@itwin/presentation-hierarchies
Version:
A package for creating hierarchies based on data in iTwin.js iModels.
107 lines • 3.24 kB
JavaScript
/*---------------------------------------------------------------------------------------------
* Copyright (c) Bentley Systems, Incorporated. All rights reserved.
* See LICENSE.md in the project root for license terms and full copyright notice.
*--------------------------------------------------------------------------------------------*/
/**
* This is pretty much a combination of:
* - https://github.com/benlesh/rxjs-for-await/blob/94f9cf9cb015ac3700dfd1850eb81d36962eb70f/src/index.ts#L33,
* - https://github.com/ReactiveX/rxjs/blob/2587ee852eb43eeb0883a7787bac2944d823392b/packages/observable/src/observable.ts#L922.
*
* Our implementation uses a linked list rather than an array to store values, which is more efficient.
*
* @internal
*/
export async function* eachValueFrom(source) {
const deferreds = new Queue();
const values = new Queue();
let error;
let completed = false;
const subs = source.subscribe({
next: (value) => {
const deferred = deferreds.pop();
if (deferred) {
deferred.resolve({ value, done: false });
}
else {
values.push(value);
}
},
error: (err) => {
error = err;
for (let deferred = deferreds.pop(); deferred !== undefined; deferred = deferreds.pop()) {
deferred.reject(err);
}
},
complete: () => {
completed = true;
for (let deferred = deferreds.pop(); deferred !== undefined; deferred = deferreds.pop()) {
deferred.resolve({ value: undefined, done: true });
}
},
});
try {
while (true) {
const value = values.pop();
if (value !== undefined) {
yield value;
continue;
}
if (completed) {
return;
}
if (error) {
// eslint-disable-next-line @typescript-eslint/only-throw-error
throw error;
}
const result = await new Promise((resolve, reject) => {
deferreds.push({ resolve, reject });
});
if (result.done) {
return;
}
yield result.value;
}
}
catch (err) {
throw err;
/* https://github.com/bcoe/c8/issues/229#issuecomment-1248533082 */
/* c8 ignore next */
}
finally {
subs.unsubscribe();
}
}
class QueueEntry {
value;
next;
constructor(value, next) {
this.value = value;
this.next = next;
}
}
class Queue {
_front;
_back;
push(item) {
const entry = new QueueEntry(item);
if (this._back) {
this._back.next = entry;
}
this._back = entry;
if (!this._front) {
this._front = entry;
}
}
pop() {
if (!this._front) {
return undefined;
}
const value = this._front.value;
this._front = this._front.next;
if (!this._front) {
this._back = undefined;
}
return value;
}
}
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