【设计模式】第17节：行为型模式之“解释器模式”

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 mainimport ("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 intExpression  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()}
}