一、简介

解释器模式为某个语言定义它的语法（或者叫文法）表示，并定义一个解释器用来处理这个语法。

二、适用场景

• 领域特定语言
• 复杂输入解释
• 可扩展的语言结构

三、UML类图

四、案例

对输入的特定格式的打印语句进行解析并执行。

package main

import (
	"fmt"
	"strconv"
	"strings"
)

type Expression interface {
	Interpret()
}

type PrintExpression struct {
	Message string
}

func NewPrintExpression(msg string) *PrintExpression {
	return &PrintExpression{Message: msg}
}

func (pe *PrintExpression) Interpret() {
	fmt.Printf("message: %v\n", pe.Message)
}

type RepeatExpression struct {
	RepeatCount int
	Expression  Expression
}

func NewRepeatExpression(repeatCount int, expression Expression) RepeatExpression {
	return RepeatExpression{RepeatCount: repeatCount, Expression: expression}
}

func (re *RepeatExpression) Interpret() {
	for i := 0; i < re.RepeatCount; i++ {
		re.Expression.Interpret()
	}
}

func main() {
	command := "REPEAT 3 TIMES: PRINT Hello"
	words := strings.Split(command, " ")
	fmt.Printf("words: %v\n", words)
	if words[0] == "REPEAT" {
		repeatCount, _ := strconv.Atoi(words[1])
		printExpression := NewPrintExpression(words[4])
		repeatExpression := NewRepeatExpression(repeatCount, printExpression)
		repeatExpression.Interpret()
	}
}