time-to-botec

main.js (9113B)

---

 /**
 * @license Apache-2.0
 *
 * Copyright (c) 2018 The Stdlib Authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
 
 /* eslint-disable no-restricted-syntax, no-invalid-this */
 
 'use strict';
 
 // MODULES //
 
 var setReadOnly = require( './../../define-nonenumerable-read-only-property' );
 var setReadOnlyAccessor = require( './../../define-nonenumerable-read-only-accessor' );
 var iteratorSymbol = require( '@stdlib/symbol/iterator' );
 var Node = require( './node.js' ); // eslint-disable-line stdlib/no-redeclare
 
 
 // MAIN //
 
 /**
 * First-in-first-out queue constructor.
 *
 * @constructor
 * @returns {FIFO} FIFO queue instance
 *
 * @example
 * var queue = new FIFO();
 *
 * // Add values to the queue:
 * queue.push( 'foo' ).push( 'bar' );
 *
 * // Remove the first value:
 * var v = queue.pop();
 * // returns 'foo'
 *
 * // Add a new value to the queue:
 * queue.push( 'beep' );
 *
 * // Remove the "oldest" queue value:
 * v = queue.pop();
 * // returns 'bar'
 */
 function FIFO() {
 	if ( !(this instanceof FIFO) ) {
 		return new FIFO();
 	}
 	this._length = 0;
 	this._first = null;
 	this._last = null;
 	return this;
 }
 
 /**
 * Clears the queue.
 *
 * @name clear
 * @memberof FIFO.prototype
 * @type {Function}
 * @returns {FIFO} queue instance
 *
 * @example
 * var queue = new FIFO();
 *
 * // Add values to the queue:
 * queue.push( 'foo' ).push( 'bar' );
 *
 * // Peek at the first value:
 * var v = queue.first();
 * // returns 'foo'
 *
 * // Examine the queue length:
 * var len = queue.length;
 * // returns 2
 *
 * // Clear all queue items:
 * queue.clear();
 *
 * // Peek at the first value:
 * v = queue.first();
 * // returns undefined
 *
 * // Examine the queue length:
 * len = queue.length;
 * // returns 0
 */
 setReadOnly( FIFO.prototype, 'clear', function clear() {
 	this._length = 0;
 	this._first = null;
 	this._last = null;
 	return this;
 });
 
 /**
 * Returns the "oldest" queue value (i.e., the value which is "first-out").
 *
 * @name first
 * @memberof FIFO.prototype
 * @type {Function}
 * @returns {(*|void)} "oldest" queue value
 *
 * @example
 * var queue = new FIFO();
 *
 * // Add values to the queue:
 * queue.push( 'foo' ).push( 'bar' );
 *
 * // Peek at the first value:
 * var v = queue.first();
 * // returns 'foo'
 */
 setReadOnly( FIFO.prototype, 'first', function first() {
 	if ( this._length ) {
 		return this._first.value;
 	}
 });
 
 /**
 * Returns an iterator for iterating over a queue.
 *
 * ## Notes
 *
 * -   In order to prevent confusion arising from queue mutation during iteration, a returned iterator **always** iterates over a queue "snapshot", which is defined as the list of queue elements at the time of this method's invocation.
 *
 * @name iterator
 * @memberof FIFO.prototype
 * @type {Function}
 * @returns {Iterator} iterator
 *
 * @example
 * var queue = new FIFO();
 *
 * // Add values to the queue:
 * queue.push( 'foo' ).push( 'bar' );
 *
 * // Create an iterator:
 * var it = queue.iterator();
 *
 * // Iterate over the queue...
 * var v = it.next().value;
 * // returns 'foo'
 *
 * v = it.next().value;
 * // returns 'bar'
 *
 * var bool = it.next().done;
 * // returns true
 */
 setReadOnly( FIFO.prototype, 'iterator', function iterator() {
 	var values;
 	var iter;
 	var self;
 	var FLG;
 	var i;
 
 	self = this;
 
 	// Initialize the iteration index:
 	i = -1;
 
 	// Create a copy of queue values (necessary in order to "snapshot" the queue; otherwise, values could come and go between calls to `next`):
 	values = this.toArray();
 
 	// Create an iterator protocol-compliant object:
 	iter = {};
 	setReadOnly( iter, 'next', next );
 	setReadOnly( iter, 'return', end );
 	if ( iteratorSymbol ) {
 		setReadOnly( iter, iteratorSymbol, factory );
 	}
 	return iter;
 
 	/**
 	* Returns an iterator protocol-compliant object containing the next iterated value.
 	*
 	* @private
 	* @returns {Object} iterator protocol-compliant object
 	*/
 	function next() {
 		i += 1;
 		if ( FLG || i >= values.length ) {
 			return {
 				'done': true
 			};
 		}
 		return {
 			'value': values[ i ],
 			'done': false
 		};
 	}
 
 	/**
 	* Finishes an iterator.
 	*
 	* @private
 	* @param {*} [value] - value to return
 	* @returns {Object} iterator protocol-compliant object
 	*/
 	function end( value ) {
 		FLG = true;
 		if ( arguments.length ) {
 			return {
 				'value': value,
 				'done': true
 			};
 		}
 		return {
 			'done': true
 		};
 	}
 
 	/**
 	* Returns a new iterator.
 	*
 	* @private
 	* @returns {Iterator} iterator
 	*/
 	function factory() {
 		return self.iterator();
 	}
 });
 
 /**
 * Returns the "newest" queue value (i.e., the value which is currently "last-out").
 *
 * @name last
 * @memberof FIFO.prototype
 * @type {Function}
 * @returns {(*|void)} "newest" queue value
 *
 * @example
 * var queue = new FIFO();
 *
 * // Add values to the queue:
 * queue.push( 'foo' ).push( 'bar' );
 *
 * // Peek at the last value:
 * var v = queue.last();
 * // returns 'bar'
 */
 setReadOnly( FIFO.prototype, 'last', function last() {
 	if ( this._length ) {
 		return this._last.value;
 	}
 });
 
 /**
 * Queue length.
 *
 * @name length
 * @memberof FIFO.prototype
 * @type {NonNegativeInteger}
 *
 * @example
 * var queue = new FIFO();
 *
 * // Examine the initial queue length:
 * var len = queue.length;
 * // returns 0
 *
 * // Add values to the queue:
 * queue.push( 'foo' ).push( 'bar' );
 *
 * // Retrieve the current queue length:
 * len = queue.length;
 * // returns 2
 */
 setReadOnlyAccessor( FIFO.prototype, 'length', function get() {
 	return this._length;
 });
 
 /**
 * Removes a value from the queue.
 *
 * @name pop
 * @memberof FIFO.prototype
 * @type {Function}
 * @returns {(*|void)} removed value
 *
 * @example
 * var queue = new FIFO();
 *
 * // Add values to the queue:
 * queue.push( 'foo' ).push( 'bar' );
 *
 * // Remove the first value:
 * var v = queue.pop();
 * // returns 'foo'
 *
 * // Add a new value to the queue:
 * queue.push( 'beep' );
 *
 * // Remove the "oldest" queue value:
 * v = queue.pop();
 * // returns 'bar'
 */
 setReadOnly( FIFO.prototype, 'pop', function pop() {
 	var value;
 	if ( this._length ) {
 		// Retrieve the "first-out" value:
 		value = this._first.value;
 
 		// Check whether we have a new "first-out" or whether we have drained the queue...
 		if ( this._first.next ) {
 			this._first = this._first.next;
 			this._first.prev = null;
 		} else {
 			// Queue is empty:
 			this._first = null;
 			this._last = null;
 		}
 		// Decrement the queue length:
 		this._length -= 1;
 	}
 	return value;
 });
 
 /**
 * Adds a value to the queue.
 *
 * @name push
 * @memberof FIFO.prototype
 * @type {Function}
 * @returns {FIFO} queue instance
 *
 * @example
 * var queue = new FIFO();
 *
 * // Add values to the queue:
 * queue.push( 'foo' ).push( 'bar' );
 *
 * // Remove the first value:
 * var v = queue.pop();
 * // returns 'foo'
 *
 * // Add a new value to the queue:
 * queue.push( 'beep' );
 *
 * // Remove the "oldest" queue value:
 * v = queue.pop();
 * // returns 'bar'
 */
 setReadOnly( FIFO.prototype, 'push', function push( value ) {
 	var node;
 
 	// Create a new queue node:
 	node = new Node( value );
 
 	// Check whether the queue is currently empty...
 	if ( this._length === 0 ) {
 		// This is the only queued node, making it both the first and last node:
 		this._first = node;
 		this._last = node;
 	} else {
 		// Link the node to the previous most "recent" node:
 		node.prev = this._last;
 
 		// Link the previous most "recent" node to the new node:
 		this._last.next = node;
 
 		// Update the queue pointer for the "last" node to the new node:
 		this._last = node;
 	}
 	// Increment the queue length:
 	this._length += 1;
 
 	return this;
 });
 
 /**
 * Returns an array of queue values.
 *
 * @name toArray
 * @memberof FIFO.prototype
 * @type {Function}
 * @returns {Array} queue values
 *
 * @example
 * var queue = new FIFO();
 *
 * // Add values to the queue:
 * queue.push( 'foo' ).push( 'bar' );
 *
 * // Get an array of queue values:
 * var vals = queue.toArray();
 * // returns [ 'foo', 'bar' ]
 */
 setReadOnly( FIFO.prototype, 'toArray', function toArray() {
 	var node;
 	var out;
 	var i;
 
 	out = [];
 	node = this._first;
 	for ( i = 0; i < this._length; i++ ) {
 		out.push( node.value );
 		node = node.next;
 	}
 	return out;
 });
 
 /**
 * Serializes a queue as JSON.
 *
 * ## Notes
 *
 * -   `JSON.stringify()` implicitly calls this method when stringifying a `FIFO` instance.
 *
 * @name toJSON
 * @memberof FIFO.prototype
 * @type {Function}
 * @returns {Object} serialized queue
 *
 * @example
 * var queue = new FIFO();
 *
 * // Add values to the queue:
 * queue.push( 'foo' ).push( 'bar' );
 *
 * // Serialize to JSON:
 * var o = queue.toJSON();
 * // returns { 'type': 'fifo', 'data': [ 'foo', 'bar' ] }
 */
 setReadOnly( FIFO.prototype, 'toJSON', function toJSON() {
 	var out = {};
 	out.type = 'fifo';
 	out.data = this.toArray();
 	return out;
 });
 
 
 // EXPORTS //
 
 module.exports = FIFO;