解释器模式(behavioral 3)

3.3 解释器模式(interpreter)

• 给定一个语言，定义它的文法表示，并定义一个解释器，这个解释器使用该标识来解释语言中的句子。

function Sum(left, right) {
	this.left = left
	this.right = right
}
Sum.prototype.interpret = function () {
	return this.left.interpret() + this.right.interpret()
}

function Min(left, right) {
	this.left = left
	this.right = right
}

Min.prototype.interpret = function () {
	return this.left.interpret() - this.right.interpret()
}

function Num(val) {
	this.val = val
}
Num.prototype.interpret = function () {
	return this.val
}

module.exports = [Num, Min, Sum]

const expect = require('chai').expect
const [Num, Min, Sum] = require('../src/behavioral/interpreter/interpreter')

describe('解释器模式 测试', () => {
	it('加', () => {
		var result = new Sum(new Num(100), new Min(new Num(100), new Num(50)))

		expect(result.interpret()).to.equal(150)
	})
})

es6 实现

class Sum {
	constructor(left, right) {
		this.left = left
		this.right = right
	}
	interpret() {
		return this.left.interpret() + this.right.interpret()
	}
}
class Min {
	constructor(left, right) {
		this.left = left
		this.right = right
	}
	interpret() {
		return this.left.interpret() - this.right.interpret()
	}
}
class Num {
	constructor(val) {
		this.val = val
	}
	interpret() {
		return this.val
	}
}

export { Num, Min, Sum }

const expect = require('chai').expect
import { Num, Min, Sum } from '../src/behavioral/interpreter/interpreter_es6'

describe('解释器模式 es6测试', () => {
	it('加', () => {
		var result = new Sum(new Num(100), new Min(new Num(100), new Num(50)))

		expect(result.interpret()).to.equal(150)
	})
})