组合模式(structural 3)

2.6 组合模式(composite)

• 将对象组合成树形结构以表示‘部分-整体’的层次结构。组合模式使得用户对单个对象和组合对象的使用具有一致性。
• 例如 办了一张永辉超市充值卡 它可以在任何门店进行消费 组合抽象类-leaf-composite

//组合抽象类
function EquipmentComposition(name) {
	this.equipments = []
	this.name = name
}

EquipmentComposition.prototype.add = function (equipment) {
	this.equipments.push(equipment)
}

EquipmentComposition.prototype.getPrice = function () {
	return this.equipments
		.map(function (equipment) {
			return equipment.getPrice()
		})
		.reduce(function (a, b) {
			return a + b
		})
}

// 设备
function Equipment() {}
Equipment.prototype.getPrice = function () {
	return this.price
}

// --leaf
//软盘
function FloppyDisk() {
	this.name = 'Floppy Disk'
	this.price = 70
}
FloppyDisk.prototype = Object.create(Equipment.prototype)

//硬盘
function HardDrive() {
	this.name = 'Hard Drive'
	this.price = 250
}
HardDrive.prototype = Object.create(Equipment.prototype)
//内存
function Memory() {
	this.name = '8gb memory'
	this.price = 280
}
Memory.prototype = Object.create(Equipment.prototype)

module.exports = [EquipmentComposition, FloppyDisk, HardDrive, Memory]

const expect = require('chai').expect
const [EquipmentComposition, FloppyDisk, HardDrive, Memory] = require('../src/structural/composite/composite.js')

describe('组合模式 测试', () => {
	it('机箱添加硬件 获取总价', () => {
		var cabinet = new EquipmentComposition('cabinet')
		cabinet.add(new FloppyDisk())
		cabinet.add(new HardDrive())
		cabinet.add(new Memory())

		expect(cabinet.getPrice()).to.equal(600)
	})
})

es6 实现

//组合抽象类
class Equipment {
	getPrice() {
		return this.price || 0
	}
	getName() {
		return this.name
	}
	setName(name) {
		this.name = name
	}
}

// composite
class Composite extends Equipment {
	constructor() {
		super()
		this.equipments = []
	}
	add(equipment) {
		this.equipments.push(equipment)
	}
	getPrice() {
		return this.equipments
			.map(equipment => {
				return equipment.getPrice()
			})
			.reduce((a, b) => {
				return a + b
			})
	}
}

class Cabinet extends Composite {
	constructor() {
		super()
		this.setName('cabinet')
	}
}

// --leaf
class FloppyDisk extends Equipment {
	constructor() {
		super()
		this.setName('Floppy Disk')
		this.price = 70
	}
}

class HardDrive extends Equipment {
	constructor() {
		super()
		this.setName('Hard Drive')
		this.price = 250
	}
}

class Memory extends Equipment {
	constructor() {
		super()
		this.setName('Memory')
		this.price = 280
	}
}
export { Cabinet, FloppyDisk, HardDrive, Memory }

const expect = require('chai').expect
import { Cabinet, FloppyDisk, HardDrive, Memory } from '../src/structural/composite/composite_es6'

describe('组合模式 es6测试', () => {
	it('设备添加硬件 获取总价', () => {
		var cabinet = new Cabinet('cabinet')
		cabinet.add(new FloppyDisk())
		cabinet.add(new HardDrive())
		cabinet.add(new Memory())

		expect(cabinet.getPrice()).to.equal(600)
	})
})