设计模式笔记(16)—解释器模式（行为型）

/// <summary>
/// 上下文信息
/// </summary>
public class Context
{
    public string Data { get; set; }
}
/// <summary>
/// 抽象表达式，声明一个抽象的解释操作
/// </summary>
public abstract class AbstractExpression
{
    public abstract void Interpret(Context context);
}
public class TerminalExpression:AbstractExpression
{
    public override void Interpret(Context context)
    {
        context.Data += "终端,";
    }
}
public class NonterminalExpression : AbstractExpression
{
    public override void Interpret(Context context)
    {
        context.Data += "非终端,";
    }
}
public class App
{
    static void Main(string[] args)
    {
        Context context = new Context();
        List<AbstractExpression> list = new List<AbstractExpression>();
        list.Add(new TerminalExpression());
        list.Add(new NonterminalExpression());
        list.Add(new TerminalExpression());

        foreach (AbstractExpression exp in list)
        {
            exp.Interpret(context);
        }
        Console.WriteLine(context.Data);
    }
}

public class Context
{
    public string Statement { get; set; }
    public int Data { get; set; }
}

/// <summary>
/// 抽象表达式类
/// </summary>
public abstract class Expression
{
    protected Dictionary<string, int> table = new Dictionary<string, int>(9);
    public Expression()
    {
        table.Add("一", 1);
        table.Add("二", 2);
        table.Add("三", 3);
        table.Add("四", 4);
        table.Add("五", 5);
        table.Add("六", 6);
        table.Add("七", 7);
        table.Add("八", 8);
        table.Add("九", 9);
    }
    public virtual void Interpret(Context context)
    {
        if (context.Statement.Length == 0)
        {
            return;
        }

        foreach (string key in table.Keys)
        {
            int value = table[key];
            if (context.Statement.EndsWith(key + GetPostFix()))
            {
                context.Data += value * this.Multiplier();
                context.Statement = 

                          context.Statement.Substring

                          (0, context.Statement.Length - this.GetLength());
            }
            if (context.Statement.EndsWith("零"))
            {
                context.Statement = 

                   context.Statement.Substring(0, context.Statement.Length-1);
            }
        }
    }
    public abstract string GetPostFix();
    public abstract int Multiplier();
    public virtual int GetLength()
    {
        return this.GetPostFix().Length + 1;
    }
}

public class GeExpression : Expression
{
    public override string GetPostFix()
    {
        return string.Empty;
    }
    public override int Multiplier()
    {
        return 1;
    }
    public override int GetLength()
    {
        return 1;
    }
}
public class ShiExpression : Expression
{
    public override string GetPostFix()
    {
        return "十";
    }
    public override int Multiplier()
    {
        return 10;
    }
}
public class BaiExpression : Expression
{
    public override string GetPostFix()
    {
        return "百";
    }
    public override int Multiplier()
    {
        return 100;
    }
}
public class QianExpression : Expression
{
    public override string GetPostFix()
    {
        return "千";
    }
    public override int Multiplier()
    {
        return 1000;
    }
}
public class WanExpression : Expression
{
    public override string GetPostFix()
    {
        return "万";
    }
    public override int Multiplier()
    {
        return 10000;
    }
}

class Program
{
    static void Main(string[] args)
    {
        string num = "五百二十";
        Context context = new Context { Statement=num};
        List<Expression> list = new List<Expression>();
        list.Add(new GeExpression());
        list.Add(new ShiExpression());
        list.Add(new BaiExpression());
        list.Add(new QianExpression());
        list.Add(new WanExpression());

        foreach (Expression exp in list)
        {
            exp.Interpret(context);
        }

        Console.WriteLine("{0}={1}", num, context.Data);
    }
}