rvx/dist/rvx.async.js

A signal based rendering library

/*!
MIT License

Copyright (c) 2025 Max J. Polster

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.
*/
import { teardown, Context, $, isolate, nest, ENV, watch, capture, captureSelf } from './rvx.js';

function useAbortController(reason) {
	const controller = new AbortController();
	teardown(() => controller.abort(reason));
	return controller;
}
function useAbortSignal(reason) {
	return useAbortController(reason).signal;
}

class AsyncContext {
	#parent;
	#tasks = $(new Set());
	#errorHandlers = new Set();
	constructor(parent) {
		this.#parent = parent;
	}
	get pending() {
		return this.#tasks.value.size > 0;
	}
	track(task) {
		this.#parent?.track(task);
		this.#tasks.update(tasks => {
			tasks.add(task);
		});
		task.then(() => {
			this.#tasks.update(tasks => {
				tasks.delete(task);
			});
		}, error => {
			if (this.#errorHandlers.size > 0) {
				for (const errorHandler of this.#errorHandlers) {
					errorHandler.push(error);
				}
			}
			else {
				void Promise.reject(error);
			}
			this.#tasks.update(tasks => {
				tasks.delete(task);
			});
		});
	}
	async complete() {
		const errors = [];
		this.#errorHandlers.add(errors);
		while (this.#tasks.value.size > 0) {
			await Promise.allSettled(this.#tasks.value);
		}
		this.#errorHandlers.delete(errors);
		if (errors.length === 1) {
			throw errors[0];
		}
		else if (errors.length > 1) {
			throw new AsyncError(errors);
		}
	}
	static fork() {
		return new AsyncContext(ASYNC.current);
	}
}
class AsyncError extends Error {
	errors;
	constructor(errors) {
		super();
		this.errors = errors;
	}
}
const ASYNC = new Context();

function nestAsync(source, component, pending, rejected) {
	const state = $({ type: 0, value: undefined });
	let promise;
	if (typeof source === "function") {
		promise = isolate(source);
	}
	else {
		promise = source;
	}
	const ac = ASYNC.current;
	promise.then(value => {
		state.value = { type: 1, value };
	}, (value) => {
		state.value = { type: 2, value };
		if (ac === undefined && rejected === undefined) {
			void Promise.reject(value);
		}
	});
	ac?.track(promise);
	return nest(state, state => {
		switch (state.type) {
			case 0: return pending?.();
			case 1: return component?.(state.value);
			case 2: return rejected?.(state.value);
		}
	});
}
function Async(props) {
	return nestAsync(props.source, props.children, props.pending, props.rejected);
}

class Queue {
	#queue = [];
	#blocked = -1;
	#controller = undefined;
	#running = undefined;
	constructor() {
		teardown(() => this.#abort());
	}
	#abort() {
		const queue = this.#queue;
		while (queue.length > 0 && !queue[0].blocking) {
			queue.shift();
			this.#blocked--;
		}
		this.#controller?.abort();
	}
	#run() {
		if (this.#running === undefined) {
			this.#running = (async () => {
				let task;
				while (task = this.#queue.shift()) {
					this.#blocked--;
					if (task.blocking) {
						try {
							task.resolve(await task.task());
						}
						catch (error) {
							task.reject(error);
						}
					}
					else {
						const controller = new AbortController();
						this.#controller = controller;
						try {
							await task.task(controller.signal);
						}
						catch (error) {
							void Promise.reject(error);
						}
						this.#controller = undefined;
					}
				}
				this.#blocked--;
				this.#running = undefined;
			})();
		}
	}
	sideEffect(task) {
		if (this.#blocked >= 0) {
			return;
		}
		this.#abort();
		this.#queue.push({ blocking: false, task, resolve: undefined, reject: undefined });
		this.#run();
	}
	block(task) {
		return new Promise((resolve, reject) => {
			this.#abort();
			this.#blocked = this.#queue.push({ blocking: true, task, resolve, reject });
			this.#run();
		});
	}
}

class Tasks {
	#pendingCount = 0;
	#pending = $(false);
	#restoreFocus;
	#parent;
	constructor(parent, options) {
		this.#parent = parent;
		this.#restoreFocus = options?.restoreFocus ?? (parent ? parent.#restoreFocus : true);
		if (this.#restoreFocus) {
			const env = ENV.current;
			let last = null;
			watch(this.#pending, pending => {
				if (pending) {
					last = env.document.activeElement;
				}
				else if (last && env.document.activeElement === env.document.body) {
					const target = last;
					queueMicrotask(() => {
						if (last === target && env.document.activeElement === env.document.body) {
							target.focus?.();
						}
					});
				}
			});
		}
	}
	#setPending() {
		this.#pendingCount++;
		this.#pending.value = true;
	}
	#unsetPending() {
		this.#pendingCount--;
		this.#pending.value = this.#pendingCount > 0;
	}
	get parent() {
		return this.#parent;
	}
	get selfPending() {
		return this.#pending.value;
	}
	get pending() {
		return (this.#parent?.pending ?? false) || this.#pending.value;
	}
	setPending() {
		this.#setPending();
		let disposed = false;
		teardown(() => {
			if (!disposed) {
				disposed = true;
				this.#unsetPending();
			}
		});
	}
	waitFor(source) {
		if (typeof source === "function") {
			this.#setPending();
			void (async () => {
				try {
					return await isolate(source);
				}
				catch (error) {
					void Promise.reject(error);
				}
				finally {
					this.#unsetPending();
				}
			})();
		}
		else if (source instanceof Promise) {
			this.#setPending();
			void source.then(() => this.#unsetPending(), () => this.#unsetPending());
		}
	}
	static fork(options) {
		return new Tasks(TASKS.current, options);
	}
}
const TASKS = new Context();
function isSelfPending() {
	return TASKS.current?.selfPending ?? false;
}
function isPending() {
	return TASKS.current?.pending ?? false;
}
function setPending() {
	TASKS.current?.setPending();
}
function waitFor(source) {
	TASKS.current?.waitFor(source);
}

function useMicrotask(callback) {
	let active = true;
	let dispose;
	teardown(() => {
		active = false;
		dispose?.();
	});
	queueMicrotask(() => {
		if (active) {
			dispose = capture(callback);
			if (!active) {
				dispose?.();
			}
		}
	});
}
function useTimeout(callback, timeout) {
	let active = true;
	let dispose;
	let handle;
	teardown(() => {
		active = false;
		clearTimeout(handle);
		dispose?.();
	});
	handle = setTimeout(() => {
		dispose = capture(callback);
		if (!active) {
			dispose();
		}
	}, timeout);
}
function useInterval(callback, interval) {
	let active = true;
	let dispose;
	let handle;
	teardown(() => {
		active = false;
		clearInterval(handle);
		dispose?.();
	});
	handle = setInterval(() => {
		dispose?.();
		dispose = undefined;
		dispose = capture(callback);
		if (!active) {
			dispose();
		}
	}, interval);
}
function useAnimation(callback) {
	let active = true;
	let dispose;
	let handle;
	teardown(() => {
		active = false;
		cancelAnimationFrame(handle);
		dispose?.();
	});
	handle = requestAnimationFrame(function next(now) {
		handle = requestAnimationFrame(next);
		dispose?.();
		dispose = undefined;
		dispose = capture(() => callback(now));
		if (!active) {
			dispose();
			dispose = undefined;
		}
	});
}

class WatchForTimeoutError extends Error {
}
function watchFor(expr, condition, timeout) {
	if (typeof condition === "number") {
		timeout = condition;
		condition = Boolean;
	}
	else if (condition === undefined) {
		condition = Boolean;
	}
	return new Promise((resolve, reject) => {
		captureSelf(dispose => {
			watch(expr, value => {
				if (condition(value)) {
					dispose();
					resolve(value);
				}
			});
			if (timeout !== undefined) {
				const handle = setTimeout(() => {
					dispose();
					reject(new WatchForTimeoutError());
				}, timeout);
				teardown(() => clearTimeout(handle));
			}
		});
	});
}

export { ASYNC, Async, AsyncContext, AsyncError, Queue, TASKS, Tasks, WatchForTimeoutError, isPending, isSelfPending, nestAsync, setPending, useAbortController, useAbortSignal, useAnimation, useInterval, useMicrotask, useTimeout, waitFor, watchFor };