Add use-set

Author: exoRift

hooks/use-set.ts

@@ -0,0 +1,121 @@
+import { type SetStateAction, useState, useEffect } from 'react'
+
+/**
+ * This is a set that causes rerenders on updates
+ * @note Effects and memos that use this set should also listen for its signal: `+INSTANCE`
+ */
+export class StatefulSet<T> extends Set<T> {
+  /** The dispatch function for the signal */
+  private readonly _dispatchSignal?: React.Dispatch<SetStateAction<number>>
+  /** THe dispatch function for redefining the set */
+  private _dispatchRedefine?: React.Dispatch<SetStateAction<StatefulSet<T>>>
+
+  /**
+   * Construct a StatefulSet
+   * @param initial        The initial value (parameter for a vanilla set)
+   * @param dispatchSignal The dispatch function for the signal
+   */
+  constructor (initial?: Iterable<T>, dispatchSignal?: StatefulSet<T>['_dispatchSignal']) {
+    super(initial)
+    this._dispatchSignal = dispatchSignal
+  }
+
+  /**
+   * Set the redefine dispatch
+   * @private
+   * @param callback The function
+   */
+  _setRedefine (callback: StatefulSet<T>['_dispatchRedefine']): void {
+    this._dispatchRedefine = callback
+  }
+
+  /**
+   * Force a signal update
+   */
+  forceUpdate (): void {
+    this._dispatchSignal?.(-1)
+  }
+
+  /**
+   * Set the instance to an entirely new instance
+   * @param           value The new instance
+   * @returns               The new instance
+   * @throws  {Error}       If there's no redefinition callback defined
+   */
+  reset (value: Iterable<T>): Iterable<T> {
+    if (!this._dispatchRedefine) throw new Error('Cannot redefine Set. No redefine callback set.')
+    const instance = new StatefulSet(value, this._dispatchSignal)
+
+    this._dispatchRedefine(instance)
+    instance._dispatchSignal?.(instance.size)
+
+    return instance
+  }
+
+  /**
+   * @override
+   */
+  override add (value: T): this {
+    super.add(value)
+    this._dispatchSignal?.(super.size)
+    return this
+  }
+
+  /**
+   * @override
+   */
+  override delete (value: T): boolean {
+    const returnValue = super.delete(value)
+    this._dispatchSignal?.(super.size)
+    return returnValue
+  }
+
+  /**
+   * @override
+   */
+  override clear (): void {
+    super.clear()
+    this._dispatchSignal?.(super.size)
+  }
+
+  /**
+   * Toggle if an element is present within the set
+   * @note This is a custom set method
+   * @param value The value to toggle
+   * @returns     The new state: true if the value is now in the set, false if the value is now not in the set
+   */
+  toggle (value: T): boolean {
+    if (super.has(value)) {
+      super.delete(value)
+      this._dispatchSignal?.(super.size)
+      return false
+    } else {
+      super.add(value)
+      this._dispatchSignal?.(super.size)
+      return false
+    }
+  }
+
+  /**
+   * Returns the set's signal. Used for effects and memos that use this set
+   * @returns A numeric signal
+   */
+  override valueOf (): number {
+    return this.size
+  }
+}
+
+/**
+ * Use a stately set
+ * @note Any effects or memos that use this set should also listen for its signal (`+INSTANCE`)
+ * @param initial The initial set value
+ * @returns       The stately set
+ */
+export function useSet<T> (initial?: Set<T> | T[]): StatefulSet<T> {
+  const [, setSignal] = useState(Array.isArray(initial) ? initial.length : initial?.size ?? 0)
+  const [set, setSet] = useState(new StatefulSet(initial, setSignal))
+
+  useEffect(() => set._setRedefine(setSet), [set])
+
+  return set
+}