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/* 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
/**
* Implementation of a CommonJS module loader for workers.
*
* Use:
* // in the .js file loaded by the constructor of the worker
*
* // in myModule.js
* // Load dependencies
*
* // Define things that will not be exported
* let someValue = // ...
*
* // Export symbols
* exports.foo = // ...
* exports.bar = // ...
*
*
* Note #1:
* Properties |fileName| and |stack| of errors triggered from a module
* contain file names that do not correspond to human-readable module paths.
* Human readers should rather use properties |moduleName| and |moduleStack|.
*
* Note #2:
* By opposition to some other module loader implementations, this module
* loader does not enforce separation of global objects. Consequently, if
* a module modifies a global object (e.g. |String.prototype|), all other
* modules in the same worker may be affected.
*/
/* global require */
/* exported require */
(function (exports) {
"use strict";
if (exports.require) {
// Avoid double-imports
return;
}
// Simple implementation of |require|
let require = (function () {
/**
* Mapping from module URI to module exports.
*
* @keys {string} The absolute URI to a module.
* @values {object} The |exports| objects for that module.
*/
let modules = new Map();
/**
* A human-readable version of |stack|.
*
* @type {string}
*/
Object.defineProperty(Error.prototype, "moduleStack", {
get() {
return this.stack;
},
});
/**
* A human-readable version of |fileName|.
*
* @type {string}
*/
Object.defineProperty(Error.prototype, "moduleName", {
get() {
let match = this.stack.match(/\@(.*):.*:/);
if (match) {
return match[1];
}
return "(unknown module)";
},
});
/**
* Import a module
*
* @param {string} baseURL The URL of the modules from which we load a new module.
* This will be null for the first loaded module and so expect an absolute URI in path.
* Note that this first parameter is bound before `require` method is passed outside
* of this module. So that typical callsites will only path the second `path` parameter.
* @param {string} path The path to the module.
* @return {*} An object containing the properties exported by the module.
*/
return function require(baseURL, path) {
let startTime = performance.now();
if (typeof path != "string") {
throw new TypeError(
"The argument to require() must be a string got " + path
);
}
// Resolve relative paths
if ((path.startsWith("./") || path.startsWith("../")) && baseURL) {
path = new URL(path, baseURL).href;
}
if (!path.includes("://")) {
throw new TypeError(
"The argument to require() must be a string uri, got " + path
);
}
// Automatically add ".js" if there is no extension
let uri;
if (path.lastIndexOf(".") <= path.lastIndexOf("/")) {
uri = path + ".js";
} else {
uri = path;
}
// Exports provided by the module
let exports = Object.create(null);
// Identification of the module
let module = {
id: path,
uri,
exports,
};
// Make module available immediately
// (necessary in case of circular dependencies)
if (modules.has(uri)) {
return modules.get(uri).exports;
}
modules.set(uri, module);
try {
// Load source of module, synchronously
let xhr = new XMLHttpRequest();
xhr.open("GET", uri, false);
xhr.responseType = "text";
xhr.send();
let source = xhr.responseText;
if (source == "") {
// There doesn't seem to be a better way to detect that the file couldn't be found
throw new Error("Could not find module " + path);
}
// Use `Function` to leave this scope, use `eval` to start the line
// number from 1 that is observed by `source` and the error message
// thrown from the module, and also use `arguments` for accessing
// `source` and `uri` to avoid polluting the module's environment.
let code = new Function(
"exports",
"require",
"module",
`eval(arguments[3] + "\\n//# sourceURL=" + arguments[4] + "\\n")`
);
code(exports, require.bind(null, path), module, source, uri);
} catch (ex) {
// Module loading has failed, exports should not be made available
// after all.
modules.delete(uri);
throw ex;
} finally {
ChromeUtils.addProfilerMarker("require", startTime, path);
}
Object.freeze(module.exports);
Object.freeze(module);
return module.exports;
};
})();
Object.freeze(require);
Object.defineProperty(exports, "require", {
value: require.bind(null, null),
enumerable: true,
configurable: false,
});
})(this);