「JAVA言語で学ぶデザインパターン入門」をC#で書いてみた【Chain of Responsibilityパターン】

「増補改訂版Java言語で学ぶデザインパターン入門」の「Chain of Responsibilityパターン」をC#で書いてみました。

GitHubにもコードを置いています。

参考 DesignPattern【Chain of Responsibility】GitHub

コード


public class Trouble
{
    private int number;
    public Trouble(int number)
    {
        this.number = number;
    }

    public int GetNumber()
    {
        return number;
    }

    public override string ToString()
    {
        return $"[Trouble {number}]";
    }
}

public abstract class Support
{
    private string name;
    private Support next;
    public Support(string name)
    {
        this.name = name;
    }

    public Support SetNext(Support next)
    {
        this.next = next;
        return next;
    }

    public void DoSupport(Trouble trouble)
    {
        if (Resolve(trouble))
        {
            Done(trouble);
        }
        else if (next != null)
        {
            next.DoSupport(trouble);
        }
        else
        {
            Fail(trouble);
        }
    }

    public override string ToString()
    {
        return $"[{name}]";
    }

    protected abstract bool Resolve(Trouble trouble);

    protected void Done(Trouble trouble)
    {
        Console.WriteLine($"{trouble} is resolved by {this}");
    }

    protected void Fail(Trouble trouble)
    {
        Console.WriteLine($"{trouble} cannot be resolved.");
    }
}

public class NoSupport : Support
{
    public NoSupport(string name) : base(name)
    {
    }

    protected override bool Resolve(Trouble trouble)
    {
        return false;
    }
}

public class LimitSupport : Support
{
    private int limit;
    public LimitSupport(string name, int limit) : base(name)
    {
        this.limit = limit;
    }

    protected override bool Resolve(Trouble trouble)
    {
        if(trouble.GetNumber() < limit)
        {
            return true;
        }
        else
        {
            return false;
        }
    }
}

public class OddSupport : Support
{
    public OddSupport(string name) : base(name)
    {
    }

    protected override bool Resolve(Trouble trouble)
    {
        if(trouble.GetNumber() % 2 == 1)
        {
            return true;
        }
        else
        {
            return false;
        }
    }
}

public class SpecialSupport : Support
{
    private int number;
    public SpecialSupport(string name, int number) : base(name)
    {
        this.number = number;
    }

    protected override bool Resolve(Trouble trouble)
    {
        if (trouble.GetNumber() == number)
        {
            return true;
        }
        else
        {
            return false;
        }
    }
}

class Program
{
    static void Main(string[] args)
    {
        Support alice = new NoSupport("Alice");
        Support bob = new LimitSupport("Bob", 100);
        Support charile = new SpecialSupport("Charile", 429);
        Support diana = new LimitSupport("Diana", 200);
        Support elmo = new OddSupport("Elmo");
        Support fred = new LimitSupport("Fred", 300);

        alice.SetNext(bob).SetNext(charile).SetNext(diana).SetNext(elmo).SetNext(fred);
        for(var i = 0; i < 500; i += 33)
        {
            alice.DoSupport(new Trouble(i));
        }
    }
}

実行結果は以下のようになります。

[Trouble 0] is resolved by [Bob]
[Trouble 33] is resolved by [Bob]
[Trouble 66] is resolved by [Bob]
[Trouble 99] is resolved by [Bob]
[Trouble 132] is resolved by [Diana]
[Trouble 165] is resolved by [Diana]
[Trouble 198] is resolved by [Diana]
[Trouble 231] is resolved by [Elmo]
[Trouble 264] is resolved by [Fred]
[Trouble 297] is resolved by [Elmo]
[Trouble 330] cannot be resolved.
[Trouble 363] is resolved by [Elmo]
[Trouble 396] cannot be resolved.
[Trouble 429] is resolved by [Charile]
[Trouble 462] cannot be resolved.
[Trouble 495] is resolved by [Elmo]

その他のデザインパターンは以下の記事から確認してください。

「JAVA言語で学ぶデザインパターン入門」をC#で書いてみた【一覧】

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