@eagleoutice/flowr-dev/util/collections/queue.js

Static Dataflow Analyzer and Program Slicer for the R Programming Language

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.ArrayQueue = void 0;
/**
 * A FIFO queue over a growable array with amortized O(1) dequeue.
 * Entries are consumed via an index (instead of costly `Array#shift` calls),
 * and the consumed prefix is dropped once it dominates the array,
 * bounding the memory overhead to twice the live queue size.
 */
class ArrayQueue {
    elements;
    idx = 0;
    constructor(initial) {
        this.elements = initial ? initial.slice() : [];
    }
    enqueue(item) {
        this.elements.push(item);
    }
    /** Returns the oldest element, or `undefined` if the queue {@link isEmpty}. */
    dequeue() {
        if (this.idx >= this.elements.length) {
            return undefined;
        }
        if (this.idx > 1024 && this.idx * 2 > this.elements.length) {
            this.elements = this.elements.slice(this.idx);
            this.idx = 0;
        }
        return this.elements[this.idx++];
    }
    get size() {
        return this.elements.length - this.idx;
    }
    isEmpty() {
        return this.idx >= this.elements.length;
    }
}
exports.ArrayQueue = ArrayQueue;
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