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/**
* @license
* MIT License
*
* Copyright (c) 2020 Alexis Munsayac
* 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.
*
*
* @author Alexis Munsayac <alexis.munsayac@gmail.com>
* @copyright Alexis Munsayac 2020
*/
/**
* A promise with controllable fulfillment
*/
function deferred() {
const obj = {};
obj.promise = new Promise((res, rej) => {
obj.resolve = res;
obj.reject = rej;
});
return obj;
}
function runThreads(...threads) {
const suspend = [];
const finished = [];
function runThread(index = 0) {
if (index >= 0 && index < threads.length) {
if (finished[index]) {
runThread(index + 1);
} else if (suspend[index]) {
suspend[index].resolve();
} else {
threads[index](
() => {
suspend[index] = deferred();
runThread(index + 1);
return suspend[index].promise;
},
() => {
suspend[index] = deferred();
runThread(index - 1);
return suspend[index].promise;
},
).then(() => {
finished[index] = true;
runThread(index + 1);
});
}
}
}
runThread();
}
async function A(next, prev) {
console.log('BEGIN A');
console.log('sending: A -> B -- C');
await next();
console.log('received: A <- B -- C');
console.log('sending: A -> B -- C');
console.log('END A');
}
async function B(next, prev) {
console.log('BEGIN B');
console.log('received: A -> B -- C');
console.log('sending: A <- B -- C');
await prev();
console.log('received: A -> B -- C');
console.log('sending: A -- B -> C');
await next();
console.log('received: A -- B <- C');
console.log('sending: A -- B -> C');
console.log('END B');
}
async function C(next, prev) {
console.log('BEGIN C');
console.log('received: A -- B -> C');
console.log('sending: A -- B <- C');
await prev();
console.log('received: A -- B -> C');
console.log('END C');
}
runThreads(A, B, C);
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