tone/Tone/core/util/Decorator.ts

A Web Audio framework for making interactive music in the browser.

import { assertRange } from "./Debug";
import { Time } from "../type/Units";

/**
 * Assert that the number is in the given range.
 */
export function range(min: number, max = Infinity) {
	const valueMap: WeakMap<any, number> = new WeakMap();
	return function(target: any, propertyKey: string | symbol) {
		Reflect.defineProperty(
			target,
			propertyKey,
			{
				configurable: true,
				enumerable: true,
				get: function() {
					return valueMap.get(this);
				},
				set: function(newValue: number) {
					assertRange(newValue, min, max);
					valueMap.set(this, newValue);
				}
			},
		);
	};
}

/**
 * Convert the time to seconds and assert that the time is in between the two
 * values when being set.
 */
export function timeRange(min: number, max = Infinity) {
	const valueMap: WeakMap<any, Time> = new WeakMap();
	return function(target: any, propertyKey: string) {
		Reflect.defineProperty(
			target,
			propertyKey,
			{
				configurable: true,
				enumerable: true,
				get: function() {
					return valueMap.get(this);
				},
				set: function(newValue: Time) {
					assertRange(this.toSeconds(newValue), min, max);
					valueMap.set(this, newValue);
				}
			},
		);
	};
}