迭代器模式(behavioral 4)

3.4 迭代器模式(iterator)

• 提供一种方法顺序访问一个聚合对象中各个元素, 而又无须暴露该对象的内部表示。

function Iterator(el) {
	this.index = 0
	this.elements = el
}

Iterator.prototype = {
	next: function () {
		return this.elements[this.index++]
	},
	hasNext: function () {
		return this.index < this.elements.length
	}
}

module.exports = Iterator

const expect = require('chai').expect
const Iterator = require('../src/behavioral/interpreter/interpreter')

describe('迭代器模式 测试', () => {
	it('遍历', () => {
		test(Iterator)
	})
})

function test(Iterator) {
	var numbers = new Iterator([1, 2, 3])
	expect(numbers.next()).to.equal(1)
	expect(numbers.next()).to.equal(2)
	expect(numbers.next()).to.equal(3)
	expect(numbers.hasNext()).to.false
}

es6 实现

class Iterator {
	constructor(el) {
		this.index = 0
		this.elements = el
	}
	next() {
		return this.elements[this.index++]
	}

	hasNext() {
		return this.index < this.elements.length
	}
}

export { Iterator }

const expect = require('chai').expect
import { Iterator } from '../src/behavioral/interpreter/interpreter_es6'

describe('迭代器模式 es6测试', () => {
	it('遍历', () => {
		test(Iterator)
	})
})

function test(Iterator) {
	var numbers = new Iterator([1, 2, 3])
	expect(numbers.next()).to.equal(1)
	expect(numbers.next()).to.equal(2)
	expect(numbers.next()).to.equal(3)
	expect(numbers.hasNext()).to.false
}