or care about. Return the
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// original method, bound to the underlying object.
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value = value.bind(target);
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}
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} else if (typeof value === "object" && value !== null &&
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(hasOwnProperty(wrappers, prop) ||
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hasOwnProperty(metadata, prop))) {
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// This is an object that we need to do some wrapping for the children
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// of. Create a sub-object wrapper for it with the appropriate child
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// metadata.
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value = wrapObject(value, wrappers[prop], metadata[prop]);
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} else if (hasOwnProperty(metadata, "*")) {
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// Wrap all properties in * namespace.
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value = wrapObject(value, wrappers[prop], metadata["*"]);
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} else {
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// We don't need to do any wrapping for this property,
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// so just forward all access to the underlying object.
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Object.defineProperty(cache, prop, {
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configurable: true,
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enumerable: true,
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get() {
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return target[prop];
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},
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set(value) {
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target[prop] = value;
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},
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});
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return value;
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}
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cache[prop] = value;
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return value;
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},
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set(proxyTarget, prop, value, receiver) {
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if (prop in cache) {
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cache[prop] = value;
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} else {
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target[prop] = value;
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}
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return true;
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},
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defineProperty(proxyTarget, prop, desc) {
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return Reflect.defineProperty(cache, prop, desc);
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},
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deleteProperty(proxyTarget, prop) {
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return Reflect.deleteProperty(cache, prop);
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},
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};
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// Per contract of the Proxy API, the "get" proxy handler must return the
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// original value of the target if that value is declared read-only and
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// non-configurable. For this reason, we create an object with the
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// prototype set to `target` instead of using `target` directly.
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// Otherwise we cannot return a custom object for APIs that
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// are declared read-only and non-configurable, such as `chrome.devtools`.
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//
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// The proxy handlers themselves will still use the original `target`
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// instead of the `proxyTarget`, so that the methods and properties are
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// dereferenced via the original targets.
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let proxyTarget = Object.create(target);
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return new Proxy(proxyTarget, handlers);
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};
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/**
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* Creates a set of wrapper functions for an event object, which handles
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* wrapping of listener functions that those messages are passed.
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*
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* A single wrapper is created for each listener function, and stored in a
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* map. Subsequent calls to `addListener`, `hasListener`, or `removeListener`
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* retrieve the original wrapper, so that attempts to remove a
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* previously-added listener work as expected.
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*
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* @param {DefaultWeakMap<function, function>} wrapperMap
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* A DefaultWeakMap object which will create the appropriate wrapper
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* for a given listener function when one does not exist, and retrieve
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* an existing one when it does.
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*
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* @returns {object}
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*/
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const wrapEvent = wrapperMap => ({
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addListener(target, listener, ...args) {
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target.addListener(wrapperMap.get(listener), ...args);
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},
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hasListener(target, listener) {
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return target.hasListener(wrapperMap.get(listener));
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},
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removeListener(target, listener) {
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target.removeListener(wrapperMap.get(listener));
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},
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});
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const onRequestFinishedWrappers = new DefaultWeakMap(listener => {
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if (typeof listener !== "function") {
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return listener;
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}
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/**
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* Wraps an onRequestFinished listener function so that it will return a
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* `getContent()` property which returns a `Promise` rather than using a
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* callback API.
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*
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* @param {object} req
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* The HAR entry object representing the network request.
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*/
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return function onRequestFinished(req) {
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const wrappedReq = wrapObject(req, {} /* wrappers */, {
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getContent: {
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minArgs: 0,
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maxArgs: 0,
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},
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});
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listener(wrappedReq);
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};
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});
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// Keep track if the deprecation warning has been logged at least once.
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let loggedSendResponseDeprecationWarning = false;
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const onMessageWrappers = new DefaultWeakMap(listener => {
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if (typeof listener !== "function") {
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return listener;
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}
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/**
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* Wraps a message listener function so that it may send responses based on
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* its return value, rather than by returning a sentinel value and calling a
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* callback. If the listener function returns a Promise, the response is
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* sent when the promise either resolves or rejects.
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*
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* @param {*} message
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* The message sent by the other end of the channel.
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* @param {object} sender
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* Details about the sender of the message.
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* @param {function(*)} sendResponse
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* A callback which, when called with an arbitrary argument, sends
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* that value as a response.
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* @returns {boolean}
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* True if the wrapped listener returned a Promise, which will later
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* yield a response. False otherwise.
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*/
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return function onMessage(message, sender, sendResponse) {
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let didCallSendResponse = false;
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let wrappedSendResponse;
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let sendResponsePromise = new Promise(resolve => {
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wrappedSendResponse = function(response) {
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if (!loggedSendResponseDeprecationWarning) {
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console.warn(SEND_RESPONSE_DEPRECATION_WARNING, new Error().stack);
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loggedSendResponseDeprecationWarning = true;
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}
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didCallSendResponse = true;
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resolve(response);
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};
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});
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let result;
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try {
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result = listener(message, sender, wrappedSendResponse);
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} catch (err) {
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result = Promise.reject(err);
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}
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const isResultThenable = result !== true && isThenable(result);
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// If the listener didn't returned true or a Promise, or called
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// wrappedSendResponse synchronously, we can exit earlier
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// because there will be no response sent from this listener.
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if (result !== true && !isResultThenable && !didCallSendResponse) {
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return false;
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}
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// A small helper to send the message if the promise resolves
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// and an error if the promise rejects (a wrapped sendMessage has
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// to translate the message into a resolved promise or a rejected
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// promise).
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const sendPromisedResult = (promise) => {
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promise.then(msg => {
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// send the message value.
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sendResponse(msg);
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}, error => {
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// Send a JSON representation of the error if the rejected value
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// is an instance of error, or the object itself otherwise.
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let message;
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if (error && (error instanceof Error ||
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typeof error.message === "string")) {
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message = error.message;
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} else {
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message = "An unexpected error occurred";
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}
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sendResponse({
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__mozWebExtensionPolyfillReject__: true,
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message,
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});
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}).catch(err => {
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// Print an error on the console if unable to send the response.
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console.error("Failed to send onMessage rejected reply", err);
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});
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};
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// If the listener returned a Promise, send the resolved value as a
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// result, otherwise wait the promise related to the wrappedSendResponse
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// callback to resolve and send it as a response.
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if (isResultThenable) {
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sendPromisedResult(result);
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} else {
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sendPromisedResult(sendResponsePromise);
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}
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// Let Chrome know that the listener is replying.
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return true;
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};
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});
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const wrappedSendMessageCallback = ({reject, resolve}, reply) => {
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if (extensionAPIs.runtime.lastError) {
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// Detect when none of the listeners replied to the sendMessage call and resolve
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// the promise to undefined as in Firefox.
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// See https://github.com/mozilla/webextension-polyfill/issues/130
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if (extensionAPIs.runtime.lastError.message === CHROME_SEND_MESSAGE_CALLBACK_NO_RESPONSE_MESSAGE) {
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resolve();
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} else {
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reject(new Error(extensionAPIs.runtime.lastError.message));
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}
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} else if (reply && reply.__mozWebExtensionPolyfillReject__) {
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// Convert back the JSON representation of the error into
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// an Error instance.
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reject(new Error(reply.message));
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} else {
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resolve(reply);
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}
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};
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const wrappedSendMessage = (name, metadata, apiNamespaceObj, ...args) => {
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if (args.length < metadata.minArgs) {
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throw new Error(`Expected at least ${metadata.minArgs} ${pluralizeArguments(metadata.minArgs)} for ${name}(), got ${args.length}`);
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}
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if (args.length > metadata.maxArgs) {
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throw new Error(`Expected at most ${metadata.maxArgs} ${pluralizeArguments(metadata.maxArgs)} for ${name}(), got ${args.length}`);
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}
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return new Promise((resolve, reject) => {
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const wrappedCb = wrappedSendMessageCallback.bind(null, {resolve, reject});
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args.push(wrappedCb);
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apiNamespaceObj.sendMessage(...args);
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});
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};
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const staticWrappers = {
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devtools: {
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|
network: {
|
|
onRequestFinished: wrapEvent(onRequestFinishedWrappers),
|
|
},
|
|
},
|
|
runtime: {
|
|
onMessage: wrapEvent(onMessageWrappers),
|
|
onMessageExternal: wrapEvent(onMessageWrappers),
|
|
sendMessage: wrappedSendMessage.bind(null, "sendMessage", {minArgs: 1, maxArgs: 3}),
|
|
},
|
|
tabs: {
|
|
sendMessage: wrappedSendMessage.bind(null, "sendMessage", {minArgs: 2, maxArgs: 3}),
|
|
},
|
|
};
|
|
const settingMetadata = {
|
|
clear: {minArgs: 1, maxArgs: 1},
|
|
get: {minArgs: 1, maxArgs: 1},
|
|
set: {minArgs: 1, maxArgs: 1},
|
|
};
|
|
apiMetadata.privacy = {
|
|
network: {"*": settingMetadata},
|
|
services: {"*": settingMetadata},
|
|
websites: {"*": settingMetadata},
|
|
};
|
|
|
|
return wrapObject(extensionAPIs, staticWrappers, apiMetadata);
|
|
};
|
|
|
|
// The build process adds a UMD wrapper around this file, which makes the
|
|
// `module` variable available.
|
|
module.exports = wrapAPIs(chrome);
|
|
} else {
|
|
module.exports = globalThis.browser;
|
|
}
|