Design Pattern : Interpreter

Design Pattern : Interpreter

Definition :

「Given a language, define a representation for its grammar along with an interpreter that uses the representation to interpret sentences in the language」

Original Context：原始翻譯前的內容

Interpreted Context：翻譯後的內容

IExpression：定義Interpret翻譯方法
ExpressionA & B ：實作Interpret翻譯方法

底下是將原本一長串的字串資料翻譯成Customer物件…

1.  IExpression

public interface IExpression
{
  Customer Interpret();
}

2.  Customer

public class Customer:IDisposable
{
    public String Name { get; set; }
    public int Age { get; set; }
    public String PhoneNumber { get; set; }
    public String Address { get; set; }
}

3.  ExpressionA

public class ExpressionA:IExpression
{
    private String content = String.Empty;
    public ExpressionA(String info)
    {
       this.content = info;
    }
    public Customer Interpret()
    {
       using(Customer customer = new Customer())
       {
          customer.Name = this.content.Substring(0, 5).Trim();
          customer.Age = int.Parse(this.content.Substring(5, 3).Trim());
          customer.PhoneNumber = this.content.Substring(8, 15).Trim();
          customer.Address = this.content.Substring(22, 50).Trim();
          return customer;
       }
    }
}

4.  主程式：
String name = "JB";
int age = 32;
String phoneNum = "0933-XXX-XXX";
String addr = "Taipei City, Neihui Street";

String info = String.Format("{0,-5}{1,3}{2,-15}{3,-50}", name, age.ToString(),phoneNum,addr);

Console.WriteLine("收到的原始資料：{0}", info);

IExpression exp = new ExpressionA(info);
Customer jb = exp.Interpret();

Console.WriteLine("姓名：{0}", jb.Name);
Console.WriteLine("年齡：{0}", jb.Age);
Console.WriteLine("電話號碼：{0}", jb.PhoneNumber);
Console.WriteLine("住址：{0}", jb.Address);

結果：
收到的原始資料：JB    320933-XXX-XXX   Taipei City, Neihui Street

姓名：JB
年齡：32
電話號碼：0933-XXX-XXX
住址：Taipei City, Neihui Street

=>可以看到原本收到的是一串的資料，經過Interpreter之後，翻譯成一個可用的物件了。

5.  Reference：
無