12345678910111213141516171819202122232425262728293031323334353637383940

/** * A classic queue. Unbounded size. */export class Queue<T> {    #arr = new Array<T|undefined>()    #start = 0

    get size(): number { return this.#arr.length - this.#start}    get isEmpty(): boolean { return this.size === 0 }
    push(item: T): void {        this.#arr.push(item)        this.#maybeShrink()    }
    pop(): T {        if (this.isEmpty) { throw new Error(`Popping from empty Queue`) }
        let index = this.#start++
        // type may be `undefined`, but only if we have a programming error.         let item = this.#arr[index]!        // unset to allow for GC of objects:        this.#arr[index] = undefined

        return item    }
    // Don't resize down on pop()s, because we might just be draining the queue    // and done with it. (in which case GC will handle it for us)    #maybeShrink() {        if (this.#start > 100 && this.#start > this.#arr.length / 2) {            this.#arr = this.#arr.slice(this.#start)            this.#start = 0        }    }}