| degenerator |
| =========== |
| ### Compiles sync functions into async functions |
| |
| Sometimes you need to write sync looking code that's really async under the hood. |
| This module takes a String to one or more synchronous JavaScript functions, and |
| returns a new String that with those JS functions transpiled into `async` |
| functions. |
| |
| So this: |
| |
| ```js |
| function foo() { |
| return a('bar') || b(); |
| } |
| ``` |
| |
| Gets compiled into: |
| |
| ```js |
| async function foo() { |
| return await a('bar') || await b(); |
| } |
| ``` |
| |
| With the compiled output code, you can evaluate the code using the `vm` module |
| in Node.js, or save the code to a file and require it, or whatever. |
| |
| Example |
| ------- |
| |
| You must explicitly specify the names of the functions that should be |
| "asyncified". So say we wanted to expose a `get(url)` function that did |
| and HTTP request and returned the response body. |
| |
| The user has provided us with this implementation: |
| |
| ``` js |
| function myFn() { |
| const one = get('https://google.com'); |
| const two = get('http://nodejs.org'); |
| const three = JSON.parse(get('http://jsonip.org')); |
| return [one, two, three]; |
| } |
| ``` |
| |
| Now we can compile this into an asyncronous function, implement the |
| async `get()` function, and finally evaluate it into a real JavaScript function |
| instance with the `vm` module: |
| |
| |
| ```typescript |
| import vm from 'vm'; |
| import { degenerator } from 'degenerator'; |
| |
| // The `get()` function is Promise-based (error handling omitted for brevity) |
| function get(endpoint: string) { |
| return new Promise((resolve, reject) => { |
| var mod = 0 == endpoint.indexOf('https:') ? require('https') : require('http'); |
| var req = mod.get(endpoint); |
| req.on('response', function (res) { |
| var data = ''; |
| res.setEncoding('utf8'); |
| res.on('data', function (b) { data += b; }); |
| res.on('end', function () { |
| resolve(data); |
| }); |
| }); |
| }); |
| } |
| |
| // Convert the JavaScript string provided from the user (assumed to be `str` var) |
| str = degenerator(str, [ 'get' ]); |
| |
| // Turn the JS String into a real async function instance |
| const asyncFn = vm.runInNewContext(`(${str})`, { get }); |
| |
| // Now we can invoke the function asynchronously |
| asyncFn().then((res) => { |
| // Do something with `res`... |
| }); |
| ``` |
| |
| |
| API |
| --- |
| |
| ### degenerator(code: string, names: Array<string|RegExp>): String |
| |
| Returns a "degeneratorified" JavaScript string, with `async`/`await` transplanted. |
| |
| |
| License |
| ------- |
| |
| (The MIT License) |
| |
| Copyright (c) 2013 Nathan Rajlich <nathan@tootallnate.net> |
| |
| Permission is hereby granted, free of charge, to any person obtaining |
| a copy of this software and associated documentation files (the |
| 'Software'), to deal in the Software without restriction, including |
| without limitation the rights to use, copy, modify, merge, publish, |
| distribute, sublicense, and/or sell copies of the Software, and to |
| permit persons to whom the Software is furnished to do so, subject to |
| the following conditions: |
| |
| The above copyright notice and this permission notice shall be |
| included in all copies or substantial portions of the Software. |
| |
| THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND, |
| EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF |
| MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. |
| IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY |
| CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, |
| TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE |
| SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. |